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Review of Additive Manufacturing and Characterization of Additive Manufacturing Machine

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3D printing, more professionally called additive manufacturing (AM) is a manufacturing technology (process) revolutionizing the world manufacturing industry. AM is a standard term adopted by the ASTM International Committee to include comprehensively methods that build 3D objects layer-by-layer using computer driven technology. It is completely different approach than traditional methods of subtracting materials from a larger work piece (for example, cutting or grinding) or conventional forming methods (for example, casting, pressing, injecting molding). Initially, 3D printing technology was developed as rapid prototyping, which enables users to create physical prototypes early in the design cycle so that flaws can be detected and corrected before they become costly. Furthermore, functional performances are optimized thereby making a product go to the market early through an iterative process of prototyping, testing, and analysis. Manufacturers started using this technology for production of finished goods due to advancement in the technology and discovery of new materials. Often, terms such as direct digital manufacturing, rapid manufacturing and solid freeform fabrication are of used to describe AM processes due to its additive technique. 3D computer data or stereolithography (STL) files drive all the processes, which contain information on the geometry of the object. This file (STL) can be obtained from 3D CAD software, medical scan data (for example, CT, MRI), or from existing objects using a point or laser scanners. The STL file breaks down the geometrical representation of the object into a simple mesh, which is manipulated into a suitable build orientation before it is converted into discrete 2D layers used by the machine. 3D printers use different types of additive manufacturing technologies, but they all share one core approach in common—they create a three dimensional object by building it successively layer by layer, until the entire object is completed. This technology continues to grow and capture the attention of many. Increasingly, companies from aerospace, motor sports, medical, dental, and consumer product industries are using additive processes to manufacture high-value parts in comparatively low volumes. Medicine will forever be changed as new bio printer actually print human tissues for bone and organ transplant. Aerospace is changing as well; most of the engineers prefer producing airplane parts with 3D printing due to the lightweight of the fabricated parts. Auto industry is not left out as well, major auto industries like Ford, Toyota, and general motors have improved the way they manufacture their parts with this technology. The objective of this paper is to have a comprehensive review of three-dimensional and micro three-dimensional printing technologies, competitors, and their available products. This paper also encompasses a characterization of MakerBot replicator desktop 3D printer (5th generation). The paper is organized as follows: Section 2 discusses different technologies in three-dimensional printing; Section 3 discusses the major competitors in 3D printing technology; Section 4 reviews different areas of applications; Section 5 discusses 3D micro printing technologies, and Section 6 discusses the major competitors in 3D micro printing technologies. Section 7 discusses the Characterization of MakerBot replicator, and Section 8 is the conclusion.
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REVIEW OF ADDITIVE MANUFACTURING TECHNOLOGIES AND
CHARACTERIZATION OF ADDITIVE MANUFACTURING MACHINES
By
SOLOMON EZEIRUAKU
FINAL PROJECT
Submitted in Partial Fulfillment of the
Requirements for the Degree of
Master of Engineering
Manufacturing Engineering
The University of New Mexico
Albuquerque, New Mexico
May 2015
EXECUTIVE SUMMARY
Today, three-dimensional printing is expanding with the introduction of new technologies,
materials, and methods. It is transforming manufacturing from the age of mass production to the
age of mass customization. The growth has accelerated over the last four years as many
organizations integrate this technology in manufacturing of their products and services. As a
result, the compound annual growth rate (CAGR) of this technology for the past three years
(20112013) was 32.3% [1]. Manufacturers are utilizing the technology to increase the
efficiency and flexibility of their production. Among the importance of this technology in the
manufacturing industry are products early to market by reducing product development time, light
weighting, and reduction of tooling and inventory. Whereas the major challenges of the
technology are cost of machines and materials, speed and throughput, and production quality
control, especially in the aerospace and medical industries. Though this technology was initially
developed for application in manufacturing, it has found use in the entire sector, including
architecture, medicine, electronics, and fashion. Currently, 3D printing of thin feature sizes have
made possible by the advent of the micro three-dimensional printing. However, the efficiency of
the technology depends on the right choice of both technology and 3D printer. As of April 2014,
there are over thirty system manufacturers of different 3D printers all over the worldthe U.S,
China, and Europe [1]. Each printer utilizes different technology in replicating parts. In order to
achieve the desired result with these systems, it is very relevant to determine the right technology
suitable for a particular application. Equally important is understanding of how the technology
and the printer workits strengths and weaknesses. The characterization of MakerBot replicator
desktop 3D printer is a good illustration of a study to determine the capability of a 3D printer.
Although the resolution of this printer is 100 microns, the minimum feature size of the printer is
about 800 microns (0.8mm). The machine (MakerBot replicator) is very good at fabricating large
objects with certain complexities. Nevertheless, it is not capable of replicating objects below 800
microns. Furthermore, surface finish is another shortcoming of this device. Due to extrusion of
semi-molten plastics, post processing is required to give the printed parts a good surface finish.
With these limitations, the machine was not capable to fabricate an IPMC holder, which contains
four holes for voltage connection. The size of the holder is 400 x 300 x 50 µm, while the size of
the holes is 80 µm each. However, an alternative three-dimensional printer has been chosen for
this project (IPMC holder). 3D Systems’ ProJet 1200 3D printer is an efficient and less
expensive machine to execute the project. ProJet 1200 is an ideal 3D printer for small, precise,
and detailed printing utilizing micro-stereolithography technology to replicate parts. With its 30
microns layer thickness, this device will comfortably replicate the IPMC holder.
Table of ContentsEXECUTIVE SUMMARY ....................................................................................... 2
1.0 INTRODUCTION ............................................................................................................................ 1
2.0 3D PRINTING TECHNOLOGIES ................................................................................................... 2
2.1 Stereolithography (SLA) ............................................................................................................ 2
2.2 Fused Deposition Modelling (FDM) .......................................................................................... 3
2.3 Selective Laser Sintering (SLS) ................................................................................................. 3
.................................................................................................................................................................. 4
2.4 Three Dimensional printing (3DP) ............................................................................................ 4
2.5 Laminated Object Manufacturing (LOM) ............................................................................... 4
3.0 MAJOR COMPETITORS IN 3D PRINTING TECHNOLOGY ............................................... 5
3.1 Formlabs ...................................................................................................................................... 5
3.2 3D Systems ................................................................................................................................... 6
3.2.1 Personal printers for 3D Systems: ......................................................................................... 6
3.2.2 Professional printers for 3D Systems: ................................................................................... 6
3.2.3 Production printers for 3D Systems: ..................................................................................... 7
3.3 Stratasys ....................................................................................................................................... 7
3.3.1 MakerBot desktop series for Stratasys: ................................................................................. 8
3.3.2 Ideal series for Stratasys: ...................................................................................................... 8
3.3.3 Design series for Stratasys: ................................................................................................... 8
3.3.4 Production series for Stratasys: ............................................................................................. 8
3.3.5 Dental series includes: .......................................................................................................... 8
3.4 B9Creator .................................................................................................................................... 8
3.5 Cubic Technologies ..................................................................................................................... 9
3.6 Optomec ....................................................................................................................................... 9
3.7 Ultimaker ..................................................................................................................................... 9
3.8 Fab@Home Project ..................................................................................................................... 9
4.0 APPLICATIONS AND RESEARCH STATUS OF 3D PRINTING TECHNOLOGY .......... 10
4.1 3D printing technologies in electronics ................................................................................... 10
4.2 3D printing technologies in medicine ...................................................................................... 13
4.3 3D printing technologies in aerospace and automobile ......................................................... 15
4.4 Unmanned Aerial Vehicles (UAV) manufacturing ..................................................................... 16
4.5 Architectural modelling ........................................................................................................... 16
4.6 Mass customization ................................................................................................................... 17
4.7 Fashion ....................................................................................................................................... 17
5.0 3D MICRO PRINTING TECHNOLOGIES .............................................................................. 17
5.1 Microstereolithograghy ............................................................................................................ 18
5.2 Laser Micro Sintering ............................................................................................................... 19
5.3 Micro three-dimensional printing (M3DP) ............................................................................. 20
5.4 Electrochemical fabrication (EFAB) process ......................................................................... 20
5.5 Laser chemical vapor deposition (LCVD) .............................................................................. 22
5.6 Focused Ion Beam (FIB) Direct Write .................................................................................... 22
6.0 MAJOR COMPETITORS IN 3D MICRO PRINTING TECHNOLOGY .............................. 24
6.1 M3D LLC ................................................................................................................................... 24
6.2 Nanoscribe ................................................................................................................................. 24
6.3 Microfabrica .............................................................................................................................. 25
6.4 MicroFab technologies Inc. ...................................................................................................... 25
6.5 EnvisionTEC ............................................................................................................................. 26
6.6 Potomac ...................................................................................................................................... 27
7.0 CHARACTERIZATION OF MAKERBOT REPLICATOR DESKTOP 3D PRINTER (5th
GENERATION) ........................................................................................................................................ 27
7.1 Fabrication of IPMC holder ..................................................................................................... 28
7.2 Methodology .............................................................................................................................. 30
7.3 Results and discussions ............................................................................................................. 34
7.3.1 Minimum feature size and print capacity ............................................................................ 38
7.3.2 Feature detail resolution and dimensional accuracy ........................................................... 39
7.3.3 Surface finishes (surface roughness) ................................................................................... 40
7.4 Recommendation ....................................................................................................................... 41
8.0 CONCLUSION ............................................................................................................................. 43
References ................................................................................................................................................... 45
1
1.0 INTRODUCTION
3D printing, more professionally called additive manufacturing (AM) is a manufacturing
technology (process) revolutionizing the world manufacturing industry. AM is a standard term
adopted by the ASTM International Committee to include comprehensively methods that build
3D objects layer-by-layer using computer driven technology [2]. It is completely different
approach than traditional methods of subtracting materials from a larger work piece (for
example, cutting or grinding) or conventional forming methods (for example, casting, pressing,
injecting molding). Initially, 3D printing technology was developed as rapid prototyping, which
enables users to create physical prototypes early in the design cycle so that flaws can be detected
and corrected before they become costly. Furthermore, functional performances are optimized
thereby making a product go to the market early through an iterative process of prototyping,
testing, and analysis. Manufacturers started using this technology for production of finished
goods due to advancement in the technology and discovery of new materials. Often, terms such
as direct digital manufacturing, rapid manufacturing and solid freeform fabrication are of used to
describe AM processes due to its additive technique. 3D computer data or stereolithography
(STL) files drive all the processes, which contain information on the geometry of the object. This
file (STL) can be obtained from 3D CAD software, medical scan data (for example, CT, MRI),
or from existing objects using a point or laser scanners [3][4]. The STL file breaks down the
geometrical representation of the object into a simple mesh, which is manipulated into a suitable
build orientation before it is converted into discrete 2D layers used by the machine. 3D printers
use different types of additive manufacturing technologies, but they all share one core approach
in commonthey create a three dimensional object by building it successively layer by layer,
until the entire object is completed.
This technology continues to grow and capture the attention of many. Increasingly, companies
from aerospace, motor sports, medical, dental, and consumer product industries are using
additive processes to manufacture high-value parts in comparatively low volumes. Medicine will
forever be changed as new bio printer actually print human tissues for bone and organ transplant.
Aerospace is changing as well; most of the engineers prefer producing airplane parts with 3D
printing due to the lightweight of the fabricated parts. Auto industry is not left out as well, major
auto industries like Ford, Toyota, and general motors have improved the way they manufacture
their parts with this technology.
The objective of this paper is to have a comprehensive review of three-dimensional and micro
three-dimensional printing technologies, competitors, and their available products. This paper
also encompasses a characterization of MakerBot replicator desktop 3D printer (5th generation).
The paper is organized as follows: Section 2 discusses different technologies in three-
dimensional printing; Section 3 discusses the major competitors in 3D printing technology;
Section 4 reviews different areas of applications; Section 5 discusses 3D micro printing
technologies, and Section 6 discusses the major competitors in 3D micro printing technologies.
Section 7 discusses the Characterization of MakerBot replicator, and Section 8 is the conclusion.
2
2.0 3D PRINTING TECHNOLOGIES
The three-dimensional printing industry though populated by a broad family of technologies,
almost every existing 3D printing machine functions in a similar way. A 3D CAD file is sliced
into a series of 2D planar sections and the printer deposits these slices layer by layer to fabricate
the part. The first commercialized technique was stereolithography, which uses a laser beam to
build the required structure [5]. Other technologies are Three Dimensional Printing (3DP) own
by MIT, Fused Deposition Modelling (FDM), Selective laser sintering, and Electron beam
Melting.
2.1 Stereolithography (SLA)
Chuck Hull developed Stereolithography being the first 3D printing technology in 1984, when he
was using ultraviolet light to cure tabletop coatings. He later established 3D Systems Company
to sell the first machine for rapid prototyping, which he later called stereolithography (SLA) [6].
The technology is a liquid based process, which involves solidification or curing of a
photopolymer when an ultraviolet laser makes a contact with a resin. A low power highly
focused UV laser traces out the first layer, solidifying the model’s cross section while leaving
excess liquid areas. Next, an elevator incrementally lowers the platform into the liquid polymer.
A sweeper re-coats the solidified layer with liquid, and the laser traces the second layer atop the
first. This process is repeated until the prototype is completed. Excess liquid is drained at the end
of the process and can be reused. This process starts with a CAD model translated to an STL file
and it is cut into slices, which contains the information for each layer [7]. Accordingly, photo
polymerization is the basic principle of this process, where a liquid monomer or a polymer
converts into a solidified polymer by applying ultraviolet light that acts as a catalyst for the
reaction. The stereolithography mechanism is shown in Figure. 1 [8].
Figure 1. Stereolithography mechanism. From [8]
3
2.2 Fused Deposition Modelling (FDM)
Fused Deposition Modeling is a trademarked term by Stratasys [9]. This technology, which is
one of the most accessible and widespread 3D printing technology, is based on material
extrusion in which a semi-liquid material is deposited by a computer-controlled print head [10].
Fused Deposition Modeling was invented by Scott Crump in 1988 who subsequently established
Stratasys to commercialize the technology [11]. In this process, a thin filament of plastic feeds a
machine where a print head melts it and extrudes it in a small thickness. Material filaments are
fed from the printer’s material bay to the extruder or print head, which moves in X and Y-axis,
depositing material to complete each layer before the base moves down the Z-axis and the next
layer begins. At the end of the print, the support materials are removed and the component is
ready to use. The materials used in this process are acrylonitrile butadiene styrene (ABS),
Polylactic acid (PLA), and polyvinyl alcohol. Advantages of this process are that no resins need
to be cured unlike stereolithography, no post-processing of the printed part required, and the
machine is less expensive. However, a finishing process is required when smooth surfaces are
needed due to supporting materials or seam lines between the layers. Also, it is a slow process,
sometimes taking days to build large complex parts [12].
2.3 Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) was developed and commercialized by DTM, which was
acquired later by 3D Systems in mid-2001 [13]. In this process, a powder is sintered by the
application of a carbon dioxide laser beam in a chamber that is slightly below the melting point
of the material in a three-dimensional printing process. A laser traces the pattern of the first
layer, sintering it together. The platform is lowered by the height of the next layer and powder is
reapplied [8]. This process continues until the part is completed. The technique is similar to
Stereolithography (SLA) in that the laser traces the cross-sectional shape before the platform
descends. Unlike SLA, powder material supports the model in this process, which makes it not
necessary for supporting structure. Materials use in this process includes metals, plastics,
combinations of metals and polymers, combinations of metals, and combinations of metals and
ceramics [14]. Figure 2 shows the SLS mechanism [13].
4
2.4 Three Dimensional Printing (3DP)
Three Dimensional Printing (3DP) is an MIT licensed 3D printing technology whereby a water-
base liquid binder is supplied in a jet onto a starch-based powder to print a part from a CAD file
[7]. Each layer begins with a thin distribution of powder spread over the surface of a powder bed.
With a technology similar to Inkjet printing, a binder material selectively joins particles where
the object is to be formed. A piston that supports the powder bed and the part in progress lowers
so that the next powder layer can be spread and selectively joined. This process continues layer
by layer until the part is completely built [8]. At the end of the fabrication, the unbound powders
are removed and the part may be processed by subjecting it to a high temperature for further
strengthening and bonding. Materials used in this process are metals, ceramics, and
metal/ceramic composites [15].
2.5 Laminated Object Manufacturing (LOM)
Laminated Object Manufacturing is an additive and subtractive process. In this technique, a
feeder mechanism places a sheet of paper, metal, or plastic over a build platform, where a base
has been built from a paper [16]. A heated roller bonds the two sheets together with an
application of a pressure. Then, a focused laser cuts the outline in the shape of each layer given
the information of the 3D model from the CAD file and crosshatches the excess area. The cross-
hatching breaks up the excess material, making it easier to be removed during the post-
processing. After the first layer, the platform lowers to allow fresh material to advance. When the
Figure 2. Selective Laser Sintering mechanism. From [13]
5
platform rises slightly below the previous height, the roller bonds the second layer to the first
layer, while the laser cuts the second layer. This process is repeated to build the model layer by
layer until the part is completely built. Papers, composites, and metals are materials used with
this technology [17]. No supporting structure is required in this process because the excess
materials crosshatched provide a good support for overhangs and models with thin wall areas.
Other advantages of this process are post processing is avoided, deformation and phase change
does not occur and large parts can be printed [8]. However, this process is unsuitable for
fabrications with complex internal cavities and low surface definition due to its subtractive
process.
Other 3D printing technologies are Electron Beam Melting (EBM), Laser Engineered Net
Shaping (LENS), PolyJet, and Direct Metal Laser Sintering. EBM is a relatively new process
very similar to SLS. The difference is what melts the powder. In this process, an electron laser
beam powered by a high voltage, typically 30 to 60KV, melts the powder before bonding occurs.
To avoid oxidation, this process takes place in a high vacuum chamber because it is intended to
build metal parts. One of the future uses of this technology is the manufacturing in the outer
space [18], [19], since it is done in a high vacuum chamber. In the LENS process, a part is built
by melting metal powder that is injected into a specific location. The molten form, which
solidifies when cooled down, is maintained with the help of a high-powered laser beam. These
processes take place in a closed chamber with an argon atmosphere. Materials fabricated with
this process are metals and alloys, for example, stainless steel, nickel-based alloys, tooling steel
and copper alloys. PolyJet is a 3D process that uses inkjet technology to manufacture 3D
models. The inkjet deposits a photopolymer in x and y-axes, which is cured by ultraviolet lamps
after each layer is finished. Parts produced through this process have high resolution with a part
thickness of 16 microns. However, parts produced by this technique are weaker than the ones
produce with SLA and SLS.
3.0 MAJOR COMPETITORS IN 3D PRINTING TECHNOLOGY
Numerous companies all over the world take part in the 3D printing industry. Many of them are
in the US, Germany, France, Japan and China. This project concentrates more in the US because
most of the companies here in the US are the biggest competitors in 3D printers. The leading
producers of 3D printers include 3D Systems, Stratasys, Cubic Technologies, Formlabs,
B9Creator, Optomec, ProMetal, Sanders Design International, Solidica and ZCorporation [13].
3.1 Formlabs
Formlabs is a Somerville, Massachusetts-based company that was founded in September 2011. It
designs and manufactures desktop 3D printers based on stereolithography technology, which
produces a professional print quality not possible with their plastic extrusion counterpart.
Formlabs’ major commercialized printer is Form 1+ with layer thickness (resolution) as high as
25 microns. The minimum feature size of this machine, which is the thinnest wall or finest point,
is 300 microns [20]. The build envelope dimensions are 125 x 125 x 165 mm (4.9 x 4.9 x 6.5 in)
[20]. In addition, other advantage of Form 1+ over other stereolithography machine is that parts
printed on this machine have a perfectly smooth surface finish.
6
3.2 3D Systems
3D Systems Corporation is a holding company that operates through subsidiaries in the United
States, Europe and the Asia-Pacific region. The company is a provider of both personal-based
and production-based 3D printers, print materials, and on-demand custom parts services for
professionals and consumers [21]. It has acquired many other 3D companies such as DTM,
ZCorporation, and the Vidar systems Corporation [22]. Hence, 3D Systems has increased its
principal print engines to stereolithography (SLA) printers, selective laser sintering (SLS)
printers, multi-jet modeling (MJM) printers, selective laser melting (SLM) printers, and plastic
jet printers (PJP) [23].
3.2.1 Personal printers for 3D Systems:
1. ProJet 1200: Maximum Build Size is 1.69 x 1.06 x 5.9 inches. Minimum layer thickness
is 30 micron and the material used for this machine is VisiJet.
2. Cube 3: Maximum Build Size is 6 x 6 x 6 inches. Minimum layer thickness is 70 micron
and the materials used are PLA/ABS plastics.
3. CubePro: Maximum Build Size is 10.75 x 10.75 x 9.5 inches. Minimum layer Thickness
is 70 micron and the materials use are PLA/ ABS/ Nylon.
3.2.2 Professional printers for 3D Systems:
1. ProJet 3510 SD, ProJet 3510 HD, and ProJet 3510 HD plusthese machines use
MultiJet Printing technology to deliver high quality, durable parts. They have 16-micron
resolution, which delivers exceptional parts with unmatched micro-detail and surface
quality.
2. ProJet 5000this machine offers a unique combination of size, precision and ease-of-use
to make it the ideal choice for printing large and small durable hard plastic parts with
superior feature quality. It offers a large build volume of 550 x 393 x 300mm, three
different print resolutions, and works with the VisiJet MX Build material. ProJet 5500X
has the same features with Projet5000, only that it delivers the highest quality, most
accurate, and toughest multi-material composites based on 3D Systems’ latest MultiJet
Printing (MJP) technology.
3. ProJet 6000ProJet 6000 uses stereolithography to create accurate and perfectly formed
3D printed parts and prototypes. Its maximum build platform size is 250 x 250 x 250 mm.
A wide choice of materials are available that exceed the properties of traditional plastic
materials including VisiJet SL Clear. VisiJet Clear is also USP (United States
Pharmacopeia) Class VI certified, making it ideal for medical product manufacturing,
especially in mass custom manufacturing projects such as hearing aids and dental
applications [24]. ProJet 7000 uses stereolithography technology to create accurate and
perfectly formed 3D printed parts. It is available in three models, SD, HD, and MP with
the largest build platform of 380 x 380 x 250 mm. Due to its large build size and choice
of materials; aerospace, automotive, heavy equipment, consumer products, and industrial
designers use it.
7
3.2.3 Production printers for 3D Systems:
Production 3D printers from 3D Systems were produced for manufacturers to give them the
option of printing different sizes of objects at reduced time. Printers from this group generate
concept models, precision and functional prototypes, master patterns, and molds for tooling, and
real end-use parts. 3D Systems have revolutionized product development through the application
of Stereolithography (SLA), Selective Laser Sintering (SLS), and Direct Metal Printing (DMP).
The major printers for this group are:
1. Stereolithography (SLA):
ProJet 6000 HD
ProJet 7000 HD
ProX 800
ProX 950
2. Selective Laser Sintering (SLS):
ProX 500
ProX 500 plus
sPro 140
sPro 230
sPro60 HD
3. Direct Metal Printing (DMP):
ProX 100
ProX 100 Dental
ProX 200
ProX 200 Dental
ProX 300
ProX 400
3.3 Stratasys
Stratasys Ltd, formerly Object Ltd., which incorporated on March 3, 1998 is a manufacturer of
3D printers for office-based rapid prototyping and direct digital Manufacturing [22]. The
company develops, manufactures, and sells different lines of 3D printers that create physical
parts from a CAD model. Its products are used in the aerospace, automotive, medical, defense,
business, industrial equipment, education, and consumer-products markets. Stratasys have
acquired so many other 3D printer-manufacturing companies, which are now one of their brands.
The companies they acquired include Objet Geometries, MakerBot, and SolidScape which they
acquired in May, 2011 [22]. Its facilities are located is the US, Brazil, Germany, Hong Kong,
Israel, and Japan. The company’s products are dependent on three technologies: Fused
Deposition Modeling (FDM), PolyJet, and Wax Deposition Modeling (WDM). Their portfolio
consists of four series of additive manufacturing systems [25] and they are the MakerBot desktop
series, the Ideal Series, the Design Series, and the Production Series.
8
3.3.1 MakerBot desktop series for Stratasys:
The company’s MakerBot desktop series represent its 3D desktop printers. This series include
replicator series, as well as the digitizer, which is a 3D scanner that allows customers to scan an
object and obtain a digital file that can be subsequently printed. The four 3D printer models for
MakerBot are MakerBot replicator mini, MakerBot replicator18, MakerBot replicator 2X and
MakerBot replicator desktop 3D printer (5th edition). All the four have the same basic technology
with the same printing resolution. The differences are build volume, material use, method of
connection, and the number of extruder installed in each of the printer.
3.3.2 Ideal series for Stratasys:
This series include its lower capacity, affordable set of 3D printers for professional use. It
comprises of MoJO and uPrint product families, both of which are FDM-based. These products,
designed for easy use in an office environment, produce professional grade parts using ABS
thermoplastics.
3.3.3 Design series for Stratasys:
Stratasys design series dramatically expedite design and development cycles, improve
communication and collaboration, and resolve issues between design and engineering. This
series includes both FDM and PolyJet-based technology. FDM is used for printing tough and
stable dimension parts while PolyJet is used for printing parts that require good surface finish.
3.3.4 Production series for Stratasys:
The production series include its Fortus and SolidScape brands, both of which are typically used
for Direct Digital Manufacturing (DDM) applications. The Fortus family, based on FDM
technology, offers large build envelopes and multiple material options.
3.3.5 Dental series includes:
With Stratasys, the future of dentistry is going digital. Stratasys has designed a 3D printing
solution for almost every dental need. Each Dental Series 3D Printer runs on one of two
patented, industry-leading technologies to build models, dental appliances directly from digital
files.
3.4 B9Creator
B9Creator, a known name in Stereolithography, is a registered trademark of B9Creations, LLC
in the United States [26]. It provides 3D printers with high resolution at affordable prices. This
machine can print in the X Y direction with an adjustable resolution of 30, 50, and 70 microns,
and Z slices as thin as 5 microns. The X Y builds area is 104 x 75.6mm and 200mm in the Z
vertical direction. Currently, they have only B9Creator v1.2 printer and other machine
accessories such as B9 poly vat, B9 vat dam, and B9 vat sweeper.
9
3.5 Cubic Technologies
Cubic Technologies, formerly Helysis Inc., develops and markets additive manufacturing
machines producing 3D objects out of thin films [27]. The company produces sheet-based 3D
printers called Laminated Object manufacturing (LOM) technology and offers services, support,
and parts for Helysis LOM rapid prototyping system. The major product from this company is
SD300 3D Printer. SD300 printer is a desktop printer that can print to an accuracy of +/- 0.2 mm
(XY) and has a laser thickness (laser spot size) of 0.165mm (165µ). The maximum model size is
170 x 220 x 145 mm (XYZ).
3.6 Optomec
Optomec is evolving the world of additive manufacturing by enabling new dimensions in 3D
printing. Its LASER Engineered Net Shaping (LENS) and Aerosol Jet families of printers
supports a range of materials for metals, electronics and other applications, and are able to
implement feature sizes never before possible [28]. Its Aerosol Jet printers enable the 3D
printing of micron-scale electronics with high volume and in a variety of structural use models,
including printing circuitry on other surfaces or products. It utilizes aerodynamic focusing to
precisely deposit electronic and materials in dimensions ranging from 10 microns up to a
centimeter scale. The LENS printer uses a wide range of metals with new level precision to
create prototypes and full-scale production of complex metal components.
3.7 Ultimaker
Ultimaker is a Dutch based 3D printer manufacturer headquartered in the Netherlands [29]. This
company uses Fused Filament Fabrication (FFF) to fabricate objects layer by layer from a CAD
file. Their two major printer models are Ultimaker 2 family and Ultimaker original. Both of the
printers create the most effortless and enjoyable 3D printing experience with groundbreaking 20
micron definition and near silent operation. They print from the same materialPLA, ABS, and
U-PET. The major difference is their build volume. The build volume for Ultimaker 2 is 230 x
225 x 205 mm while for Ultimaker original is 210 x 210 x 205.
3.8 Fab@Home Project
The Fab@Home Project is an open source, mass collaboration, and developing personal
fabrication technology aimed at bringing personal fabrication to people’s homes [30][31]. An
open source kit allows users to build their own 3D printers. Hod Lipson and Evan Malone of the
Cornell University Computational Synthesis Laboratory began Fab@Home project in 2006 but
now, the community includes hundreds of engineers, inventors, artists, students, and hobbyists
across six continents. Members include those who use their abilities to develop novel hardware
and software, which can be used for digital fabrication and for making simple unique items [30].
The major aim of this project is to put 3D printing technology into the hands of those same
10
curious and entrepreneurial individuals, and help them to drive the expansion and advancement
of the technology. The project has developed a user-editable wiki web site to publish its designs
and documentation, and set up online discussion forums for user and contributor
communications. They have shared the source code for the project through a popular open-
source online project site [31]. This web site contains detailed instructions for constructing a 3D
machine and provides user manuals, CAD files, and downloadable compiled software. They
have established an online user forum using Google Groups services (Google Inc.) to facilitate
communications between the communities [32]. The participants in Fab@Home have begun to
exchange their ideas for applications and their improvements to the hardware and software with
one another through these media. Their printer now has the hardware capability to print four
materials in a single print without changing syringes. The Fab@Home Model 1 can build objects
comprising multiple materials, with sub-millimeter-scale features, and overall dimensions larger
than 20 cm [31].
4.0 APPLICATIONS AND RESEARCH STATUS OF 3D PRINTING TECHNOLOGY
Prototyping remains the largest commercial application of 3D printing according to business
analysts, Computer Science Corporation (CSC). It was originally developed for rapid
prototyping, making a few samples during product development. Designers are able to speed up
product development and decrease commercial risk by early correction of design flaws.
However, advancements and improvements in the technology and speed as well as the materials
used have prompted commercial industries to incorporate this technology in their real
manufacturing strategy. Different 3D techniques have been applied in various fields such as
electronics, medicals, aerospace, automotive, fashion, arts, etc., to manufacture objects that are
not feasible with conventional manufacturing processes. It is being used to create intricate
geometries and shapes, thereby reducing the number of parts and assemblies needed to produce a
particular device.
4.1 3D printing technologies in electronics
As 3D printing gets more advanced and new materials are being discovered by scientists, there
are applications today where product components are being circuiticized to save space, weight,
and cost [33][34]. From the Shapeways blog [35][33]: Common electronic materials, including
conductor, dielectric, resistor, and semiconductor inks can be processed by the Aerosol Jet
system to print conformal sensors, antennae, shielding and other active and passive components.
Printing these electronic components directly on or inside the physical device eliminates the
need for separate printed circuit boards, cabling and wiring, thereby reducing weight and size
while also simplifying the assembly processes.
Department of chemical engineering, Johns Hopkins University and Department of Electrical
engineering, Princeton University have utilized 3D printing of living cells together with
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electronic components to produce a bionic ear [36]. This was achieved by fully interweaving
functional electronic components with biological tissues through 3D printing of nanoelectronic
materials such as silver nanoparticles and cell-seeded hydrogels in the precise anatomic
geometries of human organs. The printing was done by extrusion based on Fab@Home 3D
printer by extruding the two functional constituentsbiological cells and silver nanoparticles.
3D printing continues to develop in electronic manufacturing, with the accelerating development
of printable semiconductors. Researchers from Cornell University New York have demonstrated
a simple and inexpensive fabrication of functional embedded electrical circuits and useful
devices. Using Fab@Home Model 1, they demonstrated the 3D printing of LED flashlight,
functional printed circuit boards and, a child’s toy with embedded circuits [37]. The conducting
material used for this demonstration was S-26F (Silicone Solution). In addition, the structural
materials employed in the present work are materials commonly used with the Fab@Home
Model1: GE silicone II household silicone RTV sealant, and 3M DP460NS non-sagging 2-part
epoxy.
Warwick University has developed a material called carbomorph (conductive thermoplastic
composite) that could be used within 3D printers to print electronic sensors able to sense
mechanical flexing and capacitance changes [38]. The group was able to build a functional
computer game controller made entirely from cabomorph by laying down electronic tracks and
sensors as a part of 3D structure. This new advancement in 3D printing will offer a new
opportunity in the 3D printing field that will allow printed sensors and electronics to be
embedded in 3D printed objects in a single build process, without requiring complex or
expensive materials.
Recent development in 3D printing has enabled the fabrication of custom optical elements by
some researchers from Disney Research, Pittsburgh and Computational Design Lab HCL
institute Carnegie Mellon University [39]. This is fabricated in the form of high-resolution
transparent plastics with similar optical properties to Plexiglas. 3D printed optical elements allow
new optical configurations that were not previously possible, such as printing multiple materials
within a single element and combining mechanical and optical structure in the same design. This
has been achieved using stereolithography with a high resolution of 42 microns, because 3D
printing of optical quality materials typically requires a photo polymer-based process. The
optical elements were fabricated using Object Eden260V 3D printer and VeroClear transparent
material. VeroClear has similar properties to Poly methyl methacrylate (PMMA), commonly
known as Plexiglas with a refractive index of 1.47 [40].
Researchers from Graphene 3D labs are working on the potential of 3D printing to make
manufacturing easier and cheaper by using 3D printing to make electric car batteries [41].
Graphene 3D lab is a manufacturer of the graphene-based material used in 3D printing; it
unveiled a prototype 3D printable battery at the 3D printing Conference in Santa Clara,
California. According to Green Car Congress [42], materials developed by Graphene 3D Labs
can be used to incorporate a battery into a component during the build process, which makes it
possible to have electronics with built-in power sources or cars with built-in batteries.
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Taking the advantage of both 3D printing and printed electronics, Researchers at Palo Alto
Research Center (PARC), California have developed a 3D printing system with the ability of
integrating a structural material with functional electronic materials [43]. They integrated both
inkjet and extrusion print head on the same platform, along with an in-line UV-curing lamp for
photonically drying and curing both the printed Silver conductor and the polyurethane gel
structural materials. They used an inkjet print head for printing less viscous conducting ink
(silver conductor) while the extrusion print head is used for printing more viscous structural
materials (polyurethane). The printed polyurethane showed line width of 200 microns and
thickness of 100 microns, while the printed conductor lines on top of the polyurethane were
typically 35 microns in width and 1 micron in thickness.
Researchers from the University of Texas El Paso have developed a process for embedding
conductive wire and mesh into 3D printing of thermoplastic structures as an alternative to
traditional conductive ink technologies [44]. The aim of this development is to incorporate bulk
copper conductive materials into FDM in order to produce a capacitive sensor, which finds
applications in biomedical, human interface devices, material sensing, electronics
characterization, and environmental sensing. This work also allows for the additive
manufacturing of fully integrated devices such as Lab-on-chip micro fluids.
Furthermore, Jennifer Lewis, a materials scientist from Harvard University has initiated some
steps towards printing electronic devices. Firstly, she has invented a supply of functional inks
that solidify into batteries and simple components such as, electrodes, wires, and antennas [45].
She has also developed high-pressure extruders with nozzles that can squeeze out the batteries
and other components from an industrial 3D printer. Lewis’ 3D printing technology can deposit
ink from hundreds of nozzles at the same time thereby reducing the time wasted by printing from
a single nozzle. Notwithstanding, her printed lithium-ion batteries are as tiny as one millimeter
square, but they perform as conventional batteries.
A Researcher from University of Texas and center for 3D innovation both at El Paso has
developed a machine with a novel integration of technology called Multi 3D System [46]. A
multifunctional 3D machine that uses multiple technology to produce 3D objects. It uses Fused
Deposition Modelling (FDM) technology to produce parts with substantially improved
mechanical, thermal, and electrical properties. This machine has been used to manufacture space
electronics and biomedical devices.
Also, a company spinoff from Harvard [47], Voxe18, has developed a printing machine that
makes it possible to fabricate a complete circuit using 3D printing. With this new method, a
complex circuit can be fabricated using conductive ink without the need for assembly, thereby
reducing both size and cost [48]. The ink used as one of their materials is highly conductive and
printable at room temperature. They use the ink to connect electronic components, such as
computer chips and motors. As a test of the machine, the company made a quadcopter by
printing its plastic body layer by layer, systematically switching to printing conductive line that
became embedded by successive layers of plastic. Moreover, they also stop at appropriate points
in the process to add some components such as an LED.
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4.2 3D printing technologies in medicine
3D printing is transforming the practice of medicine through the possibilities of making rapid
prototypes and very high quality bone transplants and models of damaged bone of a patient for
analysis [49]. Stereolithography has becoming an efficient method of producing prosthetic
sockets. This method makes sure that the form of the socket adapts better to patients while being
more cost effective than hand or machined methods [50]. Not only can hard parts like bones be
printed, it is possible to print cells in 3D arrays that make it easy to print human tissues. In the
near future, we hope to achieve advancements in 3D printed patients-specific prosthetics,
surgical implants, cells, blood vessels, organs, casts, biomaterials, and many other medical uses.
Due to an increasing need of 3D printed structures in dental, 3D System has announced the
availability of its revolutionary all-in-one medical 3D printer, the ProJet 3510 DPPro, which the
company debut at LMT LAB DAY Chicago 2015 [51]. The production ready ProJet 3510 DPPro
gives dental and medical labs the power to print high volume precision dental wax-ups, implant
drill guides, temperature-resistant, orthodontic patterns and crown, and bridge models for all
medical users [52]. It was developed to provide access to more affordable and powerful tools for
the benefits of the medical industry.
Due to the difficulty encountered by tissue engineers in restoring the tissue and organ loss by
disease or injury, a group of researchers has designed a Bio Assembly Tool (BAT) that can
coextrude cells and biomaterials into a 3D spatially organized, viable construct [53]. This
machine is capable of using pneumatic or positive displacement pens to deposit material in a
controllable three-dimensional pattern. The BAT uses a computer aided design approach to build
three-dimensional tissue models. It is a multihead deposition machine designed to deposit both
biomaterials and cells on various surfaces to create tissues.
A renowned material scientist from Harvard University, Jennifer Lewis, is developing 3D
machines that make it feasible to use assorted materials, from living cells to semiconductors,
mixing and matching inks with precision [54]. She prints intricately shaped objects precisely
adding materials that are useful for their mechanical properties, electrical conductivities, or
optical properties. Due to her research, 3D printing technology now make objects that sense and
respond to their environment. Her projects include printed sensors fabricated on plastic patches
used by athletes to detect concussions and measure violent impacts. Recently, her group printed
biological tissue interwoven with a complex network of blood vessels. For this to be feasible, the
researchers had to make inks out of various types of cells and the materials that form the
supporting matrix. This work intends to solve one of the challenges in creating artificial organs
for drug testing or for use as replacement parts.
General Electrics (GE) healthcare has incorporated 3D printing in their healthcare
manufacturing. They have printed a transducer used for their ultrasound devices, which is the
part of ultrasound machine that converts electrical signals to sound waves [55].
Three-dimensional printing is also being used to create customized, controlled drug delivery
devices, which are designed to transport therapeutic drugs directly to targeted areas and then
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safely break down or decompose and be removed from the body [56]. Ruston from
organicNANO, a company started from technology developed at Louisiana Tech University is
using 3D printing to develop a system of delivering chemotherapeutic drugs for use in cancer
treatment, a development that could generate improved drug-delivery devices, implants, and
catheters. This is done by using medical-grade, biodegradable, and biocompatible PLA, and PCL
beads, filaments that are loaded with antibiotics or chemotherapy drugs for more focused drug
delivery system.
A surgical team from the University of Michigan’s C.S. Mott Children’s Hospital has treated
Tracheobronchomalacia in new-born using Bioresorbable Medical Implant, which is possible
through customizable 3D printing [57]. Tracheobronchomalacia, which is a difficult disease to
treat, is a respiratory insufficiency due to dynamic airway collapse [58]. This life threatening
condition was treated by implanting a customized, bioresorbable tracheal splint, which was
created with a computer-aided design (CAD) based on a computed tomographic (CT) image of
the patient’s airway, and fabricated with the use of laser-based three-dimensional printing. With
this implant, they show that high-resolution imaging, computer-aided design, and biomaterial
three-dimensional printing together can facilitate the treatment of conditions that are specific for
a given patient.
Researchers at Washington State University customized a commercial 3D printer to create three-
dimensional structures using a bone-like materials [59]. When this bone structure is bred with
bone cells in the lab, it can help support the growth of a new network of bone cells. They have
seen promising results from preliminary tests in rabbits and rats. With the success of this
development, doctors are able to custom order replacement bone tissue said Susmita Bose, co-
auto and a professor in the University [60]. The doctor only needs to get a CT scan of a defected
bone; they can convert it to a CAD file and make the scaffold according to the defect. The
researchers were able to achieve this by tweaking and optimizing a commercially available
ProMetal 3D printer, which was originally designed to fabricate metals. They also optimized the
strength of the building materials, calcium phosphate, by the addition of silicon and zinc.
As an alternative to surgical replacement of a damaged intervertebral disc, researchers at the
Medical University of South Carolina, led by a professor of Bioengineering and regenerative
medicine at Clemson University and Medical University of South Carolina, have fabricated a
prototype disc by 3D printing an outer scaffold of the disc and then seeded the scaffold with
living cells [61]. Printing the scaffold first is to make sure that it can perform the same
supportive and shock absorbing functions of the original disc. The scaffold needs to imitate the
intricately layered microstructure of the original intervertebral disc to work perfectly as an
implant. This development is safer when compared to plastic implant because the scaffold with a
living tissue could repair itself and the constant access to blood supply would reduce the risk of
infection.
3D Systems, a major stakeholder in the Three-dimensional printing industry is revolutionizing
the medical systems with their advanced and comprehensive 3D digital design and fabrication.
On March 10, 2015, they announced the new 3D printed metal orthopedic knee implants, Tibial
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Tuberosity Advancement (TTA), manufactured for Rita Leibinger Medical, a family run
business focused on innovative veterinary medical products [62]. The metal implants help
veterinarians to treat difficult medical problems in dogs’ legs. It repairs damaged ligaments in
dogs’ hind legs caused by trauma, degeneration, or genetics. The implant is inserted into the
dog’s lower leg, restructuring the mechanical forces of the bones and creating knee stability
without the need to repair the damaged ligament. This revolutionary technology has helped over
10,000 disabled dogs to walk and run again. The success of this implant is due to its complex,
open structure that promotes rapid bone ingrowth, with less risk of infection. The dogs are fully
recovered after six weeks of surgery.
4.3 3D printing technologies in aerospace and automobile
3D technology found use in manufacturing complex parts for aerospace and automotive
industries. The goal here is to make the lightest practical car and aircraft while maintaining
safety. 3D printed aircraft components are 65 percent lighter and stronger than traditional
machined parts, representing huge savings and reduced carbon emissions. Also for every 1
kilogram reduction in weight, airlines save around US$35,000 in fuel costs over an aircraft’s life
[63]. Major car manufacturers, such as GM, Land Rover, Jaguar, and Audi, have been 3D
printing auto parts for a number of years. In addition, leading aircraft manufacturersAirbus
and Boeing are using 3D printing to improve the performance of their aircraft, reducing
maintenance, and fuel cost.
General Electric (GE), the world’s largest supplier of jet engines, is turning away from the
traditional method of producing its parts. The company is preparing to produce its fuel nozzle
parts for a new aircraft engine by printing the parts with selective laser sintering instead of using
the conventional method, such as casting and welding. GE’s joint venture, CFM International,
has used three-dimensional printed nozzles in its LEAP jet engines due to go into planes by the
end of 2015 or early 2016 [55]. The company has even developed a technology to make fuel
injectors for its engines through laser 3D printing [64]. They decided to use a 3D process
because it makes parts lighter and reduces the company’s production cost. It also uses less
materials and yields significant savings for the airline. Whereas the conventional technique,
which is labor intensive, requires machining and welding several parts together, thereby scraping
high percentage of the materials. To show its effort in expanding its engineering and
manufacturing [65], GE has invested in additive manufacturing (3D Printing) by acquiring two
privately held companies which specialize in additive manufacturingOhio-based Moris
Technologies and Rapid Quality Manufacturing.
Another GE business ‘Avio’, an Italian aerospace company, is revolutionizing the aerospace
industry by developing a process for 3D printing of light-weight metals for jet engines and
turbines [66]. Their technology was developed around metal powders specifically for Laser
Metal Deposition (LMD) and Selective Laser Melting. All these powders supplied with
certificate of conformity are optimized to deliver dependable, high quality products at a cheaper
price [67]. Their technology, which allows Avio to build blades from layers of powder that are
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four times thicker than those used by laser machines, uses titanium powder fused with a beam of
electrons. This is more powerful and competitive with the currently used lasers for printing
metals and the conventional casting method. The company also developed a technology, Electron
Beam Melting (EBM) in conjunction with Sweden’s 3D company called Arcam [68]. The main
idea of this development is to improve the manufacturing of advanced aerospace parts from
titanium aluminide (TiAl) materials. TiAl, which reduces the weight of the entire pressure
turbine, is almost 50 percent lighter than the nickel based alloys used for low-pressure turbine
blades. To further buttress the importance of 3D fabrication for Ti-6Al-4V in aerospace, many
brackets for the Juno spacecraft were fabricated, machined, and tested using Arcam’s Electron
Beam Melting (EBM) additive manufacturing process [69]. In recent years, Ti-6Al-4V has been
an attractive, lightweight material for aerospace, which provides an excellent combination of
high strength, low density, high modulus, low coefficient of thermal expansion and higher
operational temperature than ordinary aluminum alloys. The three-dimensional CAD model of
every bracket drawing was obtained and few excess surfaces were included in the design to take
care of the machining to a smooth surface finish [70]. All the parts were fabricated using Arcam
Model EBM S12 machine and analyzed to obtain the merit of using additional manufacturing for
future spacecraft components. The result of this analysis indicated that the average material
properties were comparable to the wrought alloy.
Other aircraft makers like Pratt and Whitney also use similar technology [71]. Pratt and Whitney
has manufactured their engine components by utilizing two additive manufacturing methods
selective laser sintering (SLS) and Electron Beam Melting (EBM) instead of the traditional
method of casting.
4.4 Unmanned Aerial Vehicles (UAV) manufacturing
Advanced additive manufacturing technologies such as SLS, FDM have made it possible for the
creation of rigid, lightweight UAV parts and structures not otherwise feasible with conventional
manufacturing methods [72]. Because of advancements of 3D printing technologies, the UAV is
experiencing performance improvements with superior part design from a lighter weight
components and component consolidation. The University of Southampton, led by Andy Keane
and Jim Scanlan, released the first world printed unscrewed UAV called “SULSA” in August
2011[73]. This is the first plane that is free from any screws, all the structures, including total
wings, control surfaces, and doors were printed together. With this technology, an aircraft can go
from the drawing board to flight in a matter of days.
4.5 Architectural modelling
Additive manufacturing technology is a very powerful tool for architects in their business. They
can create physical models faster without worrying about the complexity of their design. Models
created with this process provide a better resolution than other processes. The major process used
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by architects is stereolithography due to the materials used and perfect resolution of this process
[74]. 3D Systems is increasing application of 3D printing by offering technologies that generates
new possibilities, both for architectural planning, visualization, and presentation. UC Berkeley
College of Environmental Design graduate students led by Professor Ronald Rael, utilizes 3D
Systems’ ColorJet printing technology for architectural production of a 3D cement structure
called Bloom [75]. It is a freestanding room built from 840 customized blocks; all the blocks
were printed from cement and polymers using the 3D Systems’ ProJet x60 printers. After
printing the blocks, it was assembled by hand, giving the room a unique design. This project,
which was the largest printed polymer, was disclosed at the fifth annual Berkeley Circus in
March 2015.
4.6 Mass customization
3D printing has changed production from the age of mass production to the age of mass
customization, making it possible for people to customize their own products. Companies now
have services, which allow consumers to customize objects using simplified web based
customization software. These items are later ordered as 3D unique objects. For example, Nokia
customers can now create custom cases for their mobile phones. Nokia has released the 3D
design for their Nokia 1520 case so that owners can customize their own cases and have it
printed [76].
4.7 Fashion
With the emergence of new 3D printing materials today, 3D printing in fashion has grown to a
certain stage. Many companies are 3D printing custom shoes, high heels, jewelry, sunglasses,
accessories, and even clothing. Companies such as Nike and Adidas have traditionally used 3D
printing in their engineering design iterations [77]. 3D wearable materials are now being
customized to fit the customers’ style. Accessories such as jewelry and eye wear are being
printed with different materials [78]. Xuberance, a Shanghai design company, has printed an
incredible wedding dress using SLS three dimensional printing, which it displayed at the
Shanghai Convention and Exhibition Center of International Sourcing in China [79].
5.0 3D MICRO PRINTING TECHNOLOGIES
Three-dimensional printing, for decades, has been utilized in different ways to produce parts not
possible by traditional methods for example, complex parts with intricate geometries. Many
manufacturing companies have integrated 3D printing into their manufacturing process due to
improvements in the technology and the discovering of new materials. Currently, numerous
materials can be printed, including metals, alloys, composites, polymer, ceramics and so on.
However, the resolution of these conventional 3D printers limits the size of parts it can fabricate,
18
thereby making them not feasible to fabricate micro parts. Hence, it cannot respond to the current
demand for high quality 3D micro components used in microelectromechanical systems
(MEMS), micro-opto-electro-mechanical systems (MOEMS), and micro-optical electronics
systems (MOES) [80]. Scientists have been working earnestly to develop micro 3D technology
due to current interest in miniaturization of products in many industries including automotive,
medicals, optics, electronics, and biotechnology sectors [81]. As a result, many new micro 3D
printing (micro additive manufacturing) technologies have been developed, which have different
applications and capabilities to accommodate the current need in manufacturing [82].
5.1 Microstereolithograghy
Microstereolithography (MSL) is a micro 3D printing technology developed and introduced by
Ikuta and Hirowatari in 1993 through the development of the Integrated Hardened (IH) polymer
stereolithography [83]. MSL uses the same principle as conventional stereolithography, in which
an UV light source is focused on a photo curable polymer, bringing about the solidification of
the photopolymer. The only difference is the method of scanning the light and the generation of
its patterns. In conventional SL, resin is photo polymerized by a scanning laser light while in
MSL, a Xenon lamp is utilized because it is cheaper and simpler. Precision of the beam steering
mechanism and platform stability determines resolution [84]. The diameter of laser spot employs
for MSL is very small (5 microns) compared with the conventional SL and the X, Y, Z
translational stages have submicron resolution. Solidification of the photopolymer occurs in a
very small area of the liquid resin layer by layer and hence MSL permits fabrication of micro
parts with 1-10 microns layer thickness. In addition, a metal 3D structure can be obtain using
both metal molding process and the initial polymer fabrication process. A polymer structure is
used as a mold or cast and the metal is electroplated into the polymer mold. At the end of the
fabrication, a chemical process such as solvent eliminates the polymer. This process is also
applicable to non-electroplatable metals and materials, which can be molded into polymers. This
technique has been commercialized by a German company, MicroTech GmbH. Currently, the
company does not sell any machine, but they offer customer services [85].
Microstereolithography is used in various areas such as micro flow sensors [86] and micro-
bellow actuators [87], fluid chips for protein synthesis [88], 3D photonic band gap structures
[89], and bio-analysis [90], [91]. This technology also found application in Bioengineering as a
scaffold for bone regeneration. Researchers from the department of mechanical engineering, the
University of Technology Vietnam and POSTECH Republic of Korea have designed and
fabricated three dimensional porous scaffolds based on a Poly Propylene Fumarate (PPF)
polymer network using this technology, which provides a new scaffold fabrication for tissue
engineering [92]. This method is preferred over classical stereolithography due to its ability to
control pore size, porosity, interconnectivity, and poor distribution [93]. In addition, a group of
researchers from MIT and Lawrence Livermore National Laboratory has utilized this technology
to produce what they refer to as micro-architected metamaterials using ceramic, metal, polymer,
as well as polymer-ceramic hybrid materials. The material produced was extremely lightweight,
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very strong, and stiff due to the unique arrangement of its structures. Table 1 shows the apparatus
specification of Microstereolithography.
5.2 Laser Micro Sintering
Laser Micro Sintering (LMS) was launched into the market by a German company, 3D-
Micromac [82]. It is a micro fabrication process based on the conventional selective laser
sintering, in which powder fine particles or pasty materials are selectively sintered ( melt and
compacted) by a laser beam to produce a part layer by layer until the last layer is fabricated. To
achieve fine details, it employed q-switched laser pulses and use of powder with smaller particle
sizes in the micron range [94]. Hence, a few modifications of the classical SLS are needed to
take into account fine particles required for this technique. The process was required to be
performed in a vacuum chamber to avoid powder corrosion due to high reactivity of fine
particles exposed to humidity and oxygen. In addition, there was a problem with the raking of
fine-grained powder, as the materials tend to compact together. A new raking system was
developed, which uses two special rakes to generate a thin layer by utilizing circular switching
motion [95]. This technique is capable of producing micro parts from both metal and ceramics
with a resolution of 30 microns and a minimum surface roughness of 1.5 microns. Several
research has been completed on the SLS printing of biocompatible materials used in tissue
engineering and medical prostheses. These materials include thermoplastic polymers, bioactive
ceramics, polymer-coated metals and metals, which have been printed with this technology [96]
[99]. The technology also found applications in the manufacturing of micro-tools. It has been
applied several times in the fabrication of tools employed as grip bits for micro manipulators or
micro positioning tools and injection molds for polymer casts [100].
Table 1. Apparatus specification of Microstereolithography
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5.3 Micro three-dimensional printing (M3DP)
Micro 3DP is a modification of conventional three-dimensional printing developed by
Massachusetts Institute of Technology, which is a process of building 3-dimensional objects by
use of powder bed and droplets of binder materials. Like other micro fabrication processes, thin
layers are required to achieve fine details of micro parts. Hence, powder with small particle size
is needed. Some advantages of fine powders are lower surface roughness and good printability
[101]. Due to high resolution required for micro 3DP machines, the thermal printing heads
utilized in conventional 3DP were replaced with high-resolution piezoelectric printing heads.
The major advantage of this process over other micro fabrication is that it is a fast process and
can be employed both in micro prototyping and direct mass production of micro parts [102],
[103]. Digital Metal is a precision inkjet process developed by Fcubic AB, Sweden for 3DP,
which employs 3DP and sintering processes to fabricate high precision micro-parts. This process
has produced a micro metal components with a resolution of 20 microns and a surface finish of
approximately 4 microns [82]. Some experiments have been completed with the Digital Metal
for a fabrication of 3D thread. The resolution of the process for this experimental work was 20
µm in X and Y and 40 microns in Z directions. As a good method for fabrication of a micro
ceramic mold, Fcubic3DP has also investigated the manufacturability of microzirconia ceramic
shells using the micro 3DP process for fast investment casting of microcomponents [104].
Additionally, Micro 3DP has facilitated fabrication of complicated micro scaffold shapes with a
fully interconnected pore network [105].
5.4 Electrochemical fabrication (EFAB) process
EFAB technology is a 3D fabrication process invented at the University of Southern California
in 1996 with funding from the Defense Advanced Projects Agency (DARPA), and has been
commercialized by Microfabrica, Inc. (formerly MEMGen Corporation), a venture-funded
company based in Van Nuys, California [106]. It is a hybrid additive manufacturing process of
micro devices with features ranging from 20µm and tolerances of 2µm without the need for
assembly [82]. The process utilizes a selective electrodeposition technique known as “Instant
Masking,” which allows metals to be electrodeposited via an opening or apertures patterned in a
compliant mask that is pressed against the surface of the substrate or the surface to be patterned.
Like other additive manufacturing process, EFAB is driven by a 3D CAD design, which is
exported as an STL file. The STL file is now imported into layerize,” a software developed by
Microfabrica, to generate 2D cross-sections printable by the machine. These 2D cross-sections,
in GSDII formats, are used to drive an e-beam producing a photomask tool that traces the cross
section to be printed. The EFAB processes start with a blank substrate and build the device layer
by layer depositing and planarizing different metals. Currently, EFAB supports three
commercialized materials to build its parts, which includes Valloy 120 metal (a proprietary fine-
grain nickel-cobalt alloy), palladium, and Edura 180 materials. All the materials are suitable for
medical devices. EFAB utilizes two metals, one is structural metal forming the original structure,
and the second metal is sacrificial that provides support during the layering process and
eventually, will be discarded. EFAB involves three key processes as shown in Figure 3 [107].
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First, a metal or sacrificial metal is selectively electrodeposited onto the substrate in areas define
by the photomask, according to the first cross-section of the main structure. Second, a structure
(the main structure) is blanket deposited, covering the first metal (fills in the areas where the first
metal was not deposited). Last, the two metals are planarized through some processes to form a
layer. These three processes are repeated until the device has been fully generated. At the end of
the build, the sacrificial metal is completely removed by a selective etching process. This
technique has multiple commercial applications, including minimally invasive medical
instruments and implants, probes for semiconductor testing, military fuzing and inertial sensing
devices, millimeter wave components, and microfluidic devices. The major advantage of this
process over other additive manufacturing methods is its capacity to fabricate fully assembled
devices with different moving parts in a micro scale thereby cutting the cost of micro assembly.
It also found use in the production of micro-transformer, semiconductor testing (spring like
probe for probing wafers), and microwave or millimeter-wave devices (for example, hybrid
coupler).
Figure 3. The EFAB process. A 3-step process performed on each layer using two
materials. At the end, one material is etched to release the structure. From [106]
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5.5 Laser chemical vapor deposition (LCVD)
Laser Chemical Vapor Deposition (LCVD) is a beam deposition direct write (DW) or micro
deposition process that selectively transforms gaseous reactants into a thin solid layer utilizing a
heat from a beam. In this process, the laser beam is focused to a spot, approximately 1µm,
through an optical microscope lens and gaseous reactants composed of the materials to be
deposited is fed into the chamber. The substrate is heated up by scanning the laser beam over it
at 0.5-5 mm/s speed to dissociate the gaseous reactant selectively, and a thin layer is formed onto
the substrate [108]. The process is repeated until the structure is fully built. The major advantage
of this technique is that gaseous reactants comprising desirable compositions can be laid at the
same time or the gases can be laid at different time, producing a multi material deposition within
the same part. This is possible because the gas reactants can be easily changed at any time during
the deposition. The list of common materials deposited using this technique is shown is Table 2
[108]. LCVD found use in microelectronic applications, such as mask repair, circuit
customization or localized doping. Another application of this process was in fabrication of 3D
photonic microparts from Al2O3 [109] and fabrication of 3D microelectric cages to trap
microparts [110]. Also, it found use in the fabrication of carbon 3D microcoils using ethylene
gas precursor [111].
5.6 Focused Ion Beam (FIB) Direct Write
This technology is very similar to laser chemical vapor deposition (LCVD) except that a focused
ion beam is used instead of laser beam for depositing the reactant gases. In this technique, a FIB
produced from a liquid gallium source is focused on both the substrate and the gaseous
precursors, depositing a thin material on the substrate to produce parts layer by layer. A stream
of gallium ions is focused to the substrate using electrostatic lenses with a spot size as low as few
nanometers. It offers higher resolution than LCVD but has a low deposition rate, approximately
0.05 µm3/s, and an aspect ratios between 5 and 10 [112]. Minimum deposition thickness possible
with this method is about 10nm and microstructure with the minimum feature size of 80nm. The
deposited materials are sometimes contaminated with Ga ions and organic impurities due to the
organometallic mixtures used [113]. FIB is mostly applied in repair works and low volume
fabrication due to its slow process [114]. It has been applied to production of 3D sealed
encapsulation in microsensors [112]. FIB has been applied to production of combined 3D metals
for dielectric materials and circuitry. It also found use in integrated circuit (IC) industry for
Table 2. A list of common materials and laser used in LCVD. From [107]
Materials Laser (wavelength)
Germane ArF (193 nm) or KrF (248 nm)
Ag
Ar+ (488)
Ni
Ar+ (488)
C
Ar+ (514.5 nm)
B
CO2 (10.6 µm)
Solocon nitride Nd-YAG
TiN
CO2
23
repairing faulty circuitry. In addition, it has been used to connect electrical circuit by drawing
conductive traces [82].
Table 3. Comparison of the key micro 3D printing.
Process Strengths and weakness Resolution Materials
(µm)
Microstereolithography Complicated, but has high Photocurable polymers;
(MSL) resolution suitable for volume production 2 hydrogels; ceramics-PZT,
suitable for 3D microparts, high alumina, and HA; Metals-
repeatability and limited materials WC, CO, Al, and Cu
Micro Selective Laser Ability of multimaterial fabrication, no
Sintering (MSLS) support structure needed, suitable for Metals-Ag,Cu, and Al;
3D microparts, facilities are required to 30 ceramics; molybdenum;
provide fine powders and post-processing and 316L; stainless steel
microparts have porosity, and high
temperature process
Micro 3DP (M3DP) Ability of multimaterial fabrication, suitable Metals and ceramics
for volume production, suitable for 3D ,
microparts, low temperature process, no 20
support structure needed, low surface
quality microparts, have porosity, and
achievable minimum feature size limited
to 200 (µm)
Electrochemical Fabrication Highly robust microparts, suitable for 3D
(EFAB) microparts and compex mechanisms Valloy-120 (Ni-Co alloy),
without the need for assembly, favorable 20 Edura-180 (electroplated
for medical devices, it can only print to a height Rh), and palladium
of 1.25mm, and complete removal of sacrificial
material difficut in some cases.
Laser Chemical Vapor Multimaterial is possible; high resolution
Deposition (LCVD) process, low-deposition rate, and high- Metals and
system complexity; high-temprature 1 semiconductors
deposition; and controlled-atmosphere
chamber is required
Focused Ion Beam (FIB) High resolution process, favourable for 3D Metals and insulators
Direct Write 3D fabrication, slow process, and sensitive 80
process
24
6.0 MAJOR COMPETITORS IN 3D MICRO PRINTING TECHNOLOGY
6.1 M3D LLC
M3D LLC is a micro 3D printer manufacturer based in Fulton, Maryland. Founded by Michael
Armani and David Jones, M3D specifically manufactures desktop micro 3D printers that are very
affordable for offices, schools, and homes. Their major brand, ‘The Micro,’ is one of the first
consumer micro 3D printer, which is highly intuitive and seamless by design [115]. Micro
Motion Technology (MMT) powers this printer, which employs high precision technology.
MMT utilizes a microchip embedded within the print head to provide precision motion
information, making it possible for ‘The Micro’ to produce very thin layers with high precision.
This printer was manufactured to print only with plasticsABS and PLA. However, it can
produce parts with metal or food items such as chocolate using plastic filament as a mold [116].
Producing parts other than ABS and PLA take a few steps: design and print a mold for your
desired metal using plastic filament. Cover the printed mold in two-part silicone (EassyMold
33710) and fill the mold with a liquid metal called “Field’s metal.” The molded metal will be
taken out from the mold when it cools down. Table 4 shows the technical specification of ‘The
Micro.
6.2 Nanoscribe
Nanoscribe GmbH, a spin-off company from the Karlsruhe Institute of Technology (KIT)
Germany, is a German company that offers 3D printers for the micro and nanometer scale as
well as photoresists. With the development of laser lithography, Nanoscribe prints photo-
sensitive materials using direct laser writing technology. Laser lithography is a non-light two
photon absorption process, in which photosensitive resin is polymerized when two photons of
near-infrared are absorbed simultaneously [117]. Polymerization occurs in the focal point
volume (laser spot size) when the laser is focused into the resin. Resolution (i.e., the voxel size)
of the printers is being determined by three factorsthe laser spot size on the material, the
25
properties of the photosensitive material, and the power of the laser source. Materials compatible
with their machines are SU-8, Ormocomp as well as IP resists [117]. Currently, their major
product is Photonic Professional GT, which won the Prism Award in 2014 in the category
“Advanced Manufacturing” at the world largest Photonics conference and exhibition [118]. It is
a user-friendly laser lithography system, which combines two modes to fabricate 3D micro and
nanometer objects. The two modes are an ultra-precise piezo-mode for arbitrary 3D trajectories
and the high-speed galvo-mode for fastest structuring in a layer-by-layer process. This printer is
the fastest 3D printer; it can print objects with speed of more than 5 terabits per second [119].
Photonic Professional GT has so many applications in different areas. In medicine, it found use
in cell scaffolds and biomimetic for example, tailoring 3D environments for cells or mimicking
structures. Also, it can be used in integrated optics, interconnects, tissue engineering, MEMS and
fabrication of microfluidic elements such as filters or mixers on microfluidic chips [117]. Table 5
shows the technical specification of Photonic Professional GT.
6.3 Microfabrica
Microfabrica is an advanced technology company based in Van Nuys, California, who has
developed a 3D microfabrication process of complex micro structures and assemblies at a scale
not possible with conventional 3D printers [120]. Their major technology is an electrochemical
fabrication (EFAB), which utilizes selective electrodeposition of metals to fabricate micro parts.
Recently, they developed a 3D printer called Mica Freeform, which mass-produce micro-scale
metal parts with micron-size features. Unlike other 3D printing techniques, it fabricates micro
metal parts with certain complexities including assembled devices. Its abilities to fabricate fully
assembled micro parts cut the cost of assembling microparts. As a micro fabrication process with
high precision, it can fabricate objects with features ranging from 20µm and tolerance of 2µm
without the need for assembly. Microfabrica technology is extensively used in high tech
industries such as medical devices, aerospace and semiconductor test [121].
6.4 MicroFab technologies Inc.
MicroFab develops and sells systems and applications for micro dispensing and precision
printing using ink-jet printing technology. Founded in 1984, MicroFab has been a leader in
Table 5. Technical specification of a photonic professional GT 3D printer.
26
developing manufacturing technologies based on piezoelectric ink-jet dispensing, which leads to
42 issued patents in ink-jet micro dispensing [122]. Ink-jet micro dispensing is attracting a lot of
attention in a wide range of industries due to its capabilities. Applications of this technology
include adhesive, liquid solder, optical and electrical polymers, and biomedical materials,
including diagnostic reagents, proteins, and DNA. They offer both application services,
equipment sales, and systems sales. MicroFab services include:
Complete SystemsMicroFab jetlab 3D printingjetlab 4-Tabletop, jetlab 4-Larger area,
jetlab 4-µBalance, jetlab II-precision, jetlab-Atmosphere, SphereJet, and VaporJet.
Printhead AssembliesPrinthead assemblies consist of the following: a fluid reservoir,
dispensing device, filter elements, mechanical mounting, connectors to the electronic controller,
and heating elements and connections to temperature controllers.
Electronics and SoftwareJet server, drive electronics, and image analysis.
Subsystems and ComponentsSubsystems and components are for customers who want to
integrate MicroFab micro dispensing technology into their own systems. They include pressure
control, drive electronics, optics for drop and substrate observation, and printhead.
MicroFab micro dispensing technology has been utilized to address challenges in tissue
engineering and regenerative medicine [123]. Areas covered are cell dispensing, growth factors,
and scaffold-construct fabrication.
6.5 EnvisionTEC
EnvisionTEC, a German company, is a 3D printer manufacturer including software and
materials. Unlike other 3D printers, EnvisionTEC produces a wide range of 3D printers based on
three different technologies [124].
Digital Light Processing (DLP) Technologythis technology builds perfactory (Personal
Factory) systems from liquid resin using DLP projector. The DLP projector translates
voxel data into liquid resin, thereby curing the liquid resin to solid. 3D printing with DPL
resembles assembling of small building blocks, each made of different volumes. Each set
of voxel data comprises a small volumetric pixel, with dimensions as tiny as 16 x 16 x 15
μm in the X, Y, Z directions, respectively.
Scan Spin and Selectively Photocure (3SP)here, a multi-cavity laser diode with an
orthogonal mirror spinning at 20,000 rpm reflects the beam through a spinning drum, and
the light passes through a series of optical elements hence focusing the light onto the
surface of photopolymer across the Y direction. The Imaging Light Source (ILS) contains
the multi-cavity laser diode, its driver, and all optics. The ILS travels in the X direction at
1-2 inches per second (material dependent) while the laser light scans the Y direction and
selectively photo-cures the liquid resin based on the data path.
27
3D-Bioplotter3D-Bioplotter is utilized for bioprinting and bioengineering. Multiple
materials are extruded in three dimensions using pressure. In this process, materials
ranging from free-flowing liquid to viscous paste are utilized to print a part by inserting
materials using a syringe. A strand of material is deposited through the syringes by using
air or mechanical pressure.
EnvisionTEC multiple printers found use in aerospace, architecture, automotive,
biofabrication and medical, consumer goods, dental education, electronics, hearing aids,
jewelry, orthodontics, and sporting goods.
6.6 Potomac
Potomac is a 3D printing company known for its innovative contributions in microfabrication of
medical devices, biotech, and electronics fabrication. Unlike other 3D printer manufacturers,
Potomac is a leader in 3D services [125]. Its areas of expertise include 3D microprinting, micro
manufacturing services, microhole drilling, laser micromachining, microfluidic devices
fabrication capabilities, and laser marking services. Potomac fabricates microparts from the
company’s high-resolution professional 3D printers that offer as low as 16-micron layer
thickness. Hence, the company can print very small part with tight tolerance. They can fabricate
parts with metals, polymers, and other biocompatible materials.
7.0 CHARACTERIZATION OF MAKERBOT REPLICATOR DESKTOP 3D
PRINTER (5th GENERATION)
As three-dimensional printing continues to develop and its applications extend to different
industries, homes, and offices, many 3D printer manufacturers have been trying to make their
products more affordable and efficient. The MakerBot replicator desktop 3D printer 5th
generation is the latest brand of desktop 3D printer from MakerBot Company, a subsidiary of
Stratasys who first patented Fused Deposition Modeling (FDM). FDM is an additive
manufacturing technique that fabricates object layer by layer until the part is fully built by
utilizing a heated thermoplastic wire. The major components of this machine include a drive
wheel (drives the wire filament to the heater), a heater (heats and melt the filament), nozzle
(extrudes the molten thermoplastic). It also includes a build plate or platform (a base on which
the molten plastic is deposited during fabrication), and a piston that moves the build plate in Z-
direction (vertical direction) when the first layer is completed. As shown in the Figure 4, the
build plate has X, Y, Z planes. The horizontal plane corresponds to the XY direction while the Z
plane corresponds to the vertical direction. A thin filament of thermoplastic (PLA) is extruded in
a molten form and is deposited on the build plate or on top of the earlier deposited filament. The
extruded filament is called a ‘road’ [126], which is quickly solidifies after being stacked by
another layer of road on the platform. The MakerBot 3D printer 5th generation, which is one of
the most popular desktop 3D printer in homes and offices print objects with a thermoplastic
28
called Polylactic acid (PLA). PLA plastics contribute to the good accuracy of this machine due to
its shrinkage and warping resistant. The machine utilizes only one extruder to print both the parts
and its supporting structures [127]. However, the supporting structures are only required for
printing overhangs and undercuts. Printing processes start with slicing of the STL file. The
machine then generates its geometrical model and supporting structure called the tool path [127],
through MakerWare software. The supporting structure is removed at the end of the fabrication.
In addition, some of the process parameters need resetting in order to achieve the desired parts.
The process parameters that affect fabricated parts in FDM printers are layer thickness
(resolution), deposition speed, percentage infill (loose or compact), number of shells, and
extruding temperature. Similar to other additive manufacturing (3D) processes, the machine
MakerBot replicator is designed to replicate any kind of intricate geometries. Nevertheless, for
the fact that this machine was unable to produce an Ionic Polymer Metal Composite (IPMC)
holder, which was the original goal of this project, there are limits to what the printer can
fabricate at minute scales. Section 7.1 discusses the IPMC and the design of a holder that
facilitates IPMC function as a microfinger.
7.1 Fabrication of IPMC holder
IPMC is an electro active polymer (EAP), which found use as a microfinger for
micromanipulation of micro objects due to its actuation under a low voltage. A holder is required
because the IPMC cannot function as a microfinger without a reliable housing (holder) that can
produce coordinated opening and closing of the fingers. The holder also contains four holes with
80-microns diameter each: two holes are for voltage connections while the other two holes are
for sensor, which senses deflection. A holder with a dimension of 400 x 300 x 50 microns was
designed to maintain a mechanical rigidity and electrical connectivity between the IPMC and a
Fig. 4. MakerBot desktop for slicing STL files.
29
wire. The two separate parts of the holder shown in Figure 5 will be assembled together with the
IPMC finger in the center to produce one microfinger of the microgripper. The two parts of the
holder will be fixed at the two sides of the finger’s base, including the four connections as
described above. The initial project to fabricate this holder changed because the MakerBot
replicator was not capable to fabricate the holder at the minute range. Since the initial goal of this
project was not feasible, there is a limit to the capability of the MakerBot replicator. Thus, a
characterization tools were developed to assess fully the performance and robustness of the
machine. Table 6 summarizes the full technical specification of the MakerBot replicator.
Holder
IPMC finger
Holder
Figure 5. Exploded view of IPMC finger with the holder
Table 6. Technical Specification of MakerBot Replicator Desktop 3D printer 5th Generation
Print Technology Fused Deposition Modelling (FDM)
Build volume 25.2L x 19.9W x 15.0H cm (9.9 x 7.8 x 5.9 inches
Layer resolotion 100 microns (0.0039 in)
Filament diameter 1.75 mm (0.69 in)
Software bundle MakerBot desktop software
Supported file types STL, OBJ, THING, MAKERBOT
Filament compatibility PLA
Nozzle diameter 0.4 mm (0.015 in)
Print file type .makerbot
Build surface Glass with blue tape
Connectivity USB, ETHERNET, WI-FI
Camera 320 x 240
XY position precition 11 microns (0.0004 in)
Z position precition 2.5 microns (0.0001 in)
30
The terms used are:
Slicing: Slicing is converting the 3D model into the form the machine software
understands. The generation of closely spaced 2D cross-sections of the 3D objects.
Raft: A raft is a surface built between the build plate and bottom of the part, which is
slightly bigger than the part to help avoid errors, by poor adhesion and warping.
Percentage infill: Percentage infill is the percentage of the inner volume of the part or the
internal structure of the part. For example, 0% infill makes the object completely hollow
while 100% infill makes the object completely solid
Number of shell: These are the outlines printed on each of the objects before infill is
printed.
Support Structures: Supports are breakaway vertical columns inserted to connect an
overhang to the build plate. Because the printer cannot print to thin air, a supporting
structure is needed to provide a base for an overhang feature. This is represented in
Figure 6. It can easily be broken away after building the object with a hand or a pair of
pliers.
Layer height (Resolution or slice height): Basically, layer height is the vertical or Z-
resolution in 3D printed objects. It defines how precisely our 3D model is converted into
a tool part (instructions) for the 3D printer
7.2 Methodology
To investigate the performance and process limit of this device, seven models were fabricated
using the MakerBot desktop 3D printer 5th generation. The test models contain samples of
geometric shapes and sizes that are commonly available on plastics, and most of these models
have features with decreasing dimensions as shown in Figures 7-11 and Table 7. The models
were produced with different process parameters to quantify a particular limitation as shown in
Support structures
Fig. 6. A structure with overhang
31
Table 8. More importantly, these parameters were chosen to make this machine produce the best
it can. All the models were designed using Solidworks CAD (Computer Aided Design) software
and were exported as STL files. Then the MakerWare software sliced the models, generated the
build model and its supporting structures. Netfabb-cleaning software was used to make sure that
none of the models had design errors [128].
Fig 7. CAD drawing of model 1.
Fig 8. CAD drawing of Model 2
32
Fig 9. CAD drawing of Model 3
Fig 10. CAD drawing of Model 4
Fig 11. CAD drawing of Model 5
33
Fig 12. CAD drawing of Model 6
Fig 13. CAD drawing of Model 7
Table 7. Features in the test Models 1-5
Model 1 (length) Model 2 (diameter) Model 3 (thickness) Model 4 (Wall thickness) Model 5 (diameter)
2 2 4 4 4
1.6 1.6 2 2 2
1.4 1.4 1.6 1.6 1.6
1 1 1.4 1.4 1.4
0.8 0.8 1 1.2 1
0.6 0.6 0.8 1 0.8
0.4 0.4 0.6 0.8 0.6
0.3 0.3 0.4 0.4 0.4
0.2 0.2 0.2 0.2 0.3
34
7.3 Results and discussions
All the models were fabricated and analyzed; there was a conscious attempt to choose process
parameters that provided the best performance of the device. These parameters include build
orientation, resolution, percentage infill, number of shells, extruding temperature, speed while
extruding, and speed while traveling. However, extruding temperature and speed were excluded
from this study because the temperature of the extruder has a fixed setting of 251 degree
Fahrenheit. According to the manufacturer, that is the optimum extrusion temperature to
maintain longevity of the extruder and also avoid some problems with the extruder such as
clogging, under extrusion, or over extrusion [129]. Bearing in mind that the main purpose of
these experiments is to investigate the minimum feature size printable with this device, most of
the process parameters were varied to figure out their contributions to the printed parts.
MakerBot MakerWare, which is the software that prepares the structure before sending it to the
printer, has three quick set profilesLow, Standard, and High. Both the resolution thickness and
rate of print of each profile is shown in Table 9. Generally, my results depend on the extruder
nozzle of this printer which is 0.4mm [130]. The 0.4mm nozzle diameter controls the layer
thickness on the XY-axis while the resolution or slice height controls the Z-plane (vertical axis),
and can always be adjusted down to 0.1mm. Using each model (models 1-5); I performed four
experiments (printing), which produced the results shown in Figures 14, 15a, and 15b.
Table 8. Model features and their purpose
Models Feature Purpose
1 Square holes Feasibility and accuracy
2 Circular holes Feasibility and accuracy
3 Square beams Feasibility and accuracy
4 Cylinder with a holes Feasibility and accuracy
5 Cylinder beams Feasibility and accuracy
6 Engine block Accuracy
7 A valve assembly Accuracy and surface finish
Table 9. Layer thickness (resolution or slice height) available in MakerBot replicator
Layer thickness (mm) Resolution Rate of print
0.3 Low Fast
0.2 Standard Average
0.1 High Slow
35
Fig 14. Printed structures of models 1, 2, and 5.
36
Fig 15a. Printed structures of models 3 and 4.
37
Fig 15b. Printed structures of models 3 and 4.
38
7.3.1 Minimum feature size and print capacity
Results from diagrams 14, 15a, and 15b revealed the minimum sizes of the common features this
device can produce. They are the features commonly found in every fabrication. Looking at all
the four experiments involving model 1, the minimum square hole printable by this device is 0.8
mm long (1A), no holes below this size were feasible. Change of build orientation on the fourth
experiment (1D) did not produce any better result. Similarly, the minimum printable circular
hole was a circle with 0.8mm diameter (2A and 2D); no holes below this size were feasible even
when the orientation was changed.
Furthermore, models 3, 4, and 5 shows that both resolution setting, number of shells and
percentage infill affect the quality of both square beam, hollow cylinder, and cylindrical beam as
shown in Figures 14 and 15b. Although the minimum square beam thickness printable from
model 3 was 0.8 mm (3B and 3C), a beam with 0.6 mm thickness was feasible when the build
orientation was changed (3D). This is because the change in the build orientation positioned the
beam thickness in the Z-direction, which is the direction that controls the resolution of the printer
[130]. Looking at experiment 3A with 2 shells and experiment 3B with 1 shell and 40% infill,
there is a hole at the center of the beams showing that for a thin wall, 1 shell and 100% infill are
required to obtain a perfect solid as seen in experiment 3C and 3D where the printed beams were
a perfect solid. Similarly, in model 4, all the wall thickness of the hollow cylinders was printed
out, but some of the wall thicknesses were very weak and open. In experiments 4B and 4C, the
minimum wall thickness printable with a perfect and airtight wall was the cylinder with 1 mm
wall thickness. Consistently with model 3, experiment 4A with 2 shells produced unexpected
results, as the wall did not form a perfect solid. However, 0.8 mm wall thickness was printable in
experiment 4D when the build orientation was changed and the wall thickness were positioned in
the Z-direction. Furthermore, cylindrical beams with 1mm diameter were feasible from
experiments 5A, 5B, and 5C while a cylindrical beam with 0.8 mm diameter was feasible from
Fig 16. Fabrication of model 6
Fig 17. Fabrication of model 7
39
experiment 5D when the build orientation was changed. Also agreeing to the statement that build
orientation affects the size of cylindrical beam printable from this machine.
Hence, MakerBot replicator is capable of producing a circular hole of 0.8mm diameter, a square
hole of 0.8 mm long, a square beam of 0.6 mm, a cylindrical hole of 0.8 mm thick, and a
cylindrical beam of 0.8 mm. Overall, MakerBot replicator can comfortably replicate any features
above 0.8 mm (800 µm) diameter or size. These results depend on the right choice of build
orientation, resolution, percentage infill, and number of shells. As shown from the results, 1
shell, 100%, and high resolution are required to obtain the expected results in printing small
holes and thin layers. In addition, it is recommended to place the wall thick in the Z-axis when
printing a feature with thin layers, in this way, high resolution of the machine will be able to
resolve the thin layers. Generally, these experiments revealed that the resolution setting has a
little influence on the feature size printable by this device.
Furthermore, this machine has a print capacity of 252 x 199 x 150 mm. It can produce any part
within this dimension without the need of dividing the part. MakerBot replicator can also print
several iterations of small parts at the same time provided the total dimension of the iteration
does not exceed the capacity given above. The capacity was determined by the printing of model
7 in Figure 17. Model 7 is a valve with six parts; the replicator was able to produce these parts at
one iteration.
7.3.2 Feature detail resolution and dimensional accuracy
Accuracy of this device was evaluated based on the following factorssharp edges and corner
definitions, circular hole definitions (circularity), and measurement of the square beams in model
3. The sharpness of the block edges decreases as the dimensions decreases as we can see in the
printed model 1 in Figure 14 and printed model 3 in the Figure 15. Imperfect edges start to
emerge from the fourth hole (1mm) and fourth square beam (1.4) of models 1 and 3 respectively.
Similarly, the circularity of the circles decreases as the diameter of the circle decreases. Poor
circularity started from the third round hole in model 2 (1.4mm). To further probe into the
accuracy of parts produced by this device, the dimensions of each printed square beams for all
the four experiments of model 3 were compared to the CAD (nominal) dimension. The
measurements were taken for the first five square beams (4, 2, 1.6, 1.4, and 1) mm using a digital
caliper as shown in Table 10. All the dimensions were obtained by averaging the five measured
values of each printed square. Positive deviations were seen in most of the measurements, which
was attributed to surface roughness. Experiments 1 and 2 (3A and 3B) produced the highest
positive deviation of 0.144 mm and a highest negative deviation of 0.04 mm. The negative
deviation is associated with an incomplete shape of the square beams. The beam shape becomes
irregular as the size decreases, which leads to decrease in the dimension. Experiments 3 and 4
(3C and 3D) produced the highest deviation of 0.332 mm. Increase in deviations in experiments
3 and 4 was due to increase in the surface roughness. Experiment 3 was performed with standard
resolution and hence has coarse surfaces. Similarly, experiment 4 was performed with a support
structure, which produces rough surface finishes of the printed structures.
40
7.3.3 Surface finishes (surface roughness)
Generally, the most obvious limitation of FDM machines, admitted by most users is poor surface
finish [131]. Parts printed with MakerBot replicator exhibit rough surfaces due to the extrusion
of semi molten plastic. It becomes worse when using standard or low resolutions due to the
passes of plastics made during the printing. Moreover, addition of supporting structure adversely
affects surface finish of a printed part. For example, the fourth experiments of models 3 and 4
(3D and 4D respectively) exhibit rough surface finish owing to the supporting structure utilized
in printing those parts. In addition, the effect of surface roughness can be illustrated with models
6 and 7 as shown in Figures 16 and 17. The major purpose of these models (6 and 7) is to
analyze both the surface finish, the effect of process parameters, and the general quality of a
typical structure fabricated with the machine. Model 6 is an engine block with certain
geometrical complexities. The print out was excellent; all the intricate edges, holes and corners
were perfectly fabricated. Nevertheless, surface finish of the structure deteriorates as the
resolution decreases. There is always a conflict between surface finish and print time. When
printing a complex structure like model 6, it takes between one and a half to two hours to
complete when printing with the highest resolution. Print time is approximately doubled from a
standard and tripled from a low-resolution print. To illustrate the influence of resolution on print
time, the time it takes to print model 6 at different slice heights is shown in Figure 18. To
balance these two factorsprint time and surface finish, it is acceptable to print with either a
slice height of 0.2mm (standard) or 0.15 mm. An acceptable surface finish is produced at this
slice height at limited period. Similarly, model 7 depicts the same problem of rough surface
finish. All the parts: body, cock, handle, nut, and plug were fabricated perfectly in one iteration.
However, the assembly did not fit in without post-processing, even when the parts were
Table 10. Deviations of test model 3 in different experiments
Norminal dimensions of the cubes 4 2 1.6 1.4 1
First experiment 4.124 2.124 1.7 1.388 0.96
Deviations 0.124 0.124 0.1 -0.012 -0.04
Second experiment 4.096 2.144 1.61 1.38 0.964
Deviations 0.096 0.144 0.01 -0.02 -0.036
Third experiment 4.182 2.332 1.874 1.662 1.272
Deviations 0.182 0.332 0.274 0.262 0.272
Fourth experiment 4.054 2.138 1.802 1.582 1.25
Deviations 0.054 0.138 0.202 0.182 0.25
41
fabricated with the highest resolution. Smoothening of the parts with a file was required before
the assembly can be feasible due to the surface roughness of the assembly parts.
7.4 Recommendation
Based on the current requirementprinters that fabricate both metals and plastics, I was able to
find two companies that have printers capable of multiple materials fabrication. Multi material
fabrications have two classifications. Some printers can print two materials at a time to produce a
printed alloyed structure aimed at improving the strength of the printed parts while very few
printers can print two different materials at different time to produce a plastic structure with
embedded electronic components made of different materials. This recommendation is based on
the later type of multi material fabrication. The only two technology that aids multi material
fabrication are Fused Deposition modelling (Fused Filament Fabrication) and Aerosol Jet
technology. In FDM, multiple nozzles are easily integrated into the system to allow multiple
materials deposited at different time during the fabrication. However, this type of multi material
fabrication is not feasible in other processes, for example Stereolithography, Selective Laser
Sintering, and Laminated Object Manufacturing because the materials are delivered as a whole
layer as a solid sheet. It is very difficult to make multi material using the current configuration of
those technologies. Voxel8 and Optomec Company manufacture the printers compared in the
table 11.
Voxel8 is the company that manufactures Developers Kit using Fused Filament Fabrication
(FFF) and Pneumatic Direct Write technology. FFF is a similar technology as FDM; it is called
Fig 18. Print time comparison for different parameter slice settings
42
FFF to avoid trademark issues with “FDM” term. Direct Write technology uses compressed air
to drive ink flow out of a cartridge, enabling controlled volumetric flow of conductive ink to a
substrate. With Voxel8’s printer, we can co-print matrix materials such as thermoplastics and
highly conductive silver inks enabling customized electronic devices. FDM prints the structural
part while the direct writing (DW) prints conductive inks on the part.
Optomec is the manufacturer of all the Aerosol Jet printers (Aerosol Jet 5x, 300 series, and 200
series) using their commercialized Aerosol Jet technology. Aerosol Jet technology have a unique
ability to print fine-feature electronic on any structural material for example polymer. The
process precisely deposits electronic and other materials in dimensions ranging from 10 microns
up to centimeter scale utilizing aerodynamic focusing. Aerosol Jet system supports a wide
variety of materials, including conductive inks, polymers, insulators, and adhesives. Based on
our need (micro scale IPMC holder) and the specifications of these machines, Aerosol Jet
printers will better execute our project due to the high resolution of the machines. The entire
Aerosol Jet machines have the same resolution. The only difference is the accuracy and precision
of the machines; the more expensive printers have better accuracy and precision.
Table 11. Multi materials 3D printers (Metal and plastic)
43
8.0 CONCLUSION
Three-dimensional printing has become advanced not only in the manufacturing industry, but
also in medicine, aerospace, electronics and so on. As advancements in the technology and
discovery of new materials expand the areas of application of this technology, it found limited
application in the MEMS industry. With the recent successes in micro three-dimensional
printing, the technology has been utilized in manufacturing of different micro systems such as
microelectromechanical systems (MEMS), micro-opto-electro-mechanical systems (MOES), and
micro-optical electronics systems (MOES). Most interestingly, some 3D printers are now
developed and customized specifically for a particular application. For example, 3D Systems has
developed and customized their ProJet 3510 DPro printer for printing high volume precision
dental wax-ups, implant drill guides, orthodontic patterns, and crown bridge models. In addition,
Voxel8 has customized their printers only for printing electronics. With this current trend, 3D
printing will soon be the major manufacturing method in so many companies. Notwithstanding
the capabilities of 3D printers, there is always a limit to its functionalities as we observed from
the characterization of the MakerBot replicator. I chose to characterize this machine because it is
the most used 3D printer with FDM technology. Moreover, the characterization was necessary
due to the inability of the machine to fabricate a micro holder for the IPMC microfinger. In the
characterization of this device, several experiments were conducted in order to determine the
strengths and weaknesses of this machine as well as the effects of varying the process parameters
of the machine. After all the analysis, some conclusions were drawn from the experiments.
Firstly, the minimum printable square hole and round hole with this device is 0.8 mm long and
0.8mm diameter respectively. Accordingly, it is very important to understand the influence of
build orientation on a printed part; desired structures are obtained only with the right deposition
orientation. Generally, it is highly recommended to use high resolution only when perfect surface
finish or thin wall is necessary, and use standard resolution in every other print. Moreover,
standard resolution will not only produce a good print, but also will be a tradeoff between the
print time and surface finish.
Secondly, the minimal printable square beam and cylindrical wall thickness with this device is
0.8mm long and 0.8mm thick respectively. Apparently, FDM machines are more efficient when
the effect of build orientation on every object is understood. Analysis showed that the MakerBot
replicator is producing structures with a maximum deviation of 0.33mm. It is assumed that this
Figure 19. Minimum IPMC holder
printable with MakerBot replicator
44
deviation was because of the rough surface finish, which is common with FDM printers.
Moreover, number of shells as well as percentage infill affects fabrication of thin layers.
Although two shells are the minimum number required for a perfect print, but 1 shell and 100%
infill are required when printing very thin layers such as 1mm.
Admittedly, FDM is not good for thin layers, especially when good surface finish is necessary.
FDM also leads to long post processing operations when printing assembly parts due to
deviations and rough surface finishes. Obviously, from these experiments, the major problems
with FDM technology are the need for supporting structures, inability to print thin layers, and
rough surface finish. Although the supporting structures can be removed by hand or pliers, the
supports sometimes affect the main structure, especially structures with thin layers. Possible
solutions to this problem include manipulating the build orientation in order to avoid the use of a
supporting structure. In addition, a software, meshmixer, is also used to generate custom
supporting structures. Custom supporting structure is more efficient because it allows the
designer to generate supports in the preferred positions where the supports can easily be removed
after printing. Overall, 3D Systems’ PolyJet 1200 printer is recommended for the fabrication of
the IPMC holder. With micro Stereolithography technology, this machine can produce a holder
at the required feature size.
Finally, this work has provided information relating to the capabilities and limitations of
MakerBot replicator 3D printer and FDM technology in general. The direct implication of this
work is the information provided in choosing the appropriate 3D printer and the best process
parameters that can effectively print our desired objects. Generally, selecting the appropriate 3D
printer for a particular application is challenging. Discovering both strengths and weaknesses of
a 3D printer can be difficult without hands on experience. However, this report provides some
useful knowledge in selecting the right tool for our intended application or project. Furthermore,
three major areas of considerations that help in selecting the right process are intended
applications, operational constraints of the machine and physical properties of the printed parts.
Above all, the MakerBot printer, and Fused Deposition Modelling in general, is used for printing
large parts out of plastics or parts where surface finish is not a big concern. It can also be used
for complex features, undercuts, and complex internal features. However, when producing parts
with thin layers out of any material other than plastics, MakerBot replicator is not the right
machine.
45
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Chapter
Most AM processes require post-processing after part building to prepare the part for its intended form, fit and/or function. Depending upon the AM technique, the reason for post-processing varies. For purposes of simplicity, this chapter will focus on post-processing techniques which are used to enhance components or overcome AM limitations. These include: