Content uploaded by Wojciech Presz
Author content
All content in this area was uploaded by Wojciech Presz
Content may be subject to copyright.
© Copyright by International OCSCO World Press. All rights reserved. 2006
VOLUME 18
ISSUE 1-2
September–October
2006
Short paper 411
of Achievements in Materials
and Manufacturing Engineering
of Achievements in Materials
and Manufacturing Engineering
Piezoelectric driven Micro-press
for microforming
W. Presz a,*, B. Andersen b, T. Wanheim c
a Institute of Materials Processing, Warsaw University of Technology,
ul. Narbutta 85, 02-524 Warsaw, Poland
b Noliac A/S, Hejreskovvej 18, 3490 Kvistgaard, Denmark,
c Dpt. of Manufacturing Engineering and Management,
Technical University of Denmark, 2800 Lyngby, Denmark
* Corresponding author: E-mail address: w.presz@wip.pw.edu.pl
Received 15.03.2006; accepted in revised form 30.04.2006
Manufacturing and processing
Purpose: Progressive miniaturisation generates necessity of micro-parts production also on the field of metal
forming. At present small pats are produced with a big presses which were designed for manufacturing much
bigger products. Further miniaturisation will not make possible to keep sufficient tolerances of products
manufacturing with these standard presses.
Design/methodology/approach: It is suggested to set up special technological lines for micro-parts production.
Such lines would consist of micro-machines based on piezoelectric actuators. The recent development of that
kind of actuators assures even up to several kilo-Newton forces and movement accuracy theoretically in atomic
scale. As a step for building the line, a micro-press with piezoelectric drive is being constructed.
Findings: The constructed press can work with direct actuator and can be also equipped with simple mechanical
movement amplifier. Micro-indenting, micro-pressing and micro-backward extrusion were successfully carried
on the press. Examples of simple sequentional and incremental micro-forming processes were also performed.
Research limitations/implications: Equipping Micro-press with additional devices like x-y or x-y-z table
positioning, automatic clamping and supplying systems etc. will able to extend its application to wide range of
microforming processes.
Practical implications: Micro-press in intention is going to be a part of industrial micro-lines for micro-
product.
Originality/value: The idea of building micro-parts with micro-machines standing as production micro-line
seems to be quite natural but so far not realised. Presented Micro-press with original construction is another
step to put this idea into reality.
Keywords: Plastic forming; Microforming; Micro-press; Piezo-driving
1. Introduction
The general trend towards higher integrated functional density
in electronic and micro-mechanical components as well as the
increasing application of micro-systems in many technological
fields is still unbroken. It means that for the production engineers
more and more geometrically complicated and smaller parts have
to be designed and manufactured. Most of such parts called mini
or micro parts, have been used in electronics and bio-medical
applications which are the main fields of interest in large
miniaturization. This tendency demands serious modification of
well-known processes, to execution of which experience collected
through years seems to be inadequate. One of such technologies is
a technology of metal forming. A stormy development of its, in
Short paper
412
Journal of Achievements in Materials and Manufacturing Engineering
W. Presz, B. Andersen, T. Wanheim
Volume 18 Issue 1-2 September–October 2006
principle new branch which is plastic micro-forming, is observed.
Considerable diminishing sizes of products causes, that this
technology gathers of completely new dimension and enters in yet
weakly recognized areas of knowledge [1,2,3]. On the other hand
many laboratories all over the World carry on intensive
investigations of replacing technologies such etching, electro-
embossing or laser cutting with metal forming technology. It is
obvious that correctly driven cold metal forming process allows to
obtain large dimension accuracy, very good surface quality and
high strength proprieties of product [4]. This is opposite to
product properties that can be reached with previously mentioned
methods based on material removing. Additionally the new nano-
materials and ultra-fine grain materials give for micro forming the
new opportunities [5,6]. Fig.1 shows free surfaces of micro
products manufactured with forward extrusion process. In case a
the billet material was standard 1070 aluminium whether on case
b the ultra fine grain (grain size about 0.6 µm) 1070 material was
used. Metal forming is besides low material consuming and
environment friendly technology. Nowadays most of all micro-
parts are produced with technologies originally dedicated to
considerably bigger products. Production is performed with
presses and tooling with installed numbers of punches. An
example of part - diode support and tooling for its production is
shown in fig.1. It is manufactured with 10 tons eccentric press.
xHow it is possible, that so large machine is used to production
of so small component?
Most probably, the reason is very simple. Technologies for
Industry orders were worked out to fit to already existing
technological lines and machines, but orders refer to smaller and
smaller parts. In result, brought this to so great differences in sizes
of machines and produced by them components.
xHowever will it be possible at further miniaturisation to
maintain indispensable dimension accuracy using hitherto
existing machines?
Fig. 1. Typical tooling for manufacturing diode connector from
0.2 mm sheet metal
Most probably, not! Setting up special technological lines
consisting from micro-machines to aim at manufacturing of
micro-parts only, seems to be a solution. Micro-press (M-press)
designed and constructed within this project is a step on the way
for this goal.
2. Concept of Micro-press
In intention, micro-press is a unit of computer controlled
production line of micro-parts [7]. Kinematics of press is based
on modern stacked multilayer ceramic actuators –SMCA [8].
Stormy development of this kind of piezoelectric materials is
observed from a dozen of years [9]. These actuators mastered
almost completely devices in which precise controlling of
movement is required [10]: discs controllers, computer printers,
manipulators, micro-switches, video cameras and many other.
Since actuators refer to the effect of crystal shape changing under
influence of voltage their movement accuracy is in atomic scale.
It makes them perfectly suitable to utilisation in micro and nano-
technologies. Good examples are piezo-driven systems for
microforming as system for micro-extrusion [11] and system for
creation of surface micro-geometries [12]. On the other hand it is
now possible to design and manufacture piezo-actuators acting
force as big as 25 kN [13]. Schematic diagram of M-press shows
Fig.2. Base units of it are: frame with installed Piezoelectric
Executive Unit PEU that works as a ram of M-press and table also
driven with piezoelectric actuators. Movement of PEW and table
with a help of displacement transducers controls computer. M-
press is equipped with microscope with digital camera making
possible observation of working space. This optical system might
be also used to superintending of technological process.
Fig. 2. Schematic diagram of M-press: 1- frame, 2- piezoelectric
executive PEU, 3- piezoelectric stack, 4- punch, 5- table, 6-
piezoelectric stack, 7- slug, 8- displacement transducer, 9-
displacement transducer, 10- microscope with CCD camera
Fig. 3. M-press: a) with direct piezoelectric executive unit, PEU:
1- piezoelectric stack, 2- rubber washer, 3-ball joint, 4-springs, 5-
punch, b) with amplified PEU : 1- piezoelectric stack, 2-
displacement amplifier, 3- PEU body, 4- springs, 5- punch, d)
amplified PEU position
413
Manufacturing and processing
Piezoelectric driven Micro-press for microforming
3. Construction of Micro-press
Modernised standard 4 pins guide die set with sliding runners
is used as a frame of press. Upper plates position is fixed with
buffers in dependence from required process. Executive unit uses
especially for this press constructed SMCA of dimensions
10x10x140 mm. This unit is designed in two variants which use
the same stack and can be easy transformed. In first variant
SMCA works direct, fig.3a, and in second as Amplified SMCA
with 4 times mechanical movement amplifier, fig.3b. In this
construction mechanical amplification based was chosen however
there are also known in such devices hydraulic amplifications
[14]. Both variants of PEU are assembled on frame of press in
manner shown in fig. 3.
Fig. 4. Micro-indenting process recorded with CCD camera
Outline press dimensions are 200 x 200 x 350 mm and
dimensions of die sets space are 70 x 70 x 90 mm. Working Space
can be observed by microscope equipped with CCD camera
connected to PC. Special software permits to registration of
process course. Several phases of micro-indenting process
recorded with it are shown in fig. 4. General view of experiment
stand shows fig. 5. For investigations press was additionally
equipped with for that purpose especially designed strain gauges
dynamometer connected with PC computer that let to measure
and record process force.
Fig. 5. Overview of experiment stand with Micro-press
M-press with direct PEU was tested to obtain two
experimental characteristics: voltage-displacement and voltage-
force, fig.6. Based on them there was calculated force-
displacement characteristic, fig.7 which delimitates press
application.. Second variant PEU with mechanical displacement
amplifier causes lineal change of force-displacement
characteristic. In this case the admissible displacement enlarges 4
times and admissible force diminishes also 4 times.
Fig. 6. M-press experimental characteristics
Fig. 7. M-press functional characteristic
General view of experiment stand shows fig. 5. M-press with
direct PEU was tested to obtain two experimental characteristics:
voltage-displacement and voltage-force, fig.6.
Fig. 8. Component after process steps: blanking, closed-die pressing
and backward extrusion
For investigations press was additionally equipped with for
that purpose especially designed strain gauges dynamometer
connected with PC computer that let to measure and record
process force. Based on them there was calculated force-
displacement characteristic, fig.7 which delimitates press
application.
Second variant PEU with mechanical displacement amplifier
causes lineal change of force-displacement characteristic. In this
case the admissible displacement enlarges 4 times and admissible
force diminishes also 4 times.
4. Application of Micro-press
M-press is suitable to perform in the small scale practically all
cold metal forming processes that are possible to perform with big
presses. An example for M-press application is pressing process
Short paper
414 READING DIRECT: www.journalamme.org
Journal of Achievements in Materials and Manufacturing Engineering Volume 18 Issue 1-2 September–October 2006
followed than with backward extrusion of preliminary punched
aluminium disk. Components after each step and cross section of
finally extruded cup are shown in fig.8. Extrusion process force
recorded with M-press dynamometer shows Fig.9. Equipping of
M-press with computer controlled and piezoelectric-driven x-y
table allows to system to be used in sequential metal forming
processes.
Fig. 9. Force in micro-extrusion process
This group of processes lies on step by step coming
deformation of only limited area of slug that results in
deformation of all planed volume. In preliminary experiments
only one direction driven table with manual control was used to
perform two kind of sequential processes: Creation of surface
pattern. (This kind of surface treatment consists in performing of
sequential stamping with shaped punch, fig.9a.) and incremental
micro-indenting, fig. 9b. Second process consists in sequential
indenting according to precise, computer controlled sequence of
deformation steps performed with shaped punch in such a way
that it leads to create of practically any shape cavity.
Fig. 10. Sequential forming: a) surface pattern creation , b) cavity
forming
M-press might also be used for incremental microforming of
foil materials [15]. These processes are planed for a future
investigations.
5. Conclusions
xThe idea of building production lines dedicated to small,
micro and even nano-products from the metal forming area
that consists of new piezoelectric driven micro-machines has
been presented
xMicro-press based on piezoelectric executive unit was design,
construct and tested. It was proved that press is suitable for
performing different micro-forming processes.
xMicro-press equipped with x-y table and controlled with
computer system is able to carry on a new* group of
deformation processes – sequential forming.
* the idea of sequential forming is certainly well known, but
synchronizing x-y movement of press table with a movement of
press ram will open new possibilities.
Acknowledgements
The Polish State Committee for Scientific Research partially
suppoted this research under contract No. 1508/T07/2004/27.
References
[1] M. Geiger, A. Messner, U.Engel: Production of micro parts –
size effects in bulk metal forming, similarity theory,
Production Engineering. Vol. IV/1, 1997, p 55-58
[2] M. Geiger, F.Vollertsen, R. Kals: Fundamentals of the
manufacturing of sheet metal microparts. Annals of the CIRP,
Vol. 45/1/1996
[3] U. Engel, A. Messner, N. Tiesler: Cold forging of micro parts
- effects of miniaturization on friction, Proceedings of
ESAFORM Conference, (1998) 77-80
[4] W. Presz: The influence of punch vibration on surface
phenomena in micro-extrusion, Proceedings of ESAFORM
Conference, (2006), to be published.
[5] A. Rosochowski, W. Presz, M. Olejnik. and M. Richert,
Micro-extrusion of ultra-fine grain aluminium, In: Multi-
Material Micro Manufacture 4M2005, eds, W. Menz and S.
Dimov, Elsevier, Oxford (2005) 161-164.
[6] W. Presz, A. Rosochowski: The influence of grain size on
surface quality of microformed components, Proceedings of
ESAFORM Conference, (2006), to be published
[7] W. Presz: Piezoelectric driven machine for micro-indenting
process, Project 503 G/0337/002 rapport, Material Processing
Institute of Warsaw Univ. of Technology, Warsaw 2003
[8] Noliac A/S – www.noliac.com
[9] C. Niezrecki et al.: Piezoelectric Actuators: State of the Art.
The Shock and Vibration Digest. Julv 2001.
[10] F. Claeyssen at al.: Piezoactuators and piezomotors for high
stroke/precise positioning applications. Adaptonic Congress
99. Conference Proceedings. Potsdam, March 3-4, 1999.
[11] S. Yasunori, I. Hiroyuki: Superplastic backward micro-
extrusion of microparts for micro-electo-mechanical systems.
Jour. of Mechanical Proc. Technology 119, (2001).
[12] M. Rosochowska: et al.: Flexible Tool System for Creation of
Surface Micro- Geometries. 4M First Int. Conf. on Multi-
Material Micro Manufacture. 29.06-1.07.2005, Karlsruhe,
Germ.
[13] W.Presz et al.: Application of piezoelectric actuators in
pressing process with vibrating tools, Conf. Proc. of
KomPlasTech 2005, 155-162
[14] A. Hess: Piezoelectric Driven Press for Production of Metallic
Microparts by Forming. "Actuator 2000",7-th Int. Conf. on
New Actuators, 19-21 June 2000. Bremen, Germany.
[15] S. Yasunori, O. Takeshi: An in-situ incremental microforming
system for three-dimensional shell structures of foil materials,
Journal of Material Processing Technology 113, (2001).
