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For parts produced by fused filament fabrication (FFF) the adhesion between the first printed layer and the printing bed is crucial, since it provides the foundation to the subsequent layers. Inadequate adhesion can result in poor printing quality or destroyed bed surfaces. This study aims at understanding and optimising the adhesion process for parts produced by FFF. The consequences of varying printing bed temperatures on the adhesion of two commonly used printing materials on two standard bed surfaces were investigated by means of an in-house built adhesion measurement device and complemented by contact angle measurements. This study shows a significant increase in adhesion forces, when printing parts at a bed temperature slightly above the glass transition temperature of the printing material.
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Plastics, Rubber and Composites
Macromolecular Engineering
ISSN: 1465-8011 (Print) 1743-2898 (Online) Journal homepage: http://www.tandfonline.com/loi/yprc20
Effect of the printing bed temperature on the
adhesion of parts produced by fused filament
fabrication
Martin Spoerk, Joamin Gonzalez-Gutierrez, Janak Sapkota, Stephan
Schuschnigg & Clemens Holzer
To cite this article: Martin Spoerk, Joamin Gonzalez-Gutierrez, Janak Sapkota, Stephan
Schuschnigg & Clemens Holzer (2017): Effect of the printing bed temperature on the adhesion
of parts produced by fused filament fabrication, Plastics, Rubber and Composites, DOI:
10.1080/14658011.2017.1399531
To link to this article: http://dx.doi.org/10.1080/14658011.2017.1399531
© 2017 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
Group
Published online: 08 Nov 2017.
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Effect of the printing bed temperature on the adhesion of parts produced by
fused filament fabrication
Martin Spoerk , Joamin Gonzalez-Gutierrez , Janak Sapkota , Stephan Schuschnigg
and Clemens Holzer
Polymer Processing, Montanuniversitaet Leoben, Leoben, Austria
ABSTRACT
For parts produced by fused filament fabrication (FFF) the adhesion between the first printed
layer and the printing bed is crucial, since it provides the foundation to the subsequent
layers. Inadequate adhesion can result in poor printing quality or destroyed bed surfaces.
This study aims at understanding and optimising the adhesion process for parts produced by
FFF. The consequences of varying printing bed temperatures on the adhesion of two
commonly used printing materials on two standard bed surfaces were investigated by means
of an in-house built adhesion measurement device and complemented by contact angle
measurements. This study shows a significant increase in adhesion forces, when printing
parts at a bed temperature slightly above the glass transition temperature of the printing
material.
ARTICLE HISTORY
Received 28 April 2017
Revised 1 September 2017
Accepted 28 October 2017
KEYWORDS
Additive manufacturing;
fused filament fabrication;
adhesion; polylactic acid;
acrylonitrile butadiene
styrene; contact angle
measurements; morphology;
glass transition temperature
Introduction
Fused filament fabrication (FFF) or fused deposition
modelling (FDM) is an extrusion-based additive man-
ufacturing technique, which relies on the extrusion of
thermoplastic filaments to produce a three-dimen-
sional object in a layer-by-layer manner [1]. The
adhesion of the first printed layer onto the printing
bed is critical, as without proper adhesion the final
part cannot be built [2]. Inadequate adhesion results
in poor-quality printed objects, likely due to shifts,
warps or delaminations of the object during the print-
ing process [3]. Therefore, the adhesion between the
extruded polymer and the printing bed should be
high enough to keep the printed object in place during
printing. On the other hand, after printing the
adhesion should be low enough so that the part can
be removed easily from the printing bed without dama-
ging the produced part and the bed surface [4].
FFF printers are commonly composed of printing
beds made of glass or polymers [2]. The printed objects
are supposed to adhere consistently onto these sur-
faces. However, this is not always the case. Thus, to
improve the adhesion of the first layer to the printing
bed, several things are recommended: (i) to clean the
printing surface to remove grease and residues from
the bed; (ii) to level the printing bed so that the first
layer is in close contact with the printing bed; (iii) to
cover the printing surface with polymeric films or
tapes like polyimide (PI) or blue painters tape; (iv) to
slightly increase the tape surface roughness by sanding
it; (v) to apply water-soluble glues, hair sprays or
special coatings; (vi) to print on a plate or film of the
same material that is being printed; (vii) to print on
cleated surfaces; and (viii) to increase the temperature
of the printing bed to a recommended value for a given
material [2,3,57].
Methods (iii) are known prerequisites done before
every printing. Methods (iiivii) require the appli-
cation of additional materials on the printing bed,
which may be difficult to apply. Based on our experi-
ence, the risk of uneven printing bed surfaces caused
by overlapping seams, folds, creases or air bubbles, is
drastically increased when using methods (iiiiv). In
this context, one practical solution is to increase the
bed temperature to improve the adhesion of the
printed material onto the printing bed during print-
ing. However, directly after printing, a non-destruc-
tive removal of the printed part may not be
attainable at this bed temperature. If the occurrence
of welding can be precluded, it may be favourable
in this regard to cool the printing bed first to a certain
temperature, at which the adhesion forces are suffi-
ciently reduced. Two main problems arise. The first
problem is to determine this operational temperature
range, whose upper limit, effective during the print,
ensures sufficient adhesion during printing, and
© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-
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built upon in any way.
CONTACT Martin Spoerk martin.spoerk@unileoben.ac.at Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, Leoben 8700,
Austria
PLASTICS, RUBBER AND COMPOSITES, 2017
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whose lower limit, adjusted after the completion of
the print, provides little adhesion for the removal of
the part. Second, the determination of the best
material combination of the printing bed and the fila-
ment is critical, e.g. to avoid excessive welding,
especially when using novel materials.
So far, no study revealed any strategies on identify-
ing an optimal printing bed temperature range for var-
ious materials and its effect on the adhesion of samples
produced by FFF in a systematic manner. For this
reason, the present work attempts to close this gap by
evaluating the adhesion forces by means of an in-
house developed device that measures the forces
required to shear-off printed strands from printing sur-
faces at different temperatures. Using this device, the
effect of temperature on the adhesion of two com-
monly used printing materials, namely acrylonitrile-
butadiene-styrene (ABS) and polylactic acid (PLA)
onto two different printing surfaces (glass and PI)
was investigated. Moreover, these measurements were
complemented by surface tension measurements and
morphology analyses of the topography of the contact
area. The systematic approach in the present work
illustrates an efficient way to optimise the adhesion
of different printing materials on various printing
bed materials. Especially for novel material com-
pounds, this methodology is of great importance for
a reliable printing process.
Experimental
Materials
PLA and ABS filaments with a mean diameter of
1.75 mm were used as printing materials. A glass mir-
ror and a PI film, glued to the glass, were used as print-
ing bed materials. All the materials were supplied by
Prirevo e.U., Austria, and used as received. Unless sta-
ted otherwise, their most important properties are
summarised according to the suppliers data sheet in
Table 1.
Printer settings
A Hage 3DpA2 (Hage Sondermaschinenbau GmbH &
Co. KG, Austria) with a brass nozzle of 0.5 mm in
diameter was used for the production of the adhesion
test specimens (see section Adhesion measurement).
A constant extrudate flow rate of 2 mm
3
s
1
and a
printing speed of 50 mm min
1
were kept constant
for all specimens. As the adhesion of printed parts is
dependent on the first layer height [5], the layer thick-
ness of the first layer was set constant to 0.2 mm. For
PLA and ABS die temperatures of 220 and 255°C
were used, respectively. The bed temperature was var-
ied between 30 and 120°C (measured with reference to
the metal surface below the printing bed) with a step of
10 K. The heaters for the printing bed are located
underneath the metal surface below the printing bed
and they were controlled by the pre-installed heating
system of the Hage 3DpA2.
For each material at a given set of conditions, 16
strands were printed, in which each strand was
100 mm in length and consisted of three layers, result-
ing in a total height of 0.6 mm. The width of each layer
is in the range of 1.65 and 1.9 mm and is independent
of the bed temperature. The distance between adjacent
strands was 12 mm. In order to obtain well repeatable
results, the printing bed was levelled perfectly before
each test and the distance between the nozzle and the
printing bed was checked to be constant at every
point on the bed before starting a print.
Adhesion measurement
The adhesion forces between the 3D-printed strands
and two printing bed materials were measured by
means of a self-developed shear-off force testing device
(Figure 1(a)) directly mounted on the printing bed. For
each measurement series, the printing bed was pre-
heated for at least 30 min. Before the print was started,
the possibly aged material in the die was removed, and
the printing bed was cleaned residue-free with the
cleaning agent Arecal (Reca, Austria). After the com-
pletion of the print of 16 strands (see section Printer
settingsfor the detailed settings), the bed temperature
was kept constant by the heaters under the building
platform and the regulation of the printing bed. The
shear-off force testing device was fixed on each corner
of the printing bed by means of clamps to prevent any
relative movement of the device, while shearing off the
printed strands. The testing device was pre-heated for
5 min on the printer in order to prevent warpage,
which can critically influence the measurements.
Before the measurement started, the metallic shearing
block ((2) in Figure 1(a)) was adjusted depending on
the printing bed material so that the vertical distance
of 0.1 mm between the shearing block and the printing
bed remained constant for the whole measurement
area. Each strand was tested separately. For each
measurement, the metallic shearing block moved hori-
zontally over the printing bed at a constant speed of
2mms
1
and sheared-off one printed strand. The
Table 1. The glass transition temperature T
G
, the density ρ, the
specific heat capacity at constant pressure C
P
and the thermal
conductivity λof the materials investigated.
Properties
Materials
PLA ABS Glass PI
T
G
a
(°C) 60.6 110.1 348.6
ρ(kg m
3
) 1250 1004 2200
C
P
(J kg
1
K
1
) 1900 1800 750
λ(W m
1
K
1
) 0.180 0.127 1.400
a
T
G
was characterised by means of differential scanning calorimetry on a
Mettler Toledo DSC 1 equipped with a gas controller GC 200 (Mettler
Toledo GmbH, Switzerland).
2M. SPOERK ET AL.
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tested strand was then manually removed from the
printing bed before the subsequent strand was tested.
At the beginning of each measurement, the shearing
block was retracted to guarantee that a lateral distance
of 12 mm between the shearing block and the next
strand was preserved to ensure similar load cell con-
ditions in every measurement. The forces, measured
by a miniature load cell (U9C 1 kN, Hottinger Baldwin
Messtechnik GmbH, Germany) ((3) in Figure 1(a)),
were displayed as a function of the displacement
(Figure 1(b)), which was measured by an inductive dis-
placement transducer (W100, Hottinger Baldwin Mes-
stechnik GmbH, Germany) ((7) in Figure 1(a)). The
analog data from the force and displacement sensors
were collected at 300 Hz with a Spider 8 Data Acqui-
sition System (Hottinger Baldwin Messtechnik
GmbH, Germany) and the software CatmanAP
V3.5.1 (Hottinger Baldwin Messtechnik GmbH, Aus-
tria). A zero-force baseline was set for each measure-
ment. For each setting (section Printer settings), the
force maxima of the 16 tested strands were evaluated
to a significance level of 5%.
Contact angle measurements
Contact angle measurements were performed with a
Krüss DSA100 (Krüss GmbH, Hamburg, Germany)
at different temperatures. Prior to the surface analysis,
ABS and PLA were pressed to plates (160 × 160 ×
2mm
3
) in a Collin P200PV vacuum press (Dr. Collin
GmbH, Germany) at 200°C for PLA and 270°C for
ABS, and 150 bar for 25 min. As printing beds, the
glass mirror and the PI film were investigated. The
resulting contact angle between each material and the
test-liquids 1-Bromonaphthalene (CAS 90-11-9) and
Ethylene carbonate (CAS 96-49-1) was measured. Fif-
teen repetitions were performed per combination, in
which the propagation of uncertainty was considered.
In all graphs, the corresponding error is displayed.
The results were evaluated as described in [8,9]. For
the contact angle measurements at higher tempera-
tures, the contact temperature between the printing
die and the printing bed was calculated as:
TContact =TF·
l
F·
r
F·CP,F
+TB·
l
B·
r
B·CP,B

l
F·
r
F·CP,F
·
l
B·
r
B·CP,B
,
(1)
in which T
Contact
is the contact temperature, T
F
and T
B
are the filament and printing bed temperatures, λ
F
and
λ
B
are the thermal conductivities of the filament and
the bed material, ρ
F
and ρ
B
are the densities of the fila-
ment and the bed material, and C
P,F
and C
P,B
are the
specific heat capacities at constant pressure of the
Figure 1. Schematic of the adhesion force testing device (a) and an illustration of a typical test sequence by means of a graph
representing the measured adhesion forces as a function of the displacement and a sketch of the corresponding measured strands
on the printing bed (b). In (a) the components of the measuring device are labelled: (0) printing bed, (1) gliding frame, (2) metallic
shearing block with linear bearings, (3) force transducer, (4) stabilising bar, (5) displacement screw, (6) transmission gear, (7) dis-
placement transducer, (8) motor and (9) printed strands. In (b) the geometry of the shearing block (rectangular element with the
horizontal arrow), the strands and the printing bed are shown schematically in a lateral and top view along with the most important
dimensions.
PLASTICS, RUBBER AND COMPOSITES 3
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filament and the bed material. The obtained values
necessary for the calculation of T
Contact
are summarised
in Table 1. For T
Contact
of the PI film, the values for λ
B
,
ρ
B
and C
P,B
are taken from the glass mirror, as the PI
film with a thickness of 0.05 mm has an insignificant
effect on T
Contact
. For further reference, the tempera-
ture refers to the printing bed temperature.
Microscopy
The contact surfaces of selected printed strands were
analysed in the optical microscope Olympus BX51
(Olympus Life Science Europe GmbH, Germany) at a
magnification of 50× under reflected light. The speci-
mens were used after testing their adhesion forces
(section Adhesion measurement) without further
modification.
Results
Adhesion forces
The adhesion forces for both PLA (Figure 2(a)) and
ABS (Figure 2(b)) show a strong dependence on the
printing bed temperature. In the case of PLA printed
on both bed materials (Figure 2(a)), up to a bed temp-
erature of 60°C a steady rise in the adhesion force is
observed. This increase can be attributed to an
enhanced chain mobility of the deposited filament
with higher temperatures [10,11]. A point to highlight
is the strong increase in the adhesion force as the temp-
erature of the printed bed augments from 60 to 70°C.
For PLA printed on PI the adhesion forces rise from
51 ± 8 to 322 ± 47 N, whereas the measured forces on
glass are enhanced even more, from 73 ± 19 to 651 ±
17 N. This is related to the glass transition temperature
(T
G
) of the printing material (60.6°C for PLA). Around
the T
G
, the segmental mobility of macromolecules is
the highest for a material, which might result in
enhanced adhesion between polymeric surfaces and
other materials [10,12]. When the segmental mobility
is increased, segments of the polymer chains can dif-
fuse into the interface and the amount of adhesion is
dependent on the extent of interdiffusion and chain
interpenetration into the interface [13].
As the temperature keeps increasing beyond 70°C,
the adhesion forces drop independent of the printing
bed material to roughly 5060% of the forces for a
bed temperature of 70°C. The described decrease can
be attributed to the changed interaction between the
molten polymer and the printing surface. A higher
negative Laplace pressure is generated, which drags a
large amount of polymer to some parts of the interface,
while other parts are underfilled. Such changes in
pressure can lead to what is referred as fingering or
SaffmanTaylor instabilities, which are wavy undula-
tions at the periphery of the contact area that can
decrease the adhesion force [14]. For the PLA printed
onto the glass, the adhesion forces reach a plateau
after 80°C. For the PI film, the behaviour is more com-
plex, since the PI is also a polymeric material and its
segment mobility increases with temperature [15].
Therefore, a continuous increase in the adhesion
force is observed as the temperature increases from
80 to 100°C. Measurements beyond 100°C were not
possible, because the adhesive used to glue the PI
film onto the glass failed at these high temperatures
and measured forces.
The adhesion behaviour of ABS printed onto the
glass or PI film exhibits a similar trend to that of PLA.
The adhesion forces increase with rising temperature
in a non-linear fashion with a maximum slightly
above the T
G
. As it was not possible to measure at temp-
eratures higher than 120°C due to limitations of the
printer bed heaters, a peak could not be observed in
the adhesion force diagram for ABS. However, it is
expected that there would be a peak after the T
G
,since
this behaviour was also observed for other amorphous
polymers such as poly(methyl methacrylate) [14]. The
adhesion between ABS and PI is much better than
that of ABS and the glass, due to closer similarities of
the polar and disperse fractions of the two materials,
expressed by the lower interfacial tensions, which is
showninsectionContact angle measurements.When
comparing the adhesion force values for PLA and
ABS, it can be clearly seen that those obtained by ABS
are significantly lower than those of PLA. However,
both materials could be printed without the risk of
detaching from the printing bed. For large-area parts,
the warpage needs to be considered, as it counteracts
the adhesion due to uneven shrinkage of the printed
layers that tend to pull the part away from the printing
surface [16]. From the authorsexperience, adhesion
forces of at least 200 N, as obtained from adhesion
measurements on strands by means of the shear-off test-
ing device, are sufficient for larger parts to hold them in
place during printing. Hence, for ABS a bed temperature
of at least 120°C (T>T
G
) and the bed material PI are
Figure 2. Adhesion forces as a function of printing bed temp-
erature and bed material (glass or PI) for PLA (a) and ABS (b).
The T
G
s of the filament materials are depicted as the blue lines.
4M. SPOERK ET AL.
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necessary to ensure proper adhesion during printing,
whereas for PLA bed temperatures higher than 60°C
(T>T
G
) independently of the bed material are more
than sufficient for a successful printing. On the contrary,
for very high adhesion forces, such as occur e.g. for PLA
and glass at 70°C, a second issue has to be considered.
Too high adhesion forces can lead to a damage of the
printing bed during cooling. Therefore, in fact, the opti-
mal printing bed temperature has to be carefully selected
within a moderate adhesion force range. For PLA and
glass, for example, printing bed temperatures between
80 and 120°C can be recommended.
As can be seen from Figure 2, for PLA a temperature
close to room temperature can be recommended for a
damage-free removal after printing for both surface
materials, as the adhesion force is close to zero at this
temperature. However, for ABS the adhesion to PI
and glass is negligible already at 50°C. Hence, the fin-
ished parts can be easily removed also at a slightly elev-
ated temperature.
Contact angle measurements
The adhesion force is dependent on the compatibility
between the two surfaces [13], which is affected by the
polarity and the thermodynamic characteristics of the
two interacting surfaces. One way to determine the com-
patibility between surfaces is to calculate the interfacial
tension from contact angle measurements [17]. The
adhesionbetween two contact materials is inversely pro-
portional to the interfacial tension values, and such
values are inversely dependent on the surface energies
and polarities of the materials in contact [9].
Figure 3 compares the interfacial tension to the
measured adhesion force at two temperatures for both
printing materials and printing beds. The selected temp-
eratures are 10 K below and above the T
G
of each printed
material. Despite the big variations, a trend towards
decreased interfacial tensions for increasing temperatures
can be seen for both PLA and ABS (Figure 3(a,c)). This
trend is in accordance with the adhesion force results
(Figure 3(b,d)), in which a drastic increase is observed
for higher temperatures. Moreover, the trend towards
higher adhesion forces for printing PLA on the glass
than on the PI surface is reflected by the interfacial tension
values (Figure 3(a)). Also for ABS, the interfacial tension
results (Figure 3(c)) reflect the trend of the adhesion
measurements (Figure 3(d)), in which the adhesion on
the glass is inferior to that on the PI film. However, the
overall trend in the contact angle measurements (Figure
3(a,c)) does not reflect the significant difference in the
adhesion forces (Figure 3(b,d)), but the contact angle
measurements rather exhibit non-significant differences
in the interfacial tension. Hence, the adhesion mechanism
cannot be solely explained by surface chemical analyses,
such as contact angle measurements.
Figure 3. Interfacial tension obtained from contact angle measurements as a function of printing bed temperatures for PLA (a) and
ABS (c) compared to adhesion forces of PLA (b) and ABS (d) at the same temperatures.
PLASTICS, RUBBER AND COMPOSITES 5
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Microscopy analysis
The adhesion of polymers onto different surfaces is
additionally affected by the surface topology and the
impurities that may be present on the surface [18].
The magnified surfaces of the printed parts after
being sheared-off at different temperatures as well as
one representative forcedisplacement curve each are
shown in Figure 4 exemplarily for PLA. Similar results
are expected for ABS and hence they were not included
in this manuscript. It can be seen that the temperature
does indeed have an effect on the resulting topology of
the printed parts.
PLA printed on the glass at 50°C (Figure 4(a)) shows
some voids on the surface, whereas the part printed at
70°C (Figure 4(b)) has a slightly smoother surface. The
higher amount of voids reduces the effective contact
area, resulting in adhesion forces of only 55 ± 16 N.
On the other hand, the smoother surface obtained by
printing on the glass at 70°C indicates a better contact
between the PLA and the glass. Due to the increased
diffusion of the polymer onto the glass and the reduced
interfacial tension, this leads to a higher adhesion force
of 650 ± 17 N and to a considerably broader adhesion
force peak as can be seen in the insert in Figure 4(b).
Another indication for the strong adhesion of the
specimen printed at 70°C (Figure 4(b)) is the defor-
mation of the first layer, displayed in the bottom of
Figure 4(b). This originates from the local bending
due to its strong adhesion and the shearing block.
The white circles, highlighted in Figure 4(b), represent
the presence of pieces of glass that had been sheared-off
from the glass during the adhesion force measure-
ments. This finding confirms that extreme adhesion
between the printed part and the printing bed might
not be favourable, since it can destroy both material
in contact, as discussed in section Adhesion forces.
When the surfaces of printed PLA on the PI film are
compared to those on the glass, an opposite trend is
observed: The smoother surface of the specimen
printed at 50°C (Figure 4(c)) has a lower adhesion
force (70 ± 11 N) than that of the specimen printed at
70°C (Figure 4(d)) (320 ± 47 N). However, when print-
ing on PI, the rougher surface does not exhibit voids,
but rather channels oriented parallel to the length of
the printed part.
The different behaviour of the specimens printed on
PI might be related to the fact that the PI is indeed a
foil, which is in turn glued on another printing bed
Figure 4. Optical microscopy images of printed PLA parts after being sheared-off from different surfaces at different temperatures:
(a) glass at 50°C, (b) glass at 70°C, (c) PI at 50°C and (d) PI at 70°C. In the top right corner of each image the corresponding adhesion
force is shown. In the bottom left corner of each image one representative forcedisplacement diagram with the same displace-
ment labelling is shown to visualise the difference in their shear failure. The circles highlight sheared-off pieces of the printing bed
and the arrows the loading direction of the measuring device.
6M. SPOERK ET AL.
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layer, while the glass is itself a rigid plate. At high temp-
eratures, when the adhesion force between PLA and PI
is high, it can be speculated that the interface between
the PI foil and the lower printing bed layer can pose a
weak link. As can be seen in Figure 4(d), the PI foil is
not torn off in the course of the shearing experiments,
indeed it is not damaged. The shearing, which in the
case of the PI foil does not take place as a uniform
motion and thus causes the channels, can also be cor-
related with the forcedisplacement curve (insert
Figure 4(d)), which does not exhibit one peak, but sev-
eral local maxima and inflexion points.
These channels can increase the contact area between
the deposited filament and the flexible PI film. Thus, the
surface favours more diffusion of the PLA molecular
segments, leading to higher adhesion forces. Also for
the surface represented in Figure 4(d), the local defor-
mation in the bottom of the illustration is observed
and a piece of the bed surface is sheared-off during
the measurement (highlighted by a white circle).
Conclusion
We present here a systematic study on the effect of the
printing bed temperature on the adhesion of parts
printed by FFF by means of an in-house developed
adhesion measuring device. It was observed exemplarily
for PLA and ABS that the optimal adhesion of the
printed sample to the printing bed can be achieved by
heating the printing bed at temperatures slightly above
the T
G
of the filament material. Increasing the tempera-
ture above the filamentsT
G
leads to a reduction of the
surface tension between the printing bed and the print-
ing material and to a larger contact area that ultimately
causes better adhesion between the bed and the filament.
We believe that the process presented in this study is
readily applicable to other thermoplastic polymers
with a T
G
above room temperature. Our findings pro-
vide the first steps for finding optimal printing bed
temperatures for novel material compounds.
Acknowledgements
Special thanks go to Petra Erdely for fruitful discussions, Phi-
lipp Huber for the construction of the adhesion device and
Florian Arbeiter, Gerald Berger, Radoslav Guran and Chris-
tof Lichal for their help with the measurements.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the Austrian Research Pro-
motion Agency (Österreichische Forschungsförderungsge-
sellschaft (FFG)) as part of the AddManu project under
grant 849297.
ORCID
Martin Spoerk http://orcid.org/0000-0001-5606-3607
Joamin Gonzalez-Gutierrez http://orcid.org/0000-0003-
4737-9823
Janak Sapkota http://orcid.org/0000-0003-2296-5623
Stephan Schuschnigg http://orcid.org/0000-0002-2601-
967X
Clemens Holzer http://orcid.org/0000-0001-5149-7895
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8M. SPOERK ET AL.
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... This should be set higher than the feedstock material's glass transition temperature in order to ensure that the first layer of extruded filament adheres completely to the building base (bed). However, this temperature should not be too high, in order to avoid printing object distortion during removal from the bed [52]. No systematic studies have revealed strategies for identifying an optimal printing bed temperature range for the various materials or the corresponding effects on sample adhesion in FDM technology. ...
... No systematic studies have revealed strategies for identifying an optimal printing bed temperature range for the various materials or the corresponding effects on sample adhesion in FDM technology. In the case of PLA and acrylonitrile butadiene styrene (ABS), it was discovered that heating the printing bed slightly above the T g of the filament material result in optimal adhesion of the printed sample to the printer platform [52]. Increasing the temperature above the T g reduces the surface tension between the platform and the extruded material, resulting in a larger contact area and better adhesion of the polymer to the printer support [52]. ...
... In the case of PLA and acrylonitrile butadiene styrene (ABS), it was discovered that heating the printing bed slightly above the T g of the filament material result in optimal adhesion of the printed sample to the printer platform [52]. Increasing the temperature above the T g reduces the surface tension between the platform and the extruded material, resulting in a larger contact area and better adhesion of the polymer to the printer support [52]. ...
Article
Full-text available
The purpose of this study is to limit the environmental impact of packaging applications by promoting the recycling of waste products and the use of sustainable materials in additive manufacturing technology. To this end, a commercial polylactide acid (PLA)-based filament derived from waste production of bio-bags is herein considered. For reference, a filament using virgin PLA and one using a wood-based biocomposite were characterized as well. Preliminary testing involved infrared spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The effect of printing parameters (nanely bed temperature, layer thickness, top surface layers, retraction speed, and distance) on the final aesthetics of 3D printed parts was verified. The results allow us to attest that the thermal properties of recycled polymer are comparable to those of virgin PLA and biocomposite. In the case of recycled polymer, after the extrusion temperature, bed temperature, and printing speed are estabilished the lowest allowable layer thickness and an appropriate choice of retraction movements are required in order to realize 3D-printed objects without morphological defects visible to the naked eyes. In the case of wood biocomposite, the printing process was complicated by frequent obstructions, and in none of the operating conditions was it possible to obtain an aesthetically satisfying piece of the chosen geometry (Lego-type bricks) Finally, mechanical testing on the 3D printed parts of each system showed that the recycled PLA behaves similarly to virgin and wood/PLA filaments.
... According to the weak boundary layer theory air pores are a starting point for fractures. [11] In other studies, M. Spoerk, et al. [12,13] measured the adhesion between glass, polyimide (PI), and polypropylene (PP) as build surfaces and polylactide acid (PLA) and ABS as printing materials. For this investigation, single strands were printed onto the build surface, which were then sheared off by a testing device. ...
... Following a possible explanation of the described behavior is given. According to previous studies [13,19] increasing temperatures lead to increased adhesion forces. Also, the thermal conductivity of the build surface material must be considered because it determines the cooling rate of the printed strand. ...
... Too high adhesion forces can lead to damaged printed parts or build surfaces when the printed part is removed after the finish of the printing process. [13] The process parameters and the combination of printing material and build surface material should be selected so that the adhesion is lost during cooling down to room temperature after the printing process. All process parameters and combinations of build surface materials and printing materials shown in this paper match this requirement. ...
... Crystallization of semi-crystalline polymers is highly temperature dependent and hence is greatly influenced by the printing parameters of FDM. Several researchers have investigated the effects of printing parameters such as the print bed temperature, ambient temperature, print speed/nozzle speed, layer thickness of the printed part, etc. [12][13][14][15][16][17][18]. ...
... • Print bed-Also commonly referred to as build plate is used as a base for deposition and cooling of the extruded filament from the nozzle in FDM process. For better adhesion and print quality, it is vital to print on a clean and heated print bed [17]. • Ambient temperature-The room temperature in a FDM chamber while the part is being printed is referred to as ambient temperature. ...
Article
Full-text available
In fused deposition modelling (FDM) based on the selected raster pattern, the developed internal thermal residual stresses can vary considerably affecting the mechanical properties and leading to distinct part distortions. This phenomenon is more pronounced in semi-crystalline than amorphous polymers due to crystallisation. Hence, this study focuses on the simulation of the FDM process of a semi-crystalline polymer (polypropylene) with raster patterns such as line (90◦/90◦), line (0◦/90◦), zigzag (45◦/45◦), zigzag (45◦/−45◦), and concentric from Cura (slicing software). The simulation provides visualisation and prediction of the internally developed thermal residual stresses and resulting warpage with printing time and temperature. The sample with a line (90◦/90◦) raster pattern is considered as the reference sample in order to compare the relative levels of residual stress and warpage in the other printed/simulated samples. Among the considered raster patterns, the concentric pattern displays the lowest amount of warpage (5.5% decrease) along with a significant drop in residual stress of 21%. While the sample with a zigzag (45◦/−45◦) pattern showed the highest increase of 37% in warpage along with a decrease of 9.8% in residual stresses. The sample with a zigzag (45◦/45◦) pattern, exhibited a considerable increase of 16.2% in warpage with a significant increase of 31% in residual stresses. Finally, the sample with a line (0◦/90◦) raster pattern displayed an increase of 24% increase in warpage with an increase of 6.6% in residual stresses.
... Fused deposition modeling (FDM) 3D printing has been widely utilized in various industries due to its custom design and cost effectiveness [1][2][3][4][5][6][7][8]. FDM 3D printing products have formed by the layer-by-layer deposition, which exhibited anisotropic characteristic and drawbacks such as poor interlayer adhesion, incomplete printing, shrinkage and low dimension accuracy resulting in low mechanical performance and their structural failure [3,5,[7][8][9]. The selection of filaments and the controlled printing conditions can be optimized for improving the drawbacks and obtaining superior mechanical performance of the FDM 3D printing products [1,2,[10][11][12]. Polymer filaments are feedstocks for the FDM 3D printing. ...
... Acrylonitrile butadiene styrene (ABS), poly(lactic acid) (PLA), and poly(ethylene terephthalate glycol) (PETG) are commonly filaments for the FDM 3D printing, which have good printability at low printing temperature ranges compared to high performance plastics, such as polycarbonate (PC), polyamide (PA, nylon), polyetherimide (PEI), and poly(ether-ether-ketone) (PEEK) [2,[13][14][15][16]. The polymer filaments have been developed by the incorporation of additives, blending and estimated suitable printing conditions to diminish the FDM 3D printing drawbacks [1,[5][6][7][9][10][11][12][13][14][15][17][18][19][20][21]. The following research performed guidelines to overcome the drawbacks. ...
Article
Full-text available
Commercial filaments of poly(lactic acid) (PLA) composites with particulate filler, carbon fiber, and copper powder with different contents were fabricated by FDM 3D printing in XZ-direction at bed temperatures of 45 °C and 60 °C. The effects of additives and bed temperatures on layer adhesion, fracture behavior, and mechanical performance of the PLA composites 3D printing were evaluated. Rheological properties informed viscous nature of all filaments and interface bonding in the PLA composites, which improved printability and dimensional stability of the 3D printing. Crystallinity of the PLA composites 3D printing increased with increasing bed temperature resulting in an improvement of storage modulus, tensile, and flexural properties. On the contrary, the ductility of the 3D printing was raised when printed at low bed temperature. Dynamic mechanical properties, the degree of entanglement, the adhesion factor, the effectiveness coefficient, the reinforcing efficiency factor, and the Cole–Cole analysis were used to understand the layer adhesion, and the interfacial interaction of the composites as compared to the compression molded sheets. SEM images revealed good adhesion between the additives and the PLA matrix. However, the additives induced faster solidification and showed larger voids in the 3D printing, which indicated lower layer adhesion as compared to neat PLA. It can be noted that the combination of the additives and the optimized 3D printing conditions would be obtain superior mechanical performance even layer adhesion has been restricted.
... an die vorherige Polymerlage. Eine gezielte Temperaturführung kann daher zur Verbesserung der adhäsiven (Polymer-Substrat) und kohäsiven (Polymer-Polymer) Eigenschaften beitragen[10,13,15,70,[77][78][79]. Im Folgenden werden Ansätze aus der Literatur zur Überwachung und Bewertung der lokalen Temperaturführung in der Werkstoffextrusion vorgestellt.Zur Bewertung der lokalen Temperaturverteilung im Prozess eignet sich insbesondere die Thermographie[78][79][80][81][82][83][84][85][86][87][88][89][90][91][92]. ...
... [18,27] Bed temperature is usually set lower than Tg and optimized for better flat layer adhesion. [1,28] (v) ID: Infill density defines the final part porosity and so the part durability. [29] Higher infill density increases the mechanical strength of the parts. ...
Article
Polylactic acid (PLA) material in filament form can be 3D printed and form complex physical models by using a low-cost material extrusion mechanism in a process that is broadly known as fused filament fabrication (FFF). Even though the PLA-FFF process has been extensively studied in the literature, its parts' mechanical response varies significantly, and it has not been studied in association with six control parameters at the same time, i.e. the infill density (ID), raster deposition angle (RDA), nozzle temperature (NT), printing speed (PS), layer thickness (LT), and bed temperature (BT). The simultaneous influence of the variable parameters on the mechanical properties is a challenging assignment and aspires to rank the six parameters' importance, model the process, and finally validate the models by using independent experiments. One-hundred twenty-five experiments run following the Taguchi L25 orthogonal array repeated five times for the study purpose. After an extensive literature survey and preliminary experiments , the parameter selection and discrete values were selected. The experimental results were analyzed using statistical tools and critically compared with that of the literature. The RDA, NT, PS, and ID significantly impact the mechanical response of the 3D printed PLA parts.
... If the stress at the part-print bed interface exceeds the strength of the adhesion, then this adhesion can break in some locations, and cause more warpage. The stress at the part-print bed interface can be lowered by using a heated bed, the heated bed works by keeping the base of the part warm and lowering the amount of differential thermal contraction at the base, meaning that generally parts printed on a heated bed will be less likely to separate from the build plate [33]. ...
Article
This work focuses on evaluating different modeling approaches and model parameters for thermoplastic AM, with the goal of informing more efficient and effective modeling approaches. First, different modeling approaches were tested and compared to experiments. From this it was found that all three of the modeling approaches provide comparable results and provide similar results to experiments. Then one of the modeling approaches was tested on large scale geometries, and it was found that the model results matched experiments closely. Then the effect of different material properties was evaluated, this was done by performing a fractional factorial design of experiments where the factors were ±15% of the baseline material properties. From this it was found that coefficient of thermal expansion (CTE) is by far the most important material property for the simulated warpage. This test was repeated with a simulated desktop printer, simulated commercial printer and a simulated room scaled printer to evaluate if the relevant material properties change as a function of length scale; it was found that as length scale increases, conduction becomes increasingly important, but this effect was still small compared to that of CTE. Finally, the effect of the environment was evaluated by running a Latin hypercube Design of Experiments (DOE) over environmental factors; it was found that the most important effects are the bed and enclosure temperatures. It also pointed to the feasibility of using radiative heating to mitigate warpage, because as length scale increases natural convection becomes less important. This work is significant because it leverages modeling and simulation to evaluate the effects of the different phenomena in 3D printing and points out some of the gaps in the current state of the art that are not evident from performing simple experiments or simple simulations, namely implementing a model for build plate adhesion.
... Aside from the influence on the morphology of the coating layer surface, the process temperature as a consequence of the printing speed may have also played a role on the joint strength itself, by virtue of the temperature effect on the polymer/metal surface tension [44]. This allowed for a greater wettability during the coating layer deposition at low printing speeds, improving the adhesion to the metallic substrate. ...
Article
The present work is aimed at utilizing an adapted version of the Fused-Filament Fabrication process as a means to produce hybrid joints comprised of sandblasted, rolled Ti-6Al-4V substrates and additively manufactured short carbon fiber-reinforced polyamide (PA-CF). Layer height (h), printing speed (v) and printing bed temperature (Tbed) for the coating layer (i.e. initial layer with unreinforced polyamide) were varied. Using the ultimate single-lap shear strength (ULSS) of the produced joints as a response, linear and polynomial regressions were fit to the experimental dataset using an approach based on Machine Learning. The linear model achieved a better accuracy, with a test R² of 0.76. It was possible to conclude that the ULSS is strongly dependent on the actual coating layer height (hreal), which in turn depends on h and v. The optimal set of parameters resulted in an ULSS of 23.9 ± 2.0 MPa. Additionally, specimens for a three-point bending test based on the ISO 14679:1997 were produced and tested to further evaluate the influence of coating layer on mechanical behavior of hybrid joints, this time focusing exclusively on their interphase component. For this test, v did not play a statistically significant role, whereas h did.
... A similar result is reported by [8], where the adhesion force between the thermoplastic and the bed is measured by means of a custom shear force testing device. As the temperature of the bed is raised above the glass transition temperature of the thermoplastic, the surface tension between the thermoplastic and the printing bed reduces, resulting in a larger contacting area and consequently better adhesion forces. ...
Article
Purpose The fused filament fabrication (FFF) process is an additive manufacturing technique used in engineering design. The mechanical properties of parts manufactured by FFF are influenced by the printing parameters. The mechanical properties of rigid thermoplastics for FFF are well defined, while thermoplastic elastomers (TPE) are uncommonly investigated. The purpose of this paper is to investigate the influence of extruder temperature, bed temperature and printing speed on the mechanical properties of a thermoplastic elastomer. Design/methodology/approach Regression models predicting mechanical properties as a function of extruder temperature, bed temperature and printing speed were developed. Tensile specimens were tested according to ASTM D638. A 3×3 full factorial analysis, consisting of 81 experiments and 27 printing conditions was performed, and models were developed in Minitab. Tensile tests verifying the models were conducted at two selected printing conditions to assess predictive capability. Findings Each mechanical property was significantly affected by at least two of the investigated FFF parameters, where printing speed and extruder temperature terms influenced all mechanical properties ( p < 0.05). Notably, tensile modulus could be increased by 21%, from 200 to 244 MPa. Verification prints exhibited properties within 10% of the predictions. Not all properties could be maximized together, emphasizing the importance of understanding FFF parameter effects on mechanical properties when making design decisions. Originality/value This work developed a model to assess FFF parameter influence on mechanical properties of a previously unstudied thermoplastic elastomer and made property predictions within 10% accuracy.
Conference Paper
Full-text available
Fused filament fabrication (FFF) is a very popular additive manufacturing technique for the production of geometrically complex polymeric parts. FFF can also be used for the production of sintered magnetic parts, as part of the shaping, debinding and sintering (SDS) process. In order for sintering to be possible, it is recommended to prepare feedstock materials with 50 vol% or more filler content. However, when the filler content increases the properties required for FFF change. In this paper the mechanical properties of filaments, the viscosity of the molten feedstock, and surface properties of the solidified feedstock were investigated as a function of strontium ferrite powder content (53 to 60 vol%). In addition printing trials were performed. It was observed that mechanical properties significantly decrease, the viscosity increases and the surface tension showed no changes as a function of powder loading. All materials were in principle printable, but the printing temperature had to be adjusted to print the most highly filled material due to its lower mechanical properties and higher viscosity.
Article
Full-text available
In this paper, 3D printing as a novel printing process was considered for deposition of polymers on synthetic fabrics to introduce more flexible, resource-efficient and cost effective textile functionalization processes than conventional printing process like screen and inkjet printing. The aim is to develop an integrated or tailored production process for smart and functional textiles which avoid unnecessary use of water, energy, chemicals and minimize the waste to improve ecological footprint and productivity. Adhesion of polymer and nanocomposite layers which were 3D printed directly onto the textile fabrics using fused deposition modelling (FDM) technique was investigated. Different variables which may affect the adhesion properties including 3D printing process parameters, fabric type and filler type incorporated in polymer were considered. A rectangular shape according to the peeling standard was designed as 3D computer-aided design (CAD) to find out the effect of the different variables. The polymers were printed in different series of experimental design: nylon on polyamide 66 (PA66) fabrics, polylactic acid (PLA) on PA66 fabric, PLA on PLA fabric, and finally nanosize carbon black/PLA (CB/PLA) and multi-wall carbon nanotubes/PLA (CNT/PLA) nanocomposites on PLA fabrics. The adhesion forces were quantified using the innovative sample preparing method combining with the peeling standard method. Results showed that different variables of 3D printing process like extruder temperature, platform temperature and printing speed can have significant effect on adhesion force of polymers to fabrics while direct 3D printing. A model was proposed specifically for deposition of a commercial 3D printer Nylon filament on PA66 fabrics. In the following, among the printed polymers, PLA and its composites had high adhesion force to PLA fabrics.
Article
A major challenge in extrusion-based additive manufacturing is the lack of commercially available materials compared to those in well-established processes like injection molding or extrusion. This study aims at expanding the material database by evaluating the feasibility of polypropylene, which is one of the most common and technologically relevant semicrystalline polymers. Expanded-perlite-filled polypropylene and ternary blends with amorphous polyolefins are evaluated to establish an understanding of their processability and their printability. A detailed study on the shrinkage behavior, as well as on the thermal, mechanical, morphological, and warpage properties is performed. It is found that smaller sized fillers result in a tremendous warpage and shrinkage reduction and concurrently improved mechanical properties than compounds filled with bigger sized fillers. Based on the optimal properties profile, a ternary blend that can overcome the shrinkage and warpage of printed parts is suggested.
Article
Microfluidic devices based on polydimethylsiloxane shown a plethora of experimental possibilities due to good transparency, flexibility and ability to adhere reversibly and irreversibly to distinct materials. Though PDMS is a milestone in microfluidic developments, its cost and handling directed the field to search for new options. 3D printing technology nowadays starts a revolution offering materials and possibilities that can contribute positively to current methodologies. Here we explored the fused deposition modelling 3D printing technique to obtain integrated, transparent and sealed microchannels made with polylactic acid, a cheap alternative material to set up microfluidic systems. Using a home-made 3D printer, devices could be assembled in a simplified process, enabling the integration of different materials such as paper, glass, wire and polymers within the microchannel. To demonstrate the efficacy of this approach, a 3D-printed electronic tongue sensor was built, enabling the distinction of basic tastes below the human threshold.
Article
In the injection moulding of thermoplastics, hot polymer melt wets a cold mould surface during filling. In contrast, ejecting can be considered as de-wetting a solid polymer from a solid mould surface. In ongoing research, we suggest that the interfacial tension γ12 predicts the resistance of a solid polymer being separated from a solid mould, i.e. low γ12 indicates elevated ejection friction and vice versa. The aim of this study was to validate this assumption for polymer PA6 and the mould surfaces M333-IP, M268-VMR, MoN, and CrC/a-C:H. To calculate γ12, we determined the five solids' surface energies at 90°C. Therefore, we conducted contact angle measurements using bromonaphtalene and ethylencarbonate and applied the OWRK method. In succeeding friction experiments, we used a friction-test injection mould to determine the ejection friction of the same material combinations at 90°C. To conclude, the four mould coatings ranked in friction to PA6 as γ12 suggested.
Book
This book covers in detail the various aspects of joining materials to form parts. A conceptual overview of rapid prototyping and layered manufacturing is given, beginning with the fundamentals so that readers can get up to speed quickly. Unusual and emerging applications such as micro-scale manufacturing, medical applications, aerospace, and rapid manufacturing are also discussed. This book provides a comprehensive overview of rapid prototyping technologies as well as support technologies such as software systems, vacuum casting, investment casting, plating, infiltration and other systems. This book also: Reflects recent developments and trends and adheres to the ASTM, SI, and other standards Includes chapters on automotive technology, aerospace technology and low-cost AM technologies Provides a broad range of technical questions to ensure comprehensive understanding of the concepts covered.
Article
This paper addresses the potential of polypropylene (PP) as a candidate for fused deposition modeling (FDM)-based 3D printing technique. The entire filament production chain is evaluated, starting with the PP pellets, filament production by extrusion and test samples printing. This strategy enables a true comparison between parts printed with parts manufactured by compression molding, using the same grade of raw material. Printed samples were mechanically characterized and the influence of filament orientation, layer thickness, infill degree and material was assessed. Regarding the latter, two grades of PP were evaluated: a glass-fiber reinforced and a neat, non-reinforced, one. The results showed the potential of the FDM to compete with conventional techniques, especially for the production of small series of parts/components; also, it was showed that this technique allows the production of parts with adequate mechanical performance and, therefore, does not need to be restricted to the production of mockups and prototypes.
Article
The friction of isotactic polypropylene and high-pressure polyethylene in contact with steel was studied simultaneously with the resistance of the polymer specimen to tear-off from steel over a wide range of temperatures. Maximum friction under conditions of initial shear and friction at steady-state sliding were determined. Friction was compared with the dynamic characteristics of polymers and a qualitative correlation was established between the characteristics studied; the friction of polypropylene is shown to be dependent on its supermolecular structure.
Article
Adhesion is a phenomenon related to microscopic and macroscopic interactions between two polymer surfaces brought into intimate contact. This includes microscopic as well as macroscopic interactions. The most important theories of adhesion for polymer-polymer interfaces are the wetting and diffusion theories. The wetting theory describes the initial stage of adhesion in bringing the two polymers into intimate contact. After molecular contact is established, segments of the two polymers diffuse across the interface and the interface heals as a function of time [1, 2]. Therefore, the extent of adhesion at polymer-polymer interfaces is determined by the extent of diffusion and the interfacial thickness between the two polymers.