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Opportunities for producing dimensionally enhanced powder-injection-molded parts
Metal Powder Report Volume 00, Number 00 August 2017
metal-powder.net
SPECIAL FEATURE
Opportunities for producing dimensionally enhanced powder-injection-molded parts Volker Piotter, Alexander Klein, Tobias Mueller and Klaus Plewa Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WK), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
During the recent decades, powder injection molding has achieved a significant position as a manufacturing technique for high value-add products. For further progress, the improved dimensional accuracy of the sintered parts is of considerable importance. Investigations into meeting this demand through an enhanced process conduct comprising an additional compression step after cavity filling were performed. To achieve improved cavity filling and investigate influencing parameters, a demonstrator design was developed which enabled the generation of thin membranes by controlled piston movements. The combined injection and embossing process reached replication accuracies of 0.15 to 0.4%. An interaction between membrane quality and the compression parameters could be asserted. Moreover, the additional compaction step allowed for reduction of the minimum membrane values to about half of the thicknesses feasible by unmodified PIM processes. Objectives In the recent decades, powder injection molding (PIM) has achieved a remarkable status in large-scale fabrication of highvalue products. The reasons for this considerable rise mainly lie in the high economic efficiency and the capability for processing a wide range of metal and ceramic materials. For example, latest trials aimed at the processing of high-entropy alloys which offer a remarkable performance of material properties. A further important benefit of PIM is the capability for near-netshape manufacturing. However, there are still certain drawbacks which limit the applicability of PIM [1–4]. One of these restrictions concerns the dimensional accuracy of the final sintered parts which is often not suitable for high value-add products and thus requires costly re-working procedures [5–12]. The main reason for this drawback lies in the hardly controllable sintering procedure, i.e. the debindered parts undergo densification and shrinkage without dimensional constraints. Therefore, density gradients, internal stresses, and other inhomogeneities might cause significant dimensional deviations or even distortions.
The usual remedy is to obey certain layout rules while designing the part geometry. One of these guidelines says that variations in the wall thickness should be kept at a minimum [13,14]. Unfortunately, many applications impede adherence to this rule. To make things worse, in many cases, the most filigree sections are the functional ones determining the applicability of the entire product. Therefore, studies of accuracy-affecting parameters in the case of parts with serious wall thickness differences were carried out. Additionally, a modified tool technology was developed allowing for the implementation of additional compression steps to obtain better dimensional constancies of the final parts.
Layout of the experimental set-up For the intended examination of the filling behavior and dimensional accuracies of parts with considerable wall thickness variations, a new demonstrator design was created: It is characterized by a relatively voluminous cylindrical ring with a thin membrane as quasi sounding board on the top (see Fig. 1). The task was to fabricate these membranes as thin as possible and to investigate the square sections and reproducibility of the thickness profiles.
E-mail address: [email protected]. 0026-0657/ß 2017 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mprp.2017.06.071
1 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 SPECIAL FEATURE
Metal Powder Report Volume 00, Number 00 August 2017
SPECIAL FEATURE FIGURE 1
Scheme of the new demonstrator design consisting of both bulky cylinder and thin membrane sections. Whereas the outer diameter in the green state was 4.8 mm, the membrane thickness can be varied in a range of 600 mm to less than 200 mm. Additionally, the lower position of the ejector piston is indicated by a dashed line. The pistons themselves allow for moving up and down, thus varying the volume of the cavity. After the injection step, the feedstock can be compacted further.
The twin-piston tool applied here had been already used for previous experiments [15,16]. During these experiments, the pistons enabled a subsequent compression of the feedstock in the membrane cavity, thus enabling a defined adjustment of the membrane thickness. Further information about the tool design and functionality can be found in [8]. Whereas the volume of the demonstrator itself was 0.065 cm3, the entire molded part had a volume of ca. 1.6 cm3. Additionally, an extension factor of 1.167 had to be taken into account to compensate the sintering shrinkage. The annular cylinder was equipped with auxiliary features to facilitate mounting in test modules at a later stage. Following the experience of previous R&D projects, melt temperature was set to 165 8C and tool temperature to 60 8C. The next task was to determine the best suitable design of the runner system and to identify critical flow conditions likely to occur. For both purposes, simulations were carried out using the software program MOLDFLOW Autodesk. In order to fill the cavity as symmetrically as possible, two different layouts of the runner system had to be considered [8]. The square-cut areas in sum were the same for both variants. For the four-point runner system, this means that surface and wall effects played a disproportionately larger role compared to the two-point design. Usually, such a constellation leads to higher shear stresses but the simulation results showed that shear rates would be in an acceptable range. Therefore, due to the less pronounced welding lines, the fourpoint design was finally chosen for the tool.
Experiments and results For the experiments described here, a typical 17-4PH micro powder injection molding feedstock was applied. Solid content was 63 vol% of the stainless steel powder with a mean particle diameter of ca. 4.5 mm. As binder, the so-called GoMikro system developed at KIT was applied. It contains 50% paraffin wax, 45% polyethylene, and 5% stearic acids plus certain additives mainly for improved powder dispersion. The injection molding machine was an Arburg Allrounder 420 C equipped with a 15 mm PIM injection unit. It was not surprising that complete filling of the membrane by a simple, i.e. unaltered, injection of the feedstock was clearly limited. Several trials including parameter variation showed that thicknesses down to approximately 400 mm were feasible. In the case of smaller gaps, however, filling became incomplete. The injection molding process itself could be performed quite accurately. For example, the outer diameter of the sintered cylinders varied in a range of only 0.15%. For further reduction of the membrane thickness, the pistons were used so as to achieve a modified process conduct: pull back the pistons to open a relatively wide membrane cavity; inject the feedstock into this cavity; push the pistons forward until the final membrane thickness is reached. The green bodies produced by this novel method were debindered and sintered using typical microPIM parameter sets, i.e. no
2 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 Metal Powder Report Volume 00, Number 00 August 2017
SPECIAL FEATURE
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special adaptation to the particular sample design was necessary. The porosities achieved were in the range of 1.6–2.1% with pore sizes of 1.7–2.1 mm. In contrast to the pure injection molding process, the smallest reliably obtained membrane thicknesses were now about 200 mm after sintering. The related variances were approximately 0.4%. Further trials to obtain even thinner membranes showed that values down to 150 mm are even feasible. If going down to 100 mm (i.e. ca. 90 mm in the sintered state), void-free membranes could be produced as well. However, due to the feedstock partly sticking on the top of the pistons, the membranes did not have a flat surface but instead revealed a certain waviness (Fig. 2) which most probably makes them unusable as resonance boards. The samples were investigated by cutting and grinding, Figs. 3–5 show square sections of membranes of different thicknesses. However, it was not the only objective of these investigations to achieve minimum membrane thicknesses: To transfer the results to other geometries, it appears to be of high importance to determine the most relevant parameters. Therefore, a DoE approach covering the most relevant parameters, namely the embossing strength (equates to the compressing force), the gap width, i.e. the distance between dye and ejector piston before embossing, and the delay time, i.e. the duration from end of injection to beginning of compression, was carried out. The quality of the membrane was defined as the command variable so the question occurred how to quantify membrane performance. For this purpose, a qualification scale system was developed which allowed to graduate the samples into different quality classes. The best ranking was defined to be 1 which means that the membrane showed no flaws, while the worst classification was 5, i.e. the membrane revealed clearly visible defects. The graduation was carried out under a light microscope with 10 samples of each parameter set to ensure statistical reliability. Although this classification was performed using green bodies, it has to be mentioned that the relative quality ranking would be
FIGURES 3–5
Cut views of green bodies manufactured to determine minimum membrane thicknesses (above: 200 mm, middle: 150 mm, below: 100 mm). Although membranes of 100 mm thickness could be obtained, the surface showed a certain waviness due to feedstock sticking on the piston top.
FIGURE 2
Plan view of a sintered sample with a thickness of ca. 90 mm. As in this case, the feedstock sticks on the piston top, a light gray haze becomes visible in the middle of the membrane.
the same or would become even more significant if sintered parts were used (Fig. 2). It was found that best and most reproducible membrane qualities were achieved if highest compression forces (embossing 3
Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 SPECIAL FEATURE
SPECIAL FEATURE
strengths) were used and if cavities were opened as wide as possible before injection (gap width). These interdependencies proved that the considerations which had led to the injection and embossing process conduct were right in principle. In contrast to the other parameters, investigation of the embossing delay time showed no significant influence. A meaningful explanation might be that the compression of the feedstock took place in the interior sections of the green body which are much less affected by cooling than the sections near to the surface, i.e. near to the relatively cool piston heads. A more detailed description of the influence of molding and compression parameters on membrane accuracy can be found in [8].
Outlook Dimensional accuracy is an important issue for PIM optimization. Apart from the general improvement of all sub-steps, flow and pressure control during the injection and after-pressure stages are in the focus of attention. Especially subsequent compression steps offer the possibility to obtain filigree sections of high dimensional accuracy even in conjunction with relatively bulky volumes. Obviously, many parameters have to be considered for this process conduct. The experiments to evaluate the influence of particular parameters and the interdependencies between them were continued. Other subjects of examination will be powder loading, powder composition (multi-modal mixtures), densities, and micro structures.
Acknowledgements This work was partly carried out with the support of the Karlsruhe Nano Micro Facility (KNMF, www.knmf.kit.edu), a Helmholtz research infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu).
Metal Powder Report Volume 00, Number 00 August 2017
Additionally, the authors are grateful to the German Research Foundation (Deutsche Forschungsgemeinschaft – DFG) (SFB 499 2011) for financial funding and to all colleagues at KIT for their support and fruitful discussions. References [1] R.M. German, Markets applications, and financial aspects of global metal powder injection molding (MIM) technologies, Metal Powder Report January/February 2012, 0026-0657, 201218–26. [2] A.A. Attia, J.R. Alcock, J. Micromech. Microeng. 4 (2011), 21 043001. [3] V. Piotter, Powder Inj. Mold. Int. 5 (3) (2011) 27–36; V. Piotter, Powder Inj. Mold. Int. 5 (4) (2011) 25–30. [4] F. Petzoldt, Powder Inj. Mold. Int. 2 (1) (2008) 37–42. [5] K. Nishiyabu, I. Andrews, S. Tanaka, Powder Inj. Mold. Int. 2 (4) (2008) 60–63, Inovar Communications Ltd.. [6] M. Beck, V. Piotter, H.-J. Ritzhaupt-Kleissl, J. Hausselt, Proc. of 10th Euspen Conference 2008, Zurich, vol. 2, (2008), pp. 179–183, ISBN: 978-0-9553082-5-3. [7] R.M. German, Metal Injection Molding, Metal Powder Industries Fed, Princeton, NJ, 2011, ISBN: 978-0-9819496-6-6. [8] V. Piotter, A. Klein, T. Mueller, K. Plewa, Manufacturing of integrative membrane carriers by novel powder injection molding, Microsyst. Technol. (2015), http:// dx.doi.org/10.1007/s00542-015-2563-y. [9] H. Miura, Deformation Control of Large Sized MIM Parts. Preprints of POWDERMET 2015 Conference, San Diego, Metal Powder Industries Federation (MPIF), 2015 ISBN: 978-1-943694-01-3. [10] D. Webster, C. Taylor, MIM Feedstock binder, influence on distortion during debinding. Preprints of POWDERMET 2015 Conference, San Diego, Metal Powder Industries Federation (MPIF), 2015 ISBN: 978-1-943694-01-3. ¨ fer, G. Tosello, H.N. Hans, AIP Conf. Proc. [11] A. Islam, N. Giannekas, D.M. Marho 1664 (2015) 110007, http://dx.doi.org/10.1063/1.4918482. [12] Y. Li, L. Li, K.A. Khalil, J. Mater. Process. Technol. 183 (2007) 432–439. [13] R.M. German, Powder Injection Molding – Design and Applications, Innovative Materials Solutions, Inc., 2003 ISBN: 0-9727642-0-8. [14] D.F. Heaney, in: D.F. Heaney (Ed.), Handbook of Metal Injection Molding, Woodhead Publishing Ltd., Cambridge, UK, 2012, pp. 29–63, ISBN: 978-0-85709066-9. [15] V. Piotter, E. Honza, A. Klein, T. Mueller, K. Plewa, Proc. of Euro PM 2013, Gothenburg, EPMA, vol. 1, (2013), pp. 293–298, ISBN: 978-1-899072-41-5. [16] V. Piotter, et al. Proc. MIM 2014 Conference, Long Beach, 24–26.2.2014, Metal Powder Industries Federation (MPIF), 2014.
4 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
metal-powder.net
SPECIAL FEATURE
Opportunities for producing dimensionally enhanced powder-injection-molded parts Volker Piotter, Alexander Klein, Tobias Mueller and Klaus Plewa Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WK), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
During the recent decades, powder injection molding has achieved a significant position as a manufacturing technique for high value-add products. For further progress, the improved dimensional accuracy of the sintered parts is of considerable importance. Investigations into meeting this demand through an enhanced process conduct comprising an additional compression step after cavity filling were performed. To achieve improved cavity filling and investigate influencing parameters, a demonstrator design was developed which enabled the generation of thin membranes by controlled piston movements. The combined injection and embossing process reached replication accuracies of 0.15 to 0.4%. An interaction between membrane quality and the compression parameters could be asserted. Moreover, the additional compaction step allowed for reduction of the minimum membrane values to about half of the thicknesses feasible by unmodified PIM processes. Objectives In the recent decades, powder injection molding (PIM) has achieved a remarkable status in large-scale fabrication of highvalue products. The reasons for this considerable rise mainly lie in the high economic efficiency and the capability for processing a wide range of metal and ceramic materials. For example, latest trials aimed at the processing of high-entropy alloys which offer a remarkable performance of material properties. A further important benefit of PIM is the capability for near-netshape manufacturing. However, there are still certain drawbacks which limit the applicability of PIM [1–4]. One of these restrictions concerns the dimensional accuracy of the final sintered parts which is often not suitable for high value-add products and thus requires costly re-working procedures [5–12]. The main reason for this drawback lies in the hardly controllable sintering procedure, i.e. the debindered parts undergo densification and shrinkage without dimensional constraints. Therefore, density gradients, internal stresses, and other inhomogeneities might cause significant dimensional deviations or even distortions.
The usual remedy is to obey certain layout rules while designing the part geometry. One of these guidelines says that variations in the wall thickness should be kept at a minimum [13,14]. Unfortunately, many applications impede adherence to this rule. To make things worse, in many cases, the most filigree sections are the functional ones determining the applicability of the entire product. Therefore, studies of accuracy-affecting parameters in the case of parts with serious wall thickness differences were carried out. Additionally, a modified tool technology was developed allowing for the implementation of additional compression steps to obtain better dimensional constancies of the final parts.
Layout of the experimental set-up For the intended examination of the filling behavior and dimensional accuracies of parts with considerable wall thickness variations, a new demonstrator design was created: It is characterized by a relatively voluminous cylindrical ring with a thin membrane as quasi sounding board on the top (see Fig. 1). The task was to fabricate these membranes as thin as possible and to investigate the square sections and reproducibility of the thickness profiles.
E-mail address: [email protected]. 0026-0657/ß 2017 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mprp.2017.06.071
1 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 SPECIAL FEATURE
Metal Powder Report Volume 00, Number 00 August 2017
SPECIAL FEATURE FIGURE 1
Scheme of the new demonstrator design consisting of both bulky cylinder and thin membrane sections. Whereas the outer diameter in the green state was 4.8 mm, the membrane thickness can be varied in a range of 600 mm to less than 200 mm. Additionally, the lower position of the ejector piston is indicated by a dashed line. The pistons themselves allow for moving up and down, thus varying the volume of the cavity. After the injection step, the feedstock can be compacted further.
The twin-piston tool applied here had been already used for previous experiments [15,16]. During these experiments, the pistons enabled a subsequent compression of the feedstock in the membrane cavity, thus enabling a defined adjustment of the membrane thickness. Further information about the tool design and functionality can be found in [8]. Whereas the volume of the demonstrator itself was 0.065 cm3, the entire molded part had a volume of ca. 1.6 cm3. Additionally, an extension factor of 1.167 had to be taken into account to compensate the sintering shrinkage. The annular cylinder was equipped with auxiliary features to facilitate mounting in test modules at a later stage. Following the experience of previous R&D projects, melt temperature was set to 165 8C and tool temperature to 60 8C. The next task was to determine the best suitable design of the runner system and to identify critical flow conditions likely to occur. For both purposes, simulations were carried out using the software program MOLDFLOW Autodesk. In order to fill the cavity as symmetrically as possible, two different layouts of the runner system had to be considered [8]. The square-cut areas in sum were the same for both variants. For the four-point runner system, this means that surface and wall effects played a disproportionately larger role compared to the two-point design. Usually, such a constellation leads to higher shear stresses but the simulation results showed that shear rates would be in an acceptable range. Therefore, due to the less pronounced welding lines, the fourpoint design was finally chosen for the tool.
Experiments and results For the experiments described here, a typical 17-4PH micro powder injection molding feedstock was applied. Solid content was 63 vol% of the stainless steel powder with a mean particle diameter of ca. 4.5 mm. As binder, the so-called GoMikro system developed at KIT was applied. It contains 50% paraffin wax, 45% polyethylene, and 5% stearic acids plus certain additives mainly for improved powder dispersion. The injection molding machine was an Arburg Allrounder 420 C equipped with a 15 mm PIM injection unit. It was not surprising that complete filling of the membrane by a simple, i.e. unaltered, injection of the feedstock was clearly limited. Several trials including parameter variation showed that thicknesses down to approximately 400 mm were feasible. In the case of smaller gaps, however, filling became incomplete. The injection molding process itself could be performed quite accurately. For example, the outer diameter of the sintered cylinders varied in a range of only 0.15%. For further reduction of the membrane thickness, the pistons were used so as to achieve a modified process conduct: pull back the pistons to open a relatively wide membrane cavity; inject the feedstock into this cavity; push the pistons forward until the final membrane thickness is reached. The green bodies produced by this novel method were debindered and sintered using typical microPIM parameter sets, i.e. no
2 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 Metal Powder Report Volume 00, Number 00 August 2017
SPECIAL FEATURE
SPECIAL FEATURE
special adaptation to the particular sample design was necessary. The porosities achieved were in the range of 1.6–2.1% with pore sizes of 1.7–2.1 mm. In contrast to the pure injection molding process, the smallest reliably obtained membrane thicknesses were now about 200 mm after sintering. The related variances were approximately 0.4%. Further trials to obtain even thinner membranes showed that values down to 150 mm are even feasible. If going down to 100 mm (i.e. ca. 90 mm in the sintered state), void-free membranes could be produced as well. However, due to the feedstock partly sticking on the top of the pistons, the membranes did not have a flat surface but instead revealed a certain waviness (Fig. 2) which most probably makes them unusable as resonance boards. The samples were investigated by cutting and grinding, Figs. 3–5 show square sections of membranes of different thicknesses. However, it was not the only objective of these investigations to achieve minimum membrane thicknesses: To transfer the results to other geometries, it appears to be of high importance to determine the most relevant parameters. Therefore, a DoE approach covering the most relevant parameters, namely the embossing strength (equates to the compressing force), the gap width, i.e. the distance between dye and ejector piston before embossing, and the delay time, i.e. the duration from end of injection to beginning of compression, was carried out. The quality of the membrane was defined as the command variable so the question occurred how to quantify membrane performance. For this purpose, a qualification scale system was developed which allowed to graduate the samples into different quality classes. The best ranking was defined to be 1 which means that the membrane showed no flaws, while the worst classification was 5, i.e. the membrane revealed clearly visible defects. The graduation was carried out under a light microscope with 10 samples of each parameter set to ensure statistical reliability. Although this classification was performed using green bodies, it has to be mentioned that the relative quality ranking would be
FIGURES 3–5
Cut views of green bodies manufactured to determine minimum membrane thicknesses (above: 200 mm, middle: 150 mm, below: 100 mm). Although membranes of 100 mm thickness could be obtained, the surface showed a certain waviness due to feedstock sticking on the piston top.
FIGURE 2
Plan view of a sintered sample with a thickness of ca. 90 mm. As in this case, the feedstock sticks on the piston top, a light gray haze becomes visible in the middle of the membrane.
the same or would become even more significant if sintered parts were used (Fig. 2). It was found that best and most reproducible membrane qualities were achieved if highest compression forces (embossing 3
Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071
MPRP-1152; No of Pages 4 SPECIAL FEATURE
SPECIAL FEATURE
strengths) were used and if cavities were opened as wide as possible before injection (gap width). These interdependencies proved that the considerations which had led to the injection and embossing process conduct were right in principle. In contrast to the other parameters, investigation of the embossing delay time showed no significant influence. A meaningful explanation might be that the compression of the feedstock took place in the interior sections of the green body which are much less affected by cooling than the sections near to the surface, i.e. near to the relatively cool piston heads. A more detailed description of the influence of molding and compression parameters on membrane accuracy can be found in [8].
Outlook Dimensional accuracy is an important issue for PIM optimization. Apart from the general improvement of all sub-steps, flow and pressure control during the injection and after-pressure stages are in the focus of attention. Especially subsequent compression steps offer the possibility to obtain filigree sections of high dimensional accuracy even in conjunction with relatively bulky volumes. Obviously, many parameters have to be considered for this process conduct. The experiments to evaluate the influence of particular parameters and the interdependencies between them were continued. Other subjects of examination will be powder loading, powder composition (multi-modal mixtures), densities, and micro structures.
Acknowledgements This work was partly carried out with the support of the Karlsruhe Nano Micro Facility (KNMF, www.knmf.kit.edu), a Helmholtz research infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu).
Metal Powder Report Volume 00, Number 00 August 2017
Additionally, the authors are grateful to the German Research Foundation (Deutsche Forschungsgemeinschaft – DFG) (SFB 499 2011) for financial funding and to all colleagues at KIT for their support and fruitful discussions. References [1] R.M. German, Markets applications, and financial aspects of global metal powder injection molding (MIM) technologies, Metal Powder Report January/February 2012, 0026-0657, 201218–26. [2] A.A. Attia, J.R. Alcock, J. Micromech. Microeng. 4 (2011), 21 043001. [3] V. Piotter, Powder Inj. Mold. Int. 5 (3) (2011) 27–36; V. Piotter, Powder Inj. Mold. Int. 5 (4) (2011) 25–30. [4] F. Petzoldt, Powder Inj. Mold. Int. 2 (1) (2008) 37–42. [5] K. Nishiyabu, I. Andrews, S. Tanaka, Powder Inj. Mold. Int. 2 (4) (2008) 60–63, Inovar Communications Ltd.. [6] M. Beck, V. Piotter, H.-J. Ritzhaupt-Kleissl, J. Hausselt, Proc. of 10th Euspen Conference 2008, Zurich, vol. 2, (2008), pp. 179–183, ISBN: 978-0-9553082-5-3. [7] R.M. German, Metal Injection Molding, Metal Powder Industries Fed, Princeton, NJ, 2011, ISBN: 978-0-9819496-6-6. [8] V. Piotter, A. Klein, T. Mueller, K. Plewa, Manufacturing of integrative membrane carriers by novel powder injection molding, Microsyst. Technol. (2015), http:// dx.doi.org/10.1007/s00542-015-2563-y. [9] H. Miura, Deformation Control of Large Sized MIM Parts. Preprints of POWDERMET 2015 Conference, San Diego, Metal Powder Industries Federation (MPIF), 2015 ISBN: 978-1-943694-01-3. [10] D. Webster, C. Taylor, MIM Feedstock binder, influence on distortion during debinding. Preprints of POWDERMET 2015 Conference, San Diego, Metal Powder Industries Federation (MPIF), 2015 ISBN: 978-1-943694-01-3. ¨ fer, G. Tosello, H.N. Hans, AIP Conf. Proc. [11] A. Islam, N. Giannekas, D.M. Marho 1664 (2015) 110007, http://dx.doi.org/10.1063/1.4918482. [12] Y. Li, L. Li, K.A. Khalil, J. Mater. Process. Technol. 183 (2007) 432–439. [13] R.M. German, Powder Injection Molding – Design and Applications, Innovative Materials Solutions, Inc., 2003 ISBN: 0-9727642-0-8. [14] D.F. Heaney, in: D.F. Heaney (Ed.), Handbook of Metal Injection Molding, Woodhead Publishing Ltd., Cambridge, UK, 2012, pp. 29–63, ISBN: 978-0-85709066-9. [15] V. Piotter, E. Honza, A. Klein, T. Mueller, K. Plewa, Proc. of Euro PM 2013, Gothenburg, EPMA, vol. 1, (2013), pp. 293–298, ISBN: 978-1-899072-41-5. [16] V. Piotter, et al. Proc. MIM 2014 Conference, Long Beach, 24–26.2.2014, Metal Powder Industries Federation (MPIF), 2014.
4 Please cite this article in press as: V. Piotter, et al., Met. Powder Rep. (2017), http://dx.doi.org/10.1016/j.mprp.2017.06.071