Advertisement

Design for Powder Metallurgy: Predicting Anisotropic Dimensional Change on Sintering of Real Parts

  • I. CristofoliniEmail author
  • A. Molinari
  • M. Zago
  • S. Amirabdollahian
  • O. Coube
  • M. J. Dougan
  • M. Larsson
  • M. Schneider
  • P. Valler
  • J. Voglhuber
  • L. Wimbert
Regular Paper
  • 37 Downloads

Abstract

Anisotropic dimensional change on sintering may strongly affect the precision of parts produced by press and sinter. In previous work a design procedure accounting for anisotropic dimensional change of axi-symmetric parts (disks and rings) has been developed on the basis of experimental data. In this work the procedure has been applied to predict the anisotropic dimensional change of real parts produced in industrial conditions, providing that coaxial rings were identified in the geometry of the actual parts. Parts were highly different for material, complexity of geometry, green density and process conditions. Parts were measured in the green and sintered state and the measured dimensional changes were compared to the predicted ones, finding a good agreement. The procedure was also adapted to predict dimensional change of an oval feature, and highly satisfactory results were obtained.

Keywords

Anisotropy Dimensional change Powder metallurgy Precision of PM parts 

List of symbols

h

Height of the part (mm)

hg

Height of the green part (mm)

hs

Height of the sintered part (mm)

εh

Dimensional change in height

ϕext

External diameter (mm)

ϕext g

External diameter of the green part (mm)

ϕext s

External diameter of the sintered part (mm)

εϕ ext

Dimensional change in the external diameter

ϕint

Internal diameter of the part (mm)

ϕint g

Internal diameter of the green part (mm)

ϕint s

Internal diameter of the sintered part (mm)

εϕ int

Dimensional change in the internal diameter

εiso

Isotropic dimensional change

Vg

Volume of the green part (mm3)

Vs

Volume of the sintered part (mm3)

R

Ratio between the internal and the external diameter in the green parts

α

Geometrical parameter relating the dimensional changes

γ

Geometrical parameter relating R and α

K

Anisotropy parameter

Notes

References

  1. 1.
    Cristofolini, I., Corsentino, N., Larsson, M., & Molinari, A. (2016). Analytical model of the anisotropic dimensional change on sintering of ferrous pm parts. Powder Metallurgy Progress, 16(1), 27–39.Google Scholar
  2. 2.
    Cristofolini, I., Menapace, C., Cazzolli, M., Rao, A., Pahl, W., & Molinari, A. (2012). The effect of anisotropic dimensional change on the precision of steel parts produced by powder metallurgy. Journal of Materials and Processing Technologies, 7(212), 1513–1519.Google Scholar
  3. 3.
    Menapace, C., Larsson, M., Torresani, E., Cristofolini, I., & Molinari, A. (2012). Study of anisotropy during sintering of ferrous alloys. In Proceedings PM2012, 2012 powder metallurgy world congress and exhibition. Yokohama.Google Scholar
  4. 4.
    Cristofolini, I., Pilla, M., Molinari, A., Menapace, C., & Larsson, M. (2012). DOE investigation of anisotropic dimensional change during sintering of iron–copper–carbon. The International Journal of Powder Metallurgy, 48(4), 37–43.Google Scholar
  5. 5.
    Cristofolini, I., Pilla, M., Larsson, M., & Molinari, A. (2012). A DOE analysis of dimensional change on sintering of a 3%Cr–0.5%Mo–x%C steel and its effect on dimensional and geometrical precision. Powder Metallurgy Progress, 3(12), 127–143.Google Scholar
  6. 6.
    Cristofolini, I., Corsentino, N., Molinari, A., & Larsson, M. (2014). Study of the influence of material and geometry on the anisotropy of dimensional change on sintering of powder metallurgy parts. International Journal of Precision Engineering and Manufacturing, 15(9), 1865–1873.Google Scholar
  7. 7.
    Corsentino, N., Menapace, C., Cristofolini, I., Pilla, M., Larsson, M., & Molinari, A. (2015). The influence of the liquid phase on anisotropic dimensional change on sintering of iron alloys. The International Journal of Powder Metallurgy, 51(2), 27–37.Google Scholar
  8. 8.
    Cristofolini, I., Pilla, M., Rao, A., Libardi, S., & Molinari, A. (2013). Dimensional and geometrical precision of powder metallurgy parts sintered and sinter hardened at high temperature. International Journal of Precision Engineering and Manufacturing, 14(10), 1735–1742.Google Scholar
  9. 9.
    Emanuelli, L., Menapace, C., Cristofolini, I., Molinari, A., & Larsson, M. (2014). Influence of sintering temperature on shrinkage anisotropy in Cr–Mo low alloy steel green compacts. Advances in Powder Metallurgy and Particulate Materials, 5, 99–107.Google Scholar
  10. 10.
    Cristofolini, I., Corsentino, N., Molinari, A., & Larsson, M. (2015). Influence of geometry and process variables on the anisotropy parameter K. Advances in Powder Metallurgy and Particulate Materials, 01, 31–40.Google Scholar
  11. 11.
    Corsentino, N., Cristofolini, I., Libardi, S., & Molinari, A. Effect of high sintering temperature on the dimensional and geometrical precision of PM Cr–Mo steel parts. In Proceedings EURO PM2014 congress and exhibition, Salzburg 21–24 September 2014. Shrewsbury: EPMA. 13_P2_EP140145.Google Scholar
  12. 12.
    Griffo, A., Ko, J., & German, R. M. (1994). Critical assessment of variables affecting the dimensional behavior in sintered iron–copper–carbon alloys. Advances in Powder Metallurgy and Particulate Materials, 3, 221–236.Google Scholar
  13. 13.
    Bernardo, E., Campos, M., Torralba, J. M., Gierl, C., Danninger, H., & Frykholm, R. (2013). Lean steels modified with a new Cu-based master alloy: Influence of process parameters in dimensional and sintering behavior. In Proceedings Euro PM 2013, international powder metallurgy congress and exhibition, 15–18 September 2013. Gothenburg.Google Scholar
  14. 14.
    De Oro Calderon, R., Gierl, C., & Danninger, H. (2016). Dimensional stability of sintered steels containing low melting point master alloys. In Proceedings world PM 2016 congress and exhibition, 9–13 October 2016. Hamburg.Google Scholar
  15. 15.
    Sainz, S, Bilbao, C., Veiga, A., & Castro, F. (2016). Enhanced control of dimensional change and mechanical properties of Fe–Cu–C PM steels under optimized sintering cycle. In: Proceedings world PM 2016 congress and exhibition, 9–13 October 2016. HamburgGoogle Scholar
  16. 16.
    Bilbao, C., Sainz, S., Veiga, A., & Castro, F. (2015). Microstructural development and effect of different Cu/C contents on dimensional changes during sintering of PM steels. Powder Metallurgy, 58(5), 328–334.Google Scholar
  17. 17.
    Bernardo, E., Oro, R., Campos, M., Frykholm, R., Litström, O., & Torralba, J. M. (2012). Effect of liquid content on dimensional stability and sinter properties of liquid-phase sintered low alloyed steels. In Proceedings of the international Euro powder metallurgy congress and exhibition, Euro PM 2012, 16–19 September 2012 (Vol. 1). BaselGoogle Scholar
  18. 18.
    Molinari, A., Menapace, C., Torresani, E., Cristofolini, I., & Larsson, M. (2013). Working hypothesis for origin of anisotropic sintering shrinkage caused by prior uniaxial cold compaction. Powder Metallurgy, 56(3), 189–195.Google Scholar
  19. 19.
    Molinari, A., Torresani, E., Menapace, C., Cristofolini, I., & Larsson, M. (2013). A study of sintering shrinkage kinetics of cold compacted ferrous green parts. Advances in Powder Metallurgy and Particulate Materials, 5, 25–32.Google Scholar
  20. 20.
    Molinari, A., Baselli, S., Torresani, E., Cristofolini, I., & Larsson, M. (2016). The shrinkage of uniaxially cold compacted iron green parts. In Proceedings world PM2016 congress and exhibition, Hamburg 9–13 October 2016. Shrewsbury: EPMA. 13_P2_EP3302140.Google Scholar
  21. 21.
    Molinari, A., Bisoffi, E., Menapace, C., & Torralba, J. (2014). Shrinkage kinetics during early stage sintering of cold isostatically compacted iron powder. Powder Metallurgy, 57(1), 61–69.Google Scholar
  22. 22.
    Molinari, A., Torresani, E., Menapace, C., & Larsson, M. (2015). The anisotropy of dimensional change on sintering of iron. Journal of the American Ceramic Society, 98(11), 3431–3437.Google Scholar
  23. 23.
    Baselli, S., & Molinari, A. (2017). The geometrical model of sintering. In CD proceedings EuroPM2017 congress and exhibition, Milano (Italy) 1–5 October 2017. Shrewsbury: EPMA.Google Scholar
  24. 24.
    Zavaliangos, A., & Bouvard, D. (2000). Numerical simulation of anisotropy in sintering due to prior compaction. The International Journal of Powder Metallurgy, 36(7), 58–65.Google Scholar
  25. 25.
    Zavaliangos, A., Missiaen, J. M., & Bouvard, D. (2006). Anisotropy in shrinkage during sintering. Science of Sintering, 38, 13–25.Google Scholar
  26. 26.
    Torresani, E., Cristofolini, I., & Molinari, A. (2015). Study of the anisotropic microstructure of the uniaxially cold compacted green parts. Advances in Powder Metallurgy and Particulate Materials, 3, 9–18.Google Scholar
  27. 27.
    Molinari, A., Amirabdollahian, S., Cristofolini, I., & Federici, M. (2016). Influence of powder deformation on anisotropy of sintering shrinkage. Advances in Powder Metallurgy and Particulate Materials, 1, 45–52.Google Scholar
  28. 28.
    Molinari, A., Zago, M., Amirabdollahian, S., Cristofolini, I., & Larsson, M. (2017) Anisotropic sintering shrinkage of ring shaped iron parts: effect of geometry and green density and correlation to the stress field during uniaxial cold compaction. In Proceedings EURO PM2017 congress and exhibition, Milan 1–4 October 2017. Shrewsbury: EPMA. 33686349.Google Scholar
  29. 29.
    Amirabdollahian, S., Deirmina, F., & Molinari, A., Study of the pores characteristics in the uniaxially cold compacted green parts by image analysis. In CD proceedings world PM2016 Hamburg (Germany) 9–13 October 2016. Shrewsbury: EPMA.Google Scholar
  30. 30.
    Molinari, A., & Torresani, E. (2015). Preliminary study to determine the sintering stress from microstructural analysis of green parts. Powder Metallurgy, 58(5), 323–327.Google Scholar
  31. 31.
    Olevsky, E. A. (1998). Theory of sintering: From Discrete to Continuum. Materials Science and Engineering Reports, 23, 41–100.Google Scholar
  32. 32.
    Bordia, R. K., Zuo, R., Guillon, O., Salamone, S. M., & Rodel, J. (2006). Anisotropic constitutive laws for sintering bodies. Acta Materialia, 54, 111–118.Google Scholar
  33. 33.
    Wakai, F., Chihara, K., & Yoshida, M. (2007). Anisotropic shrinkage induced by particle rearrangement in sintering. Acta Materialia, 55, 4553–4566.Google Scholar
  34. 34.
    Wakai, F., & Shinoda, Y. (2009). Anisotropic sintering stress for sintering of particles arranged in orthotropic symmetry. Acta Materialia, 57, 3955–3964.Google Scholar
  35. 35.
    Cristofolini, I., Corsentino, N., Pilla, M., Molinari, A., & Larsson, M. (2013). Influence of geometry on the anisotropic dimensional change on sintering of PM parts. Advances in Powder Metallurgy and Particulate Materials, 11, 49–61.Google Scholar
  36. 36.
    Raman, R., Zahrah, T. F., Weaver, T. J., & German, R. M. (1999). Predicting dimensional change during sintering of FC0208 parts. Advances in Powder Metallurgy and Particulate Materials, 1(3), 115–122.Google Scholar
  37. 37.
    Corsentino, N., Cristofolini, I., Larsson, M., Libardi, S., & Molinari, A. (2015). Anisotropy of the dimensional variation of sintered parts: a predictive model and a statistical evaluation of its reliability. In Proceedings EURO PM2015 congress and exhibition, Reims 4–7 October 2015. Shrewsbury: EPMA. 3213322.Google Scholar
  38. 38.
    Cristofolini, I., Corsentino, N., Molinari, A., & Larsson, M. (2014). A design procedure accounting for the anisotropic dimensional change on sintering of ferrous PM parts. Advances in Powder Metallurgy and Particulate Materials, 01, 115–127.Google Scholar
  39. 39.
    ISO 10360-4. (2000). Geometrical product specifications (GPS)—Acceptance and reverification tests for coordinate measuring machines (CMM)—Part 4: CMMs used in scanning measuring mode.Google Scholar

Copyright information

© Korean Society for Precision Engineering 2019

Authors and Affiliations

  1. 1.Department of Industrial EngineeringUniversity of TrentoTrentoItaly
  2. 2.European Powder Metallurgy AssociationShrewsburyUK
  3. 3.AMES Barcelona Sintering S.A.Sant Vicenç dels HortsSpain
  4. 4.Höganäs ABHöganäsSweden
  5. 5.GKN Sinter Metals Engineering GmbHRadevormwaldGermany
  6. 6.Sintex a/sHobroDenmark
  7. 7.MIBA Sinter Austria GmbHVorchdorfAustria

Personalised recommendations