Preview

Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya

Расширенный поиск
Доступ открыт Открытый доступ  Доступ закрыт Только для подписчиков

Compressibility curves of iron-base powders: Support for evaluating stresses on compaction tools or just a method for evaluation of raw materials?

https://doi.org/10.17073/1997-308X-2018-4-33-47

Полный текст:

Аннотация

The forecast of maximum stresses on compaction tools is frequently based on the so-called compressibility curves, obtained according to specific standards. The analysis of compressibility curves enables to draw a simple analytical law, to utilize for further developments. The relationship between radial and axial pressure is described. The radial pressure is the design datum for the correct dimensioning of dies. Literature data on the relationship between applied pressure and friction coefficient enables to derive a model linking compact geometry and axial pressures effectively needed to reach specific densities. For part shapes characterized by a discrete extension on height – such as bushings, for instance – the effects of geometry are linked to 2 dimensionless parameters, one of physical nature (product of the pressure ratio multiplied by friction coefficient) and one of geometrical nature (ratio between «vertical» friction surfaces and double of compaction area). These dimensionless parameters enable to draw the «real» compressibility curves, linked to specific geometries. For part shapes characterized by small height – such as thin disks or plates – the effects of geometry again depend on two dimensionless parameters: one of physical nature (ratio between two times the friction coefficient and pressure ratio) and one of geometrical nature (ratio radius/height of the thin disk). Thinner the disk, higher the pressure needed to attain a given density. The theoretical results are compared with experimental data. The agreement between experimental data and forecasts based onthe theoretical approach is good. The study proves that the standard compressibility curves, if uncritically utilized for predicting stresses acting on tools, are unsuitable to predict the stresses really acting at compaction end.

Об авторе

G. F. Bocchini

Италия
Dr., P/M consultant.


Список литературы

1. Squire A. Density relationship of iron powder compacts. Trans AIME. 1947. Vol. 171. P. 485.

2. Lee P.W.Pressed and sintered parts and their applications. In: Powder metallurgy, applications, advantages and limitations. Chapter 4. Ed. E. Klar. Ohio: ASM, Metals Park, 1983.

3. Lenel F.V. Powder metallurgy. Principles and applications. Princeton, New Jersey: Metal Powders Industries Federation (MPIF), 1980.

4. Kosko J.Mechanical properties of high-performance powder metallurgy parts. In: ASM Metals Handbook. Vol. 7. Powder metals technologies and applications.Ohio: ASM, Metals Park, 1998.

5. Kieffer R., Hotop W. Sintereisen und sinterstahl. Wien: Springer Verlag, 1948.

6. Balshin M.Ju. Dokl. Akad. Nauk SSSR. 1949. Vol. 67. Р. 831—837.

7. Balshin M.Ju. Pulvermetallurgie. Halle (Saale): Veb Wilhelm Knapp Verlag, 1954.

8. Knopp W.V. Sintered nickel steels — the path to improved properties. In: Progress in powder metallurgy: 6th Annual Meeting of MPIF. Chicago, 1960.

9. Pisarenko G.S., Troshchenko V.T., Krasovskii A.Ya. Study of the mechanical properties of porous iron in tension and torsion. In: Iron powder metallurgy. N.Y.: Plenum Press, 1968. P. ?

10. Hausner H.H. Handbook of powder metallurgy. N.Y.: Chemical Publishing Co. Inc., 1973.

11. Ferrous powder metallurgy materials: ASM Metals Handbook. 9 ed. Vol. 1. Ohio: American Society for Metals, Metals Park, 1978.

12. German R.M.Porous materials. In: Advances in powder technology: ASM Materials Science Seminar (Louisville, 1981). Ed. G.Y. Chin. Ohio: ASM, Metals Park, 1982.

13. DeHoff R.T., Gillard J.P.Modern developments in powder metallurgy. Vol. 4. Ed. H.H. Hausner. N.Y.: Plenum Press, 1971.

14. German R.M. Powder metallurgy science. Princeton, New Jersey: MPIF, 1994.

15. Thümmler F., Oberacker R. Introduction to powder metallurgy. Eds I. Jenkins, J.V. Wood. London: The Institute of Materials Science on Powder Metallurgy, 1993.

16. Zapf G. Handbuch der Fertigungstechnik. Bd. 1. Urformen. Kap. 4. Hrsg. G. Spur. München: Hanser-Verlag, 1981.

17. Schatt W., Wieters K.P.Powder metallurgy, processing and materials. Shrewsbury, UK: European Powder Metallurgy Association (EPMA), 1997.

18. Beiss P., Bōrnstein L.Group VIII: Advanced materials and technologies. Vol. 2. Materials, Subvol. A: Powder metallurgy data, Pt. 1. Metals and magnets. Berlin Heidelberg, N.Y.: Springer-Verlag, 2003.

19. Beiss P.Pulvermetallurgische Fertigungstechnik. Berlin-Heidelberg, N.Y.: Springer-Verlag, 2013.

20. Standard 35: Materials standards for PM structural parts. Princeton, New Jersey: Metal Powder Industries Federation (MPIF), 2009.

21. Iron and steel powders for sintered components. Sveden: Höganäs AB, 2002.

22. Eudier M. Propriétés mécaniques des aciers frittés. Planseeberichte für Pulvermetallurgie.1966. Vol. 14 (29).

23. Bocchini G.F. The inf luences of porosity on the characteristics of sintered materials. SAE Int. Congress and Exposition (Detroit, Michigan, 24—28 Febr., 1986). SAE Technical Paper 860148.

24. Exner H.E., Pohl D. Fracture behavior of sintered iron. Powder Metall. Int. 1978. Vol. 10 (4). P. 193.

25. Standard test method for compressibility of metal powders in uniaxial compaction: ASTM B331-85. Philadelphia, USA: American Society for Testing and Materials (ASTM), Nov. 1985.

26. Method for determination of compactibility (Compressibility) of «Metal Powders»: MPIF Standard 45. Princeton, New Jersey, USA: Metal Powder Industries Federation (MPIF), 1988.

27. Metallic powders, excluding powders for hard metals — Determination of compactibility (compressibility) in uniaxial compression: ISO Standard 3927. International Standard Organization (ISO), 1977.

28. James W.B.Microstructure development. EPMA PM Summer School (Acqui Terme, Italy, 22—29 June, 2008).

29. Duffield A., Grootenhuis P. Pressing characteristics of air-atomized copper powders: Special Report No. 58. In: Symposium on Powder Metallurgy. London: The Iron and Steel Institute, 1956.

30. Jones W.D. Fundamental principles of powder metallurgy. London: Edward Arnold (Ltd.) Publ., 1960.

31. Bocchini G.F.Density reduction due to wall friction during compaction — A theoretical approach for a reliable quantitative evaluation. In: Horizons of powder metallurgy.Part II: Int. Powder Metallurgy Conference and Exhibition «P/M 1986» (Düsseldorf, 7 —11 July, 1986). Verlag Schmid, Freiburg, 1986. Р. 849— 852.

32. Bocchini G.F.Diminuzioni di densitànella pressatura dei pezzi in metallurgia delle polveri, causate dagli attriti alle pareti — Un approccio teorico per una valutazione quantitativa affidabile. In: 5 Convegno Nazionale su «Tribologia, attrito, usura e lubrificazione», AIM e ASMECCANICA (Sorrento, Italy, 7—9 Oct., 1987); La metallurgia italiana. 1989. Vol. 81. No. 7—8. P. 613— 621.

33. Long W.M. Radial pressures in powder compaction. Powder Metall.1960. No. 6. Р. 73—86.

34. Bockstiegel G., Hewing J.Verformungsarbeit, Verfestigung und Seitendruck beim Pressen von Metallpulvern. In: 3rd Europ. Symp. on Powder Metallurgy (Stuttgart, 1968). Chapt. 1.2, 32.

35. Ernst E., Thümmler F., Beiss P., Whäling R., Arnhold V.Friction measurements during powder compaction. Powder Metall. Intern.1991. Vol. 23. No. 2. P. 77—84.

36. Ernst E. Axiale Pressvorgänge in der Pulvermetallurgie. Fortschrittberichte VDI, Reihe 2: Fertigungstechnik. Nr. 259. Düsseldorf: VDI Verlag, 1992.

37. Bocchini G.F. Friction effects in metal powder compaction. Part 1. Theoretical aspects. In: Int. Conf. on P/M and particulate materials(Seattle, 14—17 May, 1995).

38. Bocchini G.F.Inf luence of small die width on filling and compacting densities. Powder Metall.1987. Vol. 30. No. 4.

39. Mair G. Correlation between axial density and friction in the compaction and ejection of PM shapes. In: Metal Powder Report. Elsevier Science Publ. ltd., Sept. 1991. Р. 6 0 — 6 4 .

40. Bocchini G.F., Fontanari V., Molinari A. Friction and boundary layer effects on the apparent compressibility of iron powders determinated on thin disks. In: P/M World Congress(Paris, 6—9 June, 1994).

41. Bocchini G.F., Fontanari V., Molinari A.Friction effects in metal powder compaction part two. Experimental results. In:APMI/MPIF PM International Conf. Seattle, WA, 1995.


Для цитирования:


Bocchini G.F. Compressibility curves of iron-base powders: Support for evaluating stresses on compaction tools or just a method for evaluation of raw materials? Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya. 2018;(4):33-47. https://doi.org/10.17073/1997-308X-2018-4-33-47

For citation:


Bocchini G.F. Compressibility curves of iron-base powders: Support for evaluating stresses on compaction tools or just a method for evaluation of raw materials? Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya. 2018;(4):33-47. https://doi.org/10.17073/1997-308X-2018-4-33-47

Просмотров: 114


ISSN 1997-308X (Print)
ISSN 2412-8767 (Online)