Downscaling of metal-forming operations from macro- to microscale implies significant changes caused by size effects. Among these, the friction increases as reported by researchers using indirect test methods such as the ring-compression test and double-cup-extrusion test. In this study, a new test equipment is developed for studies of the size effect in metal-forming friction in the range from macro- to microscale. Investigations confirm a significant friction increase when downscaling. Visual inspection of the workpieces shows this to be explained by the amount of open and closed lubricant pockets.
GeigerM.KleinerM.EcksteinR.TieslerN.EngelU.Microforming. CIRP Ann. Manuf. Technol., 2001, 50, 445–462.
2.
PawelskiO.Ähnlichkeitstheorie in der Umformtechnik. In Umformtechnik, Plastomechanik und Werkstoffkunde (Eds DahlW.Kopp, andR.PawelskiO.), 1993 (Springer Verlag, Berlin), 158–176.
3.
VollertsenF.BiermannD.HansenH. N.JawahirI. S.KuzmanK.Size effects in manufacturing of metallic components. CIRP Ann. Manuf. Technol., 2009, 58, 566–587.
4.
EngelU.EcksteinR.Microforming – from basic research to its realization. J. Mater. Process. Technol., 2002, 125, 35–44.
5.
EngelU.Tribology in microforming. Wear, 2006, 260, 265–273.
6.
MessnerA.EngelU.KalsR.VollertsenF.Size effect in the Fe-simulation of micro-forming processes. J. Mater. Process. Technol., 1994, 45, 371–376.
7.
Geiger, M., Messner, A., Engel, U., Kals, R. and Vollertsen, F. Design of micro-forming processes: fundamentals, material data and friction behaviour. In Proceedings of the 9th International Cold Forging Congress, Solihull, UK, May 1995, pp. 155--164.
8.
Tiesler, N., Engel, U. and Geiger, M. Forming of microparts – effects of miniaturization on friction. In Proceedings of the 6th International Conference on Technology of plasticity, ICTP, Nürnberg, Germany, 19–24 September 1999, vol. II, pp. 889--894 (Springer, Berlin).
9.
DanckertJ.Analysis of the ring test method for the evaluation of frictional stresses in bulk metal forming processes. Ann. CIRP, 1988, 37(2), 217–220.
10.
GhobrialM. I.LeeJ. Y.AltanT.BayN.HansenB. G.Factors affecting the double cup extrusion test for evaluation of friction in cold and warm forging. CIRP Ann. Manuf. Technol., 1993, 42, 347–351.
11.
TanX.BayN.ZhangW.On parameters affecting metal flow and friction in the double cup extrusion test. Scand. J. Metall., 1998, 27, 246–252.
12.
Nielsen, P. S., Paldan, N. A., Calaon, M. and Bay N. Direct testing of scale effects in metal forming friction and lubrication. In Proceedings of the 4th International Conference on Tribology in manufacturing processes (ICTMP 2010), Nice, 13–15 June 2010, vol. II, pp. 497--506.
13.
SagaJ.NojimaH.AritaK.Effect of lubrication upon coefficient of friction and surface feature under high contact pressure (in Japanese). J. Jpn. Soc. Technol. Plast., 1975, 16, 398–404.
