The Influence of Lubricant Film Thickness on Friction Coefficients During Slow Speed Deep Drawing Operations

Abstract

During some deep drawing operations liquid lubricants are used under the blankholder to reduce friction coefficients. Under the clamping action of the blankholder, lubricants will be squeezed out resulting in a changing film thickness after the initial application of the blankholder load. A relationship between kinetic friction coefficient values and the loading duration of the blankholder can be observed from analysis of results recorded during simulative testing. By using a numerical model to combine empirical measurements, friction coefficients during boundary lubrication, lubricant film thickness with sheet surface topography data, it can be shown that the coefficient of friction can reliably be predicted for a given loading duration.

The effect of process and material parameters on the coefficient of friction in the flat-die test

“…It was concluded therefore that the 2-2.5 g/mm 2 of the lubricant was insufficient. Gilmour et al (2002) commented on the squeezing out of the lubricant during the application of relatively high normal pressures and the attendant thinning of the layer of lubricant. Since the weight of the sheets after the tests differed little from the pre-test value, this suggested that squeezing out of the lubricant at the sides was also unlikely to have been the cause of the noise.…”

“…The coefficient of friction was found to drop with all lubricants when the relative speed or the load was increased. Gilmour et al (2002) investigated the effect of the thickness of the lubricant film on the coefficient of friction, using the flat-die test. They concluded that the film thickness is a most important parameter in determining the tribological mechanisms in the contact.…”

Tools to Probe Nanoscale Surface Phenomena in Cellulose Thin Films: Applications in the Area of Adsorption and Friction

“…The interactions of solid surfaces and lubricant films could be categorized as physical adsorption or chemical reaction (Hsu 2004). As the thickness, the adsorption mass and structure of the adsorbed layer are crucial to the performance of lubrication (Rabinowi 1967;Grudev and Bondaren 1973;Visscher and Kanters 1990;Gilmour, Paul et al 2002) in situ techniques that can measure these phenomena are needed. Surface Plasmon Resonance (SPR) and Quartz Crystal Microbalance (QCM) are well-established noninvasive methods capable of providing a wealth of information about interfacial phenomena in situ, in real time and in fluid media (Stockbridge 1966;Nomura, Okuhara et al 1981;Nomura and Okuhara 1982;Gordon 1985a, 1985b;Johannsmann, Mathauer et al 1992;Liedberg, Nylander et al 1995;Rodahl, Hook et al 1995;Kasemo 1996a, 1996b;Mak and Krim 1997;Homola, Yee et al 1999;Bailey, Kanazawa et al 2001;Bruschi and Mistura 2001;Bailey, Kambhampati et al 2002;Wang, Mousavi et al 2003;Krim, Abdelmaksoud et (Fukuzawa, Shimuta et al 2005).…”