Indian Journal of Science and Technology

Abstract

Hydrodynamic Cu-Pb-Sn material journal bearings are widely used in automobile and industrial application because of its simplicity, efficiency and low cost. The bearing is often subjected to many stops and starts with unknown load cycles. During this transient period, friction is high and bushes become progressively worn-out, thus inducting certain disabilities. The bushes are provided with a lining of Cu-Pb-Sn material which is found in the range of 450 to 600 micron. The bearing designers are not provided the attention toward this dimension as in practice the failure of bushes observed by seizer, scoring, pitting, cavitations, loss of Babbitt due to high fatigue loads etc. The total depth of wear of healthy journal bearing is observed 150 to 180 micron up to 40000 kms run. The aim of present experimental work is to determine the effect of variable load, sliding velocity of shaft and deterministic surface roughness (R_a) of lining material on sliding wear behaviour and depth of wear of lining thickness(d_w) of Cu-Pb-Sn material bush, which is widely used as bush material in automobile engine. The highest temperature zone was determined and the bush samples are marked circumferentially as a, b, c, d, e, f, g in front side and a’, b’, c’, d’, e’, f’, g’ rear side in that region. The relationship between depth of wear of lining thickness (d_w) versus load, shaft speed, surface roughness is established by using the experimental results and regression model. The numerical result indicates that the surface roughness is most important bearing characteristics and the combined effect of load, shaft speed and surface roughness on depth of wear of lining material particularly in high temperature zone.
Keywords: Crank shaft bush, test rig, depth of wear, lining thickness, surface roughness.