Does laser surface texturing really have a negative impact on the fatigue lifetime of mechanical components?

Chia-Jui Hsu,Andreas Stratmann,Carsten Gachot,Frank Mücklich,Georg Jacobs,Simon Medina

doi:10.1007/s40544-021-0508-2

Chia-Jui Hsu, Andreas Stratmann + Show 4 more

Open Access

https://doi.org/10.1007/s40544-021-0508-2

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Abstract

Laser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different designs, namely cross and dimple patterns. Base oil ISO VG 100 mixed with 0.05 wt% P of zinc dialkyldithiophosphate (ZDDP) was supplied. The bearings with cross patterns reduce the wear loss by two orders of magnitude. The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm. The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface. Therefore, in contrast to the negative concerns, the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.

Highlights

The occurrence of pitting failure often limits the lifetime of machine components operating under rolling/sliding contacts, such as bearings and gears
Surface-initiated pitting, which begins with cracks initiated by defects, wear debris, or asperities on the surface, has caused a rising percentage of failures in modern applications [2]. This is attributed to the lower thickness of oil film that occurs when pursuing increased efficiency via reducing lubricant viscosity or adopting higher machining power, which makes the machine components operate in severe lubrication conditions, namely the boundary lubrication regime
Since the Laser surface texturing (LST) structural height is larger than the untextured roughness, the higher concentration of patterns increases the mean roughness value, which theoretically causes higher contact stress

Summary

Introduction

The occurrence of pitting failure often limits the lifetime of machine components operating under rolling/sliding contacts, such as bearings and gears. Rolling contact fatigue (RCF) is initiated by micro-cracks, and the growth of cracks eventually leads to surface pitting and failures. Surface-initiated pitting, which begins with cracks initiated by defects, wear debris, or asperities on the surface, has caused a rising percentage of failures in modern applications [2]. This is attributed to the lower thickness of oil film that occurs when pursuing increased efficiency via reducing lubricant viscosity or adopting higher machining power, which makes the machine components operate in severe lubrication conditions, namely the boundary lubrication regime. Boundary lubrication is defined as the regime with a small ratio of the oil film thickness to the mean roughness value, and is mostly associated

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