Development of comparative investigation method for timing chain wear analysis using oscillating tribometer

Abstract

This paper presents the development of a test procedure to investigate timing chain components under abrasive stress on a tribometer. Engine developers use cost and time expensive engine dynamometer tests to investigate timing chain life expectancy under different conditions. Tribometer tests are fast and cost effective, but these use standardized specimen material and geometry that greatly differ from the original tribological system of the timing chain. Manufacturing specimens from the original chain material using the original technology is complicated; surface quality and hardness properties cannot be guaranteed. The aim of research was to develop a test method for rapid and cost-effective comparison of engine lubricants, timing chain materials or coatings, as well as to assess the wear resistance of the chain to contaminants. Various uncontaminated and carbon black blended lubricants were compared using standard-based ball-on-disc tribometer tests to tribometer tests using actual timing chain components (bush-on-pin test) of a Diesel engine. Lubricants were ranked in terms of coefficient of friction and wear. Results showed that bush-on-pin tests were comparably suitable for testing lubricants when evaluated against standard ball-on-disc tribometer tests.

Timing chain wear investigation methods: Review

“…On the other hand, CB-blended oils behaved differently in the two methods. In the case of bush-on-pin, CB slightly reduced the friction, while in the case of ball-on-disc, it increased [39].…”

“…Sappok et al of the University of Kaiserslautern [33] and Paulovics et al of Széchenyi István University [18], [36]6- [39] performed experiments independently with bush-on-pin configuration (Figure 5/b); both performed on an existing reciprocating tribometer supplied with a custom adapter. The bush chains examined by the two institutes were different types, differing in size, material quality, hardness, and surface roughness.…”

“…At Széchenyi István University, the bush-on-pin test presented in the previous chapter was compared with ball-on-disc tests using standard specimens [39]. The study's goal was to assess the similarities and differences in friction and wear between the standard specimens and the chain specimens using the same oil types.…”

Selection of engine oils with tribological examinations applicable to specially operated diesel engines

“…MWSD) could be calculated corresponding to the ISO 19291:2016 standard: the wear scar diameter was measured on the surface of the ball spe-cimen parallel and perpendicular to the sliding direction and their average value was considered as MWSD value. Paulovics et al [12] proved that there is a good correlation between the MWSD value and the measurable wear volume parameters, so we have decided to measure this value instead of the wear volume, which can only be defined with a more complex and more time-consuming method.…”