Friction and wear investigations on single chain joints

The tribological behavior of machine elements is mostly influenced by the contact surfaces and the lubricant, especially for transient conditions and mixed or boundary friction. Both can be found in chain joint contacts. Chains of different types and structural designs are commonly used in drive and convey applications as well as timing drives of combustion engines, e. g. bush, roller and silent chains. The critical operating time is fundamentally limited by the wear inside the chain joints. Especially for timing chains, only a small elongation of 0.5% is admissible. Optimization of component surfaces, which includes reduction of friction and wear, is the primary goal of the German Research Foundation (DFG) Collaborative Research Centers 926 “Microscale Morphology of Component Surfaces (MICOS)”. Potential of timing chain components with modified surfaces are the focus of present research. Chain wear test rigs for investigation of entire chain drives require a considerable number of modified parts, which is not suitable for systematic tests. Therefore, a chain joint tribometer was developed and commissioned to close the gap between model tests on standard tribometers and investigations on whole chain drives by focusing on a single chain joint. Realistic load conditions were applied to the tested chain segment using a highly-dynamic engine (rotation) and linear actor (tension force) to investigate wear and friction on a single chain joint. The measurement system allows for online wear and friction detection.