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Abstract:The risk of failures associated with a distressed pin/connecting rod bearing contact without forced pin oiling is exaggerated due to ever increasing power density and torque output of modern TSI (turbocharged straight injection) and TDI (turbocharged direct injection) engines, in combination with the introduction of low-viscosity low-SAPS (sulfated ash, phosphorus, sulfur) lubricants and general engine downsizing resulting in fewer cylinders to bear the load. This forces OEMs (original equipment manufacturer) to look for innovative cost-efficient solutions to promote bushingless connecting rods without impacting reliability. One such solution is the Triboconditioning® process. Triboconditioning is an industrial surface finishing process which attempts to carry out running-in of components during their manufacture. The present paper provides an in-depth analysis of the tribological effects of Triboconditioning® on the pin/conrod contact.

Bearings are precision machine elements with very high requirements regarding the roundness, waviness and roughness of the rolling elements as well as the bearing rings. The production processes have to meet sub-micron tolerances. To verify production quality, state of the art tactile measuring technologies are used, such as roundness and waviness measurements as well as roughness measurement according to ISO 4287 [3]. To measure roundness and waviness a special gauge is used, where as a second gauge is measuring the roughness of the surface. The measurements are mostly performed in a laboratory environment checking parts in a random sampling procedure. To meet the rising demands on quality of bearings, it is necessary to increase the sample size. On the other hand, this increases the time needed for quality inspection. The optical measuring technology SCATTERING LIGHT can help to solve these contradictory demands. The technology is based on the reflection of light from a surface. It can be used to measure roundness, waviness and roughness in one single operation. Providing a clean environment, the measurements with scattering light can be automated and integrated in production processes such as honing and grinding. Furthermore, the cycle time is shorter than from the tactile measuring procedure. Results from scattering light measurements can be calibrated. Roundness and waviness are traceable to international standards. The optical result for surface roughness "Aq" is a new parameter that does not correlate to the common known Ra and Rz values but to the occasionally used Rdq value.