An analytical wear model based on CAD measurements in polyamide pinion under different working environments

This study proposes a method to assess wear in polyamide gears by measuring the volume of worn material from teeth flanks of a pinion under actual service conditions. Measurements are conducted using a microscope combined with a computer aided design "CAD" technique. First, a raster image of a tooth is recorded through an optical microscope linked to a microcomputer; then, digitalisation software is used to sort out the tooth new boundaries and finally, each tooth flank profile is obtained using spline function of the CAD software and wear evolution is deduced. Results show that the proposed CAD technique gives reproducible and sufficiently precise wear data compared to conventional weight loss approaches. Wear analyses are achieved in terms of wear morphology on both flanks as a function of number of cycles. A parametric model involving torque, pinion geometry and friction coefficient is deduced for water, detergent and dry environments.