New Reliability Validation Test for Radial Cooling Motors - An Oven Home Appliance Application

This paper presents the steps followed to define a new reliability validation test for shaded pole motors used in cooling systems of built-in ovens. The motors are fundamental for maintaining low temperature on sensitive components such as electronics, especially in high-temperature conditions such as pyrolytic self-cleaning, where the oven temperatures can reach up to 450^°C. A Design of Experiment (DoE) approach was applied considering temperature, rotating speed and supply voltage as the key stress factors. Axial play, measured as the motor's movement along the shaft axis, proved to be a consistent indicator of upcoming failures. The test showed that temperature had the highest impact on mean time to failure of the component under investigation. Evaluating the acceleration factor using the Arrhenius model it was possible to propose a new test procedure achieving a 20% decrease of validation time while keeping the target of 90% reliability with a 90% confidence level. The stress-strength analysis showed that the cooling motor under study has a reliability of 99,55% over 10 years of usage in a pyrolytic oven, with a 90% confidence level.

Keywords: Component reliability, Stress-strength, Shaded pole motor, Accelerated life testing.