Improving lifetime of domestic compressor subjected to repeated pressure loading

•Reliability test plans of multi-module product based on its BX life definition.•Acceleration method of mechanical system.•Derivation of sample size equation combined with targeted BX lifetime and accelerated factor.•Accelerated life testing with reproduction of design problems and its action plans.•Evaluation of the final product design to ensure the BX lifetime are satisfied. To enhance the lifetime of domestic refrigerator compressors subjected to repeated pressure loads, parametric accelerated life testing (ALT) as a reliability methodology is studied. It contains (1) ALT plan used on BX lifetime, (2) load analysis for the ALT, (3) parametric ALTs with action plans, and (4) assessment of the last compressor designs to make sure the targeted BX lifetime is achieved. To combine the design concepts of a compressor with parametric ALT, we have derived the approximated sample size equation, the life-stress model with an effort concept and acceleration factor. As a test case, a compressor with a newly designed crankshaft subjected to repetitive pressure loading was studied. Based on a mass and energy balance, the compressor loads were analyzed. In the 1st ALT, the failure mode was locking of the compressor due to crankshaft wear. The design fault of the crankshaft was the improper lubrication in the crankshaft. As a corrective action plan, the crankshafts were redesigned by: (1) changing the starting RPM from 1650 to 2050, (2) relocating the lubrication holes and adding a new groove, and (3) modifying the material of crankshaft from FCD450 to FCD500. In the 2nd ALT, wear on the surface of compressor crankshaft occurred. The minimum clearance between thrust washer and the crankshaft was then modified. After three parametric ALTs, the lifetime of the newly designed compressor was guaranteed to have B1 life 10 years.