Reliability evaluation for the pump assembly using an accelerated test

The pump motor assembly in a washing machine is used to drain the dirty water generated during washing the clothes. This research was aimed to develop an accelerated test as to demonstrate a reliability goal of the assembly within an affordable amount of time and in an economic way. They were evaluated under step stress margin tests first in order to verify their operating limit in certain environmental stresses and then an accelerated test (AT) was conducted to measure the annual failure rate and MTTF of them. The high temperature and the voltage were used as stress factors to accelerate the failure of the assembly. The value of the acceleration factor was estimated by 16 at the high stress condition compared to the use condition. It also showed that all 18 units must survive for 500 h at the stress condition (40 °C, 264 V) to assure the 0.07% annual failure probability of the assembly at the use condition in 90% confidence level.