Start with a use profile
Define cycles per week, typical mode, temperature, duration, load, door openings, cool-down and cleaning. A life test at one constant condition can miss failures caused by thermal transitions, grease, vibration or user handling. The test should represent the intended market and warranty exposure.
Separate subsystem risks
Heaters, relays, thermostats, electronic controls, fan motors, wiring, door hinges, seals, coatings and accessories fail in different ways. Use a failure-mode review to select endurance, thermal cycling, door cycling, overload and inspection activities. Record performance drift, not only catastrophic failure.
Report evidence honestly
A small number of passing samples does not prove that every future unit will last the same number of cycles. Reports should state sample size, censoring, failures, repairs, test conditions and the exact production revision. Do not turn an engineering screen into an unsupported lifetime guarantee.
Connect testing to production
Incoming component controls, end-of-line tests, torque and routing checks, traceability and approved-supplier control keep the validated design from drifting. When a heater, relay, fan, insulation or firmware changes, review which tests must be repeated.
- IEC 60335-2-9 safety context for portable cooking appliances: https://webstore.iec.ch/en/publication/61318