**4. Conclusions**

A systematic reliability method was proposed for a new mechanical system such as an HKS in refrigerators. It incorporated: (1) A parametric ALT plan formed on product BX lifetime, (2) a load examination for ALT, (3) customized ALTs with the design alterations, and (4) an assessment of whether the last design(s) of the product fulfilled the objective BX lifetime. Testing was conducted to subject the HKS in the domestic refrigerator to repeated impact loading.

In the first ALT, the HKS housing had insufficient strength for repeated impact loading and cracked. As an action plan, these flaws in the HKS were corrected by adding supporting ribs. In the second ALT, the torsional shaft made of ductile iron cracked. Due to its good machinability, fatigue strength, and high modulus of elasticity, iron is widely used in machine components. To improve its strength for impact loading, the torsional shaft was altered by increasing the corner roundness.

With these altered design parameters, in the third ALT, there were no design issues. The altered design parameters were assured to satisfy the lifetime need of the HKS—B1 life 10 years. With the examination of returned products from the marketplace, laboratory load evaluations and testing, and parametric ALTs with design modifications, the design flaws were identified and remedied to create a robust design with a remarkably lengthy lifetime. This parametric ALT is also recommended to be applied to other metals that can be used in the numerous machine parts such as cam, gears, automobile crankshafts, and dies [55–59].

**Author Contributions:** S.W. conducted the conceptualization, methodology, analysis, and testing and wrote the article. D.L.O. checked the analysis and writing for original draft. M.M.T. and S.M.A. review and edit the paper. D.E.W. supervised the research and paper preparation. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors state no conflicts of interest.
