A Case Report on Root Cause Analysis of No-Go Parts in Refrigerator Factory

Abstract

This paper studies the causes of customer complaint to a refrigerator manufacturer. No-Go (NG) product in manufacturing process not only affects the manufacturing cost but also increase problem about waste management. Main potential cause was identified with Quality Control (QC) tools and Failure Mode and Effects Analysis (FMEA), and it was weakness of legs of cooling blower shroud after injection process and unintended dropping of the blower in assembly station. To proof the hypothesis, the first stage of investigation with Finite Element Analysis (FEA) was performed with the drop test at the height of 0.8 m with impact angle of 45 degrees from the level of an assembly table. According to convergence testing of the FE analysis, the results were well consistent with the found defection. The FEA exhibited the stress of the model of dropping height was 135.6 MPa which almost reached the ultimate stress of the blower material. Therefore, an improvement was done by setting the assembly level at 10 cm lower to diminish the kinetic energy of unintended dropping while transferring. After the improvement was made, no any of NG products was found.