CASE STUDY OF HINGE ALIGNMENT PROBLEMS: A SIX-SIGMA QUALITY ANALYSIS

• Published in: Production and inventory management journal 2000-03, Vol.41 (2), p.1
• Main Authors: Echempati, Raghu, White, Christy
• Format: Article
• Language: English
• Subjects: Case studies; Caskets; Coffins; Conveyor lines; Dimensional analysis; Funeral industry; Manufacturers; Production management; Quality standards; Studies; Wood products
• ISSN: 0897-8336

This article describes a manufacturer of wood caskets whose plant produces about 3,000 units per day. Different species of wood are used and two types of caskets are produced, "full-top" and "cut-top." The caps of both types are attached to the shell by four hinges. During the past two years, the company has been concerned about misalignment of caps on the cut-top units. The problem is thought to lie mainly in the placement of the hinges. As a previous consistency study showed little deviation in the placement of hinges on the shell, this case study focuses on the cap hinge placement. Numerous sample units were dimensionally analyzed and their consistency in hinge locations was noted. These data were evaluated to find the six-sigma capability of the processes, and that information was used to quantitatively assess the quality of this part of cap production. On the basis of the analysis, it was determined that the locations for the hinges were out of specification. The study also found that more-than-spec was being cut and sanded off at the band saw-butt sander (BSBS) machine. A more thorough study involving designs of experiments needs to be conducted to completely understand the interactions between the various process parameters. That will help in identifying other possible causes for hinge misalignment besides those occurring at the BSBS machine. Warping of the cut-top due to stress relaxation of the wood is one. A new design has been recommended for the company's consideration. As this article was being written, we believe the company implemented some of the recommendations designed to improve its process at the BSBS machine.