Project Objectives
A home appliances manufacturer was struggling with a persistent 15% defect rate in Part X, a critical component produced in-house from short-glass fiber-filled polypropylene (PP).
The defects were undetectable during on-line quality checks and only became apparent after assembly into the final product, leading to high costs. Despite the efforts from the company’s R&D team and external Lean consultants, the root cause remained unresolved, and prior improvement attempts yielded no success.
Our intervention began with a one-week on-site visit to conduct comprehensive measurements and collect detailed data. We launched a Six Sigma project to analyze and address the problem systematically. Following the site visit, we worked remotely for several months to refine data analysis and implement targeted actions.
Key observations
• Injection Mold Design: the mold design caused rapid shrinkage of freshly injected parts, contributing to defects.
• Assembly Technology: the automated robotic assembly cell occasionally caused micro-damage to components due to programming inconsistencies.
• Quality Check Gaps: Ineffective quality control processes allowed defective parts to proceed to later production stages.
A Six Sigma project was conducted to identify the root cause of the problem, which stemmed from the technology and processes themselves. The investigation highlighted significant issues in the design of the injection mold and the technology of the robotized assembly cell, both of which were major contributors to the high defect rate. The proposed solutions and necessary changes successfully resolved the customer’s issue.
Key Achievements
• Reduced the defect rate on Part X from 15% to 1.8%.
• Improved assembly cycle time by 18%.
• Achieved annual savings of $350,000.
The problem was thoroughly resolved, ensuring it never reoccurred.
