Waste Reduction of Molded Plastic Parts by Applying Principles of Six Sigma

Abstract

AbstractSix Sigma is a method that provides organizations tools to improve the capability of their business processes. This increase in performance and decrease in process variation results in defects reduction and improvement in profits, employee morale, and quality of products or services. The main objective of this research is to minimize the non-confirming products that are manufactured using plastic injection molding and reduce the waste using Six Sigma. Using statistical techniques to quantify variation, the Six Sigma Philosophy offers a step-by-step methodology for quality improvement. The study focuses on the application of Six Sigma in plastic injection molding to enhance the quality of the finished products by removing significant flaws that occurred utilizing low-cost techniques. In this case, mostly, the focus was on reducing shrinkage defects, which accounted for almost 39% of the overall non-confirming products manufactured. Another goal was to eliminate the root causes of product rejections, by using Six Sigma’s define, measure, analyze, improve, and control (DMAIC) methodology. To achieve desired results, the proposed Six Sigma approach effectively integrates quantitative and qualitative tools such as control charts (p-chart), Pareto charts, histograms, Ishikawa diagrams, measurement system analysis, and checklists. The results show that by implementing the proposed Six Sigma approach can significantly reduce the rejection rate. It was observed that the final product quality had significantly improved, primarily in terms of defects per million opportunities (DPMO) and sigma level, which increased from 4.60 to 4.74.KeywordsDMAICControl charts (p-chart)Ishikawa diagramDPMO