การลดของเสียที่เกิดจากปัญหาน้ำรั่วในกระบวนการประกอบกระจกหน้ารถยนต์ / ปฑกรณ์ มหาศิริชวรัตน์ = Defective reduction of water leak problem in front windshield assembly process / Pathakorn Mahasirichararat
Six Sigma has been applied in this thesis for improving automobile assembly production with the objective to reduce proportion of defectives due to water leak in front windshield assembly process. This problem caused rework cost of 1,837,296.68 baht/year. The research follows the five stages of Six Sigma. Firstly, in the Define phase, the problem, objective and scope of the project were identified. Secondly, in the Measure phase, an attribute agreement analysis was performed to assess both accuracy and precision of the measurement system. Then, potential causes of problem were brainstormed and list out in the Cause and Effect Diagram. Next, the Key Process Input Variables (KPIVs) were identified and prioritized by applying Cause and Effect Matrix and Failure Mode and Effects Analysis. In the Analysis phase, the Design of Experiment was applied to find out factors that statistically affecting the proportion of defectives. In the Improvement phase, the most suitable factor levels were discovered. Finally, in the Control phase, confirmatory experiment was performed. Moreover, control plan was developed to control KPIVs and graph was used to monitor the proportion of defectives. After improvement, it was found that the proportion of defectives due to water leak in front windshield was reduced from 1.90% to 0.53%, which was 72.1% reduction. Furthermore, the rework cost was reduced by 961,515.43 baht/year.
