การลดชิ้นส่วนบกพร่องในกระบวนการทำความสะอาดชิ้นส่วนตรวจจับแสงสว่าง โดยใช้เทคนิคซิกซ์ ซิกม่า

Abstract

The objective of this independent study is to reduce the defective parts for cleaning process of the light sensors using six sigma techniques. The research procedures began from define phase, the flow diagram of production line was created with the starting point until the end of production process. In the measurement phase, the measuring system was analyzed by gage repeatability and reproducibility (GR&R) the operators related in the section of cleaning to separate the parts between adherent parts and good parts. Then the data form was created to record the data of adherent the light sensors parts after cleaned. The recorded data used for control chart’s limitation calculation before improvement by the p chart. In the analysis phase, a fishbone diagram was used to enumerate the causes of adherent parts. The study continued in finding the suitable container to collect cleaner solutions which prolong the efficiency of cleaner solution. The experimental results indicated that the most suitable container is beakers compared to stainless-based and polyethylene plastic. Experimental comparison between covered and uncovered beaker used in solution collection was conducted. The results shown that the covered beaker has more capability to maintain solution’s efficiency, the ratio of silicon is 19.770%. Moreover, the suitable time consumed in each sub-step of cleaning process was studied. The experimental designed using full factorial with 3 factors and 2 levels, i.e. factor A is the cleaner solution dipping time, factor B is the DI water dipping time and factor C is the IPA solution dipping time. We found that the only one factor affected to the proportion of the light sensors part adhesiveness is cleaner solution dipping time. Then, study of optimal conditions of the suitable time for cleaning process, the suitable time was defined as 18 minutes for cleaner solution dipping time, 10 minutes for DI solution and 25 minutes for IPA, the results were confirmed by re-experiment. In the improvement phase, the experimental methods from analysis step were conducted for improvement and the results shown the reduction of adherent defective parts 0.890%, the time usage was reduced from 1.30 hours to 1.13 hours and the proportion of adherent the light sensors defective parts were controllable. The final phase is control, provided the operators training for understanding in new improved operations and standardized these operations. Besides, the supervisory was increased with the protection of problem duplication using slide test to entrap the adherent parts as other step after checked by operators.