การปรับปรุงระบบควบคุมคุณภาพในอุตสาหกรรมฉีดขึ้นรูปพลาสติก : กรณีศึกษา / วีรพล ปัญญาวิสุทธิกุล = Improvement of the quality control system in the plastic injection molding industry : a case study / Veerapon Panyavisutthikul
To improve the quality control processes in the plastic injection molding manufacture. The research was studied by using one company as a case study. From the research, the existing quality control process of the studied company consisted of only the receipt and inspection of raw material and the finished products sample inspection which were not enough to achieve satisfied quality products. There were not any Procedure and Work Instruction documents in many parts of the company, which directly influenced to the product quality. Moreover, the company also encountered the problems of the inefficiency of the Support documents so that it resulted in the difficulties of the storage of the fundamental quality information. As the stated problems above, these problems brought the company in troubles especially on the lack of standard quality control system and the high level of the defects which were about 9% on average of the total products produced from the production processes. So the Support documents were designed and developed in order to enable us to know the causes of the defects. The results revealed the 93.47% were from the Black Dot and Short Shot in the injection process. Then the Cause and Effect diagram was developed in order to figure out all possible causes that made the products in Black Dot and Short problems. The result showed that the major causes were form 4 major causes which were from Man, Material, Machine, and Procedures. This thesis intended to solve the defect problems of the whole process, not focus on only specific area, because most causes always related to each other. The thesis was completed on the following steps: 1. Proposed and developed the organization chart in all quality responsibilities. 2. Improved the existing quality control system in 2.1 Incoming material improvement quality control system. 2.2 In process improvement quality control system. 3. Developed quality plan in order to specify the Check point and maintain the improved quality control system as a standard. 4. Summarized the results of the improvement of the developed quality control system. 5. Presented the difficulties during the study and suggested the further recommendations. After the developed system was adopted in the company, it resulted in the significant reduction of the Black Dot and Short shot defects from 6.87% at the beginning, down to 3.2% and finally improved to 1.57% consecutively.
