ThaiScience
ThaiScience
ENGINEERING JOURNAL CHIANG MAI UNIVERSITY
Volume 26, No. 02, Month AUGUST, Year 2019, Pages 121 - 130
Cost efficiency analyis for black dot defect in plastic injection process by six sigma approach
Suphachok Sengnongban and Jeerapat Ngaoprasertwong
Abstract Download PDF
Black dot is one of major quality problems in plastic injection process. The methods used to solve this problem are several different ways. This research aims to determine appropriate reduction black dot method in different conditions including price per unit and production volume per session. This finding could provide properly process and cost for each plant type. In this study, expense before process improving to decrease black dot by removing and polishing screw was 72,500 baht per month (include machine costs, overtime, shipping costs, equipment costs, etc.). Six Sigma approach; Define, Measure, Analyze, Improve and Control (DMAIC) was used to improve reducing black dot method Cause and Effect Diagram, Cause and Effect Matrix and Failure Mode and Effect Analysis (FMEA) were used to select factors which affected to black dot defect. 2k Factorial Design was applied for determination significant factor impacting black dot. The result showed removing and polishing screw can reduce black dot by 50%. This process was appropriate for high unit price and mass production. Second method was purging, adding chemical for screw-barrel cleaning process. The process could reduce black dot by 25%. It was suitable for low unit price and low production volume. After applying the black dot reduction method and calculating the cost efficiency to appropriate plant type, the total cost of reduction valued 148,000 baht per year.
Keywords
NoneENGINEERING JOURNAL CHIANG MAI UNIVERSITY
Published by : Faculty of Engineering Chiang Mai University
Contributions welcome at : http://researchs.eng.cmu.ac.th/?name=journal
