Defect Reduction in the Manufacturing Process of In-Mould Decoration of Injection Moulded Components

Abstract

The purpose of this research is to reduce the defect rate from the manufacturing process of in-mould decoration (IMD), the process combining PET film with decorative patterns are moulded together with ABS resins, which has been developed to reduce the secondary process of decorative screen printing. Recently, the case study company has produced components with a high defect rate, which increased sharply to 22.3% in June 2018. The major causes of the defect resulting from PET film peeled off. In order to reduce the defect rate, the five steps of the DMAIC Six Sigma methodology are implemented. The detail of the IMD manufacturing process was studied to identify appropriate measurement methods and factors affecting PET film peeled off by using the cause and effect diagram and its scoring matrix. Then the prioritized factors were analyzed and selected from FMEA to conduct the design of experiment (DOE) to find significant factors and optimal parameter settings for improvement and control process to prevent reoccurrence. After improvement of PET film peeled off by setting appropriate parameter as well as implementing control plans and Standard Operation Procedure (SOP) to eliminate other defects from in-mould decoration process, the result shows that the defect rate of in-mould decoration process decreased from 22.3% to 0.7% in July 2018.