Abstract:
The objective of this research is to solve a black dot problem of an automobile emergency knob product in the injection molding process by applying the principle of quality management, DMAIC approach. From the historical data, it indicated that there was the black dot problem found in the automobile emergency knob production up to 3.88% while the numbers of the customer complaints were also found at 0.22% of the total production.
The research methodology consisted of five steps according to DMAIC approach. First, the black dot problem was clearly identified the root cause of the problem in four processes; hopper washing process, material purging process, machine parameters setting process and 100% inspection process. Second, the tree diagram and hypothesis testing were used to identify and analyze the exact cause of problem. The attribute gage study was also used to evaluate the measurement system performance and then the production system was improved by using design of experiment technique. Finally, the work standard was established to control the manufacturing process.
The results showed that by applying the principle of quality management based on DMAIC approach, the black dot problem of the automobile emergency knob product in the injection molding process can be reduced from 3.88% to 0.92% whereas the numbers of the customer complaints were also decreased from 0.22% to 0.01%.In conclusion the productivity was increased and created a good image to customers. Which bring sales and profits in the future.