IMPROVING THERMOFORM PRODUCTIVITY: CASE OF DESIGN-OF-EXPERIMENT

This work is aimed to improve productivity of single-stage thermoforming process by implementing Six Sigma methodology. The process is performed at a refrigerator manufacturing company in a developing country. Six Sigma methodology – Define, Measure, Analyze, Improve, and Control (DMAIC) and Design of Experiment (DOE) is used to identify the critical factors that affect a thermoforming process’s productivity and to determine their optimal configuration using Response Optimization. The critical factors identified are: sheet temperature; sheet thickness, and; vacuum time. Optimization of these factors resulted in increased productivity of 13%, while maintaining quality. Increased productivity helped the company in minimizing the buffer stocks and the associated costs. This work revealed that single-stage thermoforming process can be made more productive by installing a pre-heating stage before inserting sheet in the machine, as it will save the critical time. For further study, more thermoforming material can be included in DOE as compared to ABS plastic which is in scope of this study.