撮要

This case provides students an opportunity to learn about major concepts of statistical process control, particularly the process control charts, process capability index, and six sigma quality. The protagonist of the case is a third-year business student majoring in operations management, who was working as an intern at Germagic Biochemical Technology (GBT) during the summer of 2021. The intern was tasked with assessing the quality performance of the production process of Germagic 4H Hand Sanitizer, as measured by the actual filled volume within the specifications of 500 ± 10 ml. By using this case study, students can easily relate to the intern’s experience as he goes through the entire process of designing the control charts, collecting the data, ensuring the process is in statistical control and stable, and eventually computing the process capability index to determine how much improvement should be made in order to achieve the six sigma quality.

This case will cover many technical issues in developing process control charts and the process capability index. Students should be able to complete the necessary calculations to develop the X-bar and R charts to monitor the process mean and range. After the process is found to be in control and stable, students can move on to compute the process capability index with reference to the design specifications and then make conclusions about how capable is the current production process to produce quality products. More importantly, students should be ready to discuss many managerial issues that the intern would face, including how to communicate complicated statistical concepts and the implications of six sigma quality for both manufacturing and service businesses to his supervisor, who is interested in expanding the scope of six sigma quality to the company’s other business areas.

學習目標

1.       Identify the appropriate tools for quantifying the quality of a product and/or a manufacturing/service process 

2.       Construct X-bar and R charts to monitor the process mean and variability and to determine if the process is in control and stable

3.       Compute the process capability index (C_pk) and interpret the result

4.       Relate the process capability index to six sigma quality and set target for improvement

5.       Discuss how six sigma quality can be applied in both manufacturing and service businesses