Publication Date

Spring 2021

Advisor(s) - Committee Chair

Dr. Mark Revels (Director), Dr. Fatemeh Orooji, and Dr. Asghar Rezasoltani

Degree Program

School of Engineering and Applied Sciences

Degree Type

Master of Science


Berry Global in Bowling Green, Kentucky produces predominantly polypropylene container closures. One variant, the 83mm lined jar closure, is produced by first being injection molded, placed in work-in-progress (WIP) hold for 24 hours to cool, and then finished through the auxiliary liner operation into a final product. While this process is an effective method to produce a quality large-diameter closure and allows the polypropylene adequate time to cool without warping out of shape, the 24-hour WIP time and the manpower needed to accomplish this can negatively impact several business metrics as well as employee safety.

The purpose of this thesis was to document the application of Six Sigma to improve the process of manufacturing 83mm lined jar closures. This was completed by executing the define, measure, analyze, improve, and control (DMAIC) process at the heart of Six Sigma to define the process, measure current WIP and desired airveyor continuous flow process metrics to analyze any impact to the closure, and put controls in place to ensure the improved process was stable. The project resulted in a successful application of the Six Sigma methodology and positive variable data results supporting a recommendation for the change to a continuous flow airveyor process.


Manufacturing | Materials Science and Engineering | Statistics and Probability