David C. Bell



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Extruded parts are conventionally made by forcing melted plastic through a steel die having a fixed opening that matches the shape of the part. Plastic parts made by extrusion include weather stripping, PVC pipe, and composite lumber. Variable geometry dies can change their opening shape during the extrusion process. Developing shape-changing dies technology offers the possibility of making parts with varying cross-sections that currently need to be made through injection molding. This is desirable as, compared to molding, extrusion tends to be faster and less expensive. Variable geometry extrusion dies have been designed and prototyped by the University of Dayton research team that confirms the validity of the concept. This research explores the limits of this new technology by creating a die that has substantial movement of components that form the die opening.

Publication Date


Project Designation

Honors Thesis

Primary Advisor

Andrew P. Murray, David H. Myszka

Primary Advisor's Department

Mechanical and Aerospace Engineering


Stander Symposium poster


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Design and Prototyping of a Variable Geometry Extrusion Die to Exhibit Significant Alteration in Shape