10/30/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation defense by Bryan Weidknecht on: A Hybrid Extrusion-Injection System for Compounding and Micro-Molding of Polymer Composites.

Candidate Name: Bryan Weidknecht
Degree: Doctoral
Defense Date: Wednesday, November 13, 2024
Time: 2-4 p.m.
Location: ETIC 345

Committee:
Advisor: David Kazmer, Professor, Plastics Engineering, University of Massachusetts Lowell

Committee Members:
Stephen Johnston, Professor, Plastics Engineering, University of Massachusetts Lowell
Davide Masato, Associate Professor, Plastics Engineering, University of Massachusetts Lowell
Jay Park, Associate Professor, Plastics Engineering, University of Massachusetts Lowell

Brief Abstract:
Micro-injection molding is a growing field focusing on large scale production of micro-sized components. This research develops and investigates a hybrid extrusion-molding process designed to minimize the total residence time during compounding and micro-molding. The objective is to design and build this system and analyze the influence of significant factors on critical responses. To achieve this, a systematic and comprehensive approach is taken in which the system is divided into three subsystems: extrusion, transition, and micro-molding. The extrusion and transition subsystems are evaluated with screw output characterization, COMSOL CFD simulation, and plunger dwell study to assess material throughput. In the micro-molding subsystem, scientific molding techniques are employed to determine optimal fill rates and packing times, which are compared to compression molding simulation results from Moldex3D. The performance of the entire system is then assessed with a Design of Experiments (DOE), determining the influence of packing pressure, machine temperature, and screw speed on tensile properties, part dimensions, and process states. Through these studies, an optimized process is suggested. Finally, a system performance evaluation indicates a reduced footprint and residence time at the expense of increased energy usage when compared to alternative industrial solutions. These findings suggest productive processing strategies for extrusion-injection molding technology.