04/08/2025
By Danielle Fretwell

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Stiven Kodra on: "Design of a Compact Mixing Extruder for Pellet-based Additive Manufacturing"

Candidate Name: Stiven Kodra
Degree: Doctoral
Defense Date: Wednesday, April 16, 2025
Time: 1:15 - 3 p.m.
Location: ETIC 345

Committee:
Advisor: David Kazmer Ph.D., Mechanical Engineering, University of Massachusetts Lowell

Committee Members*
1. Christopher Hansen Ph.D. Mechanical Engineering, University of Massachusetts Lowell
2. Juan Pablo Trelles Ph.D. Mechanical Engineering, University of Massachusetts Lowell
3. Davide Masato Ph.D. Plastics Engineering, University of Massachusetts Lowell

Brief Abstract:
This research aims to enhance pellet-based additive extrusion systems by focusing on three critical areas: screw design, performance characterization, and process-based control. The first area involves developing a compact single-screw extruder featuring a novel screw design with a reduced length-to-diameter ratio. This design incorporates advanced elements such as variable pitch flights, double flights, and mixing slots to ensure mixing, melt consistency, and improved heat transfer while minimizing energy consumption. This research will also include performance characterization with advanced control strategies tailored specifically for additive manufacturing (AM).
Steady-state evaluations will assess mass flow rate and temperature uniformity, while transient analyses will focus on the system's dynamic response to changes in screw speed and melt pressure for reliable AM operations. Specialized control systems will be developed to handle complexities associated with dynamic operating conditions, thereby improving process stability. This research is part of an open-source initiative supported by a U.S. Army grant to Re3D, aiming to produce sustainable AM solutions utilizing current plastic waste streams, ultimately demonstrated through fully functional beta prototypes.