PLSM.5250 - Plastics Engineering: Plastic Part Design for Injection Molding

Program Overview

Seminar Overview

This seminar is offered to engineers and designers involved in the design of injection molded plastic parts. The course provides a fundamental overview of the many factors associated with plastic parts that will be produced using the injection molding process. In order to design a high-quality injection molded part, the designer must select an appropriate plastic material formulation, develop a functional design, and work within the manufacturing limitations associated with the mold design and injection molding process. This seminar will cover the fundamentals of plastic materials behavior and selection, engineering design, manufacturing (moldability) considerations, prototyping, stress analysis and assembly methods. The timely subject of design for enhanced recyclability will also be discussed, as will design developments related to new injection molding technologies.

Content

INTRODUCTION
Plastic material fundamentals and review of the injection molding process.

FUNDAMENTALS OF MOLD DESIGN
Mold types; gates and runners; ejection considerations

MANUFACTURING-RELATED DESIGN CONSIDERATIONS FOR MOLDED PLASTIC PARTS
Mold filling considerations, shrinkage and warpage of molded parts, mold cooling considerations

DESIGN GUIDELINES
Uniform wall thickness; factors affecting wall thickness; parting lines; tolerances

MECHANICAL BEHAVIOR OF PLASTIC MATERIALS
Short term stress-strain behavior, creep and stress relaxation, structural design of molded plastic parts, fatigue performance, impact performance, plastic materials databases

DESIGN FOR ENHANCED RECYCLABILITY
Design-related issues that enhance or hinder the recyclability of thermoplastic products

CASE STUDY FOR A NEW PRODUCT
Steps involved in the development of a new part (including materials selection)

PROTOTYPE PART PRODUCTION
Machine prototypes; rapid prototyping techniques; cast prototypes; molded prototypes, and rapid tooling techniques

ASSEMBLY OF PLASTIC PARTS
Selection of an assembly method; press fit assembly, snap fit assembly, mechanical fasteners, thermal welding techniques for thermoplastics, adhesive bonding and solvent bonding

FUNDAMENTAL DESIGN CONSIDERATIONS FOR 'OTHER' INJECTION MOLDING PROCESSES
Structural foam, gas assist, multi-shot molding, multi-layer, metal injection molding

LAB CONTENT
Design analysis and prototyping lab
Injection molding lab

About the Facilitator

Dr. Stephen Johnston came to UMass Lowell in 2003 to pursue his M.S. degree and subsequently his Ph.D. in Plastics Engineering. His expertise is in the area of instrumentation, analysis, and simulation of the injection molding process. Dr. Johnston has worked at Lord Corp., Moldflow Corp., Bausch & Lomb Inc., and does research and consulting for numerous other companies. In the fall of 2007, he started teaching courses at UMass Lowell. His course offerings focus on mold design, product design and processing.