Robust Process Development and Scientific Molding

Overview

This class is designed for those who would like to have a basic working knowledge of polymers and injection molding. It reviews the important aspects of the factors required to develop a robust injection molding process, using the techniques of scientific molding and scientific processing. Scientific principles related to the complete molding process, from the drying of the resin to the shipping of the finished product will be discussed. Design of Experiments (DOE) for injection molding will be covered. The hands-on workshop will include development of a process using scientific molding principles, a Design of Experiments exercise.

Content

Introduction to Scientific Processing

• What is scientific processing and scientific molding
• The five critical factors to successful injection molding
• The three types of consistencies required for successful injection molding

Polymers and Plastics

• History and definition of polymers
• Crystalline and amorphous polymers - morphology of polymers
• Common commercial plastics, additives and fillers

Plastic Flow

• How is plastics flow different?
• Newtonian and non-Newtonian fluids
• Shear dependent rheology in injection molding

Injection Molding and Molding Machines

• The molding machine, screw and barrel
• Terminology of machine specifications
• Selecting the right molding machine

Drying of Plastics

• Hygroscopic materials
• "Overdrying" of plastics

Scientific Molding - The 6-Step Study

• In mold rheology or viscosity curves
• Cavity fill balances
• Pressure drop studies
• Process window studies
• Gate seal study
• Cooling study
• Post mold shrinkage

Design of Experiments (DOE) for Injection Molding

• What are DOEs?
• Factors, levels and responses
• Full and partial factorial experiments and other design types
• Analysis of the results: pareto/tornado charts and contour plots

The Aesthetic, Dimensional and Control Process Window

• The aesthetic process window
• The dimensional process window
• The recommended mold qualification procedure

Troubleshooting and Related Topics

• "Must have" list of accessories for troubleshooting
• Common molding defects and their solutions
• What to do when there is a problem - a step-by-step guide

Machine Validation

• Shot-to-shot variation
• Load sensitivity test
• Injection speed linearity test

Implementation of the Techniques at Your Facility

• Coming up with a suitable plan for improvement
• Implementation

Hands-On Workshop Experiments

Scientific Molding

• Setting up the machine parameters
• Developing a viscosity curve
• Determining cavity balances
• Determining the pressure drop
• Determining the process window
• Determining the gate seal time
• Determining the cooling time

Design of Experiments

• Factor and response selection
• Collecting the data
• Analysis of the data

Determining the Process Window

• The cosmetic process window
• The dimensional process window