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The author:

Gary F. Schiller, Erie, PA

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This book is designed to help today's plastic molding technician deal with processing issues found day to day in the injection molding environment. It not only describes the functions of the molding machine, but also the auxiliary equipment associated with the process to produce quality parts. The chapters in this book will help the user to have a more thorough and hands-on understanding of the molding machine and the material.

It explains the process from the plastics point of view, and how the material is heated, flowed, packed, and cooled to produce the desired quality parts.

This processing guide not only shows users how to find a solution to the problem but also lets them understand why they are making the change, and what effect it has on the plastic. It details solutions from a hot runner/cold runner standpoint.

Each material has a different characteristic and will present problems in different ways, but through learning to read the part and analyzing the machine, the necessary insight will be provided to remedy most issues seen in everyday molding.

The most important thing to remember when processing or making adjustments to any machine is to make just one adjustment, review the effects on the part, and if that change has no effect, return to the previous set point, before implementing another change. By making a lot of changes in the hope of solving the molding issue, it becomes unclear which change had the effect on the part. Look at the parts, watch the molding machine, and observe what each change is doing to the process and machine.

Never neglect the details:

Walk around the machine and make sure the water is on to all lines going to the mold, or have any water lines been left off? Is the machine functioning properly (pressures, times, heating, with no unusual noises)?
Make sure the mold is functioning as intended and able to produce the quality parts desired.
Observe the material: make sure it is free of contaminants (dirt, foreign resin, or water) and is dried properly.
Then review the process and make sure there are no shortcomings (process is not pressure limited, transfer position is being achieved, not timing out and cycle time achieved).

There are no magic solutions for eliminating all molding issues, but a solid understanding of these scientific molding principles will help eliminate the unnecessary waste and scrap generated from not knowing.

There are three major components to the injection molding process: the injection unit, the clamping unit, and the mold.

In the next chapters, we will discuss the different functions of each major component and how they affect the process and conditions of the material.

I would like to acknowledge and thank the following companies and people:

RJG Inc. Traverse City, MI, especially Gary Chastain, Pat Mosley, and Shane Vandekerkhof.
AIM Institute, Erie, PA, especially John Beaumont and Dave Hoffman.
Technimark LLC, Asheboro, NC, especially Brad Wellington and Bruce Winslow.
Milacron LLC, Batavia, OH, especially Kent Royer.
I would also like to thank Gary Mitchell.

Gary Schiller

37 years in the plastics industry
Certified Master Molder I, II, & Train the Trainer; past RJG instructor with over 27 years of scientific molding experience
AIM Institute graduate and alumnus – Plastics Technology and Engineering
AIM Institute Advisory Board
Practical Rheology in Injection Molding – Penn State, Erie, PA
Design of Experiments & Quality Engineering Methods – University of Colorado
TQM – Front Range Community College, Denver, Colorado
Certified Mechanical Inspector ASQ
Certified Quality Technician ASQ
Processing expert with a wide array of plastics

Core Competencies

Stack molding
Cube technology molding
Two shot molding
Insert molding
High cavitation molding
Engineering and commodity resins

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