Injection Molding Fundamentals© (Short Course)


Injection Molding Fundamentals© Short Course

October 28, 29, 30 2013

Sponsored by the Golden Gate Polymer Forum and
Presented by Lawrence R. Schmidt
LR Schmidt and Associates
Schenectady, NY

Michaels at Shoreline

2960 N Shoreline Blvd
Mountain View, CA 94043
(650) 962-1014
Get directions


This course is designed to give the attendees an in-depth understanding of the basic principles of the injection molding process. The unique coupling between flow, structure and properties in molded parts will be emphasized. The response of plastic melts to process conditions and design features will be covered at an intermediate/advanced level to establish a foundation for problem solving. Applications of new and novel technology will be discussed. Common myths and folklore which surround the molding process will also be analyzed. All topics are presented in a practical manner to foster learning by those with some technical education or background.

The course promises to be an exceptional opportunity based on the combination of an experienced and well-known speaker, a convenient location in the Bay Area, an affordable price, and a focus on practical applications.






Course material is presented for 7 1/2 hours each day including a morning and afternoon break of 20 minutes each. Lunch break is 1 1/4 hours.

Day 1 October 28

Basic Principles and Critical Design Parameters of the Injection Molding Process

I : Process Definition

  • Basic Elements
  • Cycle

II : Process Sequence

  • Amorphous and Crystalline Polymers
  • Melt Pool Generation
  • Flow in Melt Distribution Networks
  • Cavity Flows
  • Secondary Flows
  • Packing
  • Cooling

III :  Material Behavior – Part I. Simple Material Behavior

  • Shear and Extensional Deformations
  • Steady Shear Flows
  • Viscous Liquids - Resistance to Flow
  • Testing Molten Plastics
  • Commonly Used Viscometers
  • Effect of Temperature on Shear Viscosity
  • Effect of Pressure on Shear Viscosity

IV : Flow, Structure, Property Interrelationships - Part I

  • Flow Front Dynamics

Fountain Flow
Viscous Fluids

  • Viscoelastic Polymer Melts
  • Co-Injection Molding Concept
  • Mold Filling Visualization - Edge Gated Cavities
  • Hydrodynamic Skin-Core Structure

Macroscopic Features
Structure Distribution
Variables Controlling Molded-In Structure

Day 2 October 29

Fundamental Relationships Between Flow, Structure and Properties - Application of Advanced Concepts to Problem Solving

V : Flow, Structure, Property Interrelationships - Part II

  • Mold Filling Visualization - Center Gated Cavities
  • Pressure Flow in the Barrel
  • Relationship Between Fluid-Elements in the Cavity and Original Barrel Locations
  • Effects of Particulate Fillers, Long Fibers and Rubber Impact Modifiers
  • Morphology in Molded Part

Microscopic Features
Polymer Molecules
Impact Modifiers
Molecular Structures
Chain Orientation

  • Weld-Line Formation
  • Surface Properties
  • Property Distributions

VI : Computer-Aided Mold Design

  • Introduction to CAE
  • Design Approach
  • Material Properties and Other Required Input Data
  • Results and Interpretation
  • Examples
  • Commercial Design Codes

VII : Material Behavior – Part II. Complex Material Behavior

  • Material Spectrum
  • Elastic Responses
  • Characterization of Viscoelastic Melt Behavior
  • Non-Linear Effects
  • Resin Consistency
  • Flow Instabilities


VIII : Application of Basic Principles to Common Problems

  • Influence of Injection Rate on Property Variation
  • Origins of Surface Contamination
  • Surface Marks and Patterns
  • Read Through, Transfer of Cavity-Wall Defects, Mold Surface Effect
  • Effect of Molecular Orientation on Impact Strength
  • Flow Instabilities
  • Misconceptions and Myths

Day 3 October 30

Managing Viscoelastic Melt Behavior for Part Quality and Process Optimization

IX : Application of Advanced Molding Technology for Process Optimization

  • Profiled Injection Rate
  • Sequential Molding with Valve Gates
  • Injection-Compression Molding
  • Gas Assisted Molding
  • Pulsed Cooling
  • Strategies for Optimizing the Injection Molding Process

X : New Developments and Process Concepts

  • Co-Injection Molding Process Techniques
  • Multiple Live-Feed Molding
  • Melt Conditioning Prior to Injection

XI : Problem Solving Session

  • Bubbles and Voids
  • Jetting and Other Non-Standard Flow Phenomena
  • Hesitation Flow Marks and Haze
  • Problems from the Shop Floor



Larry Schmidt is President of LR SCHMIDT ASSOCIATES, a plastics consulting firm specializing in advanced process designs and product concepts, technology assessment and root-cause analysis of viscoelastic processing problems. He earned chemical engineering degrees from Ohio University, Washington University and the University of Colorado, where his PhD research was on polymer processing. Prior to starting his consulting company in 1992, he worked for General Electric for 22 years, including 11 years as manager of the polymer engineering programs in the Corporate Research and Development Center.

Dr. Schmidt has published over 50 papers, given numerous presentations on polymer processing and holds several patents. His novel mold-filling visualization results are used worldwide by engineers, designers and technologists. He is a Fellow and a Honored Service Member of the Society of Plastics Engineers and serves on the Injection Molding Division Board of Directors.



The location of the course will be Michaels at Shoreline, 2960 N Shoreline Blvd, Mountain View, CA 94043
(650) 962-1014
Get directions

  • Continental breakfast and lunch will be provided on site each day at no additional charge.
  • Additional instructions will be provided to those who register for the event before the deadline of October 18, 2013.
  • Hardcopy lecture notes will be provided to all attendees.
  • The instructors will stay until 6:00 PM to discuss specific issues.



Early Registration (Until 11:59PM September 30, 2013): $785
Late Registration (October 1 - October 18 2013): $885

  • No reservations will be accepted after 11:59PM October 18, 2013 or after the class size limit of 70 is reached.
  • Advance Registration and payment required. No drop-ins will be allowed.
  • No reservation will be considered complete until payment is received.



(1) Begin the registration process on at the bottom of this web page and follow the instructions there. Use the drop down menu to select the correct registration option
We will need your name, affiliation, and contact information as requested.
After selecting "Verify", you will be prompted to Pay by Credit Card or Pay by Check. If you choose to pay by Credit Card, you will be directed to pay at PayPal. You will receive an email notice when payment has been confirmed. If you choose to pay by check, you need to provide payment by mailing a check made out to “GGPF” in the appropriate amount. Please contact Eveleen Tang ( for further instructions.  Your registration is not complete until a check is received.

If your company requires it, the GGPF Tax ID# will be provided to you by e-mailing a request to Eveleen Tang at Please note that the conference registration fee covers the short course expenses and is not a tax deductible donation.

(2) Your registration will not be complete until payment is received. For purposes of registration dates, or for first-come first-served issues, we will use either your date of registration by credit card or the post office date on the envelope which contains the check.

(3)An automated e-mail receipt will be provided as soon as you register and is usually sufficient for corporate reimbursement. You will also be given a receipt when you arrive for the class on the first day.

(4) Reservations will be accepted in the order received until the class size limit is reached. We expect to be able to accommodate 70 attendees per day. Early reservations are encouraged. No reservations will be possible after October 18 or after attendance limits have been met.

(5) If someone else registers for you, make sure that your information is provided as the intended registrant.



(1) Cancellations by you: allowed until October 18 - you will receive a refund minus a fixed $50 administrative cancellation fee. You must cancel in writing or e-mail and have a verifiable acknowledgment from us that you have cancelled in time. No cancellations allowed after October 18. Registrants who fail to attend and who did not cancel in time will not receive a refund. If you personally cannot attend, another attendee from your organization may substitute (by arrangement only; contact Lothar Kleiner).

(2) Cancellations by us: in the unlikely event that not enough registrations are obtained, the class will be cancelled. If this happens, you will be notified by October 1 and you will receive a full refund.



For course content, or to pay by check, contact Lothar Kleiner,

For registration difficulties contact

If you cannot reach any of the above, contact Clayton Henderson, or Bruce Prime,

We are sorry but registration for this event is now closed.

Please contact us if you would like to know if spaces are still available.