Plastics Workshops and Seminars
The Science of Mold and Part Design Optimization
Hands-On Workshop
Dates: August 5 - 6, 2009
Fee: $1,095
Instructors: John Beaumont, and David Hoffman or David Rose
WHO SHOULD ATTEND:
This two-day seminar is designed for anyone involved with the development and production of plastic products or molds. This includes part designers, mold designers, and process engineers and technicians. The seminar is also well suited to managers, technical sales, and quality control personnel, as it teaches the fundamental understanding of the effects of plastic flow on the molding process, tooling design, and part design.
EDUCATIONAL GOALS:
The objective of this seminar is to provide a better understanding of the interaction between material characteristics, part design, mold design, and the molding process itself. The seminar begins down a logical path by establishing a basic understanding of material properties and how they are affected by the molding process. This includes a discussion about the influence of part design and melt conditions on shrinkage, warp, and residual stresses. Variables such as pressure, temperature, viscosity, molecular and filler orientation, and linear and volumetric shrinkage will be studied in detail. This seminar also teaches the critical relationship of the runner, gate and gating position to the successful production of plastic parts. This includes an in-depth discussion for determining the optimum runner sizes and configurations, along with techniques to determine the ideal number, location, and style of gate for a given part. The seminar also contrasts the use of cold vs. hot runners and low vs. high cavitation molds. A unique look at the development of shear induced imbalances is presented, as this topic has been shown to be one of the most significant factors in controlling cycle time, process window, clamp tonnage, and efficiency and productivity in any molding shop. Scientific explanations and real-world examples will be used to demonstrate the principles taught in this seminar and to dispel many of today’s common molding myths.
WORKSHOP OUTLINE:
1. Overview of the Injection Molding Process
- Four stages of injection molding process
- Hydraulic vs. melt pressure
- Pressures developed during molding
- Development of reactive forces on clamp force requirements
- Effects of gating pressure and forces
2. Types of Polymers
- Theroplastic vs.Thermosetting resins
- Amorphous vs. Semi-Crystalline
3. Key Material Characteristics
- Viscosity
- Laminar flow vs. turbulent flow in plastic
- and non-Newtonian properties
- Shrinkage
- Volumetric vs. Orientation Induced
- Filled versus neat materials
- Hesitation
- Warp and residual stress
- Development from variation in shrinkage
- Molding and design factors effecting warp
- Mechanical Properties
- Effect of orientation on part properties
- Weld line and meld line strength
4. Selecting Proper Gating Locations
- Gate positions
- Filling and packing considerations
- Impact of wall thickness variations
- Integral hinges and other part design challenges
5. Understanding Molds and Runner/Gating Options
- Cold runner
- 2-plate versus 3-plate molds
- Gating designs
- Hot runner systems
- Types of hot runners
- Gate tip designs
6. Understanding Runner and Gate Design Fundamentals for Single and Multi-Cavity Molds
- Single versus multi-cavity molds
- Family molds
- Runner design details and options
- Balancing the flow lengths
- Layout options
- Pressure vs. flow length vs. shear balance
- Sizes and shapes
- Optimizing runner sizes
- Effect on filling, packing, and cooling
- Constant diameter versus stepped diameters
- Hand calculations versus mold-filling analysis
- Sprue-puller designs and runner ejection considerations
- Cold slug wells
7. Shear-Induced Material Variations
- Development of shear-induced filling variations
- Filling pattern abnormalities
- Cavity-to-cavity variations and filling imbalances
- Two primary sources of variations
- Identifying the root cause
- Effect on product, process, and productivity
- How to control and manage viscosity variations inside of the mold