There are many factors to consider when creating an injection-molded part. From design, to creating prototypes, to mold-filling, plenty can go wrong during the injection-molding process. Even once you have a complete piece, it may not turn out right. Bubbles, blisters, sinks, and voids are common issues that cause a part to be rejected.
Some issues to watch for:
- Inadequate venting
- Material flow pattern design
- Gas traveling across the part surface during the fill or pack stage
- Melt flow issues
- Venturi effect
- General-purpose screws with dimensions of 18:1 L/D or lower
- Insufficient plastic
- Gate location
In the following slideshow, we’ll look at each of those defects and issues, and some tests and solutions to help address them.
Have you encountered any of these issues in your injection-molding projects? Please share your questions and experience with a comment below.
- Eliminate Bubbles, Voids, Sinks & Blisters
- Overcoming Plastics Injection Molding Problems
- Troubleshooting FlipChart for Plastic Injection Molding
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About the Author
Injection Molding (IM) Solutions
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Midland, MI 48640-3227
|John Bozzelli is a graduate of Marietta College (BS) and Ohio University (MS). His studies were interrupted for a stint in Vietnam (US Army, Purple Heart; Silver Star). Twenty years in Dow Plastics provided extensive experience in polymer synthesis, development, production, and processing. John has been a seminar leader with RJG Associates, Injection Molding Magazine, University of Wisconsin Milwaukee, General Polymers and John Klees. Competent in resin characterization and analysis, his specialty is practical, hands-on injection molding training with both small and large machines. National recognition has come through ten patents, over 60 papers covering plastics, processing, machine specifications, and over 12 years on the national seminar circuit. Feature articles such as the “Productivity”; by Plastics World and ”Scientific Molding” by Injection Molding Magazine October, November and December 1997, have highlighted a couple of exemplar case histories. Check out the August 2001 issue for applications of The Universal Set Up Sheet.John is the initiator of Scientific Injection Molding and teaches the plastic’s point of view for design and processing with a passion you will remember. Take some of your valuable time to learn practical molding techniques that improve your profits tomorrow while eliminating the state of ”fire fighting“ currently found in many molding facilities. Let us keep plastic manufacturing strong in North America.|
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