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Lesson 9: Sink Marks and Voids, Part 2

In the injection molding business, it is essential to produce high quality parts without molding defects. In part two of the lesson we will further evaluate design and process-related sink marks and voids.

Topics in this lesson include: various part design related challenges that impact the fill-to-shrinkage behavior of a molded part; the importance of evaluating and eliminating sink marks and voids prior to finalizing a part design; that injection pressure requirements may be dictated by sprue, runner, and gate sizes, but not necessarily by the wall thicknesses inside the molded part; and the way that polymer material cools inside the mold cavity may result in shrinkage and possible sink marks and void development.

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Sink Marks and Voids-2

Learn about the causes of common molding defects and how to prevent them. Continue to build your Circle of Knowledge lesson by lesson. 

Goals of Molding Defects (Level 2): 

  • Learn about the various molding defects that can occur during the injection molding process
  • Gain an understanding of how part design, mold design, and process impact molding defects
  • Analyze real-life molded parts and learn the cause-and-effect behaviors of design and process

Section Description: 

Molding defects in injection-molded parts range from minor surface defects to major structural issues impacting overall quality. This section explains common molding defects, how and why they occur, and ways to minimize or prevent them.

Each lesson includes multiple samples of molding defects using interactive 3D parts. The examples allow the user to manipulate the part to gain a clear and concise understanding of how each molding defect would appear on a real-life injection-molded part.

This section covers video explanations, interactive 3D molding defect examples, simulations, and cause-and-effect analyses.

Recommendation: Expert-Level Operators, Technicians, & Designers

Length: Lessons are approximately 15-20 minutes long each

The Kruse Training platform delivers knowledge and expertise developed over three decades in plastic injection molding. Now, companies and individuals can access a state-of-the-art online training program suited for all levels of expertise.