Countermeasures for Molding Defects – Sink Marks

Sink marks are a frequently seen issue with plastic injection molding. Small, shallow dimples or depressions are commonly observed on larger parts of the part. These flaws can reduce the visual appeal of the product and weaken its solidity as a whole.

Let us explore the concept of sink marks, their underlying causes, and strategies for reducing this unpleasant flaw.

Defect NameDescription of the DefectCause of DefectCountermeasure
Sink MarksSink marks are depressions or irregularities on the surface of a molded plastic part.There are different causes of sink marks. Below are some.
1. Cooling Rate Discrepancies
2. Material Selection
3. Injection Pressure and Temperature
4. Gate Design  
There are different approach in troubleshooting sink marks depends on its cause. Below are some adjustments that you can perform.
1. Optimize Cooling
2. Injection Process Optimization
3. Gate Design Optimization
4. Part Design Considerations  

To summarize, sink marks can pose a bothersome challenge in plastic injection molding. However, by carefully choosing materials, optimizing the process, and making design revisions, their frequency can be reduced. Manufacturers can improve molded component quality and manufacturing efficiency by understanding the causes and taking effective measures.

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