Troubleshooting Common Issues in Compression Molding Processes
Nina Jiang
Company Owner-One stop solution of plastic parts from injection/blow mold making service and injection machine and blow mold machine outsource service
Here’s a guide on troubleshooting common issues in compression molding:
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## Troubleshooting Common Issues in Compression Molding Processes
Compression molding is widely used for producing high-strength, complex plastic and rubber parts. However, various defects can arise during production, affecting quality and efficiency. Below are common issues, their causes, and possible solutions.
### 1. Short Shot (Incomplete Filling)
Causes:
- Insufficient material charge
- Low mold temperature or pressure
- Poor material flow
- Inadequate venting
Solutions:
- Increase material charge
- Raise mold temperature and pressure
- Use materials with better flow properties
- Improve venting to allow air escape
### 2. Flash (Excess Material at Parting Line)
Causes:
- Excessive material charge
- High molding pressure
- Poor mold fit or worn mold edges
Solutions:
- Reduce material charge
- Lower pressure settings
- Ensure proper mold alignment and maintenance
### 3. Air Traps and Porosity
Causes:
- Inadequate venting
- Fast closing speed
- Moisture in material
Solutions:
- Improve mold venting
- Adjust closing speed
- Pre-dry materials before molding
### 4. Warpage or Deformation
Causes:
- Uneven mold temperature
- Non-uniform material distribution
- Insufficient curing time
Solutions:
- Balance mold temperature
- Ensure even material distribution
- Optimize curing time
### 5. Surface Defects (Burn Marks, Blisters, or Discoloration)
Causes:
- Excessive mold temperature
- Trapped air causing localized overheating
- Contaminated material
Solutions:
- Lower mold temperature
- Improve venting and degassing
- Use clean, properly stored materials
### 6. Inconsistent Part Dimensions
Causes:
- Uneven material distribution
- Fluctuations in temperature or pressure
- Poor mold design
Solutions:
- Ensure even material placement
- Maintain stable temperature and pressure
- Optimize mold design for consistency
### 7. Delamination (Layer Separation in Part)
Causes:
- Contamination in raw material
- Poor bonding due to insufficient heat or pressure
- Excessive use of release agents
Solutions:
- Use high-quality, clean materials
- Ensure adequate heat and pressure application
- Limit release agent application
### Conclusion
Proper troubleshooting in compression molding involves identifying root causes and making necessary process adjustments. Regular mold maintenance, precise process control, and material handling improvements can help minimize defects and enhance product quality.
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