Common Issues And Solutions in The SMC Product Manufacturing Process

Common Quality Issues and Our Solutions

1. Short Shot

   
   Incomplete filling of the edges (especially the roots and tops of corners) of the product. Main causes:

• High melt viscosity of SMC material after heating, insufficient cavity filling before cross-linking and curing: Increase molding pressure or extend melting time.

• Excessive styrene evaporation due to prolonged storage, leading to reduced flowability: Check SMC storage time to avoid excessive styrene evaporation.

• Insufficient feeding or poor venting: Appropriately increase the feeding amount, increase venting frequency, or clean the mold.

• Excessive mold temperature or delayed pressure application causing premature curing: Reduce mold temperature or adjust the timing of pressure application.

2. Blisters/Hollows

   
   Small regular or irregular pores on the product surface, often found at the top and thin-walled areas. Main causes:

• High air and volatile content in the SMC material, poor venting: Optimize venting design and reduce the feeding area.

• Excessive feeding area or premature pressure application: Adjust the timing of pressure application to ensure gas is expelled before pressing.

3. Incomplete Curing

   
   Manifested as insufficient hardening of the product. Main causes:

• Insufficient initiator concentration or inadequate curing time: Extend curing time or increase initiator dosage.

• Low mold temperature or high reactivity resin content: Reduce mold temperature or use low-reactivity resin.

4. Color Irregularities

   
   Obvious color differences on the product surface. Main causes:

• Improper mold temperature or excessive temperature difference between upper and lower molds: Optimize the mold temperature control system.

5. Product Deformation

   
   Manifested as warping of the product. Main causes:

• Uneven cooling: Optimize the cooling system to ensure uniform cooling.

• Mold design flaws: Adjust mold structure to reduce stress concentration.

Comprehensive Recommendations

• Process Control: Precisely manage mold temperature, pressure, and feeding amount.

• Material Management: Avoid prolonged storage of SMC materials and regularly check flowability.

• Mold Maintenance: Regularly clean the mold to ensure smooth venting.

By implementing the above measures, the yield rate of SMC products can be significantly improved.