Moule à injection

1. Poor machining of the mold cavity—such as scratches, micro-pores, wear, and rough surfaces—will directly result in inferior gloss on the plastic parts. To solve this, carefully machine the mold to achieve a low surface roughness, and polish or chrome-plate the cavity if necessary.
2. Oil, water stains, or excessive release agent on the cavity surface can make the plastic surface dull and non-glossy. Clean away oil and water stains promptly, and use release agent in moderation.
3. An insufficient draft angle causes difficult demolding or excessive stress during ejection, impairing surface gloss. Increase the draft angle accordingly.
4. Poor mold venting traps excess gas inside the cavity, leading to poor gloss. Inspect and improve the mold venting system.
5. An excessively small or abruptly changing cross-section of the gate or runner creates high shear force and turbulent flow, reducing surface gloss. Properly enlarge the cross-sectional area of the gate and runner.

Moulage par injection¹ Process

1. Low injection speed results in a non-dense surface and poor gloss. Appropriately increase the injection speed².
2. Insufficient cooling for thick-walled parts causes a fuzzy, dull surface. Optimize the cooling system³.
3. Insufficient holding pressure and short holding time lead to low density and poor gloss. Raise the holding pressure and extend the holding time.
4. Low melt temperature reduces fluidity and causes poor gloss. Increase the melt temperature properly.
5. For parts made of crystalline resins such as PE, PP, POM, uneven cooling causes poor gloss. Improve the cooling system for uniform cooling.
6. Excessively high injection speed combined with an undersized gate creates a dull area near the gate. Reduce the injection speed and enlarge the gate cross-section.

Conclusion

In summary, achieving superior gloss for injection molded products⁴ requires a balance between precise mold surface finishing and optimized injection molding parameters. By addressing issues like poor venting, insufficient cooling, and incorrect injection speed, manufacturers can significantly enhance product aesthetics and quality. This guide serves as a practical reference for solving common gloss problems in production.