Injection Mold

1. If the mold cavity is poorly machined, with defects such as scratches, micro-pores, wear, or rough surfaces, it will affect the gloss of the plastic part. To address this, ensure precise machining of the mold to achieve a lower surface roughness for the cavity; if necessary, polish and chrome-plate the cavity.

2. If the cavity surface has oil stains, watermarks, or excessive mold release agent, the plastic part may appear dull or lack gloss. To prevent this, promptly remove oil and water stains, and use mold release agents sparingly.

3. If the draft angle for part ejection is too small, it may lead to difficult ejection and excessive force applied during demolding, which reduces surface gloss. Increasing the draft angle can help mitigate this issue.

4. Poor mold ventilation, which traps excess gas in the mold, can also lead to a loss of gloss. Ensure that the mold ventilation system is checked and improved as needed.

5. If the gate or runner cross-sectional area is too small or changes abruptly, the melt flow may experience excessive shear force and turbulent flow, resulting in reduced gloss. To improve this, increase the cross-sectional area of the gate and runner accordingly.



Injection Molding Process

1. If the injection speed is too low, the surface of the part may appear loose and lack luster. In this case, the injection speed should be increased appropriately.

2. For thick-walled parts, insufficient cooling can cause surface fuzziness and a dull appearance. To address this, improve the cooling system.

3. If the holding pressure is insufficient or the holding time is too short, the part's density may be low, resulting in a dull surface. Increase the holding pressure and holding time as needed.

4. If the melt temperature is too low, flowability may be poor, leading to a dull finish. Raise the melt temperature appropriately.

5. For crystalline resins, such as PE, PP, and POM, uneven cooling can cause a dull finish. Ensure uniform cooling by improving the cooling system.

6. If the injection speed is too high and the gate cross-section is too small, the area around the gate may appear dark and lack gloss. Reduce the injection speed and increase the gate cross-section area as appropriate.