First, injection mold
1. If the mold cavity is badly processed, if there are defects such as scars, micro-holes, wear, and roughness, it will inevitably react to the plastic parts and cause the plastic parts to have poor gloss. In this regard, the mold must be carefully processed to make the surface of the cavity more comparable. Small roughness, if necessary, polished chrome.
2. If there are oil stains, water stains, or release agents on the surface of the cavity, the surface of the plastic part will be dark and there will be no gloss. In this regard, remove oil stains and water spots in a timely manner, and use a mold release agent in a limited amount.
3. If the plastic part has a small draft, the mold is difficult to remove, or the force is too large during demoulding, so that the surface of the plastic part is good*. In this regard, it is necessary to increase the mold draft.
4. If the mold is poorly vented, too much gas stays in the model, which also leads to poor gloss. In this regard, check and correct the mold exhaust system.
5. If the cross-sectional area of the gate or runner is too small or abruptly changed, the shear force will be too much when the melt flows in it, which will cause the turbulent flow to flow, resulting in poor gloss. Therefore, the gate and runner should be enlarged appropriately. Cross-sectional area.
Second, injection molding process
1. If the injection speed is too small, the surface of the plastic part is not dense and the gloss is poor. In this regard, the injection speed can be appropriately increased.
2. For thick-walled plastic parts, if the cooling is insufficient, the surface will be hairy and the gloss will be dark. In this regard, the cooling system should be improved.
3. If the holding pressure is insufficient, the pressure holding time is short, so that the density of the plastic parts is not enough and the gloss is not good. In this regard, the holding pressure and holding time should be increased.
5. If the melt temperature is too low, the fluidity is poor, which can lead to poor gloss. In this regard, the melt temperature should be appropriately increased.
6. For crystalline resin, such as PE, PP, POM and other plastic parts, if uneven cooling will lead to poor gloss, In this regard, the cooling system should be improved to make it uniform cooling.
7. If the injection speed is too large and the cross-sectional area of the gate is too small, dark and poor gloss will occur near the casting product. In this regard, the injection speed and the cross-sectional area of the gate can be appropriately reduced.