1. Injection mold

1. Poor processing of mold cavity

If the mold cavity has scars, micropores, wear, roughness and other deficiencies, it will inevitably be reflected on the plastic parts, making the plastic parts have poor gloss. In this regard, the mold must be carefully processed to make the cavity surface have a smaller roughness. If necessary Chrome can be polished.

2. Stains on the cavity surface

If there are oil stains or water stains on the surface of the mold cavity, or too much release agent is used, the surface of the plastic part will be dark and dull. In this regard, the oil stains and water stains must be removed in time, and the release agent must be used in a limited amount.

3. The demoulding angle of the plastic part is too small

If the demoulding slope is too small, it will cause difficulty in demoulding, or the force during demoulding will be too large, resulting in poor surface gloss of the plastic part. In this regard, the demoulding slope should be increased.

4. Poor mold exhaust

If the exhaust is poor, too much gas will stay in the model, which will also lead to poor gloss. In this regard, the mold exhaust system must be checked and corrected.

5. Improper gate or runner design

If the cross-sectional area of the gate or runner is too small or changes suddenly, the melt will be subjected to too much shear force when flowing in it, resulting in turbulent dynamic flow, resulting in poor gloss. In this regard, the cross-sectional area of the gate and runner should be appropriately increased.

2. Injection molding process

1. Injection speed is too small

If the injection speed is too small, the surface of the plastic part will not be dense and the gloss will be poor. In this regard, the injection speed can be appropriately increased.

2. Insufficient cooling of plastic parts

If the cooling of thick-walled plastic parts is insufficient, the surface will be hairy and the gloss will be dark. In this regard, the cooling system should be improved.

3. Improper pressure maintaining operation

If the holding pressure is too small and the holding time is too short, the density of the plastic parts will be insufficient and the gloss will be poor. In this regard, the holding pressure and holding time should be increased.

4. Melt temperature is too low

When the melt temperature is too low, the fluidity is poor and can easily lead to poor gloss. In this regard, the melt temperature should be increased appropriately.

5. Uneven cooling of crystallized resin

For example, uneven cooling of plastic parts made of PE, PP, POM, etc. will lead to poor gloss. In this regard, the cooling system should be improved to allow even cooling.

6. Injection speed does not match the gate area

If the injection speed is too high and the cross-sectional area of the gate is too small, the area around the gate will be dark and have poor gloss. For this, the injection speed can be appropriately reduced and the cross-sectional area of the gate can be increased.

3. Raw materials

1. The particle size of raw materials varies greatly.

The large difference in particle size makes it difficult to plasticize uniformly and results in poor gloss. For this reason, the raw materials should be screened.

2. There are too many secondary materials in the raw materials

If too much recycled material or nozzle material is added, the uniform plasticization of the melt will be affected and the gloss will be poor. In this regard, the amount of recycled material or nozzle material should be reduced.

3. The raw material has poor temperature resistance

Some raw materials will decompose and change color during temperature adjustment, resulting in poor gloss. For this reason, raw materials with better temperature resistance should be selected.

4. Raw materials contain volatile substances

If the content of moisture or volatile matter in the raw material is too high, it will volatilize into gas when heated and condense in the mold cavity and melt, resulting in poor gloss of the plastic part. In this regard, the raw material should be pre-dried.

5. The dispersion of additives is not good

The dispersion of some additives is too poor, causing the plastic parts to have poor gloss. For this, additives with better flow properties should be used instead.

6. Impure raw materials

If the raw materials are mixed with foreign matter, impurities or incompatible materials, they cannot be evenly mixed with the raw materials, resulting in poor gloss. In this regard, these impurities should be strictly excluded in advance.

7. Too little lubricant

If the amount of lubricant is too small, the fluidity of the melt will be poor and the surface of the plastic part will not be dense, resulting in poor gloss. In this regard, the amount of lubricant should be appropriately increased.

Therefore, it also depends on whether the polishing degree of your mold meets the requirements. If there is no problem with the mold itself, you need to determine the characteristics of your ABS. You can choose high mold temperature, high speed and high pressure; cooling with chilled water can also achieve a better finish.