1. Injection mold
1. Poor processing of mold cavity If the mold cavity has defects such as scars, micropores, wear, roughness, etc., it will inevitably be reflected on the plastic parts, which will make the plastic parts have poor gloss. For this, the mold must be carefully processed to make the cavity surface have Smaller roughness, polished chrome if necessary.
2. The surface of the cavity is stained. If the surface of the cavity has oil stains or water stains, or the release agent makes too much, it will make the surface of the plastic parts dark and dull. For this, the oil stains and water stains should be removed in a timely manner and limited use Mold agent.
3. The release slope of the plastic part is too small, the release slope is too small, it will cause difficulty in demolding, or the force during demolding is too large, so that the surface gloss of the plastic part is not good, for this, the demolding slope should be increased .
4. Poor exhaust of the mold. If the exhaust is poor, it will cause too much gas to stay in the model and will also cause poor gloss. For this, the mold exhaust system should be checked and corrected.
5. Improper design of gate or runner. The cross-sectional area of gate or runner is too small or abruptly changed. When the melt flows in it, the shear force is too large, and the flow is turbulent. Large gate and runner cross-sectional area.
2.the injection molding process
1. The injection speed is too small. If the injection speed is too small, the surface of the plastic part is not dense and the gloss is poor. For this, 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 fluffy and the gloss is dark. For this, the cooling system should be improved.
3. Improper holding pressure operation, such as too low holding pressure and too short holding time, makes the density of plastic parts insufficient and poor gloss. For this, the holding pressure and holding time should be increased.
4. The melt temperature is too low. When the melt temperature is too low, the fluidity is poor, and it is easy to cause poor gloss. For this, the melt temperature should be appropriately increased.
5. Uneven cooling of crystalline resin, such as plastic parts made of PE, PP, POM, etc. If the cooling is uneven, it will lead to poor gloss. For this, the cooling system should be improved to cool it evenly.
6. The injection speed does not match the gate area. If the injection speed is too large, and the gate cross-sectional area is too small, the gate will be dark and poor gloss. For this, the injection speed can be appropriately reduced and the gate gate can be increased. area.
3. Raw materials
1. The size difference of the raw materials is large, the size difference is large, which makes it difficult to uniformly plasticize and the gloss is poor. For this, the raw materials should be sieved.
2. Too much secondary material in the raw material, such as too much recycled material or sprue material added, affects the uniform plasticization of the melt and has poor gloss. For this, the amount of recycled material or sprue material added should be reduced.
3. Poor temperature resistance of raw materials Some raw materials will decompose and change color during temperature adjustment, resulting in poor gloss. For this, raw materials with better temperature resistance should be selected.
4. Raw materials contain volatile substances. If the content of moisture or volatile substances in the raw materials is too high, they will volatilize into gas when heated and condense in the cavity and melt, resulting in poor gloss of the plastic parts. For this, the raw materials should be pre-dried. deal with.
5. The dispersibility of additives is not good. Some additives have too poor dispersibility, which leads to poor gloss of plastic parts. For this, additives with better flow properties should be used instead.
6. Impurity of raw materials If the raw materials are mixed with foreign materials, miscellaneous materials or incompatible materials, they cannot be uniformly mixed with their raw materials, resulting in poor gloss. For this, these impurities should be strictly excluded in advance.
7. Too little amount of lubricant If the amount of lubricant is too small, the melt fluidity is poor, and the surface of the plastic part is not dense, which makes the gloss poor. For this, the amount of lubricant should be increased appropriately.
Therefore, according to whether your mold polishing degree meets the requirements. If there is no problem with the mold itself, you must 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.