Poor gloss of PET injection plastic products may have the following four reasons:

1, equipment

(1) insufficient supply, which should ensure sufficient supply;

(2) refuelling time cylinder is not cleaned, which should be regularly cleaned machine cylinder.

2, mold

(1) the gate is too small or the runner is too thin, which should be redesigned according to the product gate or runner size;

(2) the surface roughness of the cavity is poor, which should improve the surface processing accuracy of the cavity or polishing chromium plating;

(3) poor exhaust or die temperature is too low, which should check whether the exhaust structure is reasonable and improved;

(4) there is no cold feed well, for this should be redesigned cold feed well.

3, process

(1) the barrel heating is not uniform, the barrel temperature is too high or too low, which should be adjusted according to the PET characteristics of the barrel temperature;

(2) the nozzle is too small or the pre-plastic back pressure is too low, and the pre-plastic back pressure should be appropriately increased;

(3) the injection speed is too large or too small, which should constantly adjust the injection speed according to the product gloss;

(4) plasticization is not uniform, which can improve the plasticization temperature or enhance the shear effect to improve the plasticization effect;

4, raw materials

(1) raw materials are not dried, PET is easy to absorb water, so it must be dry;

(2) contains volatile substances, which should be controlled in the volatile substance content below a certain content before processing;

(3) the amount of additives or release agents is too much, which should be reduced under the premise of ensuring the performance of the product.

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