Common problems of plastic injection molding black bars

In plastic injection molding processing, black streaks often appear on plastic products. The main reason is the degradation of plastic packaging materials, which is common in materials with poor thermal stability.

Causes and Countermeasures of Black Stripes in Plastic Injection Molding

(1) The product is small and the barrel is large, and the plastic stays for too long and decomposes.

(2) The proportion of recycled materials is improper, and it is decomposed by repeated heating.

(3) The screw part is damaged or the clearance of the non-return ring is large. Pay special attention to materials with high viscosity.

(4) The plastic is heated abnormally, causing the plastic to decompose locally.

(5) The rubber material of the screw is badly bitten, and too much air is involved.

(6) When the plastic lubricant is insufficient, the friction problem is serious, and the shear heat is too much, and the exhaust system is poor, causing combustion. Appropriate lubricants can be added, but if the dosage exceeds 0.2%, the flammable volatiles of the lubricant will burn back and easily produce black bars.

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