How to avoid dents and pores in the most popular i

2022-09-26
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How to avoid product dents and pores in injection molding

Product dents usually appear in the thick wall part close to the thin wall due to insufficient force on the product, insufficient material filling and unreasonable product design. Pores are caused by insufficient plastic in the mold cavity, the plastic in the outer ring cools and solidifies, and the internal plastic shrinks to form a vacuum. Its advantages and disadvantages are mostly caused by the fact that the hygroscopic materials are not dried well, and the residual monomers and other compounds in the materials

to judge the cause of pores, just observe whether bubbles in plastic products appear instantaneously during mold opening or after cooling. If it occurs instantaneously when the mold is opened, it is mostly a material problem. If it is cold low carbon steel that will also yield when it is compressed, it belongs to the mold or injection molding condition problem f0+ F1 (n)

(1) material problems:

① dry materials ② add lubricant ③ reduce volatile substances in materials

(2) injection conditions

① insufficient injection volume; ② Increase the injection pressure; ③ Increase the injection time; ④ Increase the total pressure time; ⑤ Improve the injection speed; ⑥ Increase the injection cycle; ⑦ Abnormal injection cycle caused by operation

(3) temperature problem

① the material is too hot, causing excessive shrinkage; ② The material is too cold, resulting in insufficient filling and compaction; ③ The mold temperature is too high, causing the material at the mold wall to solidify quickly; ④ The company is also mainly inclined to these two fields. The mold temperature is too low, resulting in insufficient mold filling; ⑤ The mold has local hot spots; ⑥ Change the cooling scheme

(4) mold problems

① increase the gate; ② Increase the shunt channel; ③ Increase the sprue; ④ Increase the nozzle hole; ⑤ Improve mold exhaust; ⑥ Balance mold filling rate; ⑦ Avoid interruption of mold filling material flow; ⑧ Gate feeding is arranged at the thick wall of the product; ⑨ If possible, reduce the wall thickness difference of products; ⑩ The injection cycle caused by the mold is abnormal

(5) equipment problems:

① increase the plasticizing capacity of the injection press; ② Make the injection cycle normal

(6) cooling conditions:

① the cooling of parts in the mold is too long to avoid shrinkage from outside to inside and shorten the cooling time of the mold; ② Cool the workpiece in hot water

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