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Dongguan Hongke Plastic Precision Mould Co.,Limited [Guangdong,China] Business Type:Manufacturer Main Markets: Americas , Asia , Caribbean , Europe , Middle East , Oceania , Other Markets , Worldwide Exporter:91% - 100% Certs:ISO9001, TUV, ISO/TS16949, ISO13485, ISO14001

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Analysis of the Causes and Consequences of gas generated by Injection Molds

2024-02-01

The reason why the mold produces gas when manufacturing products

① The gas is entrained in the material in the feeding system or there is air in the cavity. During the forming process, the gas in the flow channel and cavity is not discharged in time.

② The resin is not sufficiently dried and contains moisture. At the injection temperature, it evaporates and becomes water vapor.

③The injection mould temperature is high and the plastic decomposes to produce gas.

④ Certain additives in the resin volatilize or react chemically to generate gas (for example, when thermosetting plastics are formed, not only does the plastic itself contain moisture and volatile components, but also a polycondensation reaction occurs during the curing process, producing condensation water and low-molecular volatile gases).

⑤ Residual gas in the resin.

Consequences of poor injection mould exhaust

① The gas undergoes large compression and generates back pressure, and this back pressure increases the resistance of the molten material filling flow, preventing the molten plastic from filling the mold normally and quickly, so that the mold cavity cannot be filled, resulting in unclear edges of the plastic.

② There are obvious flow marks and fusion seams on the product, and the mechanical properties of the product decrease.

③ After the gas is compressed, it will penetrate into the inner layer of the plastic, causing the plastic to produce surface quality defects such as silver streaks, pores, loose tissue, and peeling.

④ After the gas in the mold cavity is compressed, it generates heat and causes the local temperature of the plastic to rise. The plastic melt decomposes, changes color, or even becomes charred and carbonized.

⑤ Poor exhaust reduces the injection mould filling speed, increases the cycle time of part forming (especially high-speed injection molding), and seriously affects productivity.

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Ms. Sophia

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sophia@hongkemould.com

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