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The definition of precision injection molds Do you really know?

2020-03-07 hqt

The definition of precision injection molds is determined according to two indicators, one is the precision of the processing equipment, and the other is the error caused by the mold processing. The comprehensive level of an injection molding machine is determined by the weight error of the injection molding machine. The error is less than 0.5% for the precision injection molding machine, the error is less than 0.3% for the ultra-precision machine, and the machine with the error of about 1% is the ordinary injection molding machine. As of the current state of the art, the world’s most precise injection molding machine can achieve an error of less than 0.15%.

The accuracy of the processed mold is mainly affected by several factors:

AS resin has a strong load carrying capacity, chemical resistance, thermal deformation resistance and geometric stability. The addition of a glass fiber additive to the AS resin increases the strength and resistance to thermal deformation and reduces the coefficient of thermal expansion. The Vicat softening temperature of the AS resin is about 110 °C. The deflection temperature under load is about 100 °C. The shrinkage of the AS resin is about 0.3-0.7%. AS resin is a hard, transparent material. The styrene component makes the AS resin hard, transparent and easy to process; the acrylonitrile component makes the SAN (AS) chemically and thermally stable.

The processing temperature of the AS resin is generally from 200 to 250 ° C. The material is easy to absorb moisture and needs to be dried for more than one hour before processing. Its fluidity is slightly worse than PS, so the injection pressure is slightly higher. Drying treatment If the storage is not suitable, the AS resin has some hygroscopic properties. The recommended drying conditions are 80 ° C for 2-4 hours.

The melting temperature is 200-270 °C. If a thick walled product is processed, a melting temperature below the lower limit can be used.

The mold temperature is 40-80 °C. For reinforced materials, the mold temperature should not exceed 60 °C. The cooling system must be well designed because the mold temperature will directly affect the appearance, shrinkage and bending of the product.
Injection pressure 350-1300 bar Injection speed High-speed injection is recommended

Runners and Gates All conventional gates can be used. The gate size must be appropriate to avoid streaks, freckles and voids.

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