Processing Performance and Conditions of ABS Injection Molding

Ⅰ. ABS Injection Molding Processing Performance
(1) Because of the strong moisture absorption as well as high water content of
ABS, the plastic parts that are made of ABS have low gloss and poor internal
quality. As a result, ABS injection molding should be dried so that the water
content is not more than 0.3%.

(2) ABS melt has obvious non-Newtonian properties. Increasing the molding
pressure can significantly reduce the melt viscosity, and its viscosity will
also decrease with the increase of temperature.

(3) ABS has a small molding shrinkage rate, and the shrinkage rate changes in
the range of 0.3% to 0.8%, so the precision of plastic parts is high.

(4) ABS injection molding has good processing performance, and there are no
special requirements for injection molding machines. Both general screw and
plunger injection molding machines can be used, but multi-purpose screw
injection molding machines have better product quality.

(5) In order to improve the quality, dimensional stability, surface gloss of
plastic parts and eliminate residual internal stress when using screw injection
mold tooling machine, it is more appropriate to control the injection volume at
about 50% of the maximum injection volume.

(6) The viscosity of ABS melt is medium, better than PC and PVC, but worse than
PS, so it is better to use straight-through nozzle.

(7) The main channel of the ABS mold is preferably conical, and the main
channel should be short, generally about 50mm, and the longest should not
exceed 100mm.

(8) The cross-sectional area of the runner must be large enough so that the
molten material can fill the cavity before the runner solidifies and compact in
the mold. The diameter of the section should generally be greater than 5mm, but
not more than 10mm.

(9) The ejection force of the ejection mechanism of ABS should not be too
large, otherwise the surface of the plastic part is prone to whitening.

(10) Although the shrinkage rate of ABS injection china plastic moulding is
small, it is easy to generate internal stress, so the plastic parts generally
need to be heat treated, and the plastic parts can be treated in hot air at 70
° C for 2 to 4 hours.

Ⅱ. Conditions for ABS injection molding temperature (1) Barrel temperature

ABS is an amorphous plastic with no obvious melting point, and the melt flow
temperature is not too high. It has sufficient fluidity above 160 °C, but if
the temperature is too high, it will not increase the fluidity. There are many
varieties of ABS, and the barrel temperature of different varieties is
different. The barrel temperature of general ABS is 180~230℃, the temperature
of heat-resistant ABS is 190~240℃, and the temperature of flame retardant ABS
is 170~220℃. The nozzle temperature is 20~30℃ lower than the barrel
temperature.

(2) Mold temperature

The level of mold temperature has a great influence on the quality of plastic
parts. During ABS injection molding, the mold temperature should be controlled
within the allowable range. Generally, the mold temperature should be
controlled at 50-70 °C.

(3) Injection pressure

The size of the injection pressure mainly depends on the structure and wall
thickness of the plastic part. Usually, the injection pressure of general ABS
is 50-70MPa, the injection pressure of heat-resistant ABS is 60-85MPa, and the
injection pressure of flame-retardant ABS is 60-100MPa. If the flow resistance
during filling is large, use a higher injection pressure. Conversely, use a
lower injection pressure.

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