ABS Plastic Injection Molding Process Knowledge

- Aug 16, 2018-

3. Injection pressure


The viscosity of the ABS melt is higher than that of polystyrene or modified polystyrene, so a higher injection pressure is used at the time of injection. Of course, not all ABS parts are subjected to high pressure, and low injection pressure can be applied to small, simple, and thick parts. During the injection process, the pressure in the cavity at the instant of gate closure often determines the surface quality of the part and the degree of silver-like defects. The pressure is too small, the plastic shrinks greatly, the chance of disengagement from the surface of the cavity is large, and the surface of the workpiece is atomized. Excessive pressure, the friction between the plastic and the cavity surface is strong, and it is easy to cause sticking.


4. Injection speed


ABS material has a better effect on medium injection speed. When the injection speed is too fast, the plastic is easily burnt or the gas is separated out, so that the weld seam, the gloss difference and the plastic redness near the gate appear defects on the workpiece. However, in the production of thin-walled and complex parts, it is necessary to ensure a high enough injection speed, otherwise it will be difficult to fill.


5. Mold temperature


The forming temperature of ABS is relatively high and the mold temperature is relatively high. Generally, the mold temperature is adjusted to 75 to 85 ° C. When producing parts with a large projection area, the mold temperature is required to be 70 to 80 ° C, and the dynamic mold temperature is required to be 50 to 60 ° C. When injecting larger, contoured, thin-walled parts, special consideration should be given to heating the mold. In order to shorten the production cycle and maintain the relative stability of the mold temperature, after the parts are taken out, a cold water bath, a hot water bath or other mechanical setting method can be used to compensate for the time of the cold type in the cavity.


6. Quantity control


When the injection molding machine is usually filled with ABS plastic, its injection volume is only 75% of the standard injection volume. In order to improve the quality and dimensional stability of the parts, the surface gloss and uniformity of the color are required, and the injection amount is required to be 50% of the marked injection amount.