ABS commonly known as acrylonitrile butadiene styrene, is made of acrylonitrile - butadiene - styrene three monomers copolymerization. Because the proportion of the three monomers is different, can have different performance and melting temperature, flow performance of ABS such as with other plastics or additives blend, it can be expanded to different uses and performance of ABS, such as impact grade, heat resistance grade, flame retardant grade, transparent grade, enhanced grade, electroplating grade.

ABS fluidity is between PS and PC, and its fluidity is related to injection temperature and pressure, of which the injection pressure has a slightly greater impact, so the molding often uses a higher injection pressure to reduce melt viscosity and improve mold filling performance.

1, plastic treatment

ABS water absorption rate of about 0.2%-0.8%, for the general grade of ABS, before processing with oven to 80-85¡æ drying 2-4 hours or with drying hopper to 80¡æ drying 1-2 hours. For the heat-resistant ABS containing PC components, the drying temperature is appropriately adjusted to 100 ¡ã C, and the specific drying time can be determined by air extrusion.

The proportion of recycled material can not exceed 30%, electroplating grade ABS can not use recycled material.

2, the injection molding machine selection

can choose Ramada's standard injection molding machine (screw length diameter ratio 20:1, compression ratio greater than 2, injection pressure greater than 1500bar). If the color masterbatch or the appearance of the product requires high material, a small diameter screw can be selected. The clamping force is determined according to 4700-6200t/m2, which needs to be determined according to the plastic grade and product requirements.

3, mould and gate design

mold temperature can be set to 60-65 ¡æ. The diameter of the runner is 6-8mm. Gate width is about 3mm, the thickness is the same as the product, the length of the gate should be less than 1mm. The vent hole is 4-6mm wide and 0.025-0.05mm thick.

4, melt temperature

available for empty injections accurate judgement. Level is different, the melt temperature is different, it is recommended that the setting is as follows:

impact level: 220 ¡æ to 260 ¡æ, 250 ¡æ for beautiful

electroplating grade: 250 ¡æ to 275 ¡æ, 270 ¡æ for beautiful

heat level: 240 ¡æ to 280 ¡æ to 265 ¡æ to 270 ¡æ for beautiful

flame retardant grade: 200 ¡æ to 240 ¡æ, 220 ¡æ to 230 ¡æ for beautiful

transparent level: 230 ¡æ to 260 ¡æ, 245 ¡æ for beautiful

glass fiber enhanced level: 230¡æ-270¡æ

For products with high surface requirements, the use of higher melting temperature and mold temperature.

5, the injection speed

fire prevention level with a slow, heat-resistant level quickly. If the product surface requirements are higher, you should use high-speed and multi-level injection injection rate control.

6, back pressure

Under normal circumstances, the lower the back pressure, the better, the commonly used back pressure is 5bar, dyeing materials need to use a higher back pressure to make the color mixture uniform.

7, retention time

In 265¡æ temperature, ABS in the glue cylinder retention time can not exceed 5-6 minutes. The flame retardant time is shorter, if you need to stop, you should first set the temperature as low as 100 ¡ã C, and then use general grade ABS to clean the melt tube. After cleaning, the mixture should be put into cold water to prevent further decomposition. If you need to change ABS material from other plastics, you should first clean the melt tube with PS, PMMA or PE. Some ABS products have no problem when they are just released, and they will have discoloration after a period of time, which may be caused by overheating or the plastic staying in the melt cylinder for too long.

8, post-treatment of products

General ABS products do not need post-treatment, only electroplated products need to be baked (70-80 ¡ã C, 2-4 hours) to passivate surface traces, and products that need to be plated can not use release agent, products should be immediately packaged after removal.

9, molding should pay special attention to matters

There are several grades of ABS (especially flame retardant grade), after plasticizing the melt of the screw surface adhesion is very large, after a long time will be decomposed. When the above situation occurs, it is necessary to pull the screw homogenization section and compression out of the rub test, and regularly clean the screw with PS and other.