Can polyvinyl wax be used in abs? ABS plastic is a material used in electronic appliances and building materials. Many electronic appliances such as washing machines, televisions, refrigerators, computers, copiers, etc. are commonly used in our daily life. ABS plastic.
1. Plastic treatment:
The water absorption rate of ABS is about 0.2%-0.8%. For general-grade ABS, it should be baked in an oven at 80-85°C for 2-4 hours or dried at 80°C for 1-2 hours before processing. hours. For heat-resistant ABS containing PC components, the drying temperature should be appropriately raised to 100°C, and the specific drying time can be determined by air extrusion.
The proportion of recycled materials can not exceed 30%, and the electroplating grade ABS cannot use recycled materials.
2. Selection of injection molding machine:
Ramada’s standard injection molding machine can be used (screw aspect ratio 20:1, compression ratio greater than 2, injection pressure greater than 1500bar). If color grains are used or the appearance of the product requires high material, a screw with a smaller diameter can be used. The clamping force is determined according to 4700-6200t/m2, which depends on the plastic grade and product requirements.
3. Mold and gate design:
The mold temperature can be set to 60-65°C. Runner diameter 6-8mm. The gate width is about 3mm, the thickness is the same as the product, and the gate length should be less than 1mm. The vent hole is 4-6mm wide and 0.025-0.05mm thick.
4. Injection speed:
Slow speed should be used for fire-resistant grades, and fast speed should be used for heat-resistant grades. If the surface requirements of the product are high, high-speed and multi-stage injection molding injection speed control should be used.
5. Back pressure:
Under normal circumstances, the lower the back pressure, the better. The commonly used back pressure is 5bar, and the dyestuff needs a higher back pressure to make the color mixing even.
6. Residence time:
At a temperature of 265°C, the residence time of ABS in the melt tube should not exceed 5-6 minutes at most. The flame retardant time is shorter. If the machine needs to be shut down, the set temperature should be lowered to 100°C first, and then the melt cylinder should be cleaned with general-purpose ABS. The cleaned mix should be placed in cold water to prevent further decomposition. If it is necessary to change from other plastics to ABS, it is necessary to clean the melt plastic cylinder with PS, PMMA or PE first. Some ABS products have no problem when they are just released from the mold, but they will change color after a period of time, which may be caused by overheating or the plastic staying in the melt cylinder for too long.
7. Post-processing of products:
Generally, ABS products do not need post-treatment, only electroplating grade products need to be baked (70-80°C, 2-4 hours) to passivate the surface marks, and the products that need to be electroplated cannot use a release agent, and the products need to be taken out Pack immediately after.
8. Matters needing special attention during molding:
There are several grades of ABS (especially the flame-retardant grade). After plasticization, its melt has a strong adhesion to the surface of the screw, and it will decompose after a long time. When the above situation occurs, it is necessary to pull out the screw homogenization section and the compressor for wiping, and regularly clean the screw with PS, etc.
Plastic ABS is not affected by water, inorganic salts, alkalis, and various acids, but it is soluble in ketones, aldehydes, and chlorinated hydrocarbons. It will cause stress cracking when it is corroded by glacial acid, vegetable oil, etc. ABS has poor weather resistance and is prone to degradation under the action of ultraviolet light; after half a year outdoors, the impact strength drops by half.
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