Common Injection Material Features(1)
Before we choose plastic processing machine, LCEQ suggest to learn about the features, advantage and disadvantage of some common injection material. This section starts with the polystyrene (ABS) and Polyolefin (PP).
1. Polystyrene (ABS)
ABS materials have good comprehensive properties, that is, high impact toughness and good mechanical properties.
Advantages of ABS
- Excellent heat resistance, oil resistance
- Chemical stability, stable size, easy mechanical processing.
- Strong hygroscopicity, moisture content should be less than 0.3%, dry before injection, drying temperature 70~80℃, drying time 2~4 h.
So an All-in-One Compact Dryer can help solve the problem of strong hygroscopicity.
Its surface can also be plated with metal and sprayed, widely used in automotive interior and exterior accessories and home appliances products.
Some tips for ABS material:
- ABS can not stay too long in the injection molding machine cartridge due to easy aging decomposition (decomposition temperature is about 250°C).
- The general material temperature is 180-230°C.
- If adding the regrind materials, please pay attention to control the proportion, generally not more than 20%.
2. Polyolefin (PP)
Polyolefin is one of the lightest plastics, whose yield, tensile, compressive strength and hardness are superior to those of low-pressure polyethylene. As general structural parts of corrosion-resistant chemical equipment and heated electrical insulation parts, PP is also widely used in automotive interior trim parts.
- The Polyolefin(PP) has outstanding rigidity, good stress-relaxation resistance at high temperature (90℃) and good heat resistance.
- PP can be used over 100℃, no deformation even at 150 ℃ if there is no external force.
- It is stable in many media except for concentrated sulfuric acid and concentrated nitric acid.
- Low molecular weight aliphatic, aromatic and chlorinated hydrocarbons have softening and swelling effects on polyolefin.
- With low-frequency electrical propertie, it is easy to form, almost non-absorbent.
The shrinkage rate of PP material is high, so it is easy to shrink hole, dent or deform. When mold temperature lower than 50℃ , the plastic parts will be with few luster and easy to produce weld marks, and flow marks. But if temperature higher than 90℃, it will be more prone to warp or deform. Plastic parts should be in uniform wall thickness, and without notches, sharp angle to prevent stress concentration.