PP sheet is polypropylene plastic
Specific gravity: 0.9-0.91 g / cm 3 Molding shrinkage: 1.0-2.5% Molding temperature: 160-220 ° C
Low density, strength and stiffness, can be used at about 100 degrees. It has good electrical properties and high-frequency insulation, which is not affected by humidity, but becomes brittle at low temperature and is not resistant to mold aging. It is suitable for making general mechanical parts and corrosion-resistant parts. And insulating parts
Molding performance 1. Crystallized material, low hygroscopicity, easy to melt fracture, long-term contact with hot metal is easy to decompose.
2. Good fluidity, but the shrinkage range and shrinkage value are large, and shrinkage, dent and deformation are easy to occur.
3. The cooling rate is fast, the pouring system and the cooling system should be slowly dissipated, and the molding temperature should be controlled. The direction of the material is low and the direction is obvious. The low temperature and high pressure are especially obvious. When the mold temperature is lower than 50 degrees, the plastic parts are not smooth and easy to produce. Poor welding, leaving marks, warping deformation is easy to occur above 90 degrees
4. The plastic wall thickness should be uniform to avoid lack of glue and sharp corners to prevent stress concentration.
PVC, polyvinyl chloride, English Poly (Vinyl Chloride)
Specific gravity: 1.38 g / cm 3 Molding shrinkage: 0.6-1.5% Molding temperature: 160-190 ° C
Mechanical properties, excellent electrical properties, strong acid and alkali resistance, good chemical stability, but low softening point. Suitable for making thin plates, wire and cable insulation, seals, etc.
1. Amorphous material, low moisture absorption, poor fluidity. In order to improve fluidity and prevent air bubbles, the plastic can be pre-dried. The mold casting system should be short and thick, the gate section should be large, and there must be no dead angle. The mold must be cooled and the surface should be chrome-plated.
2. It is easy to decompose. It is more easily decomposed with steel and copper at 200 °C. It will escape corrosion when decomposed. Irritant gas. The molding temperature range is small.
3. When using the screw injection machine nozzle, the hole diameter should be large to prevent dead angle stagnation. Good without inserts, if there are inserts should be preheated