Specific gravity:0.94-0.96g/cm3
Molding shrinkage:1.5-3.6%
Molding temperature:140-220℃
Material performance
Corrosion resistance, electrical insulation (especially high frequency insulation) excellent, can be chlorinated, irradiation modified, available glass fiber reinforced. Low pressure polyethylene has high melting point, rigidity, hardness and strength, low water absorption, good electrical properties and radiation resistance; high pressure polyethylene has good flexibility, elongation, impact strength and permeability; ultra-high molecular weight polyethylene has high impact strength, fatigue resistance and wear resistance.
Low pressure polyethylene is suitable for making corrosion resistant parts and insulating parts; high pressure polyethylene is suitable for making films, etc.; UHMWPE is suitable for making shock absorbing, wear resistant and transmission parts.
Molding performance
1、Crystalline material, small moisture absorption, do not need to fully dry, excellent fluidity, fluidity is sensitive to pressure. High-pressure injection is suitable for molding, uniform material temperature, fast filling speed and sufficient pressure-holding. It is not suitable to use direct gating to prevent uneven shrinkage and increase of internal stress. Pay attention to the choice of gate location to prevent shrinkage and deformation.
2、Shrinkage range and shrinkage value is large, the direction is obvious, easy to deformation and warpage. The cooling speed should be slow, and the mold should have cold cavities and cooling system.
3、Heating time should not be too long, otherwise decomposition will occur and burns.
4、When the soft plastic parts have shallow side grooves, the mold can be forced off.
5、Rupture of the melt may occur and should not be in contact with organic solvents to prevent cracking.
Specific gravity:1.18-1.20g/cm3
Molding shrinkage:0.5-0.8%
Molding temperature:230-320℃
Drying condition:110-120℃ 8 hours
Material performance
High impact strength, good dimensional stability, colorless and transparent, good coloring, good electrical insulation, corrosion resistance and abrasion resistance, but poor self-lubrication, stress cracking tendency, easy hydrolysis at high temperature, poor compatibility with other resins.
It is suitable for making small insulating and transparent parts of instruments and impact resistant parts.
Molding performance
1, amorphous material, good thermal stability, wide range of molding temperature, poor fluidity. Small moisture absorption, but sensitive to water, must be dried. Molding shrinkage is small, prone to melt cracking and stress concentration, so the molding conditions should be strictly controlled, and the plastic parts should be annealed.
2, high melting temperature, high viscosity, more than 200g plastic parts, it is appropriate to use the heating type extension nozzle.
3、Fast cooling speed, mold pouring system to coarse, short as the principle, should be set up cold material well, the gate should be taken large, mold should be heated.
4, the material temperature is too low will cause lack of material, plastic parts without luster, the material temperature is too high easy to overflow edge, plastic parts blistering. When the mold temperature is low, the shrinkage, elongation and impact strength are high, while the bending, compression and tensile strength are low. When the mold temperature exceeds 120 degrees, the plastic parts are slow to cool and easy to deform and stick to the mold.
3、ABS plastic (acrylonitrile butadiene styrene)
Specific gravity: 1.05g/cm3
Molding shrinkage: 0.4-0.7%
Molding temperature: 200-240℃
Drying condition: 80-90℃ 2 hours
Material performance
1、Better overall performance, higher impact strength, chemical stability, good electrical properties.
2、Good fusion with 372 organic glass, made of two-color plastic parts, and the surface can be chrome-plated, spray paint treatment.
3, there are high impact, high heat resistance, flame retardant, enhanced, transparent and other levels.
4, fluidity is a little worse than HIPS, better than PMMA, PC, etc., good flexibility.
Suitable for making general mechanical parts, wear-resistant parts, transmission parts and telecommunication parts.
Molding performance
1, amorphous material, medium fluidity, moisture absorption, must be fully dried, the surface requirements of glossy plastic parts must be a long time preheat drying 80-90 degrees, 3 hours.
2、It is advisable to take high material temperature and high mold temperature, but the material temperature is too high and easy to decompose. For high precision plastic parts, the mold temperature should be 50-60 degrees, and for high gloss heat-resistant plastic parts, the mold temperature should be 60-80 degrees.
3、If you want to solve the problem of water clamping, you need to improve the fluidity of the material, take high material temperature, high mold temperature, or change the water level and other methods.
4, such as forming heat-resistant or flame-retardant grade materials, the surface of the mold after 3-7 days of production will remain plastic decomposition, resulting in the mold surface shiny, the mold needs to be cleaned in a timely manner, while the mold surface needs to increase the exhaust position.
Specific gravity: 0.9-0.91g/cm3
Molding shrinkage: 1.0-2.5%
Molding temperature: 160-220℃
Drying conditions: —
Material properties
Small density, strength, stiffness, hardness and heat resistance are better than low pressure polyethylene, can be used at about 100 degrees. Good electrical properties and high-frequency insulation is not affected by humidity, but it becomes brittle at low temperature and is not mold resistant and easy to age.
It is suitable for making general mechanical parts, corrosion resistant parts and insulating parts.
Molding performance
1, crystalline material, moisture absorption is small, easy to melt body rupture, long-term contact with hot metal easy decomposition.
2, good fluidity, but the shrinkage range and shrinkage value is large, easy to occur shrinkage, dent, deformation.
3、Fast cooling speed, pouring system and cooling system should be slow to dissipate heat, and pay attention to control the molding temperature. The direction of low material temperature is obvious, especially at low temperature and high pressure. When the mold temperature is lower than 50 degrees, the plastic parts are not smooth, easy to produce poor fusion, leaving marks, and above 90 degrees, easy to warp and deformation.
4, the plastic wall thickness must be uniform, avoid the lack of glue, sharp corners, to prevent stress concentration.
Specific gravity: 1.05g/cm3
Molding shrinkage: 0.6-0.8%
Molding temperature: 170-250℃
Drying conditions: —
Material performance
Electrical insulation (especially high frequency insulation) is excellent, colorless and transparent, light transmission rate is second only to organic glass, coloring, water resistance, chemical stability is good. General strength, but brittle, easy to produce stress brittle crack, not resistant to benzene, gasoline and other organic solvents.
It is suitable for making insulating and transparent parts, decorative parts and parts of chemical instruments and optical instruments.
Forming performance
1, amorphous material, small moisture absorption, do not need to fully dry, not easy to decompose, but the coefficient of thermal expansion is large, easy to produce internal stress. Good flowability, available for screw or plunger injection machine molding.
2、High material temperature, high mold temperature and low injection pressure are suitable. Extending the injection time is beneficial to reduce internal stress and prevent shrinkage and deformation.
3, available in various forms of gate, gate and plastic arc connection, so as to avoid damage to the plastic parts when going to the gate. The slope of demoulding is big, the ejection is even, the wall thickness of the plastic part is even, it is better not to have inserts, if there are inserts, they should be preheated.
Post time: Aug-12-2022