PP (polypropylene) plastic
English name: Polypropylene proportion: 0.9 to 0.91 grams per cubic centimeter
Molding shrinkage rate: 1.0 2.5% molding temperature: 160-220 ℃
Dry conditions: - material performance density is small, the intensity of stiffness, hardness, heat resistance are better than that of low pressure polyethylene,
Can be used in 100 degrees, with good performance and high frequency insulation is not affected by humidity,
But low temperatures, the time-varying crisp mould aging resistance. Suitable for making general machinery parts, corrosion parts and insulation parts.
formability
Crystalline material, hygroscopicity, prone to melting body burst, long-term contact with the hot metal is easy to decompose.
2. Good liquidity, but the scope and contraction value is big, prone to shrinkage cavity. Dent, deformation
3. The cooling speed, gating system and cooling system should slow cooling, and pay attention to control the mold temperature.
Low temperature the direction clear direction. Especially when high pressure at low temperature, mold temperature is lower than 50 degrees,
Plastic parts is not smooth, easy to cause weld adverse, vestiges of 90 degrees or more prone to buckling deformation
4. Plastic wall thickness should be uniform, to avoid the lack of glue, sharp corners, to prevent stress concentration.
PE plastic (polyethylene)
English name: Polyethylene proportion: 0.94 to 0.96 grams per cubic centimeter
Molding shrinkage rate: 1.5 3.6% molding temperature: 140-220 ℃
Dry conditions: - material performance, corrosion resistance, electrical insulation, especially high frequency insulation, excellent, chloride, irradiation modification, glass fiber reinforced. The melting point of low pressure polyethylene, rigidity, hardness and high strength, small water imbibition, good electric properties and radiation resistance; High pressure polyethylene softness, elongation,
The impact strength and permeability is better; Ultra-high molecular weight polyethylene high impact strength, fatigue resistance, wear resistance, low pressure polyethylene to make corrosion resistant parts and insulation parts; High pressure polyethylene thin films are suitable for, etc.; Ultra-high molecular weight polyethylene is suitable for making shock absorption, abrasion resistance and transmission parts.
formability
Small crystal material, moisture absorption, need not to fully dry, liquidity excellent liquidity is sensitive to pressure, molding time with high pressure, temperature uniformity, filling speed, pressure maintaining full. Should not be in direct gate, to prevent uneven contraction,
Internal stress increased. Pay attention to choose the gate location to prevent shrinkage and distortion.
2. Scope and contraction value is big, obvious directivity, easy to deformed. Cooling speed should be slow, mold slag hole, and the cooling system
3. The heating time shoulds not be too long, otherwise it will decompose, burns.
4. Soft plastic parts have shallow lateral recess, forced demoulding.
5. Melting body fracture may occur, unfavorable contact with organic solvent, to prevent cracking.
PVC
English name: Poly real (Vinyl Chloride) weight: 1.38 g/cm3
Molding shrinkage rate: 0.6 1.5% molding temperature: 160-190 ℃
Dry conditions: - material performance and mechanical performance, excellent, has strong ability of resistance to acid and alkali chemical stability is good, but the low softening point. Suitable for the production sheet, wire and cable insulation, seal, etc.
formability
Amorphous material, moisture absorption, liquidity is poor. In order to improve the liquidity, prevent bubbles, plastic can advance dry. Mould gating system should be short, the appropriate gate section is big, can not have a corner. Mold cooling, surface plating chromium.
2. Easy to decompose, under the temperature 200 degrees and steel. Copper contact more decomposition, decomposition to escape when corrosion. Excitant gas. Forming temperature range is small.
3. Using screw injection machine nozzle, aperture should be larger, in case of blind Angle hysteresis material. Not with insert, insert should be preheated.
ABS (acrylonitrile - butadiene - styrene)
English name: Acrylonitrile Butadiene Styrene weight: 1.05 g/cm3
Molding shrinkage rate: 0.4 0.7% molding temperature: 200-240 ℃
Dry conditions: 80-90 ℃ for 2 hours
The material performance
1, better comprehensive performance, impact strength, chemical stability, good performance.
2, with excellent welding 372 organic glass, make double color plastic parts, and can be chrome plated surface, spray paint processing. 3, have a high impact, high heat resistance, flame retardant, enhancement, transparency level, etc.
4, liquidity than the HIPS, almost better than PMMA, PC and so on, good flexibility.
Suitable for making general machinery parts, antifriction wear-resistant parts, transmission parts and telecommunication parts.
formability
1. Amorphous materials, liquid medium, moisture absorption, must be fully dry, shiny plastic parts quality requirements must be long preheating dry 80-80 degrees, 3 hours
2. YiQu high temperature, temperature anti-embrittlement, but the temperature is too high to decomposition temperature (> 270 degree) of high precision plastic parts, die temperature YiQu 50 to 60 degrees, the high gloss. Heat resistant plastic parts, die temperature YiQu 60-80 degrees.
3, if you need to solve water lines, to improve the material liquid, to adopt high temperature material temperature, the anti-embrittlement, or change into the water.
Levels 4, such as forming heat or flame retardant material, the production of 3 to 7 days after the mold surface residual plastic decomposition, cause mould surface bright, clear in a timely manner to die, and die surface to increase exhaust location.
