1. ABS (acrylonitrile butadiene styrene copolymer)

① Typical application range:

Cars (dashboard, tool compartment doors, wheel covers, mirror boxes, etc.), refrigerators, high-strength tools (hair dryers, mixers, food processors, lawn mowers, etc.), telephone housings, typewriter keyboards, entertainment vehicles such as golf trolleys and jet sleds.

② Injection mold process conditions:

Drying treatment: ABS materials are hygroscopic and require drying treatment before processing. The recommended drying condition is for a minimum of 2 hours at 80 to 90 ℃. The material humidity should be guaranteed to be less than 0.1%.

Melting temperature: 210~280 ℃; Recommended temperature: 245 ℃.

Mold temperature: 25~70 ℃. (Mold temperature will affect the smoothness of plastic parts, and lower temperatures will result in lower smoothness.).

Injection pressure: 500~1000 bar.

Injection speed: medium to high speed.

③ Chemical and physical properties:

ABS is synthesized from three chemical monomers: acrylonitrile, butadiene, and styrene. Each monomer has different characteristics: acrylonitrile has high strength, thermal stability, and chemical stability; Butadiene has toughness and impact resistance characteristics; Styrene has easy processing, high finish, and high strength. From a morphological perspective, ABS is a non crystalline material. The polymerization of three monomers produces a terpolymer with two phases, one being a continuous phase of styrene acrylonitrile, and the other being a dispersed phase of polybutadiene rubber. The characteristics of ABS mainly depend on the ratio of the three monomers and the molecular structure in the two phases. This allows for great flexibility in product design, and has resulted in hundreds of different quality ABS materials on the market. These different quality materials provide different characteristics, such as moderate to high impact resistance, low to high finish, and high temperature distortion properties. ABS materials have excellent workability, appearance characteristics, low creep, excellent dimensional stability, and high impact strength.

2. PA6 (Polyamide 6 or Nylon 6)

① Typical application range:

Due to its excellent mechanical strength and stiffness, it is widely used in structural components. Due to its excellent wear resistance characteristics, it is also used in the manufacture of bearings.

② Injection mold process conditions:

Drying treatment: Due to PA6's easy absorption of moisture, special attention should be paid to the drying before processing. If the material is supplied in waterproof material packaging, the container should be kept closed. If the humidity is greater than 0.2%, it is recommended to dry in hot air above 80 ℃ for 16 hours. If the material has been exposed to air for more than 8 hours, it is recommended to conduct vacuum drying at 105 ℃ for more than 8 hours.

Melting temperature: 230~280 ℃, 250~280 ℃ for reinforced varieties.

Mold temperature: 80~90 ℃. Mold temperature significantly affects crystallinity, which in turn affects the mechanical properties of plastic parts. Crystallinity is important for structural components, so it is recommended that the mold temperature be between 80 and 90 ℃. It is also recommended to use higher mold temperatures for thin-walled, longer process plastic parts. Increasing mold temperature can improve the strength and stiffness of plastic parts (increasing crystallinity), but it reduces toughness. If the wall thickness is greater than 3mm, it is recommended to use a low-temperature mold at 20-40 ℃. The mold temperature for glass reinforced materials should be greater than 80 ℃.

Injection pressure: generally between 750 and 1250 bar (depending on the material and product design).

Injection speed: High speed (slightly lower for reinforced materials).

Runner and Gate: Due to the short solidification time of PA6, the location of the gate is very important. The gate aperture should not be less than 0.5 * t (where t is the plastic thickness). If using a hot runner, the gate size should be smaller than using a conventional runner, as the hot runner can help prevent premature solidification of the material. If a submerged gate is used, the minimum diameter of the gate should be 0.75 mm.

③ Chemical and physical properties:

The chemical and physical properties of PA6 are very similar to those of PA66, however, its melting point is low and the process temperature range is wide. Its impact resistance and solubility are better than PA66, but its moisture absorption is also stronger. Because many quality characteristics of plastic parts are affected by moisture absorption, it is necessary to fully consider this when designing products using PA6. In order to improve the mechanical properties of PA6, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubber, such as EPDM and SBR, is added to improve impact resistance. For products without additives, the shrinkage of PA6 is between 1% and 1.5%. Adding glass fiber additives can reduce the shrinkage to 0.3% (but slightly higher in the direction perpendicular to the process). The shrinkage of molding and assembly is mainly affected by the crystallinity and moisture absorption of the material. The actual shrinkage is also a function of the plastic design, wall thickness, and other process parameters.

3. PA12 (polyamide 12 or nylon 12)

① Typical application range:

Water meters and other commercial equipment, cable sleeves, mechanical cams, sliding mechanisms, and bearings.

② Injection mold process conditions:

Drying treatment: Ensure that the humidity is below 0.1% before processing. If the material is stored exposed to air, it is recommended to dry it in hot air at 85 ℃ for 4-5 hours. If the material is stored in an airtight container, it can be directly used after 3 hours of temperature balance.

Melting temperature: 240~300 ℃; Do not exceed 310 ℃ for ordinary materials and 270 ℃ for materials with flame retardant properties.

Mold temperature: 30-40 ℃ for unreinforced materials, 80-90 ℃ for thin-walled or large-area components, and 90-100 ℃ for reinforced materials. Increasing the temperature will increase the crystallinity of the material. Accurate control of mold temperature is important for PA12.

Injection pressure: up to 1000 bar (low holding pressure and high melting temperature are recommended).

Injection speed: High speed (better for materials with glass additives).

Runner and Gate: For materials without additives, due to the low viscosity of the material, the diameter of the runner should be around 30 mm. For reinforced materials, a large channel diameter of 5-8mm is required. The shape of the flow channel should be completely circular. The injection port should be as short as possible. Various forms of gates can be used. Do not use small gates for large plastic parts to avoid excessive pressure or shrinkage on the parts. The thickness of the gate should preferably be equal to the thickness of the plastic part. If a submerged gate is used, a minimum diameter of 0.8 mm is recommended. Hot runner molds are effective, but require precise temperature control to prevent material leakage or solidification at the nozzle. If using a hot runner, the gate size should be smaller than the cold runner.

③ Chemical and physical properties:

PA12 is a linear, semi crystalline to crystalline thermoplastic material made from butadiene. Its properties are similar to PA11, but its crystal structure is different. PA12 is a good electrical insulator and, like other polyamides, does not affect insulation properties due to moisture. It has excellent impact resistance and chemical stability. PA12 has many improved varieties in terms of plasticizing and reinforcing properties. Compared to PA6 and PA66, these materials have a lower melting point and density, and have a very high moisture regain. PA12 has no resistance to strong oxidizing acids. The viscosity of PA12 mainly depends on humidity, temperature, and storage time. It has good liquidity. The shrinkage rate is between 0.5% and 2%, which mainly depends on the material type, wall thickness, and other process conditions.

4. PA66 (polyamide 66 or nylon 66)

① Typical application range:

Compared to PA6, PA66 is more widely used in the automotive industry, instrument housings, and other products that require impact resistance and high strength requirements.

② Injection mold process conditions:

Drying treatment: If the material is sealed before processing, there is no need to dry. However, if the storage container is opened, it is recommended to dry it in hot air at 85 ° C. If the humidity is greater than 0.2%, vacuum drying at 105 ℃ for 12 hours is also required.

Melting temperature: 260~290 ℃. The product temperature for glass additives is 275~280 ℃. The melting temperature should be avoided above 300 ℃.

Mold temperature: 80 ℃ recommended. Mold temperature will affect crystallinity, which will affect the physical properties of the product. For thin-walled plastic parts, if a mold temperature below 40 ℃ is used, the crystallinity of the plastic parts will change over time. In order to maintain the geometric stability of the plastic parts, annealing treatment is required.

Injection pressure: usually between 750 and 1250 bar, depending on the material and product design.

Injection speed: High speed (slightly lower for reinforced materials).

Runner and Gate: Due to the short solidification time of PA66, the location of the gate is very important. The gate aperture should not be less than 0.5 * t (where t is the plastic thickness). If using a hot runner, the gate size should be smaller than using a conventional runner, as the hot runner can help prevent premature solidification of the material. If a submerged gate is used, the minimum diameter of the gate should be 0.75 mm.

③ Chemical and physical properties:

PA66 has a high melting point in polyamide materials. It is a semi crystalline material. PA66 can maintain strong strength and stiffness at higher temperatures. PA66 still has hygroscopicity after molding, and its degree mainly depends on the composition of the material, wall thickness, and environmental conditions. When designing a product, it is important to consider the impact of moisture absorption on geometric stability. In order to improve the mechanical properties of PA66, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubber, such as EPDM and SBR, is added to improve impact resistance. PA66 has a low viscosity and therefore good fluidity (but not as good as PA6). This property can be used to process very thin components. Its viscosity is sensitive to temperature changes. The shrinkage of PA66 is between 1% and 2%, and adding glass fiber additives can reduce the shrinkage to 0.2% to 1%. The difference in shrinkage in the flow direction and in the direction perpendicular to the flow direction is significant. PA66 is resistant to many solvents, but has weak resistance to acids and other chlorinating agents.

5. PBT (polybutylene terephthalate)

① Typical application range:

Household appliances (food processing blades, vacuum cleaner components, electric fans, hair dryer housings, coffee containers, etc.), electrical components (switches, motor housings, fuse boxes, computer keyboard keys, etc.), automotive industry (radiator grilles, vehicle body panels, wheel covers, door and window components, etc.).

② Injection mold process conditions:

Drying treatment: This material is easily hydrolyzed at high temperatures, so drying treatment before processing is important. The recommended drying conditions in air are 120 ℃ for 6-8 hours, or 150 ℃ for 2-4 hours. The humidity must be less than 0.03%. If using a moisture absorption dryer for drying, the recommended condition is 150 ℃ for 2.5 hours.

Melting temperature: 225~275 ℃, recommended temperature: 250 ℃.

Mold temperature: 40~60 ℃ for unreinforced materials. The cooling channel of the mold should be well designed to reduce the bending of the plastic part. Heat must dissipate quickly and evenly. The recommended diameter of the mold cooling cavity is 12 mm.

Injection pressure: Medium (up to 1500 bar).

Injection speed: The injection speed should be used as fast as possible (because PBT coagulates quickly).

Runner and Gate: It is recommended to use circular runners to increase pressure transfer (empirical formula: runner diameter=plastic thickness+1.5mm). Various types of gates can be used. Hot runners can also be used, but care should be taken to prevent leakage and degradation of the material. The gate diameter should be between 0.8 and 1.0 * t, where t is the plastic thickness. For submerged gates, a minimum diameter of 0.75 mm is recommended.

③ Chemical and physical properties:

PBT is one of the toughest engineering thermoplastic materials. It is a semi crystalline material with excellent chemical stability, mechanical strength, electrical insulation characteristics, and thermal stability. These materials have excellent stability under a wide range of environmental conditions. PBT has weak moisture absorption characteristics. The tensile strength of non reinforced PBT is 50MPa, and that of glass additive PBT is 170MPa. Excessive glass additives will cause the material to become brittle. The crystallization of PBT is rapid, which will lead to bending deformation due to uneven cooling. For materials with glass additive types, the shrinkage rate in the process direction can be reduced, but the shrinkage rate in the vertical direction of the process is basically the same as that of ordinary materials. Generally, the shrinkage of materials is between 1.5% and 2.8%. The shrinkage of materials containing 30% glass additives ranges from 0.3% to 1.6%. The melting point (225 ℃) and high temperature deformation temperature are lower than those of PET materials. The Vicat softening temperature is approximately 170 ℃. The glass transition temperature is between 22 ℃ and 43 ℃. Due to the high crystallization rate of PBT, its viscosity is low, and the cycle time for plastic processing is generally low.

6. PC (Polycarbonate)

① Typical application range:

Electrical and commercial equipment (computer components, connectors, etc.), appliances (food processing machines, refrigerator drawers, etc.), transportation industry

(Front and rear lights, instrument panel, etc. of the vehicle).

② Injection mold process conditions:

Drying treatment: PC materials have hygroscopicity, and drying before processing is important. The recommended drying conditions are from 100 ℃ to 120 ℃ for 3-4 hours. The humidity before processing must be less than 0.02%.

Melting temperature: 260~340 ℃.

Mold temperature: 70~120 ℃.

Injection pressure: Use high injection pressure as much as possible.

Injection speed: Use low speed injection for smaller gates, and use high speed injection for other types of gates.

③ Chemical and physical properties:

PC is a non crystalline engineering material with particularly good impact strength, thermal stability, glossiness, bacteriostatic properties, flame retardancy, and pollution resistance. The notched Izod impact strength of PCs is very high (the highest impact strength), and the shrinkage rate is very low, typically 0.1% to 0.2%. PC has good mechanical properties, but poor flow characteristics, making the injection molding process of this material more difficult. When selecting PC materials of what quality, the final expectations of the product should be taken as the benchmark. If plastic parts require high impact resistance, then use PC materials with low flow rates; Conversely, PC materials with high flow rates can be used to optimize the injection molding process.

7. PC/ABS (polycarbonate and acrylonitrile butadiene styrene copolymers and mixtures)

① Typical application range:

Computer and commercial machine casings, electrical equipment, lawn and garden machines, automotive parts (dashboard, interior decoration, and wheel covers).

② Injection mold process conditions:

Drying treatment: Drying treatment before processing is necessary. The humidity should be less than 0.04%, and the recommended drying condition is 90-110 ℃ for 2-4 hours.

Melting temperature: 230~300 ℃.

Mold temperature: 50~100 ℃.

Injection pressure: depends on the plastic part.

Injection speed: as high as possible.

③ Chemical and physical properties:

PC/ABS has the comprehensive characteristics of both PC and ABS. For example, the easy processing characteristics of ABS and the excellent mechanical properties and thermal stability of PC. The ratio of the two will affect the thermal stability of PC/ABS materials. PC/ABS also exhibits excellent flow characteristics.

8. PC/PBT (mixture of polycarbonate and polybutylene terephthalate)

① Typical application range:

Gearboxes, car bumpers, and products that require chemical and corrosion resistance, thermal stability, impact resistance, and geometric stability.

② Injection mold process conditions:

Drying treatment: It is recommended to dry at 110~135 ℃ for about 4 hours.

Melting temperature: 235~300 ℃.

Mold temperature: 37~93 ℃.

③ Chemical and physical properties:

PC/PBT has the comprehensive characteristics of both PC and PBT, such as the high toughness and geometric stability of PC, as well as the chemical stability, thermal stability, and lubrication characteristics of PBT.

9. PE-HD (High Density Polyethylene)

① Typical application range:

Refrigerator containers, storage containers, household kitchenware, sealing caps, etc.

② Injection mold process conditions:

Drying: If stored properly, drying is not necessary.

Melting temperature: 220~260 ℃. For materials with large molecules, it is recommended that the melting temperature range be between 200 and 250 ℃.

Mold temperature: 50~95 ℃. Plastic parts with a wall thickness of less than 6mm should use a higher mold temperature, while plastic parts with a wall thickness of more than 6mm should use a lower mold temperature. The cooling temperature of the plastic should be uniform to reduce differences in shrinkage. For the optimal processing cycle time, the diameter of the cooling cavity should not be less than 8mm, and the distance from the mold surface should be within 1.3d (where "d" is the diameter of the cooling cavity).

Injection pressure: 700~1050bar.

Injection speed: High speed injection is recommended.

Runner and Gate: The runner diameter should be between 4 and 7.5 mm, and the runner length should be as short as possible. Various types of gates can be used, and the gate length should not exceed 0.75 mm. Especially suitable for using hot runner molds.

③ Chemical and physical properties:

The high crystallinity of PE-HD results in its high density, tensile strength, high temperature distortion temperature, viscosity, and chemical stability. PE-HD has stronger impermeability than PE-LD. PE-HD has a low impact strength. The characteristics of PH-HD are mainly controlled by density and molecular weight distribution. The molecular weight distribution of PE-HD suitable for injection molding is very narrow. For densities ranging from 0.91 to 0.925 g/cm3, we call them the first type PE-HD; For densities ranging from 0.926 to 0.94 g/cm3, it is called the second type PE-HD; For densities ranging from 0.94 to 0.965 g/cm3, it is called the third type PE-HD. The material has excellent flow characteristics, with an MFR of between 0.1 and 28. The higher the molecular weight, the poorer the flow characteristics of PH-LD, but with better impact strength. PE-LD is a semi crystalline material with a high shrinkage after molding, ranging from 1.5% to 4%. PE-HD is prone to environmental stress cracking. Cracking can be reduced by using materials with very low flow characteristics to reduce internal stress. PE-HD is easily soluble in hydrocarbon solvents when the temperature is above 60 ℃, but its solubility resistance is better than PE-LD.

10. PE-LD (Low Density Polyethylene)

① Typical application range:

Bowl, cabinet, pipe coupling

② Injection mold process conditions:

Drying: generally not required

Melting temperature: 180~280 ℃

Mold temperature: 20-40 ℃. In order to achieve uniform cooling and more economical heat removal, it is recommended that the diameter of the cooling cavity be at least 8mm, and the distance from the cooling cavity to the mold surface should not exceed 1.5 times the diameter of the cooling cavity.

Injection pressure: up to 1500 bar.

Pressure maintaining pressure: up to 750 bar.

Injection speed: It is recommended to use a fast injection speed.

Runners and Gates: Various types of runners and gates can be used. PE-LD is particularly suitable for using hot runner molds.

③ Chemical and physical properties:

Commercial PE-LD materials have a density of 0.91 to 0.94 g/cm3. PE-LD has permeability to gases and water vapor. PE-LD has a high coefficient of thermal expansion and is not suitable for processing products that have been used for a long time. If the density of PE-LD is between 0.91 and 0.925 g/cm3, its shrinkage is between 2% and 5%; If the density is between 0.926 and 0.94 g/cm3, the shrinkage is between 1.5% and 4%. The current actual shrinkage rate also depends on the injection molding process parameters. PE-LD can resist multiple solvents at room temperature, but aromatic and chlorinated hydrocarbon solvents can cause it to expand. Similar to PE-HD, PE-LD is prone to environmental stress cracking.

11. PEI (Polyethylene Ether)

① Typical application range:

Automotive industry (engine accessories such as temperature sensors, fuel, and air handlers), electrical and electronic equipment (electrical couplings, printed circuit boards, chip housings, explosion-proof boxes, etc.), product packaging, aircraft internal equipment, pharmaceutical industry (surgical instruments, tool housings, non implantable devices).

② Injection mold process conditions:

Drying treatment: PEI has hygroscopic properties and can lead to material degradation. The required humidity value should be less than 0.02%. The recommended drying condition is 150 ℃ for 4 hours.

Melting temperature: 340~400 ℃ for ordinary materials; The reinforcement type material is 340~415 ℃.

Mold temperature: 107~175 ℃, recommended mold temperature is 140 ℃.

Injection pressure: 700~1500 bar.

Injection speed: Use the highest possible injection speed.

③ Chemical and physical properties:

PEI has strong high-temperature stability, and even non reinforced PEI still has good toughness and strength. Therefore, the superior thermal stability of PEI can be used to make high-temperature and heat-resistant devices. PEI also has good flame retardancy, chemical resistance, and electrical insulation properties. The glass transition temperature is very high, reaching 215 ℃. PEI also has very low shrinkage and good isotropic mechanical properties.

12. PET (polyethylene terephthalate)

① Typical application range

Automotive industry (structural components such as mirror boxes, electrical components such as headlights, mirrors, etc.), electrical components (motor housings, electrical couplings, relays, switches, microwave oven internal components, etc.). Industrial applications (pump housings, hand tools, etc.).

② Injection mold process conditions:

Drying treatment: Drying treatment before processing is necessary because PET has strong moisture absorption. The recommended drying condition is 120~165 ℃, and the drying treatment is 4 hours. The required humidity should be less than 0.02%.

Melting temperature: 265-280 ℃ for non filled types; For glass filled types: 275 to 290 ℃.

Mold temperature: 80~120 ℃.

Injection pressure: 300~1300bar.

Injection speed: Higher injection speeds can be used without causing embrittlement.

Runners and Gates: All general types of gates can be used. The gate size should be 50 to 100% of the plastic thickness.

③ Chemical and physical properties:

The glass transition temperature of PET is around 165 ℃, and the crystallization temperature range of the material is 120~220 ℃. PET has strong moisture absorption at high temperatures. For glass fiber reinforced PET materials, bending deformation is also very easy to occur at high temperatures. The crystallinity of the material can be improved by adding a crystal strengthening agent. Transparent products processed with PET have a gloss and thermal distortion temperature. Special additives such as mica can be added to PET to minimize bending deformation. If a lower mold temperature is used, transparent products can also be obtained using non filled PET materials.

13. PETG (ethylene glycol modified polyethylene terephthalate)

① Typical application range:

Medical equipment (test tubes, reagent bottles, etc.), toys, displays, light source covers, protective masks, refrigerator fresh-keeping plates, etc.

② Injection mold process conditions:

Drying treatment: Drying treatment before processing is necessary. The humidity must be below 0.04%. The recommended drying condition is 65 ℃ for 4 hours. Note that the drying temperature should not exceed 66 ℃.

Melting temperature: 220~290 ℃.

Mold temperature: 10~30 ℃, recommended as 15 ℃.

Injection pressure: 300~1300bar.

Injection speed: Higher injection speeds can be used without causing embrittlement.

③ Chemical and physical properties:

PETG is a transparent, amorphous material. The glass transition temperature is 88 ℃. PETG has a wider allowable range of injection molding conditions than PET, and has comprehensive characteristics of transparency, high strength, and high willpower.

14. PMMA (Polymethyl Methacrylate)

① Typical application range:

Automotive industry (signal light equipment, dashboard, etc.), pharmaceutical industry (blood storage containers, etc.), industrial applications (video discs, light diffusers), daily consumer goods (beverage cups, stationery, etc.).

② Injection mold process conditions:

Drying treatment: PMMA has hygroscopicity, so drying treatment before processing is necessary. The recommended drying condition is 90 ℃ for 2-4 hours.

Melting temperature: 240~270 ℃.

Mold temperature: 35~70 ℃.

Injection speed: medium

③ Chemical and physical properties:

PMMA has excellent optical properties and weather resistance. The penetration of white light is up to 92%. PMMA products have very low birefringence, especially suitable for making video discs, etc. PMMA has room temperature creep properties. Stress cracking can occur as the load increases and time increases. PMMA has good impact resistance characteristics.

15. POM (Polyoxymethylene)

① Typical application range:

POM has a low coefficient of friction and good geometric stability, making it particularly suitable for manufacturing gears and bearings. Due to its high temperature resistance, it is also used in pipeline devices (pipe valves, pump housings), lawn equipment, and so on.

② Injection mold process conditions:

Drying treatment: If the material is stored in a dry environment, it usually does not require drying treatment.

Melting temperature: 190~230 ℃ for homopolymer materials; The copolymer material is 190~210 ℃.

Mold temperature: 80~105 ℃. To reduce the shrinkage after molding, a higher mold temperature can be selected.

Injection pressure: 700~1200bar

Injection speed: Medium or high injection speed.

Runner and Gate: You can use any type of gate. If using tunnel gates, it is best to use a shorter type. For homopolymer materials, it is recommended to use a hot nozzle flow path. For copolymer materials, both internal and external hot runners can be used.

③ Chemical and physical properties:

POM is a tough and elastic material that has excellent creep resistance, geometric stability, and impact resistance even at low temperatures. POM has both homopolymer and copolymer materials. Homopolymer materials have excellent ductility and fatigue resistance, but are not easy to process. Copolymer materials have excellent thermal and chemical stability and are easy to process. Both homopolymer and copolymer materials are crystalline and do not readily absorb moisture. The high crystallinity of POM results in a relatively high shrinkage rate, which can be as high as 2% to 3.5%. There are different shrinkage rates for various reinforced materials.

16. PP (Polypropylene)

① Typical application range:

The automotive industry (mainly uses PP containing metal additives: mudguards, ventilation pipes, fans, etc.), appliances (dishwasher door gaskets, dryer ventilation pipes, washing machine frames and covers, refrigerator door gaskets, etc.), and consumer goods (lawn and gardening equipment such as lawn mowers and sprinklers, etc.).

② Injection mold process conditions:

Drying treatment: If stored properly, drying treatment is not required.

Melting temperature: 220~275 ℃, pay attention not to exceed 275 ℃.

Mold temperature: 40~80 ℃, recommended to use 50 ℃. The degree of crystallization is mainly determined by the mold temperature.

Injection pressure: up to 1800 bar.

Injection speed: Generally, using high-speed injection molding can minimize internal pressure. If defects appear on the surface of the product, low speed injection molding at higher temperatures should be used.

Runner and Gate: For cold runners, the typical runner diameter range is 4 to 7 mm. It is recommended to use a circular injection port and flow path. All types of gates can be used. Typical gate diameters range from 1 to 1.5 mm, but gates as small as 0.7 mm can also be used. For edge gates, the minimum gate depth should be half the wall thickness; The minimum gate width should be at least twice the wall thickness. PP materials can fully use a hot runner system.

③ Chemical and physical properties:

PP is a semi crystalline material. It is harder than PE and has a higher melting point. Due to the brittleness of homopolymer type PP when the temperature is above 0 ℃, many commercial PP materials are irregular copolymers with 1 to 4% ethylene or clamp type copolymers with higher ethylene content. Copolymer type PP materials have a lower thermal distortion temperature (100 ℃), low transparency, low gloss, and low rigidity, but have stronger impact strength. The strength of PP increases with the increase of ethylene content. The Vicat softening temperature of PP is 150 ℃. Due to its high crystallinity, this material has excellent surface stiffness and scratch resistance. PP does not have environmental stress cracking issues. Generally, PP is modified by adding glass fibers, metal additives, or thermoplastic rubber. The flow rate MFR of PP ranges from 1 to 40. PP materials with low MFR have good impact resistance but low ductility strength. For materials with the same MFR, the strength of the copolymer type is higher than that of the homopolymer type. Due to crystallization, the shrinkage of PP is quite high, typically 1.8 to 2.5%. And the directional uniformity of shrinkage is much better than materials such as PE-HD. Adding 30% glass additives can reduce the shrinkage to 0.7%. Both homopolymer type and copolymer type PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance, and solubility resistance. However, it has no resistance to aromatic hydrocarbon (such as benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. PP also does not have the same antioxidant properties as PE at high temperatures.

17. PPE (Polypropylene Ethylene)

① Typical application range:

Household products (dishwashers, washing machines, etc.), electrical equipment such as controller housings, fiber optic connectors, etc.

② Injection mold process conditions:

Drying treatment: It is recommended to conduct drying treatment at 100 ℃ for 2-4 hours before processing.

Melting temperature: 240~320 ℃.

Mold temperature: 60~105 ℃.

Injection pressure: 600~1500bar.

Runners and Gates: All types of gates can be used. It is particularly suitable for using handle shaped gates and fan shaped gates.

③ Chemical and physical properties:

Generally, commercially available PPE or PPO materials are often mixed with other thermoplastic materials such as PS, PA, etc. These mixed materials are still commonly referred to as PPE or PPO. Hybrid PPE or PPO has much better processing characteristics than pure materials. Changes in properties depend on the ratio of mixtures such as PPO and PS. The mixed material mixed with PA 66 has stronger chemical stability at high temperatures. This material has low moisture absorption and its products have excellent geometric stability. The material mixed with PS is non crystalline, while the material mixed with PA is crystalline. Adding glass fiber additives can reduce the shrinkage to 0.2%. This material also has excellent electrical insulation properties and a very low coefficient of thermal expansion. Its viscosity depends on the ratio of the mixture in the material, and an increase in the ratio of PPO will lead to an increase in viscosity.

18. PS (Polystyrene)

① Typical application range:

Product packaging, household goods (tableware, trays, etc.), electrical (transparent containers, light scattering devices, insulating films, etc.).

② Injection mold process conditions:

Drying treatment: Unless stored improperly, drying treatment is generally not required. If drying is required, the recommended drying condition is 80 ℃ for 2-3 hours.

Melting temperature: 180~280 ℃. The upper limit for flame retardant materials is 250 ℃.

Mold temperature: 40~50 ℃.

Injection pressure: 200~600bar.

Injection speed: It is recommended to use a fast injection speed.

Runners and Gates: All general types of gates can be used.

③ Chemical and physical properties:

Most commercial PSs are transparent, amorphous materials. PS has excellent geometric stability, thermal stability, optical transmission characteristics, electrical insulation characteristics, and a slight tendency to absorb moisture. It is resistant to water, diluted inorganic acids, but can be corroded by strong oxidizing acids such as concentrated sulfuric acid, and can expand and deform in some organic solvents.

The typical shrinkage is between 0.4 and 0.7%.

19. PVC (polyvinyl chloride)

① Typical application range:

Water supply pipes, household pipes, house wall panels, commercial machine housings, electronic product packaging, medical devices, food packaging, etc.

② Injection mold process conditions:

Drying treatment: Generally, drying treatment is not required.

Melting temperature: 185~205 ℃

Mold temperature: 20~50 ℃

Injection pressure: up to 1500 bar

Pressure maintaining pressure: up to 1000 bar

Injection speed: To avoid material degradation, it is generally necessary to use a relatively slow injection speed.

Runner and Gate: All conventional gates can be used. If machining smaller components, it is best to use a needle tip gate or a submerged gate; For thicker components, it is best to use a fan gate. The minimum diameter of needle shaped or submerged gates shall be 1 mm; The thickness of the fan gate shall not be less than 1mm.

③ Chemical and physical properties:

Rigid PVC is one of the most widely used plastic materials. PVC material is a non crystalline material. PVC materials are often used with stabilizers, lubricants, auxiliary processing agents, colorants, impact resistant agents, and other additives. PVC materials have non flammability, high strength, weather resistance, and excellent geometric stability. PVC has strong resistance to oxidants, reducing agents, and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid, and is not suitable for situations where it comes into contact with aromatic and chlorinated hydrocarbons. The melting temperature of PVC during processing is a very important process parameter, and if this parameter is not appropriate, it will lead to material decomposition issues. The flow characteristics of PVC are quite poor, and its process range is very narrow. In particular, PVC materials with large molecular weights are more difficult to process (such materials typically require the addition of lubricants to improve flow characteristics), so PVC materials with small molecular weights are commonly used. The shrinkage of PVC is relatively low, typically 0.2 to 0.6%.

20. SA (styrene acrylonitrile copolymer)

① Typical application range:

Electrical (sockets, housings, etc.), daily necessities (kitchen appliances, refrigerator devices, television bases, cassette boxes, etc.), automotive industry (headlight boxes, reflective borders, instrument panels, etc.), household goods (tableware, food knives, etc.), cosmetics packaging, etc.

② Injection mold process conditions:

Drying treatment: If stored improperly, SA has some hygroscopic properties. The recommended drying conditions are 80 ℃ for 2-4 hours.

Melting temperature: 200~270 ℃. If processing thick wall products, melting temperatures below the lower limit can be used.

Mold temperature: 40~80 ℃. For reinforced materials, the mold temperature should not exceed 60 ℃. The cooling system must be well designed because mold temperature will directly affect the appearance, shrinkage, and bending of the product.

Injection pressure: 350~1300bar.

Injection speed: High speed injection is recommended.

Runner and Gate: All conventional gates can be used. The gate size must be appropriate to avoid streaks, burns, and voids.

③ Chemical and physical properties:

SA is a hard, transparent material. The styrene component makes SA hard, transparent, and easy to process; The acrylonitrile composition gives SA chemical and thermal stability. SA has a strong ability to withstand loads, resist chemical reactions, resist thermal deformation, and geometric stability. Adding glass fiber additives to SA can increase its strength and thermal deformation resistance, and reduce its coefficient of thermal expansion. The Vicat softening temperature of SA is about 110 ℃. The deflection temperature under load is about 100 ℃. The shrinkage of SA is about 0.3 to 0.7%.