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Injection molding process, plastic composition and application conditions (3)

Update:17 Apr 2020
Summary:

4. PEI polyetherimide 1. Applications: automotive indus […]

4. PEI polyetherimide
1. Applications: automotive industry (engine parts such as temperature sensors, fuel and air processors, etc.), electrical appliances and electronic equipment (electrical couplings, printed circuit boards, chip housings, explosion-proof boxes, etc.), product packaging, aircraft interior equipment Pharmaceutical industry (surgical instruments, tool housings, non-implantable instruments).
2. Process conditions of injection molding: drying treatment: PEI has hygroscopic properties and can cause material degradation. The humidity value should be less than 0.02%. The recommended drying condition is 150C for 4 hours. Melting temperature: 340 ~ 400C for ordinary type materials; 340 ~ 415C for reinforced type materials. Mold temperature: 107 ~ 175C, the recommended mold temperature is 140C. Injection pressure: 700 ~ 1500bar. Injection speed: Use the highest possible injection speed.
3. Chemical and physical properties: PEI has strong high temperature stability, even if it is non-reinforced PEI, it still has good toughness and strength. Therefore, the use of PEI's superior thermal stability can be used to make high-temperature heat-resistant devices. PEI also has good flame retardancy, chemical resistance and electrical insulation properties. The glass transition temperature is very high, reaching 215C. PEI also has very low shrinkage (generally 0.4% -0.7%) and good iso-directional mechanical properties.

Five, PA6 polyamide 6 or nylon 6
1. Typical application range: Because of its good mechanical strength and rigidity, it is widely used in structural components. It has good wear resistance and is also used to make bearings.
2. Injection molding process conditions: Drying: Because PA6 easily absorbs moisture, special attention should be paid to the drying before processing. If the material is supplied in waterproof packaging, the container should be kept closed. If the humidity is greater than 0.2%, it is recommended to dry in hot air above 80C for 16 hours. If the material has been exposed to air for more than 8 hours, it is recommended to perform vacuum drying at 105C for more than 8 hours. Melting temperature: 230-280C, 250-280C for reinforced varieties. Mold temperature: 80 ~ 90C. The mold temperature significantly affects the crystallinity, which in turn affects the mechanical properties of the plastic parts. The crystallinity is very important for structural parts, so it is recommended that the mold temperature is 80 ~ 90C. For thin-walled, long-process plastic parts, it is also recommended to apply a higher mold temperature. Increasing the mold temperature can increase the strength and rigidity of plastic parts, but reduces the toughness. If the wall thickness is greater than 3mm, it is recommended to use a low temperature mold of 20 ~ 40C. For glass reinforced materials, the mold temperature should be greater than 80C. Injection pressure: generally between 750 and 1250bar (depending on material and product design). Injection speed: high speed (slightly reduced for reinforced materials).

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