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Point 5: How to Choose Between PA6 and PA66?

When high-temperature resistance above 187°C is not required, opt for PA6+GF, as it is more cost-effective and easier to process.
For applications requiring high-temperature resistance, use PA66+GF.
The HDT (Heat Deflection Temperature) of PA66+30GF is 250°C, while that of PA6+30GF is 220°C.

PA6 has chemical and physical properties similar to PA66, but it has a lower melting point and a wider processing temperature range. It offers better impact resistance and solvent resistance than PA66 but has higher moisture absorption. Since many quality characteristics of plastic parts are affected by moisture absorption, this should be carefully considered when designing products with PA6.

To ensure the mechanical properties of PA6, various modifiers are often added. Glass fiber is a common additive, and synthetic rubber may also be incorporated to enhance impact resistance.

For unreinforced PA6, the shrinkage rate ranges between 1% and 1.5%. Adding glass fiber can reduce shrinkage to 0.3% (though slightly higher in the direction perpendicular to the flow). The final shrinkage rate is mainly influenced by crystallinity and moisture absorption.

Point 6: Differences in Injection Molding Processes for PA6 and PA66

1. Drying Treatment:

PA6 absorbs moisture very easily, so pre-processing drying is critical.
- If the material is supplied in moisture-proof packaging, keep the container sealed.
- If moisture content exceeds 0.2%, dry it in hot air at 80°C or above for 3–4 hours.
- If exposed to air for more than 8 hours, vacuum drying at 105°C for 1–2 hours is recommended.
- A dehumidifying dryer is advised.
PA66 does not require drying if the material is sealed before processing.
- If the storage container has been opened, dry it in hot air at 85°C.
- If moisture content exceeds 0.2%, vacuum drying at 105°C for 1–2 hours is necessary.
- A dehumidifying dryer is recommended.