Material Drying
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PA6 Dew Point -40°C Control
Problem Phenomenon
The dryer runs normally but PA6 products still have fine silver streaks; testing finds the drying air dew point is only -20°C
Cause Analysis
The dew point of the drying air determines the dehydration capacity; at a dew point of -20°C, the residual moisture in the air still causes PA6 to reach an absorption-desorption equilibrium in the later stage of drying, with the moisture content stuck at about 0.3% and unable to decrease further
Solution
Overhaul the dryer molecular sieve, confirm that the regeneration temperature and regeneration cycle are normal, use a dew point meter to actually measure the drying air dew point which should be stable below -40°C, and replace the molecular sieve in time when it powders and fails
Key Takeaway
Dew point is the first indicator of PA6 drying effectiveness; regularly testing the dew point is more effective than extending the drying time; after confirming effectiveness, fix the parameters and practices into the work instructions to prevent recurrence
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