PC/ABS Drying: Temperatures, Times and the Mistakes That Cost You Parts

Why drying is non-negotiable

The carbonate linkage in the PC chain hydrolyses at processing temperature in the presence of water, breaking chains and cutting molecular weight. Macroscopically that means poor melt strength, brittle parts and a cliff-edge drop in impact strength, accompanied by silver streaking, bubbles and yellowing.

The damage is irreversible. Once hydrolysis happens in the barrel, re-drying afterwards helps nothing.

Recommended window

Standard PC/ABS: 90-100 °C for 3-4 hours in a dehumidifying dryer with a dew point below -20 °C. Target moisture content below 0.02%.

Flame retardant PC/ABS: halogen-free FR systems are more heat sensitive, so cap the temperature at 95 °C and extend the time to 4 hours to avoid FR decomposition and surface gas marks.

Material left unpacked for more than 8 hours must be re-dried, typically for 1-2 hours.

Common mistakes

Mistake one: substituting a hot-air oven for a dehumidifying dryer. Hot air heats the pellets but removes little moisture — especially dangerous in humid seasons.

Mistake two: pushing the temperature to 120 °C to speed things up. Above 110 °C PC/ABS pellets tend to bridge and agglomerate in the hopper, and FR grades risk decomposition.

Mistake three: watching the clock instead of the dew point. Dew point is what actually determines drying efficiency; changing the molecular sieve on schedule beats adding hours.