Sealing/Shutdowns/Startups Contamination Prevention

Most thermoplastic resins when left in the barrel, even for a short time, are likely to degrade and become a cause of product contamination. To prevent contamination or deposit formation use ASACLEAN to clean the barrel and screw and displace resins from the machine.

Shutdown & Sealing:

  1. Follow the basic ASACLEAN purging instructions prior to shutdown.
  2. When using ASACLEAN EX or NF grade for purging the barrel and screw, displace with ½ barrel capacity of a sealing grade. When using ASACLEAN PX2 grade for purging, displace with ASACLEAN PF grade for sealing.
  3. Empty the barrel.
  4. Feed one barrel capacity of the same ASACLEAN grade at a slow screw speed. For molding machines, it is best to shutdown with 1/3 – 1/2 barrel capacity of melted ASACLEAN in front of the screw. To ensure that the barrel is full check that the feed throat is still filled with ASACLEAN.
  5. Turn off the heaters.


Turn on the heaters set to at least the minimum service temperature for the grade of ASACLEAN being used. The barrel temperature must be at the minimum service temperature long enough for the heat to soak all the way to the screw prior to starting screw rotation.

  1. Set the heaters to 230°C (450°F).
  2. When ASACLEAN has completely melted, feed a small amount of fresh ASACLEAN to displace the previously charged ASACLEAN. Verify the material is free of contamination.
  3. If contamination persists, continue purging until the contamination is eliminated.
  4. Set heats to production levels.
  5. When desired production conditions are reached, begin production.

Exercise proper safety precautions and use appropriate PPE.