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Purging Procedures

For Plastic Injection Molding Machines

On this page, you’ll find instructions, proven methods, best practices and quick tips for cleaning your plastic injection molding machine with ASACLEAN purging compounds.

Purging Instructions For Plastic Injection Molding Machines

Follow these step-by-step instructions when using an ASACLEAN mechanical-grade purging compound to clean your plastic injection molding machine:

  1. Check that all zones are in the proper temperature range for the grade of ASACLEAN purging agent being used.
  2. Retract the injection unit. Run the barrel empty using maximum back pressure. Wipe the hopper and feed throat.
  3. Feed the required amount of ASACLEAN purging compound into the hopper. About one to two barrel capacities of ASACLEAN is required for purging a typical injection molding machine. The actual amount required depends on the difficulty of the application and the condition of the equipment. Start with about one barrel capacity.
  4. With the screw completely forward, increase the back pressure to the maximum level.
  5. After the ASACLEAN purging compound begins coming from the nozzle, increase the screw speed to the maximum safe level.
  6. Drop the back pressure after the ASACLEAN purging compound coming from the nozzle is almost clean.
  7. Retract the screw and perform short, high-velocity injection shots.
  8. Repeat steps 1 through 7 if contaminants are still visible.
  9. The injection molding machine is clean and purging is complete when ASACLEAN purging compound coming from the machine is visibly free of contamination.
  10. Displace the ASACLEAN purging compound remaining in the machine with the next resin, again, at the maximum back pressure and the maximum safe screw speed with the screw completely forward.

Purging Process Tips For Plastic Injection Molding Machines

  • ASACLEAN mechanical grades do not depend on chemical reactions. No soak time is required for an effective purge.
  • For maximum performance, ASACLEAN should not be diluted with other materials.
  • Do not use EX, PX2 or NF glass-filled grades for hot runner cleaning.

Purging Compound Grade Temperature Ranges

Grade °F °C
EX 390-680 200-360
UP 340-570 170-300
U 350-680 180-360
E 320-570 160-300
SX 570-735 300-390
PX2 535-790 280-420
NB 355-630 180-330
NC 355-630 180-330
NH 355-630 180-330
NF 355-630 180-330

Tips Targeting Specific Areas Of Your Injection Molding Machine

The following purging techniques should be used after performing the procedures found above.

Nozzle or check ring hang-up  color or carbon: Raise the temperature of the nozzle 20-30°C (35-55°F). If purging a heat-sensitive resin, do not exceed the safe processing temperature of the material. Feed a small amount of ASACLEAN (less than half barrel capacity). Repeat short, high-velocity injection shots until clean.

Exercise proper safety precautions and use appropriate PPE.

For further insight into our recommended purging procedures, visit the Purging Process Resource Center. This page offers you training videos, guidelines, technical documentation and more to help answer your purging compound questions.

Ready to learn even more about ASACLEAN purging compound products and services? Click here to schedule your free, 10-minute consultation with a Purging Process Expert at ASACLEAN.

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