1. Retract screw and barrel from the mold. Empty the system of the production resin, and make sure the feed areas are clean. Increase the nozzle and front zone heats by 30°C (50°F). Do not exceed 360°C (680°F).

If purging a heat-sensitive resin, do not exceed the safe processing temperature of the material. This purge procedure may need to be repeated at elevated temperatures to remove all contamination.

2. Flush the machine by running 1-4 barrel volumes of clean, natural polyethylene that is at least as stiff as the production resin, to remove most of the residual production resin.
3. With the barrel now empty and the screw in the forward position, add ASACLEAN NCR by rotating the screw until the purge extrudes from the nozzle.
4. Stop the screw, and allow the contents of the barrel to sit for a 10 – 20 minute heat soak with the screw in the forward position. ASACLEAN NCR is heat activated, so expansion will occur during the heat soak. If nozzle drool stops, jog the screw until it begins again (if sealing, turn off all heaters with the system full of ASACLEAN NCR).

Note: if feed throat temperatures exceed 120°C (250°F), turn the screw
continuously, at minimum controllable RPM during soak to prevent bridging.

5. Empty the screw and barrel. If the last of the purge is still contaminated, elevate nozzle temperatures an additional 55°C (100°F), and repeat steps 3-5.
6. Change nozzle and barrel temperatures for next resin.
7. Wait 5 minutes with an empty barrel for the ASACLEAN NCR residue to break
8. When safe, displace the ASACLEAN NCR with the next resin.
9. Begin production under normal processing conditions.

N Series Chemical Grade Purging Procedures