ASACLEAN INJECTION MOLDING PURGING INSTRUCTIONS for Transitions from High Heat Resins to Other Resins Above 360°C(680°F) to below 300°C(570°F)
- Upon completion of the molding operation, run the high heat resin from the machine, emptying the barrel. Clean the hopper and feed throat.
- Feed about 1 barrel capacity of ASACLEAN SX into the hopper.
- With the screw completely forward, increase back pressure to a moderate level (enough to keep the screw forward).
Note: If processing temperatures are at or near the maximum recommended temperature for the SX Grade, low to medium backpressure and screw speed are recommended. Backpressure and screw speed can be increased at lower temperatures within the recommended range to maximize cleaning.
- Drop the temperatures to below 700°F (370°C), before purging with the ASACLEAN SX. ASACLEAN SX should not be left idle in the machine at temperatures above 700°F(370°C) for any amount of time as decomposition may occur.
- Start to extrude the ASACLEAN SX at a slow screw speed. When it starts coming out of the nozzle, increase the screw speed to a moderate level (about 50% of the maximum).
- Continue adding ASACLEAN SX, following the above instructions until the purge pile is clean.
- Set all barrel temperatures to 625°F (330°C) and continue extruding ASACLEAN SX at a slow screw speed. Continue adding ASACLEAN SX as necessary to prevent oxygen from entering the barrel. Oxygen will accelerate material decomposition and carbon formation.
- Do not allow the temperatures in the barrel to drop below 570°F (300°C) with ASACLEAN SX in the barrel as overloading of the screw may occur when screw rotation resumes.
- Set all temperatures to 570°F (300°C) and continue extruding ASACLEAN SX at moderate screw speed.
- When all temperatures are at 570°F (300°C), stop feeding ASACLEAN SX and extrude at maximum safe screw speed. Empty and wipe the hopper, and begin feeding the lower temperature ASACLEAN grade.
- Drop the temperature settings to the processing temperature of the lower heat resin. After all of the ASACLEAN SX has been displaced by the lower-temperature grade, leave the barrel full of the lower-temperature grade and stop the screw. The lower-temperature grade will have a slightly different appearance.
- The lower-temperature grade should not be left at temperatures above 535°F (280°C), for more than 30 minutes as decomposition may occur. If it takes longer than 30 minutes to get to the required lower temperature, run a fresh barrel of ASACLEAN and continue dropping temperatures.
- When the temperature drops into the processing range of the lower heat resin, empty the ASACLEAN from the barrel. Then start feeding the next resin to be processed.
- Displace the ASACLEAN with the next resin following the standard purging procedure using the maximum safe back pressure and screw speed with the screw completely forward.
- After all of the ASACLEAN has been displaced, begin production using the normal processing conditions for the resin.