Injection Molding – Hot Runner Systems – Shutdown/Startup: Suggested Purging Procedures
The following are suggested purging procedures for injection molding – hot runner systems as it applies to shutdown and startup.
- Maintain temperature and RPM settings for resident resin.
- Retract injection unit from mold, leaving ample room for purge to exit nozzle.
- Disconnect or shut-off auxiliary feeding equipment and thoroughly clean material feed system, ensuring all components including blenders, hoppers, loaders, filters, magnets, hoses, and drain ports are cleaned.
- Empty barrel and starve the screw of the resident resin.
- Introduce Dyna-Purge (1 to 2 times barrel capacity) into empty hopper or side port. Note: actual amount needed depends on machine conditions.
- With the screw in the forward position, purge until the compound flushed out of the machine is clean. Note: If unable to purge with the screw in the forward position, set machine shot size between 50% and maximum allowable setting.
- Ensure barrel is filled with Dyna-Purge to prevent the chance of oxidation. Stop screw rotation and reduce the temperature by lowering or turning off the heat zones of the machine. Caution: as the purge solidifies, take care not to rotate screw.
- Turn on and/or raise the temperature to 50°F (10°C) above the minimum operating temperature of Dyna-Purge. Note: make sure to review start-up protocol on machinery for additional information.
- When the desired temperature of Dyna-Purge has been reached, begin rotating the screw slowly to avoid too much torque. The purge may still be stiff, so do not rotate the screw at full RPM.
- If the purge compound exiting the machine shows signs of contamination, introduce more Dyna-Purge until the compound flushed out is clean.
- Thoroughly clean the hopper and adjust temperature settings for your next production resin.
- Using your next production resin, flush out the remaining Dyna-Purge.
- Thoroughly clean machine nozzle and sprue bushing to remove any contamination. Caution: wear the appropriate personal protective equipment.
- Move machine carriage forward to make contact with mold sprue bushing.
- Continue to run next production resin through hot runners until it is clean.
- Check gates in mold for any blockage or drool and start production run.
Before performing any procedure, it is the machine operator’s responsibility to be aware of their company’s safety policy, to wear the appropriate personal protective equipment, and to make sure that only authorized personnel are in the area.
Important! The information presented herein, while not guaranteed, was prepared by competent technical personnel and is true to the best of our knowledge. NO WARRANTY OR GUARANTY, EXPRESS OR IMPLIED, IS MADE REGARDING PERFORMANCE, SUITABILITY OR OTHERWISE. This information is not intended to be all-inclusive as to the manner and conditions of use, handling or storage. Other factors may involve other or additional safety or performance considerations. While our technical personnel can respond to questions regarding safe handling and use procedures, safe handling and use remains the responsibility of the customer. No suggestions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any Federal, State or local laws.
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