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Injection Molding Purging Procedures

For Hot Runner Cleaning

On this page, you’ll find instructions, precautions, proven methods, best practices and quick tips for running ASACLEAN through hot runner channels.

Hot Runner Cleaning Procedures: Open Or Closed Mold Methods*

Cleaning of hot runner systems using unfilled purging compound grades of ASACLEAN (see grades below) may now be performed. ASACLEAN purging compound that is run through hot runner channels combines with residual materials and removes them safely while leaving a minimal amount of ASACLEAN residue.

Precautions, Proven Methods And Best Practices:

  • Unfilled grades of ASACLEAN can pass through the same clearances as the resins being processed.
  • Filled ASACLEAN grades (EX, PX2 and NF are not usually recommended for hot runner cleaning. Consult Sun Plastech Inc. for guidance on using filled grades for purging hot runners.
  • External heating systems: Raise the manifold temperature to 20°C – 30°C (35°F – 55°F) for improved flow. If running heat-sensitive resins, do not exceed the maximum safe operating temperature of the material.
  • Internal heating systems: Consult with a Purging Process Expert for technical assistance before using ASACLEAN.
  • If available, apply mold release agent to reduce the potential for material sticking to the mold surface.
  • Preparation: The entire hot runner system temperature must be within the usage range of the ASACLEAN purging compound grade to be used.

Purging Compound Grade Temperature Ranges

UP 340°F – 570°F
E 320°F – 570°F
U 350°F – 680°F

Purging Hot Runner Channels With Mold Plates Open*

Follow these step-by-step instructions when using an ASACLEAN purging compound mechanical grade to clean hot runner systems with mold plates open:

  1. After the screw and barrel have been cleaned thoroughly using the ASACLEAN purging compound, set the nozzle into the mold.
  2. Open the mold plates.
  3. Set up a safety-approved surface for collecting the purgings.
  4. Verify that the mold safety door is closed.
  5. Add enough ASACLEAN purging compound into the hopper to fill the barrel approximately ½ full.
  6. Extrude the ASACLEAN purging compound through the hot runner system starting at a medium velocity. Increase screw speed to the maximum safe level for maximum cleaning. Once ASACLEAN is flowing adequately through all of the gates, perform injection shots (air shots) with mold plates open.
  7. Visually inspect purgings for color and/or carbon contamination.
  8. If contamination remains, repeat steps 5 through 7 until the ASACLEAN purging compound is visually free of color and/or carbon contamination and has returned to a clean appearance.
  9. Purge out any remaining ASACLEAN using the maximum safe screw speed. Adjust the temperatures in the barrel and hot runners to the processing conditions for the next resin to be processed.
  10. Flush the system with the next resin to be processed using the maximum safe screw speed until the next resin is visually free of the ASACLEAN purging compound.
  11. Resume production using normal production settings.

Purging Hot Runner Channels With Mold Plates Closed*

Follow these step-by-step instructions when using an ASACLEAN purging compound mechanical grade to clean your hot runner system with mold plates closed:

  1. After the screw and barrel have been cleaned thoroughly using ASACLEAN, set the nozzle into the mold.
  2. Verify that the mold safety door is closed.
  3. To reduce the small possibility of ASACLEAN purging compound parts getting stuck in the hot runner cavities, reduce cooling time and spray the cavities with mold release.
  4. Remove pack and hold pressures and velocities. Inject ASACLEAN purging compound using short-shot molding (use only as much shot as is needed to safely remove parts from cavities – no more than 90% shot size.)
  5. Eject parts immediately, while they are still warm.
  6. Visually inspect parts for color and/or carbon contamination until parts are clean.
  7. If contamination still remains, repeat steps 4 through 6 until the ASACLEAN purging compound is visually free of color and/or carbon contamination and has returned to a clean appearance. Purge out any remaining ASACLEAN using the same method as above. Adjust the temperatures of the barrel and hot runners to the processing conditions for the next resin to be processed.
  8. Flush the system with the next resin to be processed, molding parts until the ASACLEAN purging compound can no longer be seen in the next resin.
  9. Resume production using normal production settings.

*Please Note: Although, to the best of our knowledge, the information contained herein is a fair and accurate representation, we assume no liability of any type in this regard. It remains the sole responsibility of the user to determine the suitability of the information and described product for the intended use and freedom from any patent infringement. We recommend that the user always adhere to relevant use and handling instructions from the manufacturer and supplier of any related equipment or material and that the user ascertain in all respects the suitability and safety for the intended purpose of any equipment, technique or material described herein. Any part produced containing ASACLEAN purging compound is not recommended for resale. ASACLEAN is designed only for use as a purging compound.

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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