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Thread: Cleaning hot runner / manifolds while colour changing

  1. #1
    Join Date
    Mar 2019
    Posts
    2

    Cleaning hot runner / manifolds while colour changing

    Hi all,

    Im working at place where we are working on scrap reduction right now. We got procedures in place to clean barrel (using aqua purge / dyna purge) but while using hot runner system a lot of carbon/colour contamination coming from manifolds and tool. We are doing plate pulls and de-tip cavities but sometimes that isn't enough. Is there any cleaning agent you could think of that I could run through tool that would help me out to clean it ? Our shop floor is running food related product so I would need something that wont stain tool and will be acceptable with our finished goods.

    Thank you for any of your ideas.

  2. #2
    Join Date
    Aug 2019
    Posts
    25

    Re: Cleaning hot runner / manifolds while colour changing

    I've had decent luck with ASACLEAN. This is directly from their website. It's important to follow the purging procedure as results vary by material and temps. Hope this helps.

    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 20C – 30C (35F – 55F) 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 170-300C (340-570F)
    E 160-300C (320-570F)
    U 180-330C(355-625F)*
    *If using material between 330-360C (625-680 F), local ventilation is required.
    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:

    After the screw and barrel have been cleaned thoroughly using the ASACLEAN purging compound, set the nozzle into the mold.
    Open the mold plates.
    Set up a safety-approved surface for collecting the purgings.
    Verify that the mold safety door is closed.
    Add enough ASACLEAN purging compound into the hopper to fill the barrel approximately full.
    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.
    Visually inspect purgings for color and/or carbon contamination.
    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.
    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.
    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.
    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:

    After the screw and barrel have been cleaned thoroughly using ASACLEAN, set the nozzle into the mold.
    Verify that the mold safety door is closed.
    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.
    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.)
    Eject parts immediately, while they are still warm.
    Visually inspect parts for color and/or carbon contamination until parts are clean.
    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.
    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.
    Resume production using normal production settings.

  3. #3
    Join Date
    Mar 2019
    Posts
    2

    Re: Cleaning hot runner / manifolds while colour changing

    ASACLEAN been tried but still didn't give result that we wanted. We are at point where we run dyna purge through tool but still that does make a lot of scrap in process.

  4. #4
    Join Date
    Jun 2014
    Location
    EU
    Posts
    85

    Re: Cleaning hot runner / manifolds while colour changing

    Hi,

    I just want to point out that all cleaning procedures has certain rules.
    For exaple like the implwirtz note about asacleen.

    Iv already seen the mistakes in a procedure, done by machine operators. They act like it is standard plastic material so they just screw and purge.

    Check again procedure of the cleaning if its in the exact compliance with recomendations.

    J.

  5. #5
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    651

    Re: Cleaning hot runner / manifolds while colour changing

    To clean the hot runner you have to raise temperatures and open all valve gates. Run back pressure at max with max to medium rpm. Dont recover and shoot through mold because that wont clear the runner paths.
    I prefer Slide PDQ or their new one NPT. The packets can be kneaded and dropped into the feed throat.
    Rick.

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