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Thread: Hot Runner-Nozzle Heater

  1. #21
    Join Date
    Jun 2014
    Location
    EU
    Posts
    68

    Re: Hot Runner-Nozzle Heater

    Yesterday iīv talked with Incoe representatives on the Trade fair. Generally he agreed what was said here but maybe from lack of experience he didnīt know what will happen with hot runners at high temperatures exactly (he didnīt try it yet )

  2. #22
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Rick.

    I think the friction has less chance for the cause but for the excessive cooling, I think we have some issue here; but I will try to consider verifying both idea to see where the problem is.
    I will post the result once we have the conclusion.

    Sammy

  3. #23
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Jendalf,

    That is nice to here from the INCOE themselves.
    We will try to consider of lowering the heater temp from 300 deg.c and see what will be the possible effect on the heater itself.

    Sammy.

  4. #24
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    639

    Re: Hot Runner-Nozzle Heater

    Sammy-I meant flow restriction not friction. The tip grows into the orifice and blocks the flow. Now I've seen tips that were so small they shear heated the resin to the point of thermal degradation before. Each time the mold was injected the temps would climb over 50*F!! But that didn't cause heater failure.
    Rick.

  5. #25
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Rick,

    Yes. I mistakenly accounted the friction to flow restriction.
    By the way, this is another issue, but we observed in most cases, that our product under this mold (and heater) frequently experiencing voids on the product, especially near the gate or where the tip is located.
    Do you believe this has something to do with the flow restriction or our issues with the tip or heater problem?

    Sammy.

  6. #26
    Join Date
    Jun 2014
    Location
    EU
    Posts
    68

    Re: Hot Runner-Nozzle Heater

    Any pictures? Voids can appear due high temperature but how does they look like?

    J

  7. #27
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    639

    Re: Hot Runner-Nozzle Heater

    Sammy I think that the high heats are causing the voids due to the heat or poor melt flow into the cavity. When you guys find the root cause and correct it, I think some folks will sleeping well for the first time in a long time.
    Rick

  8. #28
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Jendalf,

    It is unfortunate that I do not have the picture now but the void is inside the plastic. Now the concern is, that the product is a case that we place acid, then later due to unwanted voids, the acid leaks later at the gate or the area near the gate.

    Sammy

  9. #29
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Rick,

    We are also looking forward for the resolution of the problem and at last, you are correct, we can take some nap time.
    I will take your advises.

    Sammy

  10. #30
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Dear Rick and Jendalf,

    After I checked the condition of the mold and runner I found that it has no shut-off valve and just a free flow system. I attached the picture for reference.
    Now, looking at the condition of the nozzle, which is an obsolete version of INCOE, I think the design is not as efficient as the latest design which leaves the opportunity to the heater to extend more heating to compensate the heat loss on the material. Though the outer cap of the nozzle assy is quite thick, still the heat loss due to contact with the colder plate is still bearing on the heater.
    In addition to the concern, I found our that the this type of heater has a built-in thermocouple making it prone to frequent replacement if either the heater or the thermocouple is not working.

    I will attach the hot runner assy in the next page since I think our page has a limit for the attachment.

    Your insight with this findings is highly appreaciated and valued.

    Sammy

    Attachment 109
    Attachment 108

  11. #31
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Rick and Jendalf,

    Here is the after image when we open the hot runner system.

    Sammy.

    Click image for larger version. 

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    Click image for larger version. 

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  12. #32
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    639

    Re: Hot Runner-Nozzle Heater

    Sammy- I wonder about the rust on the manifold because that's alarming for such a simple system. Lastly I hate that so many of the drops stuck in the mold base when the manifold was pulled. I would also expect a manifold that small to pull by hand w/o lifting eyes. Check the mold base for leaking plugs, water circuits, around the manifold. I bet there are some dripping water onto the manifold; at least that would explain heat settings and rust.
    Rick.

  13. #33
    Join Date
    Sep 2015
    Posts
    17

    Re: Hot Runner-Nozzle Heater

    Rick,

    I will take that into consideration.
    By the way, what do you thick of my findings with the condition of the heater system? I know it too outdated and perhaps the cause of too much heat-loose which forces the nozzle heater to work more?

    Sammy

  14. #34
    Join Date
    Aug 2011
    Location
    Upstate of South Carolina
    Posts
    639

    Re: Hot Runner-Nozzle Heater

    Sammy, I think one end of that manifold is way too rusted to be a coincidence. I bet there's a water leak internally or it gets wet when the lines are pulled off at change over. I think the water leak is rapidly killing the heaters and due to the set points required, I bet an active leak while in the press. It may only leak when under clamp force.
    Rick.

  15. #35
    Join Date
    Jun 2014
    Location
    EU
    Posts
    68

    Re: Hot Runner-Nozzle Heater

    Hi,
    It would be really interesting to know how this case was solved and what was the rootcause.

    after 4 years, we are older (of course) and maybe more experienced...

    Sammy?
    J

  16. #36
    Join Date
    Aug 2019
    Posts
    16

    Re: Hot Runner-Nozzle Heater

    Flash Back Friday!

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