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    Re: service engineers

    Have you contacted Sumitomo Demag? Our (Demag) Newburys are Mannesman-era machines, but Sumitomo is pretty good with spares & tech support. I'm in the US though.
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    Re: Cashew Gate Ejection Issue

    The gate is the smallest diameter region of the mold so that it freezes first, but it should also obviously be the weakest section of the part and runner. If your part is fracturing at the runner...
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    Re: White streaks or spots

    Is the location of the defect always the same, or is it random? Where is it in relation to the gate? Is the problem consistent throughout the run, or is it better/worse at start up? If it is...
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    Re: loud noise during mold opening

    Check that all your mold clamps are tightened down. Also check any/all shoulder bolts in the mold, make sure any die springs are not broken and so on. It's possible that one of the mold plates is not...
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    Re: Screw Recovery Issues

    Two possible scenarios:
    • Screw not plasticating
    • Screw plasticating normally, material drooling just as fast

    In the first case, consider:
    • Material not feeding (bridging in the throat due to...
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    Re: Procerex with Mold Vac System

    I have not used Procerax for this purpose, but I have worked with tools that had inserts just to provide venting at the knit line to improve appearance. Of course, you trade discoloration for a...
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    Re: Inconsistent Shrinkage Rates

    Nylon is a semi-crystalline material so you can expect anisotropic shrink. Is this a filled grade? If not, a shrink rate of only .005 in/in consistently on all dimensions suggests that the part is...
  8. Thread: Ram speed

    by JayDub
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    570

    Re: Ram speed

    You are correct, 60 would be 60% of maximum injection speed. Check the manual - it should at least tell you what the maximum injection speed is, so you can estimate your actual speed. Some machines...
  9. Thread: Machine setup

    by JayDub
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    Re: Machine setup

    First you need screw diameter in cm. Then calculate cross sectional area of the barrel: screw diameter squared times 0.7854. Divide ram speed by ten to convert from mm/s to cm/s, then multiply by the...
  10. Thread: Machine setup

    by JayDub
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    1,058

    Re: Machine setup

    All you need is the density of the material (in g/cm3) and a tiny bit of arithmetic. Molding machines are generally rated in terms of GPPS (styrene) which has a density of 1.06 g/cm3. So if your...
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    Re: What is this defect?

    If the whitish dot is a gate vestige, then it could be burning at the gate, especially if it's a valve gate. Try slowing the injection and see if it improves. If it does, you may need a bigger gate.
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    Re: Problem during TPE processing

    As Pilot mentioned above, sharp edges in the melt flow path can cause burning. Check that when the gates are open, the valve pins are retracted out of the flow channel. If not, material flowing past...
  13. Re: How does the clamping cylinder and ejector work on this 2 platen machine?

    Wouldn't they be the return hoses? I mean, if you're going to pressurize one side of a cylinder, you have to relieve the pressure on the other side, or nothing goes anywhere, right?
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    Re: Overmolding or insert molding?

    I've had issues where if I take too long to compose a reply the system times out and logs me out. If I have more than a couple of sentences to type, I'll do it in a Word doc, then log in and...
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    Re: Unsolved ınjection problems

    The defect looks to me like shear splay. If the location is random and not close to the gates, then it is coming from the material in the barrel. Try slowing down the screw recovery speed (lower...
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    Re: Velocity-Pressure-Time Parameters

    I assume you are using two-stage molding (fill and pack/hold). You will typically control the fill stage by velocity. In this case, fill time and maximum injection pressure are machine outputs, not...
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    Re: Overmolding or insert molding?

    Need a lot more information for a constructive response. In general, I wouldn't expect PC/ABS to shrink significantly after, say, 24 hours post-molding if it was just sitting on a shelf at room...
  18. Re: Chiller water is getting dirty and brownish color

    We also use glycol in our tower water. It solves some water quality problems, but keep in mind it can also be detrimental to heat transfer in the mold.
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    Re: Boy 50T2 no SEMI-AUTO or AUTO

    Screw position is defined by shot size set point plus decompression. If the screw is not at or beyond this position (the stroke is 'made'), then the press will not operate on auto/semi-auto.

    Also,...
  20. Thread: Nanotubes

    by JayDub
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    Re: Nanotubes

    You start by mentioning IM, but then say the part is 3D printed. Is printing the permanent method of manufacture or just prototyping with the intention of molding later? Printing will limit your...
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    Re: Compressed air for cleaning?

    I would think vacuum is better than air anyway. If you suck up the fines/contamination it ends up stuck on a filter somewhere. If you blow it off, then it's back floating around in the air where it...
  22. Re: Three resin lots required for part qualification

    I work for a medical molder (regulated facility) and we write our PQ protocols to use multiple material lots "if available". The idea of PQ is to model long term behavior of the process and prove...
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    Re: Injection Molding Process Sheets

    We use machine-specific templates that we use to make job-specific set up sheets. Both the templates and set-up sheets are controlled documents, stored electronically in the doc control system. We...
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    Re: Overmold Possibility

    I like the idea of using plastic blocks to locate the part, but here are a couple of other issues to consider:

    The overmolded plastic shrinks, but the metal doesn't. You have thicker sections of...
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    Re: Liquid color issue

    You may not be able to get good mixing from the GP screw. If you read the Celcon processing guide (which I highly recommend you do), what you ideally need is a barrier screw with a high (3 – 3.5)...
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