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  1. Replies
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    Re: Heated molds and temps

    Most engineering resins are semi-crystalline and these long strands of the polymer have to curl back up into little crystals during cooling. These little crystals only form at certain temps (glass...
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    Re: Rapid Prototyping and 3D Printing

    Yes, my 3-D printing guy orders all kinds of different filaments and liquid resins. He got the magnetic filament at some online shop. I will ask him tomorrow for specifics and get back to you.
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    Re: core deflection

    A couple of questions, is it cavity specific (always the same 10 cavities good, or different all the time)? What is the diameter of the core? You are going from a hot drop to a cold drop so this may...
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    Re: Rapid Prototyping and 3D Printing

    We had a lot of trouble cooling our mold as well. We ended up blasting both sides with air along with periodically spraying mold release. We are experimenting with heat sinks but so far no real...
  5. Thread: flow marks

    by MTUHusky
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    Re: flow marks

    I think he is suggesting a faster flowing material to try an eliminate the flow hesitation marks.

    I'm confused by the flow pattern, it looks like the flow pattern is moving away from the end of...
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    Rapid Prototyping and 3D Printing

    Hey guys,

    Just wondering what everyone is doing with regards to rapid prototyping and 3-D printing? My company has been experimenting with the technology and have recently made some fun...
  7. Thread: flow marks

    by MTUHusky
    Replies
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    2,975

    Re: flow marks

    Is your hand at the end of fill or at the beginning? It does look like flow hesitation (tiger striping) as Rick pointed out. The causes could be many. What is your shot size and transfer position set...
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    Re: Expired Materials

    "Expired" is probably a bad term to use. Plastic sitting over long periods of time can become oxidized. This is a form of degradation and it can cause all sorts of issues from discoloration, to...
  9. Re: New to injection moulding - Am I being realistic?

    JNMANN,

    To answer your question directly, no you are not being naive thinking you can make great parts on budget machines. My company buys used machines all the time and we make automotive parts...
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    Re: Inconsistent surface finish

    When you swapped lots of material, what was done with the old lot? Do you have any methods to analyze the material such as a Melt Flow Index? One possible reason for the success with changing the...
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    Re: Inconsistent surface finish

    Rick does have an excellent point here if you're getting gas traps between the multiple gates and those gas traps are being "dragged" across a long flow path then you might be seeing...
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    Re: Inconsistent surface finish

    You said the finish is glossy in some areas and not in others, that picture looks like the mold is textured, is the mold textured or smooth? If it is textured, you can get ghosting from the texture...
  13. Re: NEWBIE ALERT! I'm a layman and I need help figuring what material I'm describing...

    Look into a piece of software called "CES Material Selecter". It is an amazing program that has a huge database of materials that can be organized into charts and criteria related to what you need it...
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    Re: RJG Dynamic Cavity Imbalance

    You essentially turn off pack/hold and get the parts about 95% full under the same conditions you derived in your fill viscosity study. Then weigh each cavity and see how balanced your fill is. There...
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    Re: Verifying Clamp Tonnage

    I have used something called "Fuji Paper", I have also heard it called "pressure paper". There are different grades of it that will turn a bright red color when it reaches a certain pressure. I use...
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    Re: Help!, Warped walls with PP

    Just one more thought,

    Your running PP which is semi-crystalline so you will have orientation affecting warp. Do you know what size nozzle tip the previous molders were using? The smaller the...
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    Re: Help!, Warped walls with PP

    Suhas is absolutely right, that design sucks. Processing that warp out is going to be a daily struggle if you can do it at all. I would recommend you change the design if possible (I am sure it is...
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    Re: Injection Pressure

    The equation you are looking for is:

    Delta_P = (8*FlowRate*Length*Viscosity)/(Pie*r^4)

    notes:

    FlowRate is not the same as injection speed.

    Viscosity you are going to have to get from a...
  19. Re: injection pressure set on the injection molding machine controller

    Hello Ulynovsk,

    1. There should be a way to change the settings in the machine to give you linear or volumetric injection rates.
    2. You don't want your process to hit the high limit pressure in...
  20. Re: Flir or other infrared camera as a processing aide

    Hey Joel,

    All of the Foreman and project engineers at my shop run FLIR C3 cameras not just for the molds but for the cooling lines and to check heater bands too. We have had great success since...
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    Re: Fiber orientation.

    Fiber orientation can be affected by shear which is going to be controlled by injection speed and part thickness. I will assume you cant change part thickness either so to get more orientation you...
  22. Re: Insert mold stainless steel rod using acetal

    Ah, I see what you are trying to accomplish. I have no experience with inserts being able to move after molding but it sounds like it may be possible.
    A few things I would try:
    -Dropping them in...
  23. Re: Insert mold stainless steel rod using acetal

    The bad news is that Acetal material likes to stick to cores (i.e. a steel rod), especially if it is not heated and cooled properly.

    So its only 8mm long and 2.5 mm diameter. To minimize...
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    Re: Material cushion variation

    That first picture looks like you have a terminal there that is now filled with plastic, I would check your terminal shutoff to make sure it's not worn out but I would expect that you would see a lot...
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    Re: Van Dorn HT 85 buttons not working

    I can share your pain. We call the Van Dorn buttons "punch buttons" because we usually have to hit them really hard to get them to register. Wish I could help, we have change controllers with little...
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