How to manufacture / bend small copper u-channel // Tape Cover
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    Default How to manufacture / bend small copper u-channel // Tape Cover

    Hi,

    does anyone have an idea how to manufacture following part:

    img_2384.jpgimg_2385.jpgimg_2386.jpgimg_2387.jpg

    I have milled the outline of this part (which is okay) but I'm stuck at bending it so far.

    thanks,
    Mark

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    stamping press/

    And a set of dies.

    cahh chunk!

  3. Likes TJMark, mymachinery liked this post
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    Thank you for your feedback!

    Do you have any idea how much the die would cost to make something similar?
    Or can this be performed with some standard dies and fine tuning afterwards?


    I have some CNC machining experience but absolute no idea about stamping.

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    Quote Originally Posted by TJMark View Post
    Thank you for your feedback!

    Do you have any idea how much the die would cost to make something similar?
    Or can this be performed with some standard dies and fine tuning afterwards?


    I have some CNC machining experience but absolute no idea about stamping.

    I would say that you haven't a chance in hell to produce that part except if you would do it by way of hand cutting and filing craftsmanship.

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    Do you have experience with making such dies? Or does anyone have here?
    I wonder what a die for that should look like.

    As mentioned I have some CNC experience, I know about CAD/CAM as well. I have a small CNC at home as well which should be capable of milling tool steel with a small carbide bit (so far I mostly milled soft steel and aluminium).
    for the actual part I have done much more already (small soft steel gears m0.3; electronics for it; milled an accurate body) and this is the last part that is open on the list. I do have a plan b and c for that but I also want to learn more about the process for making such u-channel parts.

    Speed also doesn't matter if it takes me one day to make one part that's just fine, so I see where the problems are.

    I just did a test before:
    I got some tool steel for testing last week (SKD61) seems like I can mill it like butter with my CNC and the carbide endmill which I've bought. So I'm looking forward to learn more about the stamping process.

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    - should the folding / cutting procedure be split into multiple stages?

    - are the dies still fixed in such a tool nowadays?
    https://5.imimg.com/data5/QN/IP/MY-8...ts-500x500.jpg

    I think I will try to visit a stamping company next week to get more information about it as well

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    It sounds like you are looking at very low volumes when you say if it takes a day for one part....
    In which case, if your material is copper, you don't need tool steel for the dies.
    It seems that you have already cut out the blank, from what you have said.
    With your CNC mill you may be able to able to make a simple punch and die to fold this part.
    The parts you show in the link above I would call "bolsters". This would be needed for correct alignment of the dies. Again, quite simple for a very small quantity. Make prevision to attach your punch and die to the bolster.
    Then a a simple hydraulic shop press would do the job.
    A lot of work, but I would say possible and you would certainly learn a lot from the experience.
    There's lots of books on press tool design out there...

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    Quote Originally Posted by TJMark View Post
    Hi,

    does anyone have an idea how to manufacture following part:

    img_2384.jpgimg_2385.jpgimg_2386.jpgimg_2387.jpg

    I have milled the outline of this part (which is okay) but I'm stuck at bending it so far.

    thanks,
    Mark
    Used to work on stuff like this all the time, as you say complete the outline first then bend to suit, with care you may be able to just use a male former.
    Tony

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    Agree for one-up it is going to take some time., a custom roll bender might be made.
    a die tryout made of oak might be an aid.

    That is a very nice-looking part you made.

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    A hand operated press brake (Diacro 1624 for instance) would be ideal for that part. 2 bends with a simple linear V shaped punch and die (no tool steel needed) would do it. Bending tolerances, with care, can be held within .005".

    Agree with you that milling the blank first, then bending is the way to go. Bend allowance should have been determined first (empirically) before milling the profile. Most likely only a couple tweaks will be required to modify your present toolpath.

    The left end "curves" aren't a problem, but the right end curved bends might be, depending on final tolerances. If they don't have to be close, those features can be formed after bending. The vertical "wall" needs some minor shrinking, easiest to do in copper.

    So some questions:

    Tolerances? Lot size? thickness of material? Alloy?

    On edit: the wall height at the extreme right end may make for problems if trying to form it with a V die. I'm sure there's a work around, though.

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    Quote Originally Posted by neilho View Post
    A hand operated press brake (Diacro 1624 for instance) would be ideal for that part. 2 bends with a simple linear V shaped punch and die (no tool steel needed) would do it. Bending tolerances, with care, can be held within .005".

    Agree with you that milling the blank first, then bending is the way to go. Bend allowance should have been determined first (empirically) before milling the profile. Most likely only a couple tweaks will be required to modify your present toolpath.

    The left end "curves" aren't a problem, but the right end curved bends might be, depending on final tolerances. If they don't have to be close, those features can be formed after bending. The vertical "wall" needs some minor shrinking, easiest to do in copper.

    So some questions:

    Tolerances? Lot size? thickness of material? Alloy?

    The answers are getting better and better thank you.

    Tolerances, 0.005 should be more than enough. 0.02" would also be okay.
    I have 2 designs for this item so far.

    The volume I'm targeting at is around 50-60 at the moment.
    Thickness of the material 0.032 inch copper.
    Material copper.

    I will try to do some drawings about a die and post them here, maybe someone can give me some feedback here afterwards.
    I just went through some books about metal stamping dies and it feels like some special art which needs a lot experience.. however my part for sure will only require some subset of that knowledge.

    cover_modified.jpgcover_full.jpg

    Following I took from a youtube video
    metalstampingdies.jpg

    as for what I understand the die is fixed to that "compound die"

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    I don't know how you make the right end without a custom die.
    IF I was making single digits I would test bend some stock to get a feel for the real bend allowance, then CNC the outline in the flat
    Cutting the right end radius so that when it is bent the radius could be TIG welded up.

    Guys that really know how to make dies can tell you the right way, but if I had to make one tomorrow on my little manual press brake, that is how I would do it.

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    making dies for that sort of part that you only need 1 a day is completely impractical, total waste of time, you will never recoup the expense

    mill what what you can, finish with needle files features you couldn't reach and then fold it, which can become tricky with the "impossible" features you've put in the design, think VERY carefully if you need those "windows" that you introduced in your part compared to the original
    impossible-feature.jpg

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    Quote Originally Posted by jz79 View Post
    making dies for that sort of part that you only need 1 a day is completely impractical, total waste of time, you will never recoup the expense

    mill what what you can, finish with needle files features you couldn't reach and then fold it, which can become tricky with the "impossible" features you've put in the design, think VERY carefully if you need those "windows" that you introduced in your part compared to the original
    impossible-feature.jpg
    The windows are there for easier bending, that would be the milled version. I tried to mill the original version already and had issues with bending.

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    you're not making it easier to bend, more like - easier to distort while trying to bend

    the feature I circled there with red, those thin strips will not stay intact and in shape during the folding, I guarantee you that, instead I'd make the top opening larger to eliminate that strip and the side wall (windowless) would become the new edge, even then you can expect distortion while trying to make that _fold_, notice I'm talking about folding intentionally, it implies usage of box&pan folder, not a press brake with V and thin goose neck die to reach the middle, folder gives you advantage of holding on of the edged between fingers so that it stays intact, and it might be even possible to reach the bottom of the part with standard fingers

    this is part is quite intricate, pretty much exactly the opposite of what one would like to learn on working with sheet metal...

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    I was thinking about those small edges before already and I somewhat think they're not pressed but laser cut in the original part after the bending process.
    The idea about the side windows is to mill the outline and side windows first - afterwards bend it and finally mill the top windows.

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    those bends are trivial without the windows, especially if the top holes aren't there, you should have zero problems with that, you're probably using wrong tools/techniques if you're having trouble with that, and instead of talking about all the possibilities, I already suggest you what will work

    goose neck punch and v die will also work, especially if you're milling the top holes after, but getting the right goose neck die might be difficult, forming the whole thing in a U shape die might also be possible, but I doubt it would be worth the trouble considering the amount you need to make per day

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    I think I will just make the U-channels first and then mill face by face, I took 2 steel bars squeezed the 0.8mm sheet into it and grooved a small path into it for folding --- this worked surprisingly well.
    Afterwards I was able to fold it by hand.
    I was able to fold exactly the size I need and it looked very good.
    When I tried to fold it without the groove it didn't work and looked terrible.

    For the small cutouts I have some 0.5mm chinese endmills here (bought them by accident ages ago, while I broke 2 of them already I was able to drive it into the material slowly and manually, so I think I can do the fine structures with such kind of endmills and CNC with constant slow feedrate) I'll use the biggest possible endmills for the larger slots, and just for the fine-tuning the smallest one.

    cut.jpg

    1. stage pink cut outline
    2. stage fold
    3. stage final milling green

    that's how I'd do it now...


    ----

    I'm just curios:
    a die... does anyone have experience with making dies for such an item?
    How would someone start with that?
    Stamp the outline and fold it? a multi stage operation?
    but how about the small walls? I see no sign of deformation in the small walls which makes it look like as if those parts are laser cut after folding a blank.

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    Default Making a formed stamped sheet metal part

    Quote Originally Posted by TJMark View Post
    Hi,

    does anyone have an idea how to manufacture following part:

    img_2384.jpgimg_2385.jpgimg_2386.jpgimg_2387.jpg

    I have milled the outline of this part (which is okay) but I'm stuck at bending it so far.

    thanks,
    Mark
    My first question is How Many do you Need? That will determine the process. If only 1 to 10, Layout and Cutout as previously suggested. Make a cheap form die to form the part in an press or form in the press-brake. If you need a whole lot more, It's a new ball game! A punch press having sufficient tonnage and size. A "perf and blank" die and a "form die". Or a Progressive Die to produce a part at every stroke. In any case you'll need to figure the flat pattern: To calculate the Bend Allowance around the radii. (The sin of one (1) degree) .01745 X the arc X the inside radius + 1/3 the stock thickness.

    All the Best,
    Roger

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    First, some questions.

    How many do you need to make?

    How much can each part cost to make?

    For high volume this would be done on stamping presses with custom made dies for blanking (cutting the outline) and then forming (making the bends).

    For low volume the parts could be cut by any number of processes from CNC machining to having them water-jetted or laser cut by companies who do that work.

    Unless there's something I didn't notice it looks as if the bending could be done in a press brake with modified punch and die.


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