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cast dies??

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  • cast dies??

    I was wondering if anybody has any info on composit die making. I want to use an epoxy or carbon fiber type material. Something that I can pour into a mold so I can make dies that can stamp parts in very thin copper sheet. Obviously I wouldn't expect the die to handle much more than a couple thousands copper sheet. Maybe even a urathane. I have done some research in to this but seem to be hitting a wall. If anybody has any info on this subject it would be greatly appreciated. Thanks,
    Jim

  • #2
    How long a run?

    For simplicity's sake I'd give tooling plastic a try but I don't know how long it'd last.

    ProCast is relativley cheap at around $70 for a kit. That's about 1 1/2 Gal of liquid A/B.

    A patternmaker's supply house will have some.

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    • #3
      "Couple thousands"? !!!
      I hope it's mighty thin sheet. You may be better off using a zinc alloy. I forget the exact name. It can be poured into a form to make dies. Auto makers and suppliers use it but I don't think they even get "thousands" out of a set of dies.

      When the dies wear out, melt it down and re-pour into your mold.

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      • #4
        Sorry,
        Let me clarify. Copper sheet a couple thousandths thick. Not a couple thousand stamps. Hopefully 25 to 50 stampings.

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        • #5
          Oh.

          UHMW-PE can be melted and formed into a mold.

          If you're working with sheet that is only a couple of thousandths, the epoxy/fiberglass should work. I'd use a steel carrier for the dies though.

          I used an epoxy form for a lower press die once. I used 1" x 1/8 flat formed in a circle and tack-welded to a piece of 6x6x1/2" scrap. I kept layering fiberglass mat then pressed my form into it. After it hardened, I poured another layer of just epoxy and laid the form into it. Try not to use more than 1/8" of unreinforced epoxy.

          I did about 150 recessed and flanged holes in 20ga. steel with it. Probably could have done a 150 more. The hole was prepunched. The dies just formed a flange and step.

          [This message has been edited by CCWKen (edited 04-03-2005).]

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          • #6
            I think glass would be overkill since it doesn't add anything. The forces involved are compresive. Even in a glass matrix it's the resin that's going to be taking the load. A material capable of maintaining an edge with a solid backing and cast around locator pins should do the job. Depending on the complexity of the shape a steel male punch can be made with a plastic female cast around it would work. The plastic can be recast as needed and the male shoud hold up.

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            • #7
              Kirksite is a well known castable material for dies. Pretty much pure zinc I think.
              Still available, there could well be other materials too.

              http://www.hoyt-darchem.demon.co.uk/contents.html

              For example, the guys who make steel repro body panels for old Fords etc - but this is fairly serious stuff compared to .002 copper.

              You may get away with something much simpler. How about sulfer - this is what we used to use for taking accurate impressions of dies. You simply heat it up in a can using butane or similar flame and pour it when it melts. It smells a little, especially if you overheat it! Would it stand up to pressing?? Possibly not!

              I have read of prototype sheetmetal panels being formed by placing the panel on a one-sided die and then pressing a large block of rubber (or urethane, no doubt) down onto the panel.

              [This message has been edited by Peter S (edited 04-03-2005).]

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              • #8
                Jim, There is a mass casting resin available from Tool Chemical Co.(www.toolchemical.com) that will do what you are looking for and more.The shop I was working for at the time was doing a lot of short run prototype parts , and we used this Resin several times with exelint results.They have several types of resin with fillers (Aluminum, Steel,Aggrigate)to help with the stability of the die. We made a 2 into 1 Y for an exaust system that was 16ga. with some tight radius areas, stamped 75 pcs and the die was still in good shape. Also stamped some frame brackets out of .125" steel ,Only need a few pcs and it worked great. Good luck Shawn

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                • #9
                  Copper you can do on plaster if the detail isn't too great.

                  Like mentioned above a rubber block for the male side is all you need,something around 20-30 shore A would work,about like crepe rubber if I rememeber the shore scale correctly.
                  I just need one more tool,just one!

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                  • #10
                    We made our patterns with a CNC mill in machinable wax poured a Silicone mold and then cast the dies in a rigid Urethane.

                    Used a homemade press and a 20 ton jack to press. The rigid urethane was the male die and 50D Urethane was the female die. The detail of the tooling marks in the wax was in the finished copper parts. Used what Alaskan Copper called "tooling copper".

                    The tooling marks are just the different finish as the mill did a zig-zag of conventional mill/climb mill toolpaths. The good news is the detail was excellent. The bad news is you only get a couple of parts and then the die degrades.

                    The choice of materials and processes was partly to introduce students to CNC mill and the molding materials.

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                    • #11
                      Devcon Liquid Steel.

                      Has to be supported on the walls.

                      You also have to use urethane on the top of the die to push the copper into the epoxy.

                      I routinely shape 18 gauge copper and silver sheet this way.

                      Anneal first, as it makes it much easier.

                      Check out http://www.bonnydoonengineering.com/

                      -jacob

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