Bending a Thin walled extrusion

We have to radius a thin walled Aluminium channel. Have any one got some information regarding how to bend tubes and pipes by encapsulating them in some low melting point alloy??

The reason I have to encapsulate is the channel deforms when we fill it and radius. Its T5 Aluminium with a wall thickness of 0.08. The problem we are facing is what kind of mold material should I use to encapsulate. In other words I need some reusable mold ( becoz I have to ben some 700 pieces) in which I can put my channel and pour the alloy to encapsulate. Is there a particular material with which I can make this mold???

Please note the channnel is 6.5 feet long and is bent the Hard way.

Reply to
Sai
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What section? Sizes? Radius?

You could use Wood's metal or something similar. Wood's melts at about

70°C, but contains cadmium. There's also a zinc alloy that melts at nearly 100°C. But these alloys are quite brittle.

How about a mandrel tube bender?

Nick

Reply to
Nick Müller

Its a four feet radius. The most difficult thing to figure out is, what material should the mold be made of. Can i make the mold out of aluminium , place the channel and then pour the molten metal/alloy around it?? If so will the alloy stick to the mould, as it is same material as my channel?

Reply to
Sai

Its a four feet radius. The most difficult thing to figure out is, what material should the mold be made of. Can i make the mold out of aluminium , place the channel and then pour the molten metal/alloy around it?? If so will the alloy stick to the mould, as it is same material as my channel?

Reply to
Sai

You don't mention how much distortion is acceptable.

As far as I can see there is no way to bend AL channel (the hard way) without;

  1. Distortion
  2. Without VERY expensive tooling. Sounds like a re-engineering of the project would be in order.

Ken.

Reply to
Ken Davey

What are the dimensions of the two sides and back of the channel, and is that .08" thickness the same on all three sides?

Jeff

Reply to
Jeff Wisnia

Pages 5-7 of

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PDF about bending items encapsulated in cerrobend) talk about an oiled "long metal pan or trough" for casting cerrobend around an extrusion. Also mentions using a plastic pipe as a form. Some other sources refer to resin, nylon, brass, and RTV-60 molds. Eg,
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and
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Given that you are shaping 700 pieces, it might be worthwhile to make up special forms to fit on your bender. See the pictures on 4th page of 6MB PDF
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The rest of this post is probably off-topic for your purposes, being on a tangent about styrofoam molds used for cerrobend casting. Radiation therapy beam blocks require mold sides that taper towards a perspective point, as shown in Figure 1 of

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Figure 3 is a good picture of a manual cutter. See
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for some one-sided discussion on how awful it is to make blocks manually rather than using Clark's machine. Anyhow: hot-wire-cut styrofoam is a commonly used mold material for making oddly shaped chunks of low melting point alloy for radiation blocks for radiation therapy. ("Polystyrene cellular foam board Dow styrofoam®" used with "Low melting alloy - 158° - Bismuth - 50% Tin 31.3% Lead 26.7% Cadmium 10%" according to page 3 of
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which also has safety precautions for handling alloys like this.) There's a picture of a block in slide 13 on page 7 of
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summary, if you need a complicated mold you can cut it out of foam board, but I have no idea how many good castings you would get per mold. (Almost every radiation therapy block is a custom one-off, molded once, used for a few weeks of treatment, then melted down.)

-jiw

Reply to
James Waldby

Wood's metal or Cerroben is reallly what you want. The mold needs to be a little bit larger than the channel for best results. You can then run it through a 3 cheel bender with no problems. The metal won't stick to the aluminum so there are no worrys there. I will note that Cerrobend isn't cheap so you will only want to buy as much of it as needed.

-- Why do penguins walk so far to get to their nesting grounds?

Reply to
Bob May

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