Machining aluminum

Another week zooms by! I’ve been working on sourcing for the aluminum heating block. One thing that’s a bit elusive is finding shops to prototype the block out of 1100 aluminum. Most prototype shops stick to 6061, which is a strong material, but we want as high conductivity and low specific heat as we can (reasonably) get, and 1100 is the purest alloy of aluminum.

The material itself is cheap but because it’s a softer (I think) grade of aluminum, it takes more time to machine. CNC machine time adds up very quickly so Josh and I are both putting out requests for quotes to different shops. Chime in if you have experience with this :)

5 thoughts on “Machining aluminum

  1. Kyle

    I’ve had good luck with Solid Concepts. The prices are reasonable and the turn around times are pretty swift for CNC. You can specify 1100 aluminum, they most likely will not have any in stock but will just source a small piece quickly, probably from McMaster-Carr.

    A quick search on confirms ~30% thermal conductivity advantage of 1100 over 6061 but have you found in practice big differences in latency? What about trying an alloy higher in copper content if that is the case – I presume your design does not use this piece for anything structural as you are already willing to accept 1100 aluminum.

  2. Tom


    I asked a friend of mine about the 1100 aluminum. And he said:

    “(15:24:42) : don’t know why they are hung up on 1100 aluminum
    (15:24:44) : no point
    (15:24:54) : heat transfer is very similar to the other alloys
    (15:25:03) : the fraction of a difference, not worth the trouble
    (15:25:33) : if it’s that critical use copper
    (15:25:47) : copper is like double the transfer of AL
    (15:55:02) : In their narrative they tell you that it’s important to have a dialog with your machine shop
    (15:55:06) : cause those guys know a lot
    (15:55:12) : so, if they were doing that
    (15:55:22) : I’m sure that the shop would have told them
    (15:55:29) : no point in using that alloy”

    FYI….unless there is another reason for using 1100 aluminum?


  3. tito Post author

    Hi guys,
    Thanks for the comments! Tom, I sent you an email, thanks for your ideas!

    Kyle, yes we chose 1100 based purely on its thermal properties. Thanks for the link to matweb, I didn’t know there was such a good resource out there for thermal properties.


  4. Tom Benedict

    When looking at materials, it’s important to look at how machinable it is. One reason why prototype shops like to stick to 6061 aluminum is it’s really straightforward to machine. By comparison, machining 1100 is like machining chewing gum. Chances are a shop will make a part out of 1100 if you ask them, but they’re going to charge for any extra time and tooling necessary to make them. If it’s a high tolerance part, the costs will go up quickly.

    Copper is also not so fun to machine, but it’s easier than the pure aluminum alloys. Currently, copper is an expensive material to work with. I don’t see that cost going down any time soon.

    One gotcha with making any solid part for heat exchange is that you then add the thermal mass of the part into your heating and cooling cycles. This will slow things down. Take a look at your rate requirements and see if there’s another way to tackle the problem. Good example: Most of the home brewers I know use a wort cooler to get their mixture from 212F to 100F so they can pitch their yeast. A friend of mine built one using 50′ of 1/4″ copper pipe hooked up to a hose. The copper pipe was coiled into a double coil that could be lowered into the wort pot, and cold tap water was run through it. The time to bring 5gal of 212F liquid down to 100F was under two minutes. Low mass, low cost, and high performance. I know you can’t use this approach for what you need, but it serves as an example.

    Best of luck.


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