Copper alloys, relatively pure, that are best for machining

I have a design to mount a sensor on an instrument and the customer wants copper for thermal conductivity. The parts will be .200 thick and 4" long so an alloy that will be relatively stable would be best. Tellurium copper 145 looks the best. Anyone comment on machining it?

We cut all of our sink edm electrodes from "telco" aka Tellurium Copper or C145

It cuts great, pretty much like aluminum except it will wear out tools a bit faster. If you go over 800-1000sfm or so with carbide it will start to burn out tools quicker.

Ditto on on Tellurium copper C145 is what you want. Turns and mills more like brass than pure copper.

Silver is even more thermally conductive than copper....

Hello Laminar flow,
Copper and its alloys exhibit quite different thermal conductivity from alloy to alloy. Here is a simple link to some basics:
https://www.copper.org/publications/pub_list/pdf/a1360.pdf

Having spent my life designing instrumentation stuff, I have observed that many instrument SPECIFIERS have NO CLUE as to how some of the parameter choices that the people charged with building said instruments will have on the final performance of the device. Leaving the choice of material to you, with little specific guidance as to service temperature or the expectation as to the technical needs that the sensors material might have is a good path to unhappiness. My point is just that sometimes you have to badger the requester and explicitly query their needs. For example, if the sensor is to be used at cryogenic temperatures, Oxygen Free Copper is the only choice, although even there there may be huge subtleties known to those who deal with ultra-low temps.

Anyway, If you can nail down the temperature range the sensor will be used for, you can make a more informed choice. If you note the bottom of page 11 of the referenced document, above, the thermal and electrical properties of different alloys vary by a factor of 10. At ultralow temps, compared to OFC these alloys might look like insulators (I have not looked up the data, but it is easy to find). I was in fact so embarrassed I did look it up. There are a huge number of scholarly articles, but this one had some interesting data at lower temps:
Cryogenic Properties of Copper

If you find yourself lost in the maze of copper alloy designations, perhaps this will help a little:
https://www.copper.org/resources/properties/db/datasheets/all-alloys.pdf

Anyway, sharp tools and the right feed rates and surface speeds will get through most any copper alloy in good order.

Good luck!!
All the best,
Michael

Thanks everyone, would work out fine with the copper C145. Silver would be fun too.

Finished the first part and C145 is quite nice to machine.

Wow, .020" holes through .750 of C145? I'm impressed. You made me go get my detector and check the plate. I could detect no Beta or Gamma. Don't have an alpha probe so could not check for Alpha.

I used to make putters for Piretti Golf, and the copper was one of their best sellers, at the time.
We used C145 exclusively. It machines beautifully.

Doug.

Doug said:

First we had to get authorization from the FDA since the material is slightly radioactive.

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laminar-flow said:

Wow, .020" holes through .750 of C145? I'm impressed. You made me go get my detector and check the plate. I could detect no Beta or Gamma. Don't have an alpha probe so could not check for Alpha.

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Slightly? its a waste of most anyone's time even think about the radioactivity of tellurium.

by my math which is probably slightly wrong.. if you had a mole of tellurium (127 grams), you would have to wait one hour for 1.85 atoms of 130tellurium to emit two betas. i don't know how far the betas are going to make it through the tellurium itself, so you're going to need to roll a kilogram of it into a very, very thin foil.. and wait a long time to measure anything.

Yes, I looked up Tellurium and it is not radioactive in the normal sense. Especially the small amount in C145.

But on another unrelated note... how is C101 to machine? The next project is to turn some .750 parts.

I gave C101 everything my machine had for this (8k RPM on a 1/4" 3-flute) with a 0.003" cut per tooth and 12% stepover for the profiling and it came out mirror finished on the sides. Same with the facing passes but it looks like there was some microscopic smearing or maybe some vibration? It looks jeweled. That front face has been hit with 1000grit to remove the jeweling from the facing pass since I wanted to highlight the swirling cusps from the engraving.

We use C110 copper for a lot of electrical stuff. I don't know how it compares to C145, but I do know that it cuts beautifully.

I received some Copper 101 and did a quick face and it does seem to have a few spots where it smears. Other than that it seems fine. Thanks,