Does anyone here have experience working with sintered copper heat-pipes?

[Bhima Pandava]

I'm building a system using a Streacom case. These cases use sintered copper heat-pipes to direct the heat from the CPU to the large heatsinks which make up the sides of the case. Unfortunately, the layout of motherboard I'm using isn't completely compatible with the pre-bent heat-pipes which came with the kit (the RAM is in the way). So I've ordered a set of straight heat-pipes the appropriate diameter & length and plan on bending them to fit. Fortunately, the layout I have does not require any tight fits or sharp corners; rather just a large-ish "U" bend (to circumnavigate the RAM) with each end flattened for a few cm to provide a larger mating area.

In the (admittedly somewhat distant) past I've worked with copper tubing & piping, so I'm not completely ignorant to the difficulties that this could pose. However, I've never worked with tubing with sintered copper lining the interior or with tubing that was filled and sealed. So I'm hoping that someone here has some experience with this and would be willing to comment on it.

Thanks!

 

[steelghost]

From a general metallurgy POV, these heatpipes are a) thin walled and b) possibly already somewhat work hardened.

So I'd suggest trying to bend them any more than a little bit is pretty likely to result in cracks. You could try and anneal the copper with a propane torch and then bend it, but it's thin enough that I wouldn't be confident of doing that without boiling the internal fluid and causing a leak, or even oxidising through the tubing wall.

That said, I could be way off. I'd get more pipes that you need and plan on losing a few while you figure out how to do it. If you're trying to bend to a specific radius, try and make a former that will get you an even curvature, and support the pipe to prevent kinks. Good luck!

 

[Sterling_Aug]

Sounds like a poor design to me using a sintered copper tubing instead of soft copper tubing that allows user modification.

 

[SBD]

Industry standard specs for sintered copper in electrical applications would put you at 20%+ for elongation at failure; meaning it's not overly brittle. Structural copper alloys (no reason for use in a heat pipe) would be 10% or less, so that would pose a problem. That said, the supplier of your heat pipe is probably not providing a set of metallurgical specification in the user manual, so it's not like you'll really be able to make an informed decision on the matter either way.

Gentle bends in thin walls are usually ok for all but the most brittle metals, but you'd be at a serious advantage if you could figure out a uniform elevated temperature (no torches...) to work at that won't damage the fluid inside. Maybe do a pre-heat in your oven on the 'warm' setting and start bending sloooooowly around a mandrel to give yourself time to inspect for cracking as you go.

Try it. Post pics

EDIT:

Sounds like a poor design to me using a sintered copper tubing instead of soft copper tubing that allows user modification.

I would contend that increasing the cost for 100% of your users by using wrought copper over sintered copper so that ~1% of users can do home-brew modifications to your part would be a poor design. People that need custom solutions get to pay for the luxury...

 

[Sterling_Aug]

SBD[/url]":iwt8l6d2]I would contend that increasing the cost for 100% of your users by using wrought copper over sintered copper so that ~1% of users can do home-brew modifications to your part would be a poor design. People that need custom solutions get to pay for the luxury...

Then the OP is at fault for using an incompatible mobo and RAM combo in the case. He should find out what parts the case manufacturer has designed for so there is no interference.

 

[Devin]

Exactly.

Although now that particular ship sailed, the oven trick sounds helpful.

 

[AgentQ]

How did this turn out?

Also, where did you pick up the heat pipes? I could use some for another project.