How can this part be manufactured? 10

[sampsonr]

Hi There,

I'm looking at getting this part manufactured out of copper which has internal cooling chambers. It needs to be made from 1 piece and needs to be water tight. Does anyone know of a process that can produce this?

Approximate dimensions are 500mm x 60mm x 25mm

Ideally I would like to cast it but the only process I've come up with so far be a sintering process such as sls.

Any help would be greatly appreciated.

Cheers,
Roy.

 

[Artisi]

Look at investment (lost wax) casting.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[sampsonr]

I thought about investment casting but I thought you would struggle with the cavity. Do you know any examples of investment casting with cavities?

 

[GregLocock]

With lost wax -how would you get the plaster or sand out of the internal tube?

It's a big deal on engine blocks, where the hollow features are much larger and less intricate than you are proposing.

Cheers

Greg Locock


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[tbuelna]

You could investment cast the part using a soluble core. It won't be cheap, but it can be done. The internal passages are created by first creating a core from a soluble wax material, over-casting the core with a wax material that is not soluble to form the rest of the part exterior, dissolving the soluble core from the wax pattern using a suitable solvent, slurry coating the wax pattern, and finally melting the wax pattern from the investment mold.

The most difficult part of the process would be removing the investment material from inside the cored passages. This is typically done using water jet.

A more practical approach would be to machine the part in two halves, and then diffusion bond them together. For a copper heat exchanger, machining and diffusion bonding would allow greater precision in the passages and wall thicknesses. Which would result in a more efficient heat exchanger.

Good luck.
Terry

 

[tygerdawg]

It needs to be made from 1 piece

Why? So-o-o-o-o-o much easier & less expensive if you make it an assembly.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[kingnero]

true. having it watertight would be possible by several means, but furnace brazing would be my first choice.

 

[ornerynorsk]

For cost considerations, you could even consider a hydro-formed shell with a brazed cover and fittings. The one piece requirement increases the difficulty and processing time, and therefore the cost, by enormous proportions.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[fegenbush]

kingnero,

Furnace brazing was my first thought as well. If the volume (quantity) is high enough, the complex piece could be cast economically and a plate used for the closure. If the volume is low, machining becomes a valid option, but precision machining of copper is not very fun.

 

[marty007]

Just thinking outside the box here, but is there any way you can make a material substitution to brass?

If so it could open up options in the 3D printing world: Link

If not, ignore this post...

 

[ctopher]

Are the tolerances of the internal structures critical? Can it be a cast surface?
The different processes mentioned above will work.
Also, with recent improvements with the sintering process such as SLS, that can give you a good part.

Chris, CSWA
SolidWorks 13
ctopher's home
SolidWorks Legion

 

[Compositepro]

Machining one piece with the flow channels, and then furnace brazing on a flat plate would be my choice

 

[arunmrao]

I agree with compositepro. Have you considered 3D sand moulding . It is commercially available ,and then you could pour molten copper,traditional way. Decoring or removing sand from internal cavities should not be a problem.

 

[sampsonr]

Thanks for all the responses.

So to make it out of a single part - casting maybe achieved with some difficultly. SLS rapid prototyping would also probably work however expensive? (I'm pretty sure you cad print / sinter copper)

Options if it is split into 2 parts - Furnace brazing or diffusion bonding.

I'm not against making it in 2 parts if its a lot more cost effected then a single part and can still be water tight.

So from everyone's suggestions above could I assume the most cost method would be to cast or machine the part in two halves and furnace braze them together? This part may end up mass manufactured.

Cheers,
Roy.

 

[Compositepro]

Actually, a more common way to make the type of heat exchanger you are making, is to furnace braze a coil of copper tubing to the back of a flat plate. The tubing has no seams to leak. It's not as pretty but is much less costly.

 

[MikeHalloran]

The geometry is not ideal for the process, but I think you can electroform a copper part like that on a sacrificial aluminum armature.

In particular, you'd have to deposit a _lot_ of copper, and mill off most of it to get the external prismatical shape.


Servometer is one supplier of electroformed parts.





Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

Along with Mike's idea, there were some crazy suggestions we had (over beers, after work in the rocket factory) along the lines of: plating copper onto a coiled/looped piece of indium or Wood's metal wire, then melting out the indium. It would take a long time to build the flat shape via a plating/deposition process, but it could work. Other suggestions along the lines of plasma spray deposition over a suitable plastic or sintered carbon shape, or (in some shapes) packing and sintering a powdered metal over such shapes, with the carbon/plastic later "burned" out in a hot hydrogen furnace. Finally, there are some production parts made by casting aluminum or zinc alloys over stainless tubing; it might be possible to do similar tricks with copper, if you can find a ductile tube with a high enough melting point. All of these additive methods may have "issues" with the porosity inherent in the additive process, whether casting, electrodeposition, or plasma/flame/CV deposition. Bi-metal methods may have "issues" with differential thermal expansion and subsequent fatigue due to thermal cycling, especially where the bond between the metals is a brittle "intermetallic" phase. Fun to think about though.

 

[MikeHalloran]

Your next problem is that the process tradeoffs balance differently at different levels of production, and with particular details or artifacts that you may or may not feel are important to the gozinta.

E.g., at high volumes, you could coin/coldpress/impactextrude the halves, at a rate of many per minute, with some limits on depth, but you might have to accept some degree of mismatch after the brazing or diffusion bonding operation. At low volumes, you could CNC machine the halves, but copper is not fun to machine.

At most volumes, brass would be superior to copper for workability/chip_friability/scrap_value, at a very slight deficit in thermal conductivity.

To be frank about it, I regard insistence on pure copper, as opposed to another of the infinity of coppermetals (see copper.org), as an 'amateur track'.




Mike Halloran
Pembroke Pines, FL, USA

 

[msquared48]

To me, if this does not have a cover over it, it seems like an ideal application for a robotic router, depending on the thickness of the copper that has to remain.

If it has a cover, then I yield to what the experts have already said here...

Mike McCann
MMC Engineering

 

[KENAT]

"internal cooling chambers" Mike.

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