How is this manufactured? I'm stumped 1

[themilkmaid]

I'm working on a project that requires a heat sink for a high power LED. The unit shown in the linked images works well, the problem is that I can't figure out how it was manufactured and I need to create something similar but customized to this project.

This heat sink is from a fairly high volume product. The material is aluminum, and it's anodized. The part is not machined, there are very sharp inside corners that they would never bother with since they serve no purpose. There is 0deg draft on any of it, so it's not die cast. As far as I know you can't metal injection mold aluminum, so that's ruled out. There's no way a high volume part would be sand cast.

Am I missing something? Is there some sort of automated high volume equivalent to sand casting? The bottom face is smoothed with a secondary operation, but the rest of it can be a bit rough. I have Googled everything I can think of with no success.

Any ideas?

http://files.engineering.com/getfil...35-afe4-ffc3f8cd312f&file=20140422_233448.jpg

http://files.engineering.com/getfil...ea-a0da-f0993342be3e&file=20140422_233501.jpg

http://files.engineering.com/getfil...9b-a98f-bdea5d4f3c70&file=20140422_233526.jpg

 

[IRstuff]

http://coolingsource.com/images/design-resources/Heat-sinks-comparison-chart-082609.pdf

http://www.electronics-cooling.com/...onvection-air-cooled-fully-ducted-heat-sinks/

TTFN
faq731-376

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[berkshire]

themilkmaid (Mechanical)
You can investment cast Aluminum. and do modified die casting. See IRstuff's second link electronics cooling etc.,
B.E.





)



You are judged not by what you know, but by what you can do.

 

[MikeHalloran]

The fully radiused edges of the fins contraindicate routing the entire unit from a solid billet.
Those fins could be extruded and sheared to length at a pretty decent rate.
... then bonded or brazed to the contact plate, using a positioning fixture of some kind.


I can't quite eliminate impact extruding the whole thing from a slug a little thicker than the contact plate, but I'd expect a little bigger radius at the root of the fins.
... or maybe the part is smaller than I imagine it; there's no dimensional context in the photos.


The finish texture looks like a fine powder coat that wasn't sintered quite enough to make it run.


Or, the finish texture could be an artifact of selective laser sintering of the whole thing from aluminum powder. ... but I can't imagine that being fast enough for production, unless someone found a way to make it deposit metal as fast as flame/arc spraying.


... If I had one guess as to how the part in the photo was made, I'd go with SLS, and not real fast.


For a low-tech contrast, ISTR that at least some radial engine cylinder heads of WWII vintage had their super-fine fins cut from solid forgings by mechanical reciprocating hacksaws. ... a technology which is not amenable to the exact geometry you've illustrated, but offers a possibility.






Mike Halloran
Pembroke Pines, FL, USA

 

[tbuelna]

While it would be possible to make the part using diffusion bonding or furnace brazing, I don't think either process would be economical for mass production of a consumer product.

Looking at the photos, another possibility might be making the part using sintered aluminum powder.

 

[CELinOttawa]

What about laying up a custom feeder of flat stock (and the one little bar) through a form and friction welding the circular back on? This would then be advanced through the form and cut to give the desired fin length before the process would repeat for the next part.

 

[MintJulep]

Vibration welding was my thought as well.

 

[themilkmaid]

Thanks everyone! I think IRstuff and berkshire nailed it, investment casting. I never thought of investment casting as a high-volume process but I am now reading about it being used in automotive. According to the design guides you can get thin wall, there's no draft required, and tolerances are good.

(Sorry about the lack of scale, FYI it's about a 3" diameter)

 

[themilkmaid]

Actually, I stand corrected. After reading through the link IRstuff sent I realize that this part is "cold forged"... it seems to be a process that's often used in heat sinks.

http://www.led-heatsinks.com/sale-1...ed-downlight-heat-sink-pin-fin-heat-sink.html

 

[ornerynorsk]

If you have a say in the matter, design for diecasting or impact extruding. Your parts will be a fourth the cost.

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.

 

[KENAT]

milkmaid, what are your volumes going to be like?

While not suitable for truely high volume work (Rubber) Plaster Molding might be able to make that part (not 100% sure about the fin depth ratio).

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[themilkmaid]

KENAT, I'm probably ordering in batches of 5000. Annual volume will depend on sales of the product.

 

[KENAT]

Oh, well in that case I don't think my suggestion will work for production.

However, if you need to do prototyping it may be of use, I've dealt with these guys before

http://aljcast.com/

but there are other places too.

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[themilkmaid]

Good contact, thank you KENAT.

 

[hendersdc]

Definitely forged. I have had good experience with these guys for custom heat sinks. Malico

I have used them for prototype qtys and am just getting into production volumes in the mid 100's. They should have no problem with 5000 pcs lots.

They also have state side reps that are very responsive.

 

[themilkmaid]

Thanks hendersdc!

 

[dhengr]

Themilkmaid:
I’ll bet you could take a piece of 3"x3" bar stock, say 2' long; mill 1/8" slots every 1/4" o/c along the length; mill the slots 2.8-2.9" deep, with a round toothed saw blade; heat the continuous side sufficiently to form the entire bar around a piece of 2" pipe, without significant cracking in the continuous material. Then oven braze the whole formed doughnut to a base plate.

 

[Pud]

It may have been sand shell cast?

Shell casting

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[Medeski]

I've used Radian a looong time ago. They were pretty helpful and have a nice gallery of custom heatsinks and how they were manufactured.

 

[hendersdc]

Medeski,

We used Radian in the past too, it actually turned out they were just reselling the Malico heat sinks (at a significant mark up).