How is this (Heatsink) Manufactured?

[ryandias]

See attached image:

There seems to be little to no draft on the pins which leads me to believe it is not a die casting process.

Is it a post mold welding process?

Can anyone enlighten me?

 

[Medeski]

Pins are made separate and later staked to the block? Forged? Machined out of a solid block? We had some custom heatsinks made that way (finned, machined from solid block) from Radian. This link shows some of the processes they use.

http://www.radianheatsinks.com/index.php?act=viewDoc&docId=18

Any particular reason why you want to know?

 

[ryandias]

they state "precision forging".

I read a bunch about it earlier, and they said they use a heated die (almost the same as the aluminum insert) and then high pressure to produce near 0 draft parts.

Impressive designs, better surface areas.

We have been seeing competitors using similar products and I want to be competative or otherwise tell my boss why we should not use that technology.

 

[Medeski]

Well it seems like you know more about it than me (-: . Sounds similar to the "precision forging" on the Radian website. Are you manufacturing heatsinks or using them?

 

[drawoh]

ryandias,

How big is that thing?

It could be an investment casting. There are people out there who investment cast heat sinks similar to yours. Most of the ones I have seen have plates on either side with the pins in between. Your part is relatively simple.

JHG

 

[ryandias]

it is very small. Roughly 2" x 2" I'd day.

we are looking for serial production - X00,000 parts / year.

investment casting is not cheap enough at our rate.

the key to this heatsink is the lack of draft. This creates a much denser possible pin spacing.

We design heatsinks to be used with our motor controller products. Outsorce the designs to casting suppliers.

Thanks guys.

 

[TVP]

These parts are forged (forward extrusion) using a tool to apply counter pressure to the individual pins. The counter pressure changes the stress state (more compression) so that the material is more formable, with no draft on the relatively long pins being a significant benefit. This definitely is not an investment casting, as the casting alloys have substantially inferior microstructures to wrought alloys when it comes to thermal conductivity.

 

[ryandias]

TVP

Thanks for the detailed theory.

What is the counter pressure you spoke of?

Is it like the pin tips get pushed into the outter mold so that they become 0 draft? (shortening the depth of the pin to raise the pressure)

 

[TVP]

ryandias,

The counter pressure is applied by a tool within the die at the same time as the punch is pressing on the material (see attached image). The counter force is lower than the punch force, thus resulting in a net forward extrusion. Google "Osakada extrusion counter pressure" and you will find a lot of research by the Japanese researcher Kozo Osakada on this subject.

 

[unclesyd]

As you state this is for in house use have you looked at Micro Cooling from Wolverine. I believe this is the smallest you cna get for any quantity.

http://www.microcooling.com/

 

[ornerynorsk]

This is definitely an impact extrusion.

 

[flash3780]

You could friction weld the wires onto the plates (spin them up and push them together until they stick). However, if you were making any great quantity, impact extrusion is probably the way to go.

 

[EngineerTex]

I remember reading this article in Machine Design a few weeks ago and looked it up to realize that it was from nearly three years back. :O Wow how time files.

http://machinedesign.com/article/die-cast-aluminum-squeezes-out-steel-0208

I clicked on the link for the company that was profiled in the article (SPX Contech), but it seems to be held by a cyber-squatting firm and a press release from SPX says Contech was sold off.

http://investors.spx.com/ReleaseDetail.cfm?ReleaseID=232782

I don't know how you would get in contact with these guys besides trying the phone number in the Machine Design article or doing a little investigation, but their process may be what you're looking for.

Engineering is not the science behind building. It is the science behind not building.

 

[MintJulep]

It's just a sand casting.

The pins are separate parts, probably extruded rod. Look at the ends, they're just nastily cut to length with a hack saw.

Line up your pins, dump some sand around them, leave some amount of end protruding into the cavity for the body.

Pour in your molten whatever.

Everything fuses together and solidifies.

 

[ScottyUK]

It it were cast, would the plate remain soft and ductile enough to allow it to be bent over to secure it to the plastic moulding? The bend is pretty tight and is acute, but there's no sign of cracking even when the image is zoomed in. Or would these lugs be cast in that shape and the plastic moulding designed to deflect a little to clip in to place?


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If we learn from our mistakes I'm getting a great education!

 

[ornerynorsk]

Ditto on what you said Scotty. Not a sandcasting. My bet is still with an impact extrusion.

 

[KENAT]

I don't know, looking at the bent lugs, maybe they were cast in the 'bent' condition. I'm not sure they look like they were bent over. Most of the 'spring' might be in the plastic part.

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