Author Topic: Heat spreader  (Read 1283 times)

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Online cncjerryTopic starter

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Heat spreader
« on: July 31, 2016, 02:47:27 am »
This is the second time I was contracted to machine heat spreaders.  The first time I thought the person sent me a model that wasn't importing correctly because it loaded into my CADCAM system as 20mm x 15mm.  Turned out that was the size.  After being anodized to make it nonconductive, it was clamped to a PC board and used to spread heat across several surface mount components on an RF board.  I've made small parts before but usually the things I'm machining involve hammers and 8,000lb clamping force vises.  I've done a lot of precision work though, like making gears for old clocks, etc.

The guy contracted again for heat spreaders and this one pushed the limits.  The outside dimensions are 7.5mm x 7.6mm.  The small step on the right channel is .2mm high (.0079").  I used a 1/32" end mill to rough out the channels and then finished them with a .015" end mill.  To put that in perspective, a lead on a typical ceramic capacitor is .024".  For miniature machining, this type of work wouldn't even get me in the contest.  I've seen people make working machines that sit on a dime.

The picture doesn't do it justice as the tool marks that are visible could be buffed out just by rubbing the part on a piece of paper.  I'll leave the finishing to the customer as even 2000 grit sandpaper would quickly spoil the edges.

 

Offline calexanian

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Re: Heat spreader
« Reply #1 on: July 31, 2016, 03:46:56 am »
Cool. I never have to do anything tiny like that. We just have another shop down the road EDM the small stuff.
Charles Alexanian
Alex-Tronix Control Systems
 

Online cncjerryTopic starter

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Re: Heat spreader
« Reply #2 on: July 31, 2016, 04:03:12 am »
I've seen some amazing things done with EDM and if the entry price wasn't so high I would have one.  You still have all the typical table problems with backlash, linearity, etc but they cut just about anything (conductive).  The total machine time on one of these parts was nearly an hour as the end mills will break just looking at them. All you hear is a little 'ping' and there goes 25 bucks.  EDM would have been a fraction of the time as well.
 

Offline David Hess

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Re: Heat spreader
« Reply #3 on: July 31, 2016, 07:05:45 pm »
I am surprised that a thermally conductive elastic pad is not a more economic solution for him.
 


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