joek
November 4, 2010, 8:26pm
21
I’ll venture that the rough texture is simply a byproduct of the planing process. Machining is not so much “cutting” metal as it is plowing and crushing the material ahead of the cutter such that it yields. The upper surface is more deformed than the lower as it is on the inside of the curve and also cannot be burnished by the cutting tool. (I have an old 3rd edition of Materials and Processes in Manufacturing by DeGarmo that has some interesting closeup photos.)
I just looked at a long, continuous chip that came from drilling a hole in Aluminum. The lower surface is very shiny. The upper surface is a dull, matte finish. It is not as pronounced as the heatsink, but definitely noticeable. And that’s just a thin chip.
they appear to me to be too thin for that,unless they used abrasive cutters, like what’s on a chop saw, but not the brute force your describing
Here’s a picture of an old shaper taking off a 2" x 1/32" chip from a piece of steel.
And a video of a fairly large cut, again in steel. http://www.youtube.com/watch?v=YEIzbCD8qWc
Seems easy enough on Copper or Aluminum.
joek
November 16, 2010, 5:12pm
23
problem isn’t whether it can cut or not, the fins are too thin, and would have been destroyed in the process.
The links providing for the process clearly show it making fins that thin.
The second picture in post #22 shows a copper heat sink being skived. Skiving is also used to make long, continuous ribbons of metal from a large, round blank. I wish I could find a good video of the process.
