Unusual metal machining process?

What would this process be called? Aluminium heatsink used for mounting electronic components to , to conduct away heat to the air . Some sort of chisell cutting advance and repeat while
still hot after casting/extruding?, surely not done cold?
http://home.graffiti.net/diverse:graffiti.net/chisel_vane_heatsink.jpg
a steel rule laid across it, plus a close up showing the slightly angled cuts
http://home.graffiti.net/diverse:graffiti.net/chisel_vane_heatsink2.jpg
The remaining uncut spine is about 4mm wide and the original bulk of metal must have been about 9mm wide to be cut down, each side, to a 4mm spine.
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
N_Cook wrote:

Milled from both sides simultaneously with gang tooling and then formed. Small stuff like this is also frequently sintered metal.
--

John R. Carroll
www.machiningsolution.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The fins are only 0.7mm thick and no sign of machining marks just a slightly granualar looking surface on the concave side of each vane and a smooth surface on the convex side. I don't see how a milling process can be involved. Are you saying the original bulk would have been about 4 + (2x27mm ) wide ? , the fins are about 27mm along the curve. A milling process would not leave those 5 degree or so off axis cuts along the spine.
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
N_Cook wrote:

Yeah, they are milled straight and then roll formed in place. Bar stock is pulled through a machine that does both sides and both operations at the same time.

Sure it would. You form grind the tools/cutters and gang them on an arbor. You are thinking of this as a milling operation done vertically from the top. It isn't. It's done horizontally with multiple cutters on an upper and lower arbor as a long length of stock is pulled through.
I didn't see a ground plane on the heat sink but if there is one it's bonded after the long bar has been cut to individual lengths and in a furnace. Like I said, a lot of this stuf is pressed and sintered as well. Depends on the material and - most importantly - quantities. Hardened carbide dies aren't cheap whereas wire cutting the forming sections and grinding the gang tooling is.
--

John R. Carroll
www.machiningsolution.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have a heat sink similar to that somewhere. To me it looked like something done similar to a metal shaper not going through, leaving the chip attached to base metal. I'm not sure how the process works but I've seen video of aluminum cans being made by a small piece of aluminum being pressed in a die and flowing around a punch. Perhaps the fins heat enough to be formed while being cut?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

conduct
metal
This is an end on view
http://home.graffiti.net/diverse:graffiti.net/chisel_vane_heatsink3.jpg
showing the granularity which probably suggests a shearing action. Looks as though the first operation was 4 knife cuts about 2mm deep (assuming 9mm thick slab to start with ) which when chiselled? up give those (2 sense) tapering ends to the knife cuts The lines on the spine probably show a guillotine to chop to length. The back face of these vanes is quite smooth in appearance mainly.
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm not sure what the process is actually called, but I call it "shaving." It's probably done on something like a shaper, as one other poster suggested. It's certainly not milled or sintered.
I've often wondered if heat sinks made like this were any good, because the integrity of the shaved off material is suspect in my mind. If the material is cracked, it won't have the same thermal conductivity. It's possible that this can be okay if the right alloy is used.
- ----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA -----------------------------------------------
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've never seen such a heatsink with a broken vane. There is a variant where the tip of each vane is sharply turned into a spiral before the main run of the curved vane.
I amagine it is all done just immediately after the extrusion, the knife cuts and then the 5 degree set chisel action on both sides , then chopped to length.
A very efficient process in the sense of no material loss in machining.
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

If the texture in the photo is accurately portrayed on my computer screen, it's machined with wirecut EDM. Not cheap, but the best way to do it in small quantities.
If it's a high-production part, then it's something else.
-- Ed Huntress
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

conduct
Would that process give the alternating surface appearance effect? There's not much point in taking a photo of the other end showing the appearance of the convex sides of the vanes as it looks like polished aluminium except for about 5mm at the open end of each vane. That has an appearance half way between polished and that granular appearance, so probably won't show up in a pic.
What I don't understand is why the "polished" looking faces look just that. with not the slightest trace of any striations from a cutting action, I will try looking under a microscope.
I assumed the process was producing one cut surface and one cleaved process like a chisel or plane-blade. If it was done at the same time as extrusion then relatively light forces of a knife through butter.
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I'm afraid I don't follow what you mean by alternativing surfaces. If you explained it earlier in the thread, sorry, I missed it.

That suggests EDM. The EDMed surface texture is non-directional and just grainy, looking at it under a microscope. It can range from coarse to the naked eye, to highly polished.
Do you know if this thing is something made special, in small quantities, or is it a production piece?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

or
I looked under a x30 microscope and both surfaces show striations, at that level of viewing, in the sense of chisel cuts if produced like that.
There were 10,000s to millions of them produced for mainlly Sony makes of domestic hi-fi amplifiers of the 1970s and 80s.
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


That wouldn't be wire EDM, then. Fine striations suggest extrusion. And that quantity suggests they weren't cut, except that they were sliced off from the extrusion.
-- Ed Huntress
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
N_Cook wrote:

It`s a process called 'Skiving'
Ron(UK)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So it does, which begs the philological question - what's the connection with the work-shy ?
-- General electronic repairs, most things repaired, other than TVs and PCs http://www.divdev.fsnet.co.uk/repairs.htm
Diverse Devices, Southampton, England
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
N_Cook wrote:

So that means that the dole office is full of orthogonal planers?
Ron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ed Huntress wrote:

Ed,
If you will forgive my hopping in here, These heatsinks were popular in Japanese consumer electronics about thirty years ago. They always looked shaped to me. The bright surface is formed as the curls are cut. The "polish" was just a nice finish.
Kevin Gallimore
----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! >100,000 Newsgroups ---= - Total Privacy via Encryption =---
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I guess I should look again, Kevin. When the quantities get as large as they were described, the usual method today is extrusion. From my quick look at the photos it looked like a difficult production-broaching job. I don't know what our Brit friends mean by "skiving" (in the US, the term is traditionally applied to a form-turning operation that's like scraping).
Anyway, I'll take another look.
-- Ed Huntress
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 2 Jun 2008 19:07:55 -0400, with neither quill nor qualm, "Ed

The term "skiving" is used in the leather industry for cutting leather into thinner layers.
"Are microtomes used only on tissue, or can/are some be used on metal, too?" he queried.
--

To change one's self is sufficient. It's the idiots who want to change
the world who are causing all the trouble --Anonymous
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've never heard skiving in terms of metal working.
In leather working skiving it the process of thinning the edge of a piece of hide, usually with a knife.
The process we use to put a glue splice in a flat belt is skiving. I it is also used to thin the edges so the seams in your shoes won't be two thicknesses. You use a knife to make a cut like you're filleting a smallmouth bass.
I envision a process like making a "fuzz stick" back in Boy Scouts.
A knife or a series of knives take a planing cut on the edge of the aluminum, raising a series of fins.
It would produce a piece just like the picture (the fins look way to thin for extrusions). It would be a really inelegant process though. The sort of thing I would expect from the third world.
I would also expect it to be a dead end technology .
Paul K. Dickman
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.