In article ,
Anthony wrote:
James Holbrook wrote in news:XrYLd.7157$HZ.2520
@okepread07:
Hello,
I'm getting ready to turn some small parts out of aluminum.
The parts I'm making are basically discs of about 24mm diameter and 3mm
thickness with a few holes drilled for lightening. The most important
criteria are beauty (looks good with no gauling) and machinability.
I've seen all sorts of grades and am confused as to which is the better
grade to use.
What grade aluminum should I get and what type of tool. HSS or Carbide?
[ ... ]
If you want the best possible finish, a diamond tool is it for aluminum
(PCD tipped tool). Get the largest radius your part geometry will allow.
6061 or 7075 for the material.
Agreed -- though PCD diamond can be rather expensive. And
*never* use them on steel or iron. They are hard enough, but hot steel
or iron tends to dissolve carbon (including diamonds) into the alloy,
making it harder.
Don't confuse PCD (PolyCrystalaine Diamond) with the so-called
"diamond tool holder", which holds a HSS lathe bit at an angle which
presents a diamond-shape cutting surface.
And if you use carbide inserts (one of the suggestions in
Harold's branch of the thread -- if you are not up to grinding your own
HSS toolbits), *don't* use TiN (Titanium Nitride -- a yellow-gold color)
coated carbide. TiN coatings rounds the edges slightly, making for
duller tools. Aluminum wants the sharpest edge that you can get. The
best of the carbide inserts are the ones which have been ground to final
dimensions, instead of just formed as sintered to final shape which is
common. (I've got some very small ones, in 55 degree diamond shape
which fit the tool holders for my Emco Maier Compact-5/CNC which I
sometimes use when I need a really sharp carbide on my larger machines,
as they are ground to final dimensions.
TiN coatings are good for other materials, such as steel, where
they avoid BUE (Built-Up Edge -- an accumulation of metal which welds
itself to the edge and destroys the resulting finish.)
Good Luck,
DoN.
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