I acquired a piece of precission machined cast aluminum tooling plate
and wonder if others have used this type of material and for what.
The piece I have is 5/8 inch thick and about a foot square.
Looks like it would be good for vise jaws, but think there might be
some better use for it.
My opinion? Not great for vise jaws. Being cast, it's quite soft and
doesn't machine all that well. It's not really much of a prize if you
don't have need for aluminum tooling plate. It's normally used as the name
implies---for tooling. Base plates for large fixtures, for example.
Cast tooling plate is good for stability. So it won't move like a
similar wrought plate made from 6061. Threads pull out easier than
6061 so inserts are comminly used. The "precision machined" surface
actually isn't unless someone machined it after buying the plate. The
surface looks machined because the aluminum is cast against a machined
surface. I used to wonder how the factory got that shiny machined
surface when I never could quite match it myself. I figured they maybe
used diamond cutters running dry at very high speeds to save time.
Then I found out the stuff isn't machined afterall.
I did some looking around on the internet. And found this at
which says they do take off a few
The piece I have still has the protective film on it and looks as if
it was machined with some kind of big rotating cutter.
Ultimately, it was a process pioneered
by Hunter Engineering that led to today=92s most advanced cast aluminum
company, a forerunner of Alumax, developed a horizontal, continuous
caster to produce individual plate thicknesses. Alumax refined the
technology to bring dimensional control and stability to the next
level. The original product (named CC-70) has evolved to become the
state-of-the-art material known as Mic-6=AE Precision Machined Cast
Aluminum Plate. Alcoa, which acquired Alumax in 1998, now produces and
markets Mic-6=AE Precision Machined Cast Aluminum Plate at its Mill
Products facility in Lancaster, Pennsylvania.
The Mic-6=AE manufacturing technology involves a patented continuous
casting technique that allows precise casting to near net thickness -
the =93as-cast=94 thickness is only a few thousands of an inch greater
than the final plate thickness. Using a continuous flow of molten
aluminum, casting speed and the rate of solidification are tightly
controlled. A spinning nozzle inert filtration (SNIF) unit provides
additional filtration and degassing, virtually eliminating internal
defects. Proprietary equipment removes heat from both plate surfaces
at a carefully balanced rate so thermal gradients are stabilized. As a
result, grain size and distribution are identical on both plate
This unique casting process gives Mic-6=AE a granular structure that
resembles a honeycomb (see Figure 1). In the solidification process,
aluminum (which has a higher melting point than the alloying
ingredients) forms the cell core with alloy elements concentrated
between the cells. This segregation of low and high melting point
compositions imparts characteristics that make Mic-6=AE highly
machineable, producing small, uniform chips in a variety of high speed
After casting, the Mic-6=AE plate is subjected to thermal treatment in
excess of 700 degrees F for up to 10 hours. The resulting product is
fully stress relieved (fully annealed), eliminating stresses that
developed during casting as well as any heat-treating effects that may
have occurred during or after solidification. The material is =93dead
soft=94, comparable to the =93O=94 temper designation in wrought aluminum.
These steps result in a significant design benefit for Mic-6=AE=85there is
no decrease in mechanical properties when the plate is exposed to
elevated temperatures. This is true for both extended periods of high
temperature and cyclical exposure (even an infinite number of thermal
cycles). Once the Mic-6=AE plate is returned to room temperature, its
tensile properties are the same as they were prior to exposure. There
is no over-aging, which occurs in solution heat-treated plate, or the
partial annealing that is characteristic of strain-hardened material.
Accordingly, Mic-6=AE is recommended for applications where high
temperature conditions would be a problem for wrought aluminum
Machine it to serve as a fixture for some piece which you are
machining multiples of, to assure that they all are done the same way.
Small ones could be sized to fit in the vise, ideally with a
step on one end to define its location with respect to one side of the
fixed vise jaw for repeatability (given zeroing on the fixed jaw before
inserting the fixture).
Larger ones would be mounted directly on the table, with a pair
of keys to align with the T-slots, and a notch at each end to accept
hold-down bolts into T-nuts.
One machinist who I worked with for a while made one (about
1-1/2" thick) on a pair of tall 'I' shaped legs which he planned to bolt
down to the outer T-slots on a Bridgeport, but then he changed his mind
and put a big projection of similar thickness to clamp in the jaws of
the vise while the legs defined the height. On top of that, he put some
3/4" thick tooling plate, and would regularly drill and tap it and
machine stops and such to hold a workpiece (this was on a Bridgeport
clone which had been converted to CNC). After a while, he would face
mill it a bit thinner and continue to use it to make new fixtures.
Eventually, it would get too thin, and he would replace that top face
The tooling plate is flatter than normal aluminum stock, and is
of a precise thickness.
It can also be used as part of something you are building if you
get it inexpensively enough, and especially if you can benefit from the
A good thing to make with a couple of slabs of that is a gear
train, with the plates bored for the bearings.
I'm building a prototype 4-stroke gas engine
and I used 1/2" MIC6 for the baseplate, sides and
cylinder mount. Good stuff, flat enough that
I don't have to fly cut it and I was able to
find a vender that would cut up a sheet to the
rough sizes I need and gave me the drops.
MIC6 is also industry standard for electronics
and mechanical assembly and test fixtures.