On 01/29/2019 03:27 PM, Gene Heskett wrote:
Greetings all;
I just found the only way to cut this panel alu is to keep the tool cold
with a blast of air at around 125 psi blowing on the nut and tool.
Anything less and the heat telegraphing down the tool from the motors
front bearing, combined with the alox formation and friction gets the
tool so hot it burns the cutting oil away and welds the alu into the
flutes of a 4mm coated SC tool. Hell to pick it out.
My idea of how to work aluminum is to take very light
depth/width of cut, and keep the cutter moving along at a
high feedrate, to prevent the heat from building up at one spot.
I can't believe the spindle bearing is heating up the
cutter. If so, then the bearing has already burned out.
But, aluminum gets hot from the cutting action (supposedly
there is heat generated by the "burning" of the freshly
exposed metal in air, too). But, I think it is just the
heat of cutting accumulating in the workpiece.
I don't have a 25000 RPM spindle working here, so am
unfamiliar with the actual numbers, but you want very small
chip/tooth numbers, like .0001". This will eat up your
cutter faster, it can handle a LOT more chip/tooth, but the
heat has to be dealt with. You should be running at a
feedrate of 20 IPM or so, or faster if you can.
I use water-based coolant, as I do aluminum almost
exclusively. That probably removes a lot more heat than an
oil-based coolant (or brushed-on cutting oil, for sure!)
Jon
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