Newbie; Feedrate on CNC 6040 and layer thickness

Hi
I bought a CNC 6040 (lower quality CNC from China, 1.5kW spindle)
I will use it primarily for wood and plexiglass.
But, I need to cut some aluminium, and have a question:
I know that this machine has limited rigidness and power and lowering the feedrate will just warm up the drill bit.
So my idea is to run it with a decent/pretty fast feedrate, and just reduce the layer thickness milled per run. Down to lets say 0.2mm per layer and 200mm/min
I want to reduce the torque on the drill, so that the machine doesn't warp/bend during the run.
Is that a good idea?
Thanks
Klaus
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snipped-for-privacy@hotmail.com wrote:

Yes, on a machine with limited stiffness, taking shallow cuts at higher feedrates should work, then one final pass to finish the surface at the full depth. Keeping the feedrate up prevents local heating of the work, which leads to disaster when the aluminum gets soft.
This WILL wear your tools faster, but that is the price you pay on a lightweight machine. Cobalt or solid carbide tools help on the wear situation.
Jon
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On Monday, March 10, 2014 8:24:43 PM UTC+1, Jon Elson wrote:

Ok, thanks for the information :-)
Is there any rule of thumb of drill size, drill RPM and corresponding feed rate for aluminium (and other materials)
And perhaps a good book for a novice or a link?
Cheers
Klaus
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snipped-for-privacy@hotmail.com wrote:

I'm still confused by your combination of milling and drill bits. You do not do milling with drill bits, you use milling cutters for that. They have totally different side relief than a drill bit. If drilling dry, you have the problem of work heating, but peck drilling may help.
There is both DEPTH of cut and WIDTH of cut. These are separate parameters. If cutting into a plate of material, the step-over from the last pass would be the DEPTH, and the plunge in Z would be the width of the cut. For the first cut, you have no choice but to cut the full diameter of the cutter when making a slot. Unless using VERY small tools, you'd never take as light a cut as .2mm, I'd maybe do a full mm or even more each pass. I work in inch units, and usually do about .050" side depth of cut and .050" Z plunge, with a 1/8" end mill. I generally run that at 2800 RPM and plow the full cutter diameter at 5 or more IPM, and then make side-cut only passes at 15 IPM or so. Then, I usually leave .010" for a clean-up pass.
Jon
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