Air

[rpe]

Has anyone used air power in there design? Is it possible?

[Geof]

What would you power with air, spindle or axis drives or both? I think there are good arguments against either:

The efficiency is very low going from the power you put into the electric motor driving the compressor which supplies the air to the power you can get out of the air motor driving the spindle. I seem to recall seeing the figure of 8 to 1; in other words if you have an air motor putting out 1 horsepower you need an 8 hp motor driving the compressor supplying the air.

This leads to a second disadvantage which is noise. Both the compressor and the air motor are noisy, in the case of the air motor it can be very noisy.

Also an air motor is prone to speed variation and even stalling under a variable load such as when the depth of cut varies.

There is one potential advantage to an air motor and that is the possibility of very high speed when the tool and cut is very small.

Regarding driving the axes the low efficiency applies here as well as the speed variation under varying loads. Actually programmable automatic machines in the past have used air cylinders for driving the axes but these used separate hydraulic cylinders to control the speed.

I think you would be embarking on a very ambitious design and building project trying to do an air powered machine to no advantage.

[Andre' B]

If you are going to ask a question like that it is considered polite to provide some background info.

Air powered cell phone, not so practical.
Air powered car, better but still not all that good.
Air powered mine car, now the advantage of a lack of sparks to set off an explosion start to out weigh the disadvantages.
Air powered oil well pumps and other mining equipment, very practical in a very select situation.
http://www.cobalt.ca/index.php/ragged-chutes
http://cobaltmininglegacy.ca/power.php
Air powered die grinder, used all over the place.
Air cylinders, again all over the place.