The problem is, for instance, aluminum melts at approximately 1220 deg F = and cooling your air supply down by a paltry 60 or so degrees will have = a neglible efferct on total heat transfer at best--at worst, no effect = or perhaps it could even be negative. =20
You've intentionally reduced total mass air flow to the part itself by = throwing away the heated portion--air which is in all probablilty is say =
150 deg F or so--IOW, no where near the temp where there is a = significant danger of any cutting tools clogging up and that sort of = thing....air which all by itself (though hot to the touch) would be = perfectly adequate where the goal is keep the part / chips / temp at = some temperature well below the danger zone....When it comes down to it, despite the claims of the various vendors, I = really do have serious doubts that any more heat is carried away from = the workpiece by using the cold air out of a vortex tube than would be = carried away by simply using the same amout of total of mass air flow = that would have been output into a standard air nozzle at room temp = directly from the compressor instead.