06-05-2015, 07:01 PM
Semi-synthetic, full synthetic and soluble oil coolants (a.k.a. cutting fluids), plus tapping compounds all have EP (extreme pressure) additives for lubricity. Those EP additives do aid the cutting process, otherwise why would we use cutting oil on HSS drills in metalworking? Or is it just used to have the tool heat up and smell the sulfur laden smoke?