Machine tool coolant filtration has been used extensively in metal cutting operations for the last 200 years.  In the beginning, machine coolants consisted of simple oils applied with brushes to lubricate the machine tool.  Occasionally, lard, animal fat, or whale oil was added to improve the oil’s lubricity.  As cutting operations became more severe, machine coolant formulations became more complex.  Today’s machine coolants are special blends of chemical additives, lubricants, and water formulated to meet the metalworking industry’s performance demands.

Types of Machine Coolants in the Market

There are now several types of machine coolants on the market, the most common of which can be broadly categorized as cutting oils or water-miscible fluids.  Water-miscible fluids, including soluble oils, synthetics, and semi synthetics, are now used in approximately 80 to 90 percent of all applications.  Although straight-cutting oils are less popular than they were in the past, they are still the fluid of choice for certain metalworking applications. Essentially there is water, water with oil and synthetic coolants.  Adding oil or synthetic materials to the water does several things.  It adds rust preventative, and it helps carry away the heat, it more effectively removes particles, helps prevent corrosion, and retards or prevents bacteria and fungus build-up.

Oil is superior in applications where heat transfer is critical.  The most common, extreme example of this is tapping deep holes.  It is challenging to get a good flow of material across the work face in this application, so the machine tool coolant filtration must provide maximum lubricity and heat transfer.  This application is also effortless to control the spray and keep the coolant away from the operator since all the work takes place in a deep, sealed hole.

Synthetic Coolants

Synthetic coolants are superior in grinding applications where a strong flow across the workforce is possible and desirable.  The synthetic coolants do not transfer heat and oils, but the flow possible in grinding applications more than makes up for that.  Besides, open grinding such as flat, exposed surfaces throws a great deal of machine tool coolant filtration into the air in various size droplets.  Oil-based coolants are more likely to trap and contain metals and particles.  Besides, there is the problem in breathing petroleum products.

Specific synthetic lubricants can be superior in terms of lubricity and heat transfer to petroleum-based products.  Perhaps the most common example is the synthetic products available for automotive applications.  In high-performance automobile engines such as Corvette engines, the dealers strongly recommend synthetic lubricants over natural petroleum lubricants because of the extreme requirement for lubrication and cooling. Some machine tool coolant filtrations are a lot easier to test than others.  Some coolants show a color change as the amount of dissolved coolant gets greater.  Some coolants trap particles and float them in suspension a lot better than others.  Some coolants are safer than others, and some work better for grinding.  Some are also much safer to breathe and dispose of.   For easy testing, we recommend clear coolants.