Synthetic metal working fluids often provide the best cooling performance among all cutting fluids. Synthetic cutting fluids do not contain any oil.They are water based concentrates, which form a clear or translucent solution when added to water. These fluids contain synthetic water-soluble lubricants, rust and corrosion inhibitors, water softeners, EP additives, surfactants, anti-foam and anti-bacteria additives (biocides) etc.
There are several advantages of synthetic cutting fluids viz.: good stability in hard water, resistance to foul smell, low viscosity and thus good cooling and wetting, good rust and corrosion protection, low mist, non-toxic, completely non-flammable and non-smoking, good filtration with standard filters, biodegradable easy handling, cleaning and maintenance etc. There are few disadvantages also viz.: insufficient lubricity for heavy duty applications, reaction with non-metal parts, easily contaminated by foreign oils etc. Another problem caused by synthetics is the sticky and gummy residue that is sometimes left when water evaporates from the solution mix. Further metal safety on non-ferrous metals is a problem with some synthetics because of their relatively high pH (8.5 to 10.0) and the lack of oil to act as an inhibitor.
They present less of a disposal problem than emulsifiable oils, because synthetics are easier to treat than emulsifiable oils before they can be disposed. Development work on cutting fluids is devoted to improve the synthetic fluid technology and synthetics are most definitely the products of the future.
Synthetic fluids are supplied in form of concentrates, which are mixed with water before use,the dilution ratio depends on the severity of application.