Introduction to Coolant

A coolant is a substance, typically liquidor gas, that is used to reduce or regulate the temperature of a system. Anideal coolanthas high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosion of the coolingsystem.

The term also covers cutting fluids. Industrial cutting fluid hasbroadly been classified as water-soluble coolant and neat oil cutting fluid. Water- soluble coolant is oil in water emulsion. It has varying oil content fromnil oil (synthetic coolant).

Function of Coolant

1. Lubricating

The lubrication is where the coolant penetrates into the contact area between grinding wheel and workpiece to form a lubrication layer to reduce the interface friction. This reduces the grinding force and abrasive wear as to extend the tool life of grinding wheel. The oil-based coolant has superior lubrication performance than the water-based coolant. Some additives are frequently added to the coolant to improve the lubrication performance of the coolant.

2. Cooling

The coolant has cooling effect for both workpiece and grinding wheel. For workpiece, the coolant absorbs heat, which protects the geometric accuracy and surface quality of workpiece; For grinding wheel, the coolant can immediately and rapidly cool abrasive grains with high temperature. This thermal shock effect can promotes the self-sharpening of the abrasive grains. Cooling function is associated with thermal conductivity, specific heat and vaporization heat of the coolant.

3. Cleaning

The coolant remove the chips and broken abrasive grains from gap between grinding wheel and workpiece, or the porous structure of grinding wheel, as to avoid affecting the processing accuracy and maintenance of the machine. This cleaning performance is related to the permeability, fluidity and pumping pressure of coolant. The permeability is associated with the surfactant contained in coolant, while the fluidity is correlated to the viscosity of coolant. Coolant with good permeability and low viscosity has good cleaning performance. In addition, it is suggested to pumping coolant at a large flow rate and with high pressure to improve its removing ability of chips and abrasive grains.

4. Rust Protection

Because the new surface after grinding has high energy, it is very easy to react with oxygen and other substances in the air, resulting in the oxidation of workpiece. The coolant form a protection layer on the ground surface of the workpiece as to prevent workpiece from contaminations or oxidation.