Oil-based cutting fluid has good lubricity and poor cooling effect. Compared with oil-based cutting fluid, water-based cutting fluid has relatively poor lubrication performance and good cooling effect. Slow cutting requires cutting fluid to have strong lubricity. Generally speaking, when the cutting speed is lower than 30m/min, cutting oil is used. When the cutting speed does not exceed 60m/min, the cutting oil containing extreme pressure additives is effective for cutting any material. When cutting at high speed, oil-based cutting fluid has high calorific value and poor heat transfer effect, which will lead to high temperature in the cutting area, smoke and fire in the cutting oil, and thermal deformation of the workpiece due to high temperature, which will affect the machining accuracy of the workpiece, so water-based cutting fluid is often used.

Emulsion combines the lubricity and rust prevention of oil with the excellent coolability of water, and has good lubricity and coolability at the same time, so it is very effective for high-speed and low-pressure metal cutting that generates a lot of heat. Compared with oil-based cutting fluid, emulsion has the advantages of high heat dissipation and cleanability, and economy brought by water dilution, which is beneficial to the health and safety of operators and makes them happy to use it. In fact, except for materials that are particularly difficult to machine, emulsion can be used for almost all light and medium load cutting and most heavy load machining. Emulsion can also be used in all grinding processes except complex grinding processes such as thread grinding and groove grinding. The disadvantage of emulsion is that it is easy to breed bacteria and mold, and the effective components in emulsion are chemically decomposed, which makes it stink and deteriorate. Therefore, generally, low-toxic organic fungicides should be added.

The advantages of chemically synthesized cutting fluid are economy, fast heat dissipation, strong cleanability, good visibility of workpiece, easy control of machining size, and stronger stability and corrosion resistance than emulsion. The disadvantage of synthetic cutting fluid is that it has poor lubricity when used under some harsh conditions, which will cause the moving parts of machine tools to get stuck. Adhesion and wear, the sticky residue left by chemical synthetic liquid will affect the movement of machine parts and rust the overlapping surfaces of these parts.

I hope this answer helps you?