Water soluble cutting fluids, also known as coolants, are lubricants used in the machining and grinding industry to cool the tool and workpiece, improve surface finish quality, and remove chips from the cutting zone. Unlike straight cutting oils , coolants are diluted with water ranging from 3% to 10% concentration .
The advantages of using coolants over straight cutting oils include:
Faster Speeds
Higher machining and grinding speeds can be performed using coolants without sacrificing tool life and surface finish quality due to its significantly higher heat capacity compared to neat cutting oils. These are applicable for processes such as grinding, drilling, tapping, milling, turning, cutting or sawing.Economical Costs
Coolants are generally cheaper since water is added so less product is used to accomplish the same operation. However, there are additional maintenance costs on monitoring of pH, concentration, and bacterial levels that are not needed with straight cutting oils.Ease of Washing
Coolants are easier to wash and remove from machined or ground parts compared to straight cutting oils due to its viscosity and consistency similar to water. This improves productivity for procedures with succeeding operations such as other machining and grinding processes, welding, or fastening.Chips Flushing Ability
Compared to straight cutting oils, chips are easier to flush when using coolants due to its viscosity and consistency.
For high-friction, high depth-of-cut, and low-speed operations that require more lubrication over cooling (e.g., broaching, hobbing, and gear cutting), straight cutting oils are still generally recommended. Proper handling and use of coolants should also be observed to prevent issues such as stinky smell from bacterial growth , skin irritation and dermatitis , and foaming .
