Water Soluble Cutting Fluids, or Coolants as it is commonly referred to, have found extensive use in the machining and grinding industry as of the present time. This fluid is typically diluted with water from as low 3% concentration up, all the way up to 10%. Water Soluble fluids used in machining and grinding processes provide several advantages over straight cutting oils,
1.) Faster speeds – the water component allows a significantly higher ability to absorb heat (vs neat oils), and thus higher machining or grinding speeds may be performed without sacrifice in tool life and surface finish. Applicable processes with higher speeds would include milling, turning, most grinding, drilling, tapping, cutting or sawing.
2.) Economical costs – costs compared to straight oils are lower due to the effect of water dilution, though this may at times be misleading, as using water-soluble fluids entails maintenance procedures not required with cutting oils. Maintenance procedures include regular monitoring of concentration, ph, and bacterial levels.
3.) Easier washability – normally machined or ground parts are subject to other succeeding machining and grinding processes, or perhaps assembly, to include welding and fastening, that require surfaces that are free from soils. The water-like consistency and viscosity of coolants are more readily removed from work-piece surfaces using conventional washing procedures, as compared to parts with straight oils.
3.) Better chip flushing ability – again, the water-like consistency of coolants enables a more efficient way to wash away metal debris from the machining and grinding area.
On the other hand, water-soluble cutting fluids may not be appropriate for high-friction, high depth-of-cut, and low-speed processes that require more lubrication rather than cooling. The process such a broaching, hobbing, gear cutting will benefit more from the use of neat cutting oils. A coolant’s rust and corrosion protection are also not as strong as with oils, of course.