The present invention provides a process for producing a water-miscible
metalworking fluid involving combining about 90 wt. % to about 5 wt. %, based on the weight of the fluid, of water and one or more additives chosen from plasticizers, chelating agents, biocides, surfactants, dispersants, dyes, odorants, extreme pressure agents, anti-oxidants and
corrosion inhibitors with about 10 wt. % to about 95 wt. %, based on the weight of the fluid, of a polyether
polyol produced by mixing an active
hydrogen compound with a double
metal cyanide (DMC) catalyst in a reactor vessel, charging to the reactor vessel a mixture containing two or more alkylene oxides to activate the catalyst, and continuously feeding one or more alkylene oxides to produce the polyether
polyol, wherein a 1% solution in water of the polyether
polyol has a
cloud point of from greater than about 32° C. to less than about 53° C., the polyether polyol has a number average
equivalent weight of from greater than about 1,600 Da to about 10,000 Da, and a four-hour
aerosol inhalation exposure to the polyether polyol has a LC50 of greater than about 5 mg / L. The water-miscible
metalworking fluid produced by the inventive process may find use in cooling and / or lubricating
metal surfaces during one or more of
grinding,
cutting, boring, drilling and turning of
metal parts.