| abstract |
An aqueous cutting or grinding fluid is fed to at least one machine tool having at least one cutting tool, and the used fluid is collected. Solids are removed from the used fluid to produce a supply of clarified fluid. A pH of 8 to 9.5 is maintained in the clarified fluid by addition of a base. Deionized water is supplied to the system to replace water losses, and a watermiscible lubricant is supplied to maintain a lubricant concentration in the system from 1 to 25 percent. Tramp oil is removed from the clarified fluid by passing a portion of the clarified fluid through a centrifuge, to maintain a tramp oil content of not more than 2 percent in the clarified fluid, and the resulting clarified fluid is reused. |