RECLAMATION OF USED OILS: PART 5 CUTTING OILS AND COOLANTS

ALTHOUGH the fluids used in the machining of metal are included generally under the heading of lubricants, it is well known that their main function is that of a coolant. However, the importance of these oils and solutions to the engineering industry, the very large amounts consumed and the fact that the efficiency of any machining operation depends greatly on their condition, all warrant their inclusion in any series of articles dealing with reclamation. These fluids belong to two main classes. The straight cutting oil (which in practice is more often than not a blend of mineral oil plus fatty oil, sulphur‐ or chlorine‐containing body), and the soluble oil which yields an aqueous emulsion, milky or clear, and of varying fineness of dispersion.