ABSTRACT
A major benefit obtained by the use of a cutting fluid is longer tool life. One way of achieving this is by reducing tool temperature, since a small fall in tool temperature produces a large increase in tool life, for example a fall of 25 °C increases the tool life by 150 per cent. A cutting fluid must be pleasant to use. It must not fume, it must not irritate the skin or the eyes, and it must not smell offensively. The first neat oils to be used were the natural fats, such as lard oil. It was found that a proportion of fatty oil blended into mineral oil gives a more fluid product, which is chemically more stable, and just as good a lubricant. The lubrication afforded by soluble oils, while being better than that of solution fluids, is much inferior to that of neat oils.
