The flash temperature concept

A survey is given of the history of the flash temperature concept and of the importance it has increasingly gained in the lubrication and design of rubbing components that are prone to scuffing, such as highly loaded gear teeth and cams and tappets. This survey is followed by an outline of the theory that is based on this concept, and formulas for calculating flash temperatures are given and discussed for a few representative cases. Finally it is shown how the postulate about the constancy of the temperature at incipient scuffing, which so far may be upheld only under certain restrictive conditions, can be used, in conjunction with the aforementioned formulas, both for design purposes and for the selection of suitable lubricating oils.