An indentation method for measuring wear.

This paper describes a mcthod for accu rately measuring the wear that takes place on the bearing ~urfaces of machinery . The method consists of mak ing minute indentations in the wearing surface by means of a specia ll y shaped d iamond point. As materia l is worn from t he surface, t he dimen sions of th.e marks change ,dth the amount of materia l removed. Measurements of the dimensions of these ma rks before and a fter weal' provide a means for determining the amo unt of wear that has taken place. Apparatus is descr ibcd fo r using this method for the meaS lll"cm ellt of wear occ urring in the cylinders of a ircraft, engines. The results of tests with engin es in opera tion ind icate t ha t the method is p rac ticable. Cur ves a re also given showing typ ical weal' da~a obtai ned in engine cy Ii nclcrs. The chief advall tages of the method ove r the usua l methods a re ( i ) greater acc uracy. (2) a precise indi cation a s to where \\'ear occurs, a nd (3) the measurements a re not a fl'eeted by growth , shr ink age o r di stor tion of the mac hi ne e lemen t uncl eI' test.