New test method and apparatus for measuring galling resistance

Abstract

Galling is a severe type of wear that can occur when relative motion exists between contacting surfaces. It is characterized by surface protrusions and an increase in surface roughness of one or both components. Galling can occur vary rapidly; under certain mating conditions it can occur in as little as one cycle and can even lead to the eventual seizure of mating components. In this study, a new test method and apparatus for measuring the galling resistance of mated materials was developed. Tests were conducted on self-mated stainless steel to determine the threshold galling stress. The new test method requires the use of two specimens, namely a stationary button and a rotating cylinder. The end of the stationary button contacted the rotating cylinder along the cylinder's length, thereby creating line contact. Galling occurred along the line of contact when the cylinder was rotated and the load between the specimens was increased. The threshold galling stress was calculated using force measurements from a load cell on the stationary button. In addition to measuring the force between the specimens, the torque required to rotate the cylindrical specimen was measured in order to determine the frictional force between the cylinder and button.