A new profile roughness measurement approach for involute helical gears

With increasing quality requirements of involute gear contact surfaces resulting from grinding, superfinishing, polishing and coatings of various types, surface characterization at the roughness scale is becoming more important. Typical gear roughness measurements are made in an arbitrary coordinate system using roughness measuring instruments which are difficult to relate to gear meshing action and therefore gear functionality. A method has been developed which allows well defined, repeatable measurements to be taken using conventional roughness measuring instruments and then transform the results into the functional gear meshing coordinate system. As part of the method a mathematical model describing the gear geometry and alignment method was developed. The method has been validated by standard gear profile measurement.