Measuring the Wear Volume of Cylindrical Bushings with a Roundness Measuring Instrument

During accelerated life tests linear pneumatic cylinders fail because the guide bushing in the front head wears out and leakages from sealings become unacceptable. Wear measurements on the inner surface of these bushings are challenging and require a rotary scanning system which is not usually available in standard optical profilometers or stylus profilometers. In this paper a roundness measuring machine has been exploited as a rotary contact profilometer to scan the inner surface of guide bushings which suffered wear loss after endurance tests. Two scanning strategies were compared which exploit the measurement routine usually applied to determine the tolerance of cylindricity and straightness of holes. Results thus obtained were compared with the results of a wear volume analysis performed through a benchmark optical technology available on the market of optical profilometers. The accuracy of the method was investigated at a preliminary stage by increasing the number of profiles acquired by the roundness measuring instrument, and the deviation from the reference value from optical profilometry is presented.