Non contact wear measurement on pneumatic seals
Abstract An experimental methodology aimed at the evaluation of wear in pneumatic seals is presented. New equipment was designed and manufactured in order to measure the radial thickness of worn material on the sealing edge both axially and circumferentially, by means of a laser sensor, as well as to avoid the necessity of disassembling the seals. The methodology is intended as an instrument for a quick comparison of seal prototypes and is proposed as an alternative to those methods that globally quantify the wear of samples by measuring their loss of weight or volume. Results obtained on a NBR commercial lip seal are presented.
The Influences of Environmental Factors on Abrasive Wear of FKM, NBR and CR, page: 1-8
Wear resistance is an important factor which influences the working life of many rubber products such as seals and conveyor belts. Most rubber products operate in presence of corrosion, ozone, thermal cycling and heat during the service life. In this experimental study, the influences of environmental factors such as ozone, corrosion, thermal cycling and environmental stress on abrasive wear behaviors of FKM, NBR and CR rubbers were investigated. Abrasion tests were performed to determine tribological properties of samples. The roughness of wear surfaces and hardness of samples were measured. The surfaces of samples before and after exposing ozone were carried out with microscope. The all of the environmental factors caused to decrease of hardness of samples. The volume loss and wear rate values of all samples exposed to ozone increased. The all samples exposed to NaCl solution have highly wear resistance. After ozone tests, the cracks and ruptures from surfaces were occurred in some samples. FKM has the most stress-cracking resistance in the tested materials.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.