scope:

This Technical Report presents an evaluation of a round-robin test of vibration measurement methods for determining vibration in hand-held grinders. The aim of the round-robin test was to establish a test method that could meet the requirement of ISO 20643 for measurement of vibration emissions in three directions, for accordance with the planned-to-be-revised ISO 8662-4. The value obtained by such a test method must correspond to the highest vibration values likely to occur under typical and normal working conditions of the machine, i.e. the upper quartile of the vibration in real use. This acknowledges that the upper boundary of "typical and normal" conditions can be exceeded by some conditions of "real use". Vibration at grinding can mainly be divided into vibration caused by unbalance of the grinding wheel and process vibration generated by the contact between the grinding wheel and the work piece. The unbalance part has been shown to be the greater of the two and ISO 8662-4 is based on this. In this Technical Report, the test method consists of a number of averaged measurements using an unbalance disc, with an unbalance corresponding to the upper limit of the unbalances found among real grinding wheels. Whereas ISO 8662-4 covers all types of hand-held grinders, the round-robin test presented in this Technical Report was based on grinding with depressed centre-wheels, one of the most common grinding applications.