Anyone working with electrical tools will be familiar with the high vibrations that are transmitted from the tool to the body. These vibrations impede work, have a negative effect on quality and represent a health risk when used frequently. The powered rotating disc in angle grinders, for example, creates an imbalance that causes these undesirable vibrations.
The Schaeffler Group's application engineering team has developed a solution to this problem - the Autobalancer - that is claimed to reduce vibration in angle grinders by more than 50 per cent, which makes working more comfortable, more productive and improves the health and safety of users. Since limiting guidelines and values are not exceeded, it is no longer necessary to document usage times. AEG Milwaukee (part of the TTI group of companies) is already using the Autobalancer on its angle grinders on an OEM basis.
Schaeffler's Autobalancer is a compact sealed unit that is mounted onto the angle grinder's drive shaft. The device is simply slid onto the shaft, where it replaces the driving plate. The cavity between the solid plate and the drawn sleeve is partially filled with oil. The balls inside the oil can move freely and create a counterforce to any imbalance. For this reason, the shaft has to be manufactured to very tight tolerances. All outside surfaces of the Autobalancer are protected by Schaeffler's Corrotect coating.
Strict guidelines in the EU
The EU Directive 2002/44/EC, which must be complied with throughout Europe, defines the maximum permissible vibration threshold values for electrical tools. Both the vibration intensity and the exposure time determine the daily vibration level. The directive stipulates that an electrical tool is considered to be critical from a vibration value of 2.5m/s2 upwards if it is used continuously for more than eight hours. In such cases, the risks must be evaluated more precisely and the employees must be notified. If a threshold value of 5m/s2 is exceeded, working hours with the tool must be reduced. This requires traceable documentation of usage times. Employers are obliged to assess the vibration exposure of their employees and reduce it as soon as the limiting values are exceeded.
The health hazards arising from constant exposure to vibration should not be underestimated, since these can, in some cases, lead to employees being unable to work. Schaeffler Group therefore claims to have made a decisive contribution to improving industrial health and safety.
For more information on Schaeffler's Autobalancer, visit www.schaeffler.co.uk.