Power tools have been known to induce the risk of vibration-related diseases. An acute disease that is caused by regular exposure to hand-arm vibration (HAV) is known as white finger or Raynaud’s disease. There are other vibration-related diseases such as: permanent and painful numbness and tingling in the hands and arms, painful joints and muscle weakening, damage to bones in the hands and arms.
Vibration issues have been an important topic in the power tool sector ever since the EU guideline 2002/44/EC where the employer can be held liable for vibration-induced injuries. Depending on
the vibration value associated
with a power tool the daily usage
will be limited (Figure 2).
According the EU guideline,
Figure 2 shows that a power
tool can be used continuously if the vibration level is at 2.5 m/s2-rms or less, while a power tool with a vibration level of
5.0 m/s2-rms will be limited to
8 hours of usage.
Some factors that contribute to angle grinder vibration include:
The main cause of vibration in an angle grinder is due to the changing mass imbalance of the grinding disk during operation (Figure 3).
Manufacturers have introduced anti-vibration handles and gloves to reduce the exposure to vibration. However, these methods do not cure the problem and most workers do not like the reduced precision when these anti-vibration methods are employed.
The XYO balancer can compensate for dynamic or static unbalanced forces during operation. As a result, the XYO balancer-equipped angle grinder will continue to provide consistent performance even when the mass imbalance varies due to wear of the grinding disk that is associated with typical use.
The objective of the test was to determine the impact that a prototype XYO balancer would have on reducing the vibration of angle grinders (Figure 4).
Testing was performed on two different brands of angle grinder. Both grinders used 125 mm (5”) diameter disks. Four disks with different mass imbalances were used in the test:
Figure 5 shows test disks that were prepared in accordance with ISO 8662-4. The prototype XYO balancer was installed on the spindle, replacing the backing flange, as shown in Figure 6.
Vibration levels were tested with and without the prototype XYO balancer. Triaxial accelerometers were used to record the vibration measurements (Figure 7).
See the “Appendix” Tab for additional details of the testing procedures.
Table 1. Summary of vibration results for Grinder #1
Table 2. Summary of vibration results for Grinder #2
As part of the life cycle testing, photographs were taken of the grinding disks at the start and end of the test cycle as well as at the end of every 25 runs to record disk wear. Figure 11 shows the disk on the left (without XYO) displayed more wear than the disk on the right (with XYO). Based on this amount of disk wear, it is estimated that disks will last three to four times longer for an angle grinder with XYO.
The XYO balancer can have a significant impact on vibration of angle grinders. The XYO balancer can provide the following benefits:
Perpetual Industries wants to work with a capable and innovative angle grinder manufacturer to optimize and implement the XYO technology and provide a strong competitive advantage in the market.