HSENI article | Alternative processes to grinding in order to lower or eliminate risk to workers using angle grinders

The Challenge

Hand-held angle grinders are widely used across many sectors, including steel frame fabrication. Real-use measurements on angle grinders show upper quartile values in the range 7 to 9 m/s², this means that there is a risk of ill health to operators regularly using these machines for as little as 20 minutes per day and a high number of hand-arm vibration syndrome (HAVS) RIDDORs are investigated from steel frame fabrication. Grinders also typically produce LAeq noise levels of around 90 to 95 dB(A), making them a significant contributor to occupational noise exposure.

In addition to hand-arm vibration (HAV) and noise, many hand-held grinder users are also exposed to other physical hazards such as dust. Methods used to control dust, such as masks and water suppression systems, do not make any contribution to mitigating the effects of HAV and noise or to reducing musculoskeletal disorders.

The most effective way of controlling exposures from grinders is to reduce or eliminate the use of these machines.

This project investigated alternative processes to grinding as well as methods designed to reduce emissions from grinders. We tested a range of different abrasive wheels such as: standard grinding wheels, flap discs, ceramic discs, fibre disc with a rubber backing pad, diamond discs and carbon discs. In addition, alternative tools were tested such as rebar cutters, bevelling machines and an angle grinder with a built in autobalancer. The tools and wheels were subjected to 3 different tests: grinding, bevelling and cutting. Noise, vibration and dust measurements were taken for each test.

The Solution

For all tasks there are alternatives that could reduce the worker's exposure to vibration, noise and dust when compared to standard wheels and angle grinders. In addition, there are machines available that may produce higher levels of  vibration, but significantly reduce the time to complete the task and therefore reduce a worker's exposure. For example, although the bevelling machine tested produced nearly twice the vibration level, it completed the task in a tenth of the time.

For the grinding task it was found that the fibre disc and rubber backing pad produced the lowest vibration and completed the task in the quickest time. When the standard angle grinder was used with anti-vibration handles, it was shown to consistently reduce vibration regardless of the wheel used. The flap disc produced the lowest noise; however, the operator commented that a flap disc is not ideal for grinding off welds and instead would be used to finish. The ceramic disc produced the lowest amount of dust.

The three bevelling machines produced lower noise, vibration, dust and were more efficient than a standard angle grinder. The bevelling machines also produced negligible amounts of dust due to the nibbling action of the machine on the metal rather than a grinding action.

For cutting using an angle grinder, the lowest vibration and dust was produced using a diamond disc. However, this disc was inefficient at completing the task and, in some cases, did not cut the whole way through the rebar in the measurement period. The lowest noise and the quickest was the carbon disc. An alternative machine for cutting is a rebar cutter and this was shown to be lowest in all emission categories. In addition, the rebar cutter does not produce any dust due to its compression action, and the operator commented that they could not feel any vibration through the handles.

The Outcome

This work has shown that there are alternative machines and wheels that can reduce vibration, noise and dust emission values when compared to standard angle grinders and discs. However, it is important that dutyholders take a holistic view and look at the overall reductions that can be made. Alternatives to angle grinders should be considered where possible.

In this application, HSE guidance is highly relevant: it is important to identify efficient machines for the job, avoiding any high noise or vibration models, and then manage the remaining noise or vibration risk.

This work has enabled HSE to benchmark the performance of products that claim to provide an advantage with regards to the reduction of vibration, noise and dust, whilst providing information on credible and practical methods for reducing vibration, noise and dust exposures of grinder users.

In addition, this work has allowed promotion of effective angle grinder controls to HSE Inspectors, and to the wider industry through guidance drafted in collaboration with trade associations. It is intended to directly link into enforcement activities and advice.

For more information contact  HSE by using this enquiry form.