Good vibrations

With hundreds of thousands of workers using power tools every day in the Middle East, Adam Dawson looks at the health problems associated with tool vibrations and what manufacturers are doing to overcome these issues.

Tool manufacturers have addressed the issue of HAVS by adding anti-vibration features to their products.
Tool manufacturers have addressed the issue of HAVS by adding anti-vibration features to their products.

Over the last ten years many tool manufacturers have incorporated anti-vibration systems into their products following thousands of compensation claims by people who have been exposed to hand-arm vibration. Governments are even starting to take notice and legislation has already been introduced in some regions such as Europe to reduce the amount of vibration to which workers are exposed.

So what is hand-arm vibration? It is the vibrations transmitted when using tools, such as hammer-drills or handheld grinders, into the hands and arms and it affects people who regularly use this type of equipment in their work. Occasional exposure is unlikely to cause harm, but if you are using this equipment for long periods, hand-arm vibration can cause a range of conditions known as hand-arm vibration syndrome (HAVS) or more specific ailments such as carpal tunnel syndrome.

"It's important to identify symptoms at any early stage to stop the effects from becoming more serious," stresses Barbara Hewitt from the UK's Health and Safety Executive (HSE).

"People affected by [HAVS] can expect to suffer from a numbness in the fingers and a loss of strength in the hands. You also lose the sense of touch and pain and fingers can go white (blanching) as the blood supply to them becomes restricted," adds Hewitt.

At first HAVS may only occur on cold and wet days and affect only the ends of one or more fingers. As the condition develops, the amount of cold needed to trigger the symptoms reduces and some people suffer from permanent numbness.

Carpal tunnel syndrome is another disorder that can occur. This happens when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The result may be pain, weakness, or numbness in the hand and wrist radiating up the arm.

"HAVS is a problem for all concerned," states Mutaz Al Maani, marketing director of tool manufacturer Hilti. "It's not just the employees who suffer but the company as well, because of the reduction in productivity of your staff."

Most Hilti tools now come with active vibration reduction (AVR) installed and in the UK the firm offers on-site vibration measurement to make sure that tools used don't breach new European Union (EU) regulations.

"Vibration reduction isn't just a marketing ploy, but a genuine safety issue," stresses Al Maani. "In the Middle East there isn't much concern over HAVS and there are currently no regulations in place. Any protection that is given to workers in the region comes from the manufacturers who are making safe tools to EU standards.

"It was the manufacturers who responded first to the problems of HAVS five years ago and now European governments have started to take over the role with new regulations," he states. Hilti's UH 650 hammer-drill is an example of a tool that adheres to EU regulations by having a typical vibration at the main grip of 11m/sec². Hilti also provides an alternative to drilling, with the GX 100 gas-driven fastening system which punches fixings into place.

In July 2002 the EU issued the directive 2002/44/EC, with the aim of protecting workers against HAVS. The regulations introduced an exposure action value of 2.5m/s2, at which level employers should introduce technical and organisational measures to reduce exposure. An exposure limit of 5.0m/s2, which should not be exceeded, was also set.

Rajeeb Rose, systems specialist for Bosch agrees that there is little talk of HAVS in the Middle East but stresses that this is because most tools already have vibration controls installed as standard. "Most heavy-duty equipment in the Middle East is already installed with anti-vibration mechanisms of some sort," says Rose. "Bosch uses vibration control handles that reduce vibration by up to 80% in certain tools."

Bosch was one of the first manufacturers to introduce mini angle-grinders with a vibration-damped handle to the market in 2001. It has continued to develop such products, introducing a series of six large angle-grinders in 2005, such as the 1873-8, which is the manufacturer's first 2.2kW, 8,500revs/minute angle-grinder. All the new producets include handles that cut vibrations by up to 60%.

Usman Ghani, marketing manager of Milwaukee stresses that anti-vibration tools have proved to be popular. "They are a big selling feature," he says. "Obviously new regulations have come into force in Europe, so the manufacturers are making sure that their products adhere to the rules and vibrate less."

Milwaukee even has its own online calculator to help power tool users work out their individual exposure to vibrations. Its tools feature a patented, built-in, anti-vibration system including dampers, active springs and an auto-balancer that reduces vibrations by up to 50%. These features can be seen on Milwaukee's range of large rotary hammers such as the MPHE 40 SQ or the MPHE 45 SQ, both of which also feature softgrip handles.

Dewalt is another manufacturer that has introduced a new range of angle grinders with anti-vibration side handles. Its 0.18m and 0.23m ranges have handles that are rubber over-moulded to combat the vibrations created by larger discs operated at low revs/minute speeds. Using the tool with the lowest vibration level is not always the best option however, as vibrations from a power tool are often a product of the application rather than the tool itself. To cut down on the chances of being exposed to HAVS it is important to reduce the trigger time ie the amount of time needed to complete the job.

According to the HSE there are certain steps to take to help workers avoid overexposure to HAVS. "Workers are advised against gripping handles too tightly and should be encouraged to vary the positions they hold the tool in," explains Hewitt. "It's also advised that workers take regular breaks of at least 10 minutes away from the tool and wear anti-vibration gloves. Smoking is also seen as a catalyst for HAVS, as chemicals in tobacco can affect blood flow," she adds.

Bouts of HAVS may ease off if symptoms are mild and workers stop using vibrating tools, but it is not yet clear whether nerve symptoms can improve completely once they have developed. By selecting tools with anti-vibration features you can keep productivity high and avoid problems of staff downtime on site.

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