9 Essentials to Ensure Safe Operation of Bonded Abrasive Wheels

With the vast majority of accidents being caused by user error, there is a lot that cutting and grinding wheel users can do to prevent problems occurring – both before and during use. 

The rotational speed of a handheld grinder is 80m/s, equivalent to 290km/h or 180mph – roughly the same speed as a Formula 1 racing car. For a 100m/s machine you’re looking at 223mph. These two stats underline how crucial it is that bonded abrasives are handled with care.

Read on for SAIT’s top stipulations to ensure safe and smooth operations with cutting and grinding wheels.

Correct storage

Abrasive wheels are sensitive to moisture and temperature: if stored incorrectly they will degrade before their time.

It is therefore essential to store abrasive wheels in premises with moderate temperature and humidity. Direct exposure to sunlight and contact with aggressive chemicals must be avoided, and wheels should not be placed directly on the floor, near cold or damp walls or near heat sources such as stoves or heaters.

Wheels should be stored in their original packaging, which guarantees maximum protection. Once removed from the packaging, they must be kept in special racks.

Invest in quality

Beware cheap wheels, particularly if you have a high-performance application. There are many variables within a wheel – low-grade abrasive grains, resin or fillers used within the recipe can affect the overall performance of the wheels. There may also be less reinforcement used within the product, making them less resistant to lateral pressures. Alongside this, cheap wheels are also often a false economy: they don’t last as long, which results in more wheel changes and downtime for operators.

But with one wheel looking pretty much the same as another on first glance, how do you separate the best from the rest? The answer lies in the label, where you’ll find key indicators of quality – European-manufactured wheels that meet the mark will feature the logo of The Organisation for Safety of Abrasives (oSa) and should also have EN12413 (the European standard referring to safety requirements for bonded abrasive products) printed onto the wheel.

Look for ISO 9001 certification in your manufacturer as well.

Do not modify

Another key cause of accidents is wheel modification, specifically attempts to increase the size of bores in order to make them fit onto machines that they were ultimately never designed for. Hammering out of bores, or forcing wheels onto machines introduces cracks which are often invisible and which radiate out from the centre when the wheel is put into use. This can result in the explosion of the wheel. Always pick a wheel that is a native fit to the mounting apparatus of your machine, rather than attempting any adaptations.

Match wheel and application

One of the major contributors to wheel breakage is utilising a wheel that is not appropriate for the material being processed. If a wheel is not the right match for the material, the operator will often have to lean more heavily on their machine, which inflicts stress on the wheel and increases the chance of breakage. By selecting the appropriate hardness of wheel, the operator can achieve free cutting/grinding and therefore minimise problems. As a rough guide, soft wheels are preferred on hard materials and hard wheels are preferred on soft materials.

Also remember that cutting wheels should never be used to grind – unlike grinding wheels (used at a 30-45-degree angle) they must be used at a 90-degree angle of cut only.

Do not exceed maximum speed

The maximum RPM for any given wheel is clearly stated on its label. RPM is calculated based on the diameter of the wheel. 80m/s is the industry safety standard.

Inspect before use

There are many situations that can damage an abrasive wheel; by the time wheels have reached the end user there have been many opportunities for damage to occur - in transit, on-site storage, handling etc. As such, wheels should be visually inspected before they are mounted onto the machine - damaged packaging is the first sign of a potential problem. If it is known that a wheel has been dropped, it should be discarded – even if there is no visible damage, as wheels can crack internally. Likewise, operators should be cautious in how they lay portable machines down when wheels are mounted – awkward or careless placement can result in chipped edges. Never use a damaged wheel.

Adhere to dates

Bonded abrasive wheels have an expiry date of three years, dictated by EN12413. The reason for this is because the bond absorbs moisture over time – even when wheel storage is up to scratch.

The expiry date can be found near the bore, either on the label or the metal bushing on the reverse of the wheel. Expired wheels should never be put into use.

Proper PPE

Workers engaged in operations with bonded wheels must be properly protected with goggles, gloves, aprons and dust masks, to protect them in the event of wheel breakage and the expulsion of material from the workpiece.

Abrasive wheels in use on machines can reach noise levels of 85Dba (the upper exposure action value specified in the Control of Noise at Work Regulations 2005) or more. Impaired hearing can result from extended exposure to such levels, therefore ear muffs or equivalent must be deployed.

Don’t remove guards

Accidents caused by removing the guards from machines are unfortunately more frequent than one might wish. Guards should never be removed from machines – operators who do so often cite that they need to get into awkward components. If you are contemplating this dangerous action, a reassessment of your processes is required – for instance, a die or pencil grinder might be a more suitable machines for your needs.

Does your organisation need help with technical specification of abrasive wheels? Our team are hands-on and ready to assist. Get in touch via our contact form or on 0344 801 3355 to enlist their expertise.