Why have abrasive wheel and disc safety training?

Why have abrasive wheel and disc safety training?

I think this is a reasonable question that may be asked by an operator, supervisor, safety officer or manager. Why should an operator of equipment that uses abrasive products, having never had an injury, have training? For a supervisor or manager the time taken to have training is an expense in lost production. I as a trainer would freely admit that the majority of delegates know how to use the machine that they use for cutting, grinding, sanding or polishing. The safety officer will often put safety procedures in place in the form of risk assessments that if followed should prevent the risk of injury, serious or otherwise.

Each year thousands of people attend accident and emergency hospital wards with injuries that have been sustained when using equipment that uses abrasive products. When we run training courses we often find that at least one or two of the delegates have been injured sometime in the past when using abrasive products. Some delegates can tell of friends and collegues who in the past have been seriously injured. Then their are those that will tell us of a near miss that could have ended in tradegy.

Typical injuries include:

  • Small particles of abrasive or work material that hit the eye.
  • Flying debris that causes facial damage.
  • Wounds to the head, hand and arms and the upper part of the leg from contact with a wheel or disc.
  • Burns from sparks setting fire to clothing.
  • Hearing loss due to excessive noise.
  • Damage to fingers and hands through excessive vibration.
  • Lung problems caused by dust contamination.

In every case, without exception, the injury was totally avoidable. In some cases it was the use of poorly designed, low standard or totally inappropriate personal protective equipment (PPE). In some cases a severe lack of proper preparation and risk assessment. For some it may be using poorly maintained machinery or abrasive products totally unsuitable for the job in hand.

Training should be about how to avoid the injuries described. Each injury is costly to the employer in lost production and can be devastating for the individual concerned. As a trainer I have never come across someone who has been injured when using the right PPE. Training should be about:

  • Preparation and risk assessment.
  • Undertstanding the hazards involved.
  • The right PPE.
  • How to avoid the dangers.

This blog contains the thoughts of Mike, one of our trainers.

Surface blending of stainless steel

Working with stainless steel tubing youv’e managed to grind away the burrs, high spots and weld excess. But as you go finer in grit size the disc is causing a darkening or ‘burning’ of the steel. Conventional zirconia abrasive grain is ideal for work on stainless but when you attempt to use P120 or finer you may just find the burning problem increases. Finer grit sizes will only exacerbate the problem.

This is where non-woven products can provide the answer you need. Non-woven products are made up of strong synthetic mesh and a high quality abrasive. Effectively they provide a finer finish without increasing heat levels preventing damage to the work-piece. They are available in all forms and sizes including belt for portable belt sanders, disc for angle grinders, ‘roloc’ type and spindle mounted wheels for use with drills and die grinders and also for offhand use on belt sanders and bench grinders.

You can find out more, including video, by clicking the links below:

 

Personal Protective Equipment (PPE) check list for users of portable cutting equipment

• Prior to starting work. A thorough risk assessment should be employed. By assessing risk to the operator and those in the immediate vicinity suitable PPE can be determined.

Helmets and bump caps. Check date of manufacture and CE mark of helmet (EN 397:2012) or bump cap (EN812:2012). Hard hats should not be used after 3 years from date of manufacture. Check suitability of helmet or bump cap in respect of size and use in temperatures of extreme heat or cold.

Eye and face protection. Always use full face visor to EN 166:2001 (B) that has a mechanical strength to protect from objects with a speed of up to 120 M/S. Welders masks should conform to EN 175:1997 (B). Check suitability of visor to extremes of temperature and ability to protect operator from molten metals. Persons working in the area of an operator may wish to consider the use of full face visor and those that may be visitors or working within 10 to 30 metres of the working area safety glasses to EN 166:2001 (F).

Hearing protection. The safe working limit is 80 decibel with the requirement for hearing protection to be worn when the daily exposure exceeds 87 decibel. Consideration should be given to the type of hearing protection as these machines, when used, often exceed 87 decibel.

Respiratory protection. Careful consideration should be given to the type of filter protection required as the cutting or grinding process may produce fine dust particles, liquid particles, vapour or gas. The protection should be fit tested to avoid contamination and have a CE marking.

Hand and arm protection. When using these machines the risks from vibration and sparks causing injury can be alleviated by using gloves or leather gauntlets. Great care should be taken to ensure the protection does not inhibit safe control of the machine.

Suitable clothing should be worn at all times. For long periods of cutting or grinding leather overalls and hood may be used to give protection to the head, neck, shoulders and torso. However regardless of the design all clothing should be fire retardant.

Foot protection. Especially when cutting, the workpiece may move and fall from its safe position and could cause injury. It is vital that foot protection is used to give protection from falling or moving objects. Various designs are available but should conform to EN ISO 20347:2004 and a 200J toe cap.

The above offers only limited guidance to the checks required to determine the type of PPE to be used. More detailed guidance is available from the Health and Safety Executive website
www.hse.gov.uk.

Safety hazards involved with using portable cutting and grinding equipment

As with any power tool personal protective equipment is vital when using angle grinders. Typical hazards when using angle grinders can be summarised as follows:

  • Flying particles. When used correctly particles of the work material as well as that of disc will leave the working area. These particles may leave the working area at speeds of up to 80 Metres per second (M/S), approximately 180 miles per hour. Although the guard should be positioned in a manner that protects the operator, some of the particles may impact on the body. It is vital that operators wear protection suitable for impact resistance that covers the eyes but also the face as particle impact can cause serious scarring to the skin. Attention should be paid to others nearby who may require the same protective equipment or at least protective spectacles or goggles. As well as protection to the face many of the particles coming from the working area will be in the form of sparks. These sparks can easily set light to clothing. Where possible the use of leather overalls and gauntlets should be considered as well as flame retardant clothing.
  • Noise. Noise from the machine during use can damage hearing. Care should be taken in choosing the right type of hearing protection to prevent loss of hearing or damage that may result in industrial diseases such as tinnitus. Advice on many aspects of hearing are available to read and download on the Health and Safety Executive (HSE) web site.
  • Vibration. The effects of excessive vibration to an operator’s health can be devastating and as with noise can worsen with use. Hand arm vibration syndrome (HAVS) can leave the operator with pain and restrictive use of fingers, hands and arms. The HSE have extensive information available to read and download including methods to monitor vibration and the effect it can have on the health of an operator. Improvements have been made to angle grinders to reduce vibration and their are many type of gloves available that can reduce the effects of vibration. More on HAVS.
  • Dust and vapours. This may stay air born for a considerable time especially when angle grinders are used in confined spaces. Under all circumstances the operator should wear appropriate respiratory protection. Consideration should be given to the type and nature of the dust and vapours in determining the level of respiratory protection required as well as the protection required by others in or near the working area. Correct fitting of the mask is important to avoid the problem of dust entering the respiratory area. As with noise and vibration useful information is available on the HSE website.
  • Insecure work-piece. Because of the surface roughness of the work-piece care should be given as to the type of gloves required in its handling. When working with an angle grinder the work-piece needs to be fully secure, to prevent possible kick-back, allowing the operator to use the angle grinder two handed with one on the handle and the other hand on the body of the machine. Because of this, and especially with regard to cutting components, it may be expected that part of the work-piece may move from the working area. Therefore it is vital that the operator wears shoes or boots that give adequate protection from any possible contact.

For many operators the above mentioned hazards are typical of their working environment. Other types of PPE may be required to work safely and can include high visibility clothing, hard hat and more.

At Abtec we recognise that PPE is a vital part of keeping the operator of the angle grinder safe from injury. We strongly recommend before using an angle grinder the operator has suitable training in the use of angle grinders and in the use of the correct type of PPE.

More on training

Safety advice when using angle grinders

Used correctly, assessing potential risks and hazards, and with appropriate PPE, discs used on angle grinders can be highly efficient and safe for the purpose for which they were designed.

Operators of angle grinders should always check the following:

  • When changing a disc on an angle grinder the angle grinder has been isolated from its power source.
  • Suitable personal protective equipment (PPE) is worn during use.
  • The spindle speed of the angle grinder does not exceed the maximum operating speed of the disc in revolutions per minute. (RPM).
  • The angle grinder should be checked for safety. Including guard, retaining nuts ,switch, electric cable, plug, spindles and handle and if pneumatic, couplings and hose. Any damage parts should be replaced prior to use. Excessive vibration may indicate worn bearings that may create instability in the disc. Remove grinding debris that may have settled on the guard as this may come loose during use.
  • Check for any damage to the disc such as chips, cracks, warping or contamination. Destroy damaged discs.
  • Only use discs that are designed for the purpose indicated on the disc. If in doubt seek advice.
  • When using type 41 (Flat cutting discs), type 42 (depressed centre cutting disc) or type 27 depressed centre grinding disc) check the use by date has not been exceeded. This is usually found on the metal reinforcement around the bore of the disc.
  • The disc should sit on the base flange of the angle grinder securely. Depressed centre discs are designed so that the disc is raised above the base of the guard.
  • Diamond cutting blades have a rotational direction that must be aligned with the direction marked on the angle grinder.
  • When replacing the retaining nut do not over-tighten as the disc will tighten to the spindle on start up. Over-tightening may crack the disc. Special care should be taken when securing the retaining nut, with the use of a pin spanner, to thin cutting discs.
  • Rotate the disc by hand to make sure it does not come into contact with the guard.
  • Adjust the guard to be between the operator and the disc. This is important as the guard will have to be adjusted to a position suitable for either cutting or grinding.
  • Allow newly mounted discs to run at operating speed, with the guard in place, for a reasonable time before commencing cutting or grinding. During this test no person should be in line with the opening of the guard.
  • The operator should consider the proposed working area and carry out a thorough risk assessment prior to starting the angle grinder.

More safety advice

  • Always handle and store discs and wheels carefully. Cutting discs should be stacked horizontally or flat. Depressed centre discs should be placed on top each other or stored in the original packaging. Store discs away from damp atmosphere and extreme temperatures.
  • Check conformity to the respective standard of the product used. EN12413 for bonded abrasive (type 27,41 and 42 discs). EN13236 for superabrasives (diamond blades). EN13743 coated abrasives (flap and fibre discs).
  • Consider using discs marked with OSA logo. The Organisation for the Safety of Abrasives.
  • Always secure the work-piece firmly while it is being cut or ground.
  • Always use the angle grinder in a comfortable position, where the work-piece is well balanced and the angle grinder is well supported.
  • Grind at an angle above 30 degrees to the work-piece with a depressed centre grinding disc.
  • Keep the working area clear to avoid operator trips or falls. Special care should be taken with electric leads and air hose.
  • Never use a damaged discs. Destroy damaged discs.
  • Never force a disc on to a machine spindle.
  • Never use an angle grinder in poor condition.
  • Never use an angle grinder without its guard.
  • Avoid applying side pressure to a cutting disc.
  • Never try to stop a disc by applying pressure to the periphery of the disc. Always switch the machine off and allow the wheel to stop revolving.
  • Do not allow the disc to be trapped or pinched in the cut.
  • Do not apply excessive pressure onto the disc so that the driving motor slows down.
  • Never grind on the side of a cutting disc.
  • Never attach more than one disc to machine.
  • Do not drop or lower an angle grinder by the cable or airline onto the floor. A disc can be easily cracked, if it is put down hard, by the weight of the machine. This is a common cause of disc breakage.
  • Always use an angle grinder with both hands with the handle in place.

More on training in the safe use of abrasive wheels and discs.

More on OSA

Abrasive polishing products for use with angle grinders

Polishing with angle grinders

  • Diamond polishing pads for stone based products. These are available in 100mm, 125mm and 150mm diameter and in grit sizes 50, 100, 200, 400, 800, 1500 and 3000. Suitable for surface polishing of concrete, granite, marble. Extreme caution needs to be taken when using a conventional angle grinder as its speed and power may create excess heat during polishing. To obtain maximum benefit from diamond polishing pads use a variable speed machine at low speed.

More on diamond polishing pads

  • Flap discs for polishing. Finishing is a penultimate step to reduce surface roughness, apply a cosmetic finish and prepare the surface for polishing. Manufactured from a high quality felt and used in conjunction with a polishing compound these flap discs can create a mirror finish on metals.

More on flap discs for polishing

Abrasive cleaning products for use with angle grinders

Cleaning may be described as the need to remove material (rust, paint, surface deposits) for the purpose of returning to the original surface finish or removing (keying) the material prior to sanding. This process can be achieved with the use of various types of wire or abrasive.

  • Wire brushes: Twist knotted wire brush wheels are ideally suited for brushing out welded joints and brushing sharp corners. Bevel brushes are designed for brushing hard-to-reach areas such as edges and corners and are available in 115mm, 125mm and 178mm diameter versions. Cup shaped wire brushes are also available and are suited for surface cleaning of mainly flat or lightly contoured areas. Cup shaped  wire bushes are available either with an aggressive twist-knott or with crimped wire in diameter sizes 65mm, 80mm and 100mm. Care should be taken when deciding the type and size of the brush as its maximum speed may not be suitable for smaller angle grinders. Twist-knotted wire brushes are usually secured to an angle grinder by a retaining nut whereas cup brushes have an M14 thread suitable for angle grinders 115mm and greater.

More on wire brushes for angle grinders.

  • Cleaning fleeces: Ideal for use on metals including stainless steel, wood and plastic. These are made of silicon carbide abrasive on intertwined nylon fibres in synthetic resin and gently hardened and applied to a  glass fibre backing and available in diameters 115mm, 125mm and 180mm. Ideal for the removal of old paint, rust and welding splatter without scratching the surface of the work-piece, cleaning and smoothing wood and plastic. Also available in longer-lasting ceramic abrasive.

More on cleaning fleeces. Silicone carbide abrasive.

More on cleaning fleeces. Ceramic abrasive.

Abrasive sanding products for use on angle grinders

Sanding with angle grinders sometimes referred to as linishing differs to grinding only in that finer grit sizes are often used to remove excess material. P40, P60 with finer grit sizes, P80, P100 and P120 employed to create improved surface finishes.

  • Fibre backed sanding discs consist of a single layer of abrasive bonded to a fibre backing. (These require a suitable backing pad often made of a rubber compound with a metal core. The fibre disc is secured to the backing pad by a retaining nut that screws on to the spindle of the grinder.). The fibre disc offers greater flexibility, especially on contours, over flap discs.  It has the advantage of sanding most metals, stone based materials and wood. Discs are available in 100mm, 115mm, 125mm and 180mm diameter. As with grinding discs aluminium oxide abrasive is used on most steels and silicon carbide on stone based materials with both being able to be used on wood. Zirconia is a cool cutting abrasive ideal for use on stainless steel as well as wood. Long-lasting, cool cutting and aggressive with a faster cutting rate ceramic abrasive is ideal for most metal sanding. If you find it difficult to get into small areas consider using smaller fibre discs that can be used with a die grinder or drill and a quick release mechanism. Available in 50mm and 75mm sizes.

More on fibre backed discs.

More on backing pads for fibre discs.

More on 50mm and 75mm sanding discs with a quick release mechanism. (Not for use with angle grinders).

  • Semi-flexible sanding discs.  Sanding of stone based products. These are available in 115mm, 125mm and 180mm diameter. Silicon carbide abrasive is bonded on to a heavy duty fibre backing. Use for sanding stone based materials including marble, granite, concrete, cast iron and fibre glass. Requires a suitable backing pad.

More on semi-flexible sanding discs.

  • Flap discs. Sanding of most metals. These are available in 100mm, 115mm and 125mm diameter. Aluminium oxide abrasive is used for mild steel sanding whilst the more popular zirconia aluminium oxide abrasive is designed for sanding stainless steel (INOX). Long-lasting and aggressive with a faster cutting rate ceramic abrasive is ideal for most metal sanding applications.

More on flap discs.

  • Surface blending discs and wheels. These were originally developed for use in surface preparation but are increasingly used where sanding discs may have been used in the past. They have the advantage of having an extremely open structure. This allows dissipation of heat and dust avoiding the clogging that may be associated with single layer abrasive discs. They are also capable of removing significant amounts of material but by easing on the pressure can create a superior surface finish. Surface blending discs allow greater control and less downtime by reducing the need to change worn or degraded discs. These discs are available in silicon carbide abrasive or the longer lasting ceramic abrasive. Available in 115mm, 125mm and 178mm diameters.

More on surface blending discs. Silicone carbide abrasive.

More on surface blending discs. Ceramic abrasive.

Abrasive cutting products used on angle grinders

Cutting discs and blades are ideal for cutting apart or into a range of materials.

  • Resin bonded type 41 (flat sided) and type 42 (depressed centre) reinforced cutting discs. For cutting most metals, stone based materials, plastics. Tough with limited flexibility and strong. These are available in 100mm, 115mm, 125mm, 150mm, 180mm and 230mm diameter. Aluminium oxide abrasive is used for mild steel cutting whilst silicon carbide abrasive is used for most stone based material including concrete as well as plastic piping. Special abrasive discs are made for cutting stainless steel (INOX) and aluminium. Thin width cutting discs offer fast cutting, minimum effort, precise cutting, low vibration and less burring. Available in all diameters including 0.75 mm and 1 mm widths for 115mm diameter. Smaller diameter discs are available for specialist cutting machines.

More on cutting discs for metals.

More on cutting discs for stone based materials.

  • Laser welded diamond blades. Available in 100mm, 115mm, 125mm, 150mm, 180mm and 230mm diameter. Diamond is the ideal abrasive for cutting stone based building and construction materials including hard masonry, block paviors, granite, marble, breeze blocks, concrete paving blocks. Special blades are available for tile cutting and the removal of mortar. Abtec supply diamond blades manufactured by Dronco. Strict quality controls, including diamond selection, ensure a consistent cutting blade for the respective field of application. Laser welded blades have segments welded to a high quality steel core to prevent distortion. As segment losses are almost fully excluded, laser welded blades, ensure the best operational safety possible.

More on diamond cutting blades.

  • Circular saw blades. Designed for cutting wood, plastic, pvc, mdf, fibreglass and plasterboard. Important. Not for use on metal and stone. For use only on 115mm angle grinders.

More on circular saw blade for use with angle grinders including demonstration video.

  • Diamond cutting blades in 100mm and 125mm diameter are used for cutting glass fibre reinforced plastic (GRP) and composite materials.

More on diamond cutting blades for GRP.