Category Archives: Angle grinder discs and wheels

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.

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.

Abrasive grinding products used on angle grinders

Grinding may be defined as the removal of excess material involving relatively coarse grit sizes. The angle grinder is ideally suited for this job and various types of discs can be employed for this purpose and include:

  • Resin bonded type 27 depressed centre reinforced grinding discs. For grinding most metals and stone based materials. These are available in 100mm, 115mm, 125mm, 150mm, 180mm and 230mm diameter. Tough, rigid and strong these are ideal for removing excess material and where surface finish is not critical. Aluminium oxide abrasive is used for mild steel grinding whilst silicon carbide abrasive is use for most stone based material including concrete. Special abrasive discs are made for grinding stainless steel (INOX), and aluminium. Type 27 grinding discs should be used at an angle of 30 degrees producing a slight bevel on the periphery. Avoid using the flat of the disc as this may result in contact between the work-piece and the retaining nut. These discs are ideally suited for heavy grinding applications, especially when used with larger diameter discs, where 24 or 30 grit are used for rapid stock removal.

More on resin bonded type 27 discs for metals.

More on resin bonded type 27 discs for stone based materials.

  • Resin bonded cup stones and cones. Designed for use with angle grinders, cup stones and cones give a very high stock removal rate making them ideal for coarse and aggressive surface grinding applications. M14 thread suitable for use with angle grinders 115mm and above. Please observe maximum speed (RPM) when fitting to an angle grinder.

More on resin bonded cup stones and cones for metals and stone based materials.

  • Fibre backed discs consist of a single layer of abrasive bonded to a fibre backing.(These require a suitable backing pad). This offers greater flexibility, especially on contours, over depressed centre type 27 discs. These 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 abrasive is ideal for use on stainless steel (INOX) as well as wood. Long-lasting, cool grinding and aggressive with a faster cutting rate ceramic abrasive is ideal for most metal grinding.

More on fibre backed discs for grinding metals, wood and stone based materials.

More on backing pads for use with fibre discs on angle grinders.

  • Semi-flexible discs are used for surface grinding of stone based products. These are available in 115mm, 125mm and 180mm diameter and should be used with a suitable backing pad. Semi-flexible discs are composed of silicon carbide abrasive with a heavy duty fibre backing and used for grinding stone based materials including marble, granite, concrete, cast iron and fibre glass.

More on semi-flexible discs.

  • Flap discs are designed for surface grinding of most metals. These are available in 100mm, 115mm and 125mm diameter in grit sizes P40, P60, P80 and P120. Aluminium oxide abrasive is used for mild steel grinding whilst the more popular and versatile zirconia aluminium oxide abrasive is ideal for grinding both steel and stainless steel (INOX). Long-lasting and aggressive with a faster cutting rate ceramic abrasive is suitable for most metal grinding. Flap discs outlast fibre discs allowing less down-time and are less aggressive than resin bonded type 27 grinding discs. A cost effective answer to grinding of most metals.

More on flap discs.

  • Diamond cup grinding wheels for grinding of stone based products. These are available in 100mm, 115mm, 125mm and 180mm diameter. Suitable for surface grinding of all types of masonry materials including concrete, natural stone, floor pavement and construction-site materials. Available in single or double rim with up to a 10mm layer. Diamond abrasive should not be used for grinding metals. Care should be taken when deciding the type and size of the wheel as its maximum speed may not be suitable for smaller angle grinders.

More on diamond cup grinding wheels

  • Diamond electroplated grinding wheels are used for grinding of stone based products as well as ‘in situ’ sharpening of tungsten carbide tipped tooling used on stump grinders.

More on electroplated diamond abrasive wheels

Common abrasive grain sizes used on discs and wheels for angle grinders

Abrasive grain size.

The grain or grit size is most important in determining a disc or wheel’s ability to achieve the required surface finish and remove stock. The size is designated by a number which increases as grain size decreases. For example 10 grit has a median size of about 2.00 mm and 60 grit 0.25mm.

Standard sizes are used in all Abtec discs as specified in the European Standards laid down by FEPA.

Coated abrasive size is preceded by the letter ‘P’.

Typical grain sizes of discs used on angle grinders:

Coarse< 16, 20, 24, 30, 36, 40, 46, 50, 60, 80, 100, 120, 150 > Fine

Bond types for discs and wheels used on angle grinders

Bond types

Resinoid bond.

Type 27, 41 and 42 discs are usually resin bonded with a fabric reinforcement. Resinoid bonded discs are based on thermosetting phenolic resin. ‘Fillers’ may be added to improve the mechanical strength or to act as grinding aids on dry grinding operations. Resinoid bonds are cured by heating in ovens under carefully controlled conditions at selected temperatures between 150C and 200C.

Resinoid discs are tougher and less rigid than vitrified wheels. Their inherent toughness makes them ideally suited to heavy duty operations at high operating speeds. (80 M/S).

Vitrified bond.

Vitrified wheels have a high modulus of elasticity therefore highly rigid and brittle. This bond is not  suitable for use with angle grinders except under carefully controlled conditions.

Adhesive bonded discs and wheels.

Referred to as a coated abrasive, adhesive bonded discs and wheels have a backing that may be composed of paper, cloth or vulcanised fibre depending on the severity of the application. Paper backed discs are generally not used with angle grinders due to the high grinding forces imposed during grinding or sanding.

Electroplated bonded discs and wheels.

A single coat of diamond particles is plated on to a steel form where it is held in a layer of nickel. The particles stand well proud of the surface and electroplated wheels provide free machining on materials such as GRP, fibreglass, carbon fibre and ceramics.

Abrasive grain types for use with angle grinders

Aluminium oxide.

This abrasive is commonly used in most applications involving discs used on angle grinders. It is tough, blocky abrasive and is wear resistant, although loss of sharpness may be critical when working on hard metals and stainless steel. More friable white abrasive is used in conjunction with thin (less than 2mm width) discs for reducing cutting times.  Often competitively priced compared to other abrasives. Versatile can be used for grinding and sanding of most metals and wood. Often designated by the letter A or WA in the specification of the disc.

Zirconia aluminium oxide.

It has a unique self-sharpening characteristic which gives it long life on rugged stock removal operations. Ideal for use on most metals and wood its long-lasting cutting characteristics and controlled fracturing of the grain make it especially suitable for use in flap discs on stainless steel. Often designated by the letter Z or ZA in the specification of the disc.

Silicon carbide.

Harder yet more friable than conventional aluminium oxide is ideal for sanding glass, non-ferrous metals (aluminium, brass, bronze, magnesium and titanium), rubber, plastics, fibrous woods, leather, enamel and many stone based materials. Silicon carbide is superior to any other abrasive in its ability to penetrate and cut faster under light pressure. Often designated by the letter C or GC in the specification of the disc.

Ceramic aluminium oxide.

Ceramic aluminium oxide is a long lasting, tough, dense abrasive due to its micro structure. The extremely small micron size particles break off during grinding, producing multiple new cutting edges. As it stays sharp, especially when used in medium and high pressure operations, it cuts at a higher rate than other abrasives. Ceramic abrasive can be used on most metals and woods.

Diamond.

The abrasive is the hardest of all abrasives and is ideally suited for cutting and grinding of many stone based materials. Special diamond cutting discs are also available for use on reinforced concrete. However diamond abrasive should not be used for cutting or grinding of ferrous metals as it causes extreme abrasive wear.