Angle Grinders: Equipment Check Guidance

This document provides guidance on pre-use and end-use checks for angle grinders used in construction, engineering, fabrication and maintenance work: mains-electric machines (including 110V site supply), battery models, and the common 115mm, 125mm and 230mm sizes. It covers equipment checks, disc selection and condition, operator safety considerations, and hand-arm vibration (HAV) obligations. Air-powered grinders used in workshops follow the same disc and guard checks, with their air supply checked as described in the breaker guide's air-supply section.

For consistency, this document uses grinder for each individual machine and disc for the mounted abrasive wheel, cutting disc, flap disc, or wire wheel. Checks described here are visual and operational only and do not replace inspection, servicing, or repair by a competent person. Where a defect involves the guard, the spindle, a power cord, or any safety-critical component, the grinder should be assessed by a competent person before it is returned to service. If there is any doubt about a grinder's safety at any point during a check, take it out of service until that assessment has happened. This guidance should be used alongside your organisation's site-specific risk assessments and safe working procedures. It does not cover cutting and grinding technique, workpiece clamping, or hot work permit systems, which belong in method statements and your organisation's own procedures.

Hand-Arm Vibration: Where Grinders Sit

Grinders are not the loudest entry in the vibration table, but they are one of the most used, and that is exactly the trap. The HSE's exposure calculator lists standard angle grinders at 3 to 10 m/s² with a recommended value of 7, and larger 220 to 300mm machines at 4 to 11 with 9, and the full magnitudes table shows what that means in practice: at those values the 100-point exposure action value arrives in about an hour on a standard grinder, and inside 40 minutes on the big ones. Because grinding and cutting sessions feel short individually, operators routinely accumulate more grinder time in a day than anyone would guess, alongside whatever else they have run.

The real figure on any given day depends on the machine's condition, the disc's condition and balance, the material, and how hard the tool is pressed into the work. A worn or unbalanced disc, failing bearings, or leaning on the machine to force a cut all push transmitted vibration up, and a damaged disc raises a far sharper risk than vibration alone.

The Control of Vibration at Work Regulations 2005 requires employers to manage HAV exposure and keep daily exposure below defined thresholds.

Pre-Use Check

A pre-use check should be completed each time a grinder is brought into use. Where vibration exposure is tracked in Toolminder, the pre-use check is presented automatically before timing begins, so it is completed as part of starting work with the machine. Checks are typically completed in 2-3 minutes where no issues are found.

PPE Requirements

• Eye and face protection: grinding and cutting throw high-velocity fragments, and a bursting disc throws them with far more energy. Impact-rated protection to EN 166 is essential, and standard safety glasses typically carry only the low-energy F grade: goggles or a face shield rated to the medium-energy B grade, worn over safety glasses, are the appropriate standard for grinder work, per your organisation's risk assessment
• Hearing protection: hearing protection to EN 352 is essential; grinders operate well above the levels at which it becomes mandatory under the Control of Noise at Work Regulations 2005, and the noise Regulations guide covers the thresholds
• Respiratory protection: cutting or grinding concrete, mortar, or stone releases respirable crystalline silica, and grinding metal produces its own fume and dust. RPE per your organisation's COSHH assessment should be worn, with an FFP3 respirator the common minimum for masonry work, alongside water suppression or on-tool extraction where the assessment requires it. Tight-fitting RPE such as an FFP3 mask only protects a wearer who has been face-fit tested for that specific model
• Head protection: an industrial safety helmet to EN 397 where site rules require it, and always where work is overhead
• Gloves and clothing: snug-fitting gloves in good condition and no loose clothing, drawstrings, or lanyards near a spinning disc. Anti-vibration gloves should not be relied upon as a control measure for HAV exposure: the HSE advise that their effectiveness at these frequencies is limited. Reducing trigger time and keeping machines and discs in good condition are the effective controls. Warm, dry hands do, however, matter: cold hands are more vulnerable to vibration injury
• Fire precautions: sparks travel further than people expect. Combustibles cleared or protected, a suitable extinguisher within reach, spark direction controlled, and your organisation's hot work permit arrangements followed where they apply

Isolation Before Hands-On Checks

Every disc change and every hands-on inspection starts with making the grinder incapable of running.

• On mains-electric grinders, unplugged from the supply before any work on the disc, guard, or spindle. Switching off at the trigger is not isolation
• On battery grinders, the battery physically removed before any disc change or inspection. With the pack seated, a bumped paddle or slider is all it takes
• Spindle lock used only with the machine isolated and the disc stationary; the correct pin spanner or key used, never improvised
• Grinders taken out of service due to a safety-critical defect should be tagged or labelled clearly to prevent use by another operator, and physically separated from serviceable machines where possible, with a service job raised in Toolminder so the fault is formally recorded and tracked

Disc Selection & Condition

Disc failures are the characteristic grinder accident, and almost all of them trace back to selection, condition, or mounting. This is where the check earns its keep.

• Correct disc type for the task and material: grinding discs for grinding, cutting discs for cutting, and never side pressure on a cutting disc, which is designed to take load only on its edge
• Disc diameter and bore correct for the machine. An oversized disc on a smaller machine exposes disc beyond the guard and overspeeds the disc's design assumptions
• Disc speed rating checked against the machine. The maximum speed marked on the disc must be equal to or greater than the no-load speed marked on the grinder. A disc rated below the machine's speed can burst at full revs, and this single check is the most important line in this document
• Expiry date checked on resin-bonded discs: bonded discs carry a use-by date on the metal centre ring, typically three years from manufacture. An expired disc is a defect, not a suggestion
• Disc condition inspected before mounting and before each session: no cracks, chips, gouges, uneven wear, or discolouration, and no disc that has been dropped, soaked, or stored damp used. Bonded abrasive weakens invisibly with moisture and abuse
• Diamond blades carry no expiry date, but they are not exempt from inspection: segments checked for wear, undercut, cracks, and missing teeth, the core checked for cracks and distortion, the blade matched to the material, and the rotation arrow matched to the machine's direction. A blade that has shed a segment is a defect, not wear
• Flap discs with torn or missing flaps, and wire wheels shedding wires, replaced rather than run out
• One disc at a time: never stack two cutting discs together to widen a cut or stiffen a thin disc. Flanges are designed to clamp a single disc, and a stacked pair is a bursting risk
• Mounting correct: the right flanges for the disc type, seated flat, tightened per the handbook and not overtightened, with the disc running true. Blotters used where the disc type requires them
• Wood-carving and chainsaw-type discs are high-risk accessories that many organisations prohibit outright; fit one only where your organisation's risk assessment explicitly permits it, and never a circular saw blade
• Spare discs stored dry and flat, in their packaging, not loose in the bottom of a van

Guard, Handles & Body

• Guard fitted, correct for the disc type, and secure. A closed-side cutting guard for cut-off work where your machines and policy provide one; the guard adjusted so the closed portion sits between the disc and the operator; and clamped so it cannot rotate under load. A grinder is never used without its guard
• Side handle fitted and tight, in the position that gives control for the task. Grinders are two-handed tools, and the side handle is where anti-vibration elements live on machines that have them
• Body and casings free of cracks and impact damage, vents clear of packed dust, and all fasteners present and tight
• Spindle and flange threads undamaged, with the spindle lock engaging and releasing cleanly

Power Source Checks

Mains-Electric Grinders

• Supply is the site-standard reduced low voltage (typically 110V centre-tapped in the UK) or protected per your organisation's arrangements
• Cord in good condition along its full length: no cuts, abrasion, crushing, or taped repairs, with the cord anchorage intact and the plug undamaged. A grinder's own sparks are a common cause of cord damage, so check near the machine end particularly
• Portable appliance testing or formal inspection in date per your organisation's regime, with the label legible. Toolminder can hold each machine's test records against the asset
• Switch behaviour correct: the machine starts and stops positively, any lock-on function used only where your organisation permits it, and a machine with restart protection confirmed not to restart on its own after a power interruption, per the handbook
• No excessive sparking from the vents, burning smells, or intermittent cutting out, any of which is a fault

Battery Grinders

• Battery charged and correctly seated and latched before work, with the casing free of cracks, swelling, or signs of water ingress and the terminals clean
• Battery physically removed, not just switched off, before any disc change or hands-on work, as covered under Isolation Before Hands-On Checks
• Spare batteries carried and stored per the manufacturer's guidance, protected from contact with metal objects and from extremes of temperature

Operational Check

• After mounting a disc, the machine run at no-load in a safe position, with the disc plane pointed away from the operator and others, per the handbook, before the disc first touches work. A defective disc usually fails in the first moments at speed
• Machine runs smoothly with no abnormal vibration at the handles. A grinder that buzzes or wobbles has an unbalanced or damaged disc, a mounting fault, or failing bearings, and the cause is found before work starts
• In use, the disc allowed to reach full speed before it touches the work, per standard manufacturer and HSE guidance
• Trigger or paddle operates positively and the disc stops in the expected time when released; a brake, where fitted, pulls the disc up noticeably faster, and a braked machine that has stopped braking is a fault worth reporting
• Any failed task should prompt a reason for failure and supporting photos. Raise a service job immediately within the app
• Use the observations field to note early signs of wear, unusual vibration, or running issues. Proactive reporting prevents unplanned downtime and protects operator health

Work Area & Planning

• Silica dust controls in place per the COSHH assessment for any masonry cutting or grinding: water suppression or on-tool extraction, RPE worn, and other trades kept out of the dust
• Sparks managed: direction controlled away from people, combustibles, and anything pressurised; screens used where others work nearby; and a check of the area after finishing, since grinder sparks can smoulder unnoticed
• Workpiece secure: clamped or held so it cannot move, close the cut, and pinch the disc
• What's behind the cut confirmed before cutting into walls, floors, or fixed structures: cables, pipes, and hidden services are found by scanning and drawings under your organisation's procedures, not by the disc
• Cord and hose routes kept behind the operator and clear of the disc
• Other people kept clear of the working arc, particularly the plane of the disc, where a burst disc's fragments travel
• Cold weather planned for: cold hands are more vulnerable to vibration injury, so warm dry gloves and shorter trigger-time sessions matter in winter
• Trigger-time rotation planned where the day is grinder-heavy, using each operator's remaining daily exposure rather than guesswork

Grinding Plastics, GRP & Composites

A grinder is often the nearest tool when plastic needs cutting or dressing, and it is frequently the wrong one. Thermoplastics respond to an abrasive disc's surface speed by melting rather than cutting: the disc loads and glazes, the cut edge smears, and the material starts producing fume instead of dust.

• Heat is the hazard to manage. Overheated PVC gives off acidic, corrosive fume; overheated polyurethane can release isocyanates, a major cause of occupational asthma. The smell of burning plastic during a cut is the signal to stop, let the work cool, and rethink the method, not to press on
• Light pressure, intermittent contact, and the lowest effective speed keep plastic below its melting point, and a loaded, glazed disc is changed, not forced
• GRP and other glass-fibre composites grind rather than melt, and their dust is a respiratory and skin irritant controlled under COSHH: extraction, FFP3 RPE, and covered skin are the standard, with the same face-fit requirement as any other tight-fitting mask
• For plastic pipe and ducting, purpose tools such as pipe cutters or fine-tooth saws usually cut cleaner and safer than an abrasive disc, and for finishing or deflashing plastic components, a variable-speed tool run slow beats a grinder's fixed high speed
• Where plastics work is regular, the COSHH assessment should name the specific material being worked, because what comes off a hot disc depends entirely on what the plastic is

End-Use Check

An end-use check should be completed each time a grinder is finished with and returned to storage. Where exposure is tracked in Toolminder, an end-use check can be configured to run automatically when the machine is stopped. Completing it closes the operator's usage record for that session, which is what makes the day's many short grinder sessions add up honestly.

Cleaning & Condition

• Machine isolated before cleaning begins: unplugged or battery removed
• Body and vents cleared of dust and grinding debris; packed metallic dust inside a grinder shortens its life and can track across live parts
• Disc removed where your procedures require it for storage, inspected honestly, and expired or damaged discs disposed of, not returned to the box
• Cord inspected as it is coiled, which is when the day's damage gets found, and coiled loosely without tight kinks
• Guard and spindle checked clear of packed debris

Wear & Damage Review

• Handles and body re-checked after the day's use, especially if the operator noticed any change in vibration during the session
• Switch, brake, and restart behaviour re-confirmed if anything felt different in use
• Any new damage or running issues recorded with notes and photos before the machine is returned to storage. Raise a service job if a fault requires attention before next use

Storage & Transport

• Machine stored dry and secure, out of reach of unauthorised users, with batteries managed per the manufacturer's guidance
• Discs stored flat and dry in their packaging, segregated by type, where damp and impact cannot reach them
• For transport, the machine secured against movement and never carried by its cord
• Check saved to the asset history, with operator usage time recorded and visible to supervisors for HAV exposure monitoring

HAV Exposure: Operator Responsibilities

Operators using grinders should be aware of their cumulative daily vibration exposure and should report any symptoms of hand-arm vibration syndrome (HAVS), including tingling, numbness, or whitening of the fingers, to their supervisor immediately. Early reporting is important as HAVS is a progressive condition and symptoms can become permanent if exposure continues without intervention. The guide to HAVS symptoms and employer responsibilities covers what to look for and what should happen next.

Operators should also be aware that vibration exposure on a given day is cumulative across all equipment used. Grinder work rarely happens alone: an hour on a breaker or a session on a hammer drill draws from the same daily budget, and the magnitudes table shows how quickly the combinations add up.

Common Situations

Important Notice

This document is intended as general guidance only and does not constitute legal, safety, or compliance advice. It does not replace any statutory obligations, manufacturer instructions, or the requirements of relevant legislation including PUWER, the Control of Vibration at Work Regulations 2005, the Control of Substances Hazardous to Health Regulations 2002, or HSE guidance including HSG17 on abrasive wheels where applicable. Organisations are responsible for determining appropriate inspection intervals, exposure limits, training requirements, and procedures for their own equipment and circumstances. Earlsmere Limited accepts no liability for any loss or damage arising from reliance on this document.