Abrasive Wheels Terms and Glossary.

B

Bonded Abrasive

Abrasive grit (such as aluminium oxide, silicon carbide or zirconia) held together by a bond - vitrified, resinoid or rubber - to form a wheel or disc. The bond type affects how the wheel cuts, wears and must be stored and handled.

Blotter

The paper or card washer fitted between the wheel and each flange. Blotters cushion the wheel and spread clamping force evenly. They must be clean, undamaged and the correct size every time a wheel is mounted.

C

Cutting Disc

A thin bonded wheel (often Type 41) designed for cutting only. Cutting discs must never be side-loaded for grinding, as side pressure can shatter the wheel.

Cumulative Trauma

Injury that develops gradually over time due to repeated exposure rather than a single incident. Hand-arm vibration syndrome (HAVS) and noise-induced hearing loss from prolonged grinder use are cumulative rather than acute.

E

EN 12413

The European safety standard for bonded abrasive products. It sets out the markings every wheel must carry, including the maximum operating speed, dimensions, wheel type and expiry date.

Environment

The physical conditions where grinding or cutting takes place - space, flooring, lighting, dust, sparks near flammable materials, noise and nearby people. The environment is one of the key factors in an abrasive wheel risk assessment.

H

HSA

Health and Safety Authority - the national body in Ireland with responsibility for securing health and safety at work. The HSA enforces health and safety legislation and provides guidance on Abrasive Wheels.

Hazard

Something with the potential to cause harm. In abrasive wheel work, hazards include disc-burst from a damaged or wrong-speed wheel, eye injuries from sparks and fragments, hand-arm vibration, dust exposure, noise, sharp edges and unstable workpieces.

L

Lacerations

Cuts to the hands, arms or face - one of the most common abrasive wheel injuries. They result from disc contact, kickback or a bursting wheel, and are prevented by correct guarding, technique and PPE.

Line of Fire

The path a wheel fragment or the tool itself would take if the wheel bursts or kicks back. Operators should always stand to one side of the wheel, never directly in line with it, especially on start-up.

M

Mounting

The act of fitting an abrasive wheel to a spindle, including fitting flanges, blotters and tightening the nut to the correct torque. Under SI 36/2016 Regulation 30, only operators authorised in writing by their employer may mount a wheel.

Machine Guard

The fixed or adjustable cover that encloses the non-working portion of an abrasive wheel. On bench and pedestal grinders it must cover at least 180 degrees of the wheel. On angle grinders the guard must always be fitted and positioned between the operator and the work.

Maximum Operating Speed

The peripheral speed - expressed in m/s or RPM - marked on every wheel under EN 12413. A wheel must never be run above its marked maximum operating speed. Overspeed is the most common cause of wheel burst.

P

PPE

Personal protective equipment for abrasive wheel work - impact-rated eye and face protection, gloves, hearing defenders and respiratory protection for dust. PPE is the last line of defence after wheel selection, guarding and safe systems of work.

Pedestal Grinder

A floor-standing grinding machine with a wheel on each end of the spindle. The guard must enclose the wheel, and the work rest must be set within 3 mm of the wheel to stop work being trapped.

R

Risk Assessment

The process of identifying hazards, evaluating the risk of harm, and determining appropriate control measures. Employers must conduct risk assessments for abrasive wheel tasks.

RPM (Revolutions Per Minute)

The rotational speed of the machine. The machine's RPM must never exceed the maximum operating speed marked on the wheel under EN 12413. Overspeed is the most common cause of wheel burst.

S

SI 36/2016

The Safety, Health and Welfare at Work (General Application)(Amendment) Regulations 2016. Commonly known as the Abrasive Wheels Regulations, SI 36/2016 sets the Irish legal requirements for wheel selection, safe mounting, guarding, PPE, inspection and written authorisation.

Safe System of Work

A procedure that results from systematic examination of a task to identify all hazards and defines safe methods to ensure hazards are eliminated or risks minimised. For abrasive wheels this includes correct wheel selection, mounting, guarding, PPE and operator authorisation.

Ring (Sound) Test

A pre-use check on vitrified (bonded) wheels. The wheel is suspended and tapped gently with a non-metallic object at four points. A clear ringing tone indicates the wheel is sound. A dull or dead sound means the wheel is cracked and must be destroyed.

T

TWE Framework

A risk assessment framework for abrasive wheel tasks: Task - Wheel - Environment. Assessing these three factors identifies the right wheel, the right guard, the right PPE and the right controls for every grinding or cutting operation.

Truing

Restoring the running concentricity of a wheel so it runs true on its spindle. Truing is done with a dressing tool on the wheel face. A wheel that is out of true vibrates, loads the bearings and is a leading cause of early wheel failure.

Type 27 / Type 41 / Type 42

EN 12413 wheel shape codes. Type 27 is a depressed-centre grinding wheel (side use). Type 41 is a flat cutting wheel (edge use only - never side-load). Type 42 is a depressed-centre cutting wheel. Using the wrong type is a common cause of wheel burst.

W

Wheel Burst

The catastrophic failure of a wheel that flies apart at speed, throwing fragments at high velocity. It is usually caused by overspeed, a damaged or wrong wheel, poor mounting or side-loading. Correct selection, ring-testing and guarding prevent it.

Work Rest

The adjustable support on a bench or pedestal grinder. It must be set within 3 mm of the wheel so the workpiece cannot be drawn into the gap, and adjusted only when the wheel is stationary.

Written Authorisation

Under SI 36/2016, only an employee who is trained and authorised in writing by their employer may mount an abrasive wheel. The authorisation records who may mount which wheels on which machines.