Topics explained – Angle grinders

Angle grinders can be a dangerous power tool. Kickbacks can result in severe cuts. Discs can shatter or disintegrate producing fragments which may become lodged in the operator’s eyes or other parts of the body, potentially causing a fatality.

Caution: 9 inch (230 mm) angle grinders have been banned on some work sites due to the increased risk of injury. The increased power and size of the unit will cause more severe kickback and gyroscopic effects (i.e. makes the grinder difficult to manoeuvre). A risk assessment to identify alternative methods and tools should be carried out prior to selecting a 9 inch (230 mm) angle grinder.

Risk control measures

  • consider whether an angle grinder is actually the best tool to perform the task, because another tool may be just as, or even more, effective
  • when purchasing a grinder, choose one with adjustable handles that can be moved to suit both left and right-handed operators
  • choose a grinder that has an automatic cut-off or dead-man switch as part of the handgrip. This is designed to cut off power as soon as finger pressure is released. Automatic cut-off switches may not be available on smaller models and may not be practicable for certain tasks
  • do not use a grinder that is larger, heavier or more powerful than is necessary, as it is much easier to control a lighter tool
  • guards must not be removed. The guard should cover half of the disc and be positioned between the disc and the operator
  • ensure that the correct type of disc is used for the task being performed. The wrong disc could shatter or ‘grab’ the work piece causing kickback
  • when using a grinder fitted with a cutting disc, keep the depth of cut to no more than double the disc thickness and avoid plunging the disc too far through the work piece
  • provide operators with training and instruction in safe work procedures for angle grinders
  • provide one-on-one supervision for workers receiving training in the use of angle grinders or people who are unfamiliar with their use
  • use welding screens to stop other workers being hit by flying particles and sparks
  • ensure all workers maintain a safe distance from any person who is in the process of grinding
  • ensure all grinders are regularly checked for electrical safety and that all defects are repaired by a competent person.

Before use

Before using an angle grinder, ensure that:

  • the guard and handles are secure
  • there are no defects or damage to the disc (a disc which has been dropped may have developed cracks and should not be used)
  • the correct flange and locking nut is in place for the type of disc being used (otherwise the disc can shatter at high speed)
  • the tightening tool supplied by the grinder manufacturer is used to tighten the disc as other methods can damage the disc and grinder
  • the correct disc diameter and central disc hole size for the spindle is used
  • the correct type of disc is used for example grinding discs for grinding and cutting discs for cutting
  • the correct type of disc is used for the material being cut or ground.

During use

Follow these suggested safe practices when an angle grinder is in use:

  • use two hands to operate the grinder. One hand should grip the handle and dead-man switch (if provided), while the other hand supports the weight of the tool
  • allow the grinder to ‘run up’ to operating speed before applying it to the job
  • hold the grinder against the work piece with minimum pressure, so the disc does not ‘grab’ and cause it to kickback
  • never bump the grinder onto the object, or let the disc hit any other object while grinding
  • keep the grinding disc at a 15 to 30-degree angle to the object. Ensure the work piece is held firmly, either as part of a larger item or in a bench vice
  • where possible, keep the work at waist height during grinding
  • adopt a comfortable stance with feet apart so you feel well-balanced, and ensure you have a clear view of the job
  • never use a grinder between your legs while sitting on the floor
  • stop at regular intervals for a short break to rest your hands and arms
  • never put a grinder down until the disc stops rotating
  • remove the plug from the power point before changing discs
  • never use a cutting disc for grinding or a grinding disc for cutting
  • when not in use, disconnect the power and place the grinder on a bench with the disc facing upwards.

Personal protective equipment

It is recommended that you use appropriate Personal Protective Equipment including:

  • wide vision goggles, safety glasses or a face shield
  • ear muffs or ear plugs
  • safety boots with steel toecaps
  • overalls or other fitted clothing
  • well-fitted gloves that allow a good grip of the tool.