Machine guarding in mechanical plant: why it matters

Machine guarding is the physical barriers, devices and controls that stop people from reaching the dangerous parts of a machine, such as rotating shafts, nip points, cutting blades and moving tooling. It matters in any workplace where machines run, from a small workshop to a large plant. Under the WHS laws, dangerous parts of plant must be guarded or otherwise controlled, so the risk is removed at the source rather than left to the operator's care.

Guarding works best when it is planned. You need to know which parts of each machine are dangerous, which guard suits the job, how people will work safely while the guard is open, and how you'll check that it's still doing its job.

What is machine guarding?

Machine guarding covers the measures that protect workers from hazards created while a machine runs, is serviced or is cleaned. A guard should stop access to the danger zone without creating a new hazard. Where possible, it should be fixed to the machine. If it can't be fixed to the machine, it should be secured in a way that stops it being moved or removed casually.

Guarding is needed on machines in many settings, including workshops, factories, warehouses, workshops for woodworking and metalworking, and farms. Injuries range from cuts and burns to fractures, crush injuries and amputations.

What hazards does guarding control?

• Rotating and reciprocating parts, such as shafts, couplings, belts, pulleys and pistons.
• Nip, shear and crush points, where two parts move together or a moving part closes on a fixed one.
• Cutting and sharp edges, such as saw blades and blades on slicers.
• Ejected parts and debris, such as swarf, chips, sparks and broken tooling.
• Entanglement, where loose clothing, jewellery, hair or gloves are caught.
• Unexpected start-up, when a machine restarts during cleaning, clearing a jam or maintenance.
• Electrical contact with live components or cables.

Types of guards and safeguards

No single guard suits every machine. The right choice depends on the hazard, how the operator loads and unloads the machine, and how often the guard needs to be opened.

Guarding within the hierarchy of controls

Guarding is an engineering control. It sits below elimination and substitution in the hierarchy of controls, and above administrative controls and PPE. Before you fit a guard, ask whether the hazard can be removed. Could the task be automated, or could the part be loaded remotely? If not, guard it. Then use procedures and training to support the guard, and treat PPE as the last line.

A checklist for guarding a machine

1. Assess the risk. Identify each dangerous part, how the machine is used and who comes near it.
2. Choose the guard. Pick the type that matches the hazard and how often access is needed.
3. Install it properly. Check the guard is fixed or secured, can't be bypassed easily, and doesn't create a pinch point of its own.
4. Test the safeguards. Check interlocks, light curtains and emergency stops work before the machine is put back into service.
5. Control maintenance. Use lockout and tagout to isolate the energy source before anyone works inside the guard.
6. Train the people involved. Operators, maintenance staff and supervisors should know what the guard does and how to report a fault.
7. Inspect and record. Check guards on a schedule set by your risk assessment and the manufacturer's instructions, and keep a record.

Our guide to lockout and tagout explains the isolation steps in detail.

Common mistakes

• Guards removed for convenience and never put back, often to speed up clearing a jam.
• Interlocks bypassed with tape, jumpers or a key left in the switch.
• Guards that were never fixed so they are easy to lift off or open.
• No safe method for maintenance, so people reach into the machine while it's still energised.
• Machines bought second-hand that arrive without guards, with no risk assessment done on them.
• No records, so no one can show what was checked, when, or by whom.

Records to keep

If a regulator or an insurer asks how you control guarding, you should be able to show your records. Keep:

• a risk assessment for each machine;
• a machine guarding policy that sets out roles and responsibilities;
• an SOP for each machine that covers start-up, shutdown, cleaning and clearing jams;
• training and competency records for everyone who works with the machine;
• inspection and maintenance logs, including any guard changes;
• a lockout and tagout log;
• incident and near-miss reports.

The machine guarding checklist and machine guarding risk assessment form are a practical start. For the procedures that run the machine, see the working with guarded machinery SOP.

Common questions

Does every machine need a guard? Any dangerous part of plant needs to be guarded or otherwise controlled so people can't come into contact with it. Your risk assessment decides which guard is right, and whether a machine is safe to use without one.

Can a guard be removed for maintenance? Only under a controlled procedure. Isolate the machine with lockout and tagout first, and replace the guard before the machine is restarted.

Do older machines need guards? Yes. The duty applies to all plant, old or new. If an older machine lacks adequate guarding, assess the risk and upgrade the guard or the controls.

Who should inspect the guards? A competent person. Use the manufacturer's instructions and your risk assessment to set how often, and keep a record of each inspection.

This is general information, not legal advice. Check the current law with your WHS regulator.