Safeguarding machinery: First line of defence

Guarding a robot cell.
Photo: Gen A Stock adobecom

Safeguarding machinery is the essential first line of defence against potentially serious injuries.

Many machines used in plants have moving parts that rotate, reciprocate, punch, slide, grind, use toxic or corrosive chemicals, or generate extreme heat, noise and vibration. Guards are fitted on the machinery and equipment to protect against direct contact with moving parts, mechanical failure, electrical failure and human error. When guards are missing or improperly used, potential for injury ranges from severe cuts to crushed hands and arms, amputation and even death.

Safeguards include barrier guards, safety devices, shields, awareness barriers, and warning signage. Some examples include wire cages around fans, blade guards on table and band saws, and covers on drive belts and electrical switch boxes. These methods are used on their own or in combination to protect the machine operator and other employees in the area. Some machines have a built-in interlock switch that prevents activation unless the machine guard is in place. Never disable the interlock switch!

Hierarchy of controls

When selecting a safeguard or combination of safeguards, always start at the top of the hierarchy to control the hazards. Use a lower control method only when a more effective solution isn’t possible.

Here are controls and examples from most to least effective:

Elimination. Remove the hazard from the workplace. Examples include process design, redesign or modification, including changing the layout to eliminating hazards; eliminate or reducing human interaction in the process; and automating tasks, material handling (lift tables, conveyors, balancers) and ventilation.

Substitution. Replace hazardous materials or machines with less hazardous ones; for example, machines that have energy containment or machines with lower energy (lower speed, force, pressure, temperature, amperage, noise, or volume).

Engineering controls. Remove the hazard at the source by installing safeguards or complementary measures such as emergency stop devices, platforms and guardrails for fall protection.

Systems that increase awareness of potential hazards. Examples include lights, beacons, strobes, backup alarms, notification systems, as well as hazard warning signs, placards and labels.

Administrative controls. They alter the way work is done and include training, housekeeping processes, and safe job processes (rotation of workers, changing work schedules).

Personal protective equipment to reduce exposure. This includes protective eyewear and face shields, hard hats, hearing protection, hand protection and protective footwear.

Team members must never operate equipment without a machine guard in place. Ensure they understand that if a guard is missing, don’t operate the tool and report the situation to a supervisor.

The Canadian Centre for Occupational Health and Safety (CCOHS) in Hamilton contributed this article. CCOHS provides information, training, education, management systems and solutions that support health and safety programs and the prevention of injury and illness in the workplace. Visit www.ccohs.ca.

This article originally appeared in PLANT Magazine’s May-June 2020 print issue.