Tips, Mistakes, and Standards for Machine Guards

Machine guards aren’t just nice to have – they’re specified for employers within OSHA standards.

How can you create a safe employee work environment around all machines? From nip points and rotating parts to flying chips and sparks, machines have high-hazard elements that can injure and even kill unprotected workers.

Here are the most common types of machine guards, their respective OSHA standards, and more information on keeping your employees safe.

Common Machines that Require Guards

There are a vast number of machines that require guards, but some are more commonly used than others. Here are some of the most frequently used machines that require guarding per OSHA standards.

General Industry Machinery

This category includes woodworking machinery, abrasive wheels, mills, calenders, power presses, forging machines, and mechanical power transmission apparatuses. It also includes machinery specific to the textiles, telecommunications, and baking industries.

For small or hand-held machinery, barrier guards are standard protective devices that keep workers safe. For heavier machinery, guard rails can help keep workers safe while protecting expensive equipment like forklifts in a warehouse, manufacturing facility, or distribution center.

Maritime Industry Machinery

Longshoring operations require specific requirements for machine guarding of “danger zones” on machines. This includes any machinery on waterborne craft, from engines and motors to generators and propulsors.

Construction Industry Machinery

The construction industry uses various large and small tools to complete residential and commercial building projects. Hand-held tools, abrasive wheels, woodworking tools, hydraulic equipment, and air receivers are just a few examples of machines that need guarding.

Agriculture Industry Machinery

The agriculture industry often employs heavy machinery to carry out repetitive tasks on farmland. Cotton gins and tractors are machines that require guards to protect workers.

Types of Machine Guards

OSHA identifies three main categories of machine guards that apply across various machines: barrier guards, two-hand tripping devices, and electronic safety devices. Here’s a bit more about each and their corresponding OSHA standards for further reading.

Barrier Guards

Barrier Guards are protective devices used in full-revolution and part-revolution mechanical power presses. These guards keep the operator’s hands and arms away from the “danger zone” set by the machine. Because of their ease of use, they’re often the go-to safety measure for most machines.

What does OSHA have to say about barrier guards? There are a few regulations outlined in standard 29 CFR 1910.217(c)(2)(i):

• On a power press, a barrier guard must keep hands or fingers from touching the point of operation.
• Openings can’t exceed the limits in inches outlined in Table O-10.
• The barrier guard can’t create pinch points between the guard and moving parts. A pinch point is any area where a body part could be caught.
• The guard must be secure and not easy to remove.
• Machines should still be able to be inspected regularly without damaging the guard.
• The point of operation on the machine must still be as visible as possible to the operator.

Two-Hand Tripping Devices

Two-hand trips are safety devices used on full-revolution clutch power presses. These devices require simultaneous operation of two trigger buttons outside the press’s “danger zone.” Triggering a machine stroke requires only one action with a trip control, while a two-hand control requires continuous pressure. This device also ensures the operator’s hands are away from the point of operation.

Here are the OSHA standards for two-hand tripping devices, from 29 CFR 1910.217(c)(3)(viii):

• If more than one operator uses a press, each operator should have a two-hand trip. The trip must require both operators to work the slide simultaneously too. 
• Two-hand trips must follow specific construction requirements. Learn more about these by checking out 29 CFR 1910.217(b)(6).
• You must use the safety distance formula to determine the correct distance between the two-hand trip and the point of operation.
• The position of two-hand trips must be secured so that the controls can only be moved by a supervisor or safety engineer.

Electronic Safety Devices

Electronic safety devices include rubber-insulating blankets, matting, covers, gloves, and sleeves. These devices prevent unintended contact with live parts, particularly if the voltage exceeds 50 volts. One way to protect against electronic hazards is by securing the equipment in a room, vault, elevated platform, or site 8ft (or higher) from the floor, along with sturdy screens acting as guards. 

Signs must be posted near entrances to alert people to electrical hazards and restricted access for unauthorized personnel. Grounding is an additional measure to reduce the risk of electric shocks. Circuit protection devices such as fuses, circuit breakers, ground-fault circuit interrupters, and arc-fault interrupters limit or stop current flow in case of overloads, ground faults, and short circuits.

Read the full standard, 1910.137(a)(2), to learn more about electronic safety devices.

Tips for Success

While machine guarding is a complex topic, a few rules of thumb can help employers remain compliant and keep employees safe from hazards. They are:

• Machine guards shouldn’t create unnecessary complications. For example, if a machine guard creates a new hazard, makes it difficult to clean, lubricate, or inspect a machine, or requires extra steps to be used properly, there’s probably an alternative method for guarding that’s much safer.
• When possible, a guard should completely prevent contact. Many of the OSHA standards (for example, the “maximum width” rule for openings) concern preventing human contact with a hazardous or moving part. If communication is possible, a guard is ineffective.
• A guard shouldn’t hinder the operation of the machine. If a guard keeps a machine from functioning, it should be repaired or replaced.

Learn more about machine guarding against our Machine Safeguarding website page. We offer helpful courses and materials that remind your workplace about safety and keep OSHA standards top-of-mind.