Machines kill and maim. That’s why OSHA sets out strict machine guarding requirements in the Machinery and Machine Guarding Standard (29 CFR 1910, Subpart O). Here’s a 15-step game plan to help you comply.
How the Machine Guarding Standard is Organized
Subpart O includes 2 basic kinds of machine guarding requirements:
15 Steps to Take
As with other hazards, the first step in machine hazard control is machine hazard assessment. In the context of machine guarding, hazard assessment enables you to identify the hazards posed by particular machines and the guards necessary to control them. Hazard assessment should be performed on each machine in your workplace not only when it’s first installed but also:
Focus on hazards in the 3 principle zones of danger that may require use of machine guards under the OSHA standard:
Step 3: Look for Hazardous Machine Motions and Actions
What makes machinery so dangerous to workers are the mechanical motions and actions like the movement of rotating parts that can create in-running nip points. It’s crucial to factor the different types of mechanical motions and actions into your hazard assessment, including:
The next phase of the assessment is to evaluate identified hazards and what should be done to control them. Consider the type of machinery, the manufacturer, where and when it was purchased, the location of the machinery, preventive maintenance requirements. Also look at how many workers operate the machinery and the current training program for new workers, as well as any machine guards you currently use. Questions to ask when doing your assessment:
At this point, the strategy shifts from hazard assessment to hazard control and the implementation of machine guards. The OSHA standard requires employers to use one or more of 5 machine guarding methods to protect the operator and other workers:
In selecting guarding methods, keep in mind that guards must meet the following basic principles under the OSHA Standard:
Point of operation guards must meet the appropriate OSHA standard for the kind of machine and hazard involved. Guards may be supplemented with—though not replaced by—special handtools that allow operators to place and remove materials from the machine without sticking their hands in the danger zone.
Revolving drums, barrels and containers must be guarded by an enclosure that’s interlocked with the drive mechanism, so that the barrel, drum or container can’t revolve unless the guard enclosure is in place.
OSHA requires proper guarding of prime movers, i.e., steam, gas, oil and air engines, motors, steam and hydraulic turbines and other equipment used as a source of power for the machine.
Each continuous line of shafting must be secured in position against excessive endwise movement. Additional rules apply to horizontal shafting 7 feet or less from the floor. Shafting under bench machines must be enclosed by a stationary casing, or a trough at sides and top or sides and bottom, as location requires.
Pulleys with any part 7 feet or less from the floor or working platform must be properly guarded. Pulleys serving as balance wheels (e.g., punch presses) on which the point of contact between belt and pulley is more than 6 ft. 6 in. from the floor or platform may be guarded with a disk covering the spokes.
Where both runs of horizontal belts are 7 feet or less from the floor level, the guard must extend to at least 15 inches above the belt or to a standard height. Exceptions: Where both runs of a horizontal belt are 42 inches or less from the floor, the belt must be fully enclosed; and in powerplants or power-development rooms, a guardrail may be used in lieu of the guard.
Gears must be guarded by a complete enclosure, a standard guard at least 7 feet high extending 6 inches above the mesh point of the gears or a band guard covering the face of gear with flanges extended inward beyond the root of the teeth on the exposed side or sides.
Sprocket wheels (other than manually-operated sprockets) and chains must be enclosed unless they’re more than 7 feet above the floor or platform. Where the drive extends over other machine or working areas, protection against falling must be provided..
All things being equal, machine guards should be made of metal and created by the company that manufactures the machine they’re intended to guard.
First choice: Affix the guard to the machine. If that’s impossible, the guard must be physically secured to the floor or another location near the machine.
You must inspect machine guards regularly and immediately after incidents or operational changes that may harm their effectiveness. Defective guards must be removed from service and replaced so that the machine doesn’t remain unguarded.