Machine Guarding
Machine guarding is one of the most critical safety requirements in general industry. OSHA 1910 Subpart O (Machine Guarding) requires that machinery be equipped with guards to protect operators and nearby workers from contact with moving parts that could cause injury. Hazardous parts of machines include: points of operation (where work is performed on the material), power transmission apparatuses (gears, pulleys, belts, chains, rotating shafts), and other moving parts that can create injury even when not at the point of operation. Nip points — where two rotating parts come together, or a rotating part passes near a stationary surface — are particularly dangerous because they draw in and crush whatever contacts them.
Types of guards: Fixed guards are permanent barriers that cannot be removed without tools — the most effective and preferred type. They require no adjustment and provide continuous protection. Interlocked guards are connected to the machine's power system so the machine cannot operate when the guard is open or removed — used when frequent access is needed for feeding material or maintenance. Adjustable guards can be set to accommodate different sizes of material — less protective than fixed but more versatile. Self-adjusting guards move to accommodate material passing through and return to rest position — common on table saw blade guards. Safeguarding devices include: two-hand controls (both hands must activate the machine simultaneously), presence-sensing devices (light curtains, capacitance, and similar), pullbacks (pull worker's hands away when machine cycles), restraints (prevent hands from entering danger zone).
Machine guarding requirements: guards must prevent workers from reaching over, under, around, or through the guarding, must be fastened securely, must not create additional hazards, and must not interfere with normal machine operation. Guards must be made of durable materials. Workers must never remove or defeat guards — this is a serious violation. If a guard is removed for maintenance, LOTO procedures must be used. After maintenance, the guard must be replaced before the machine is restarted. Regular inspection of guards for damage, proper installation, and completeness is part of any effective safety program.