Machine Guarding

Avoiding potential hazards by following proper machine guarding techniques

Machine Guarding accidents occur when precautions are not taken. An operation could get stuck, lose a finger, lose a limb or die from improper guarding. Each operator should be familiar with various types of common machinery and the related OSHA safety standards.  Some of the machines that require guarding are; mechanical power presses, milling  machines, drill presses, shears, press breaks, hand held power tools, power transmission equipment, woodworking equipment and robotics. Workers should be able to recognize hazards such as those created by points of operation, rotating, reciprocating, and other machine function which may allow an operator to be in danger of pinch points or flying sparks, chips or materials. Employee exposure to unguarded or inadequately guarded machines is prevalent in many workplaces. Consequently, workers who operate and maintain machinery suffer approximately 18,000 amputations, lacerations, crushing injuries, abrasions,  and over 800 deaths per year.

Moving machine parts have the potential to cause severe workplace injuries, such as crushed fingers or hands, amputations, burns, or blindness. Safeguards are essential for protecting workers from these preventable injuries. Any machine part, function, or process that may cause injury must be safeguarded. When the operation of a machine or accidental contact injure the operator or others in the vicinity, the hazards must be eliminated or controlled. This page contains general information on the various hazards of mechanical motion and techniques for protecting workers.

Machine guarding hazards are addressed in specific standards for the general industry, marine terminals, longshoring, and the construction and agriculture industries.

Fixed
As its name implies, a fixed guard is a permanent part of the machine. It is not dependent upon moving parts to function. It may be constructed of sheet metal, screen, wire cloth, bars, plastic, or any other material that is substantial enough to withstand whatever impact it may receive and to endure prolonged use. This guard is usually preferable to all other types because of its relative simplicity.

Interlocked
When this type of guard is opened or removed, the tripping mechanism and/or power automatically shuts off or disengages, the moving parts of the machine are stopped, and the machine cannot cycle or be started until the guard is back in place. An interlocked guard may use electrical. mechanical, hydraulic, or pneumatic power or any combination of these. Interlocks should not prevent “inching” by remote control if required. Replacing the guard should not automatically restart the machine. To be effective, all removable guards should be interlocked to prevent occupational hazards.

Adjustable
Adjustable guards are useful because they allow flexibility in accommodating various sizes of stock.

Self-adjusting
The openings of these barriers are determined by the movement of the stock. As the operator moves the stock into the danger area, the guard is pushed away, providing an opening which is only large enough to admit the stock. After the stock is removed, the guard returns to the rest position. This guard protects the operator by placing a barrier between the danger area and the operator. The guards may be constructed of plastic, metal, or other substantial material. Self-adjusting guards offer different degrees of protection.

See osha.gov for machine guarding standards

Click here for a machine guarding program