Machine Guarding & Safety

There are as many hazards created by moving machine parts as there are types of machines. Safeguards are essential for protecting operators from preventable injuries.  Any machine part, function, or process that might cause injury must be safeguarded. When the operation of a machine or accidental contact with it could injure the operator or others in the vicinity, the hazards must be either controlled or eliminated.  Examples of the types of equipment that could be used at the University that require machine guarding include (but are not limited to): saws, lathes, milling machines, and grinders.

Hazardous Mechanical Motions and Actions

A wide variety of mechanical motions and actions may present hazards to the operator. These can include the movement of rotating members, reciprocating arms, moving belts, meshing gears, cutting teeth, and any parts that impact or shear. These different types of hazardous mechanical motions and actions are basic in varying combinations to nearly all machines, and recognizing them is the first step toward protecting operators from the danger they present.

The basic types of hazardous mechanical motions and actions are:

Motions

  • rotating (including in-running nip points)
  • reciprocating
  • transversing

Actions

  • cutting
  • punching
  • shearing
  • bending

Where Mechanical Hazards Occur

Dangerous moving parts in three basic areas require safeguarding:

  • The point of operation: that point where work is performed on the material, such as cutting, shaping, boring, or forming of stock.
  • Power transmission apparatus: all components of the mechanical system that transmit energy to the part of the machine performing the work. These components include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears.
  • Other moving parts: all parts of the machine that move while the machine is working. These may include reciprocating, rotating, and transverse moving parts, as well as feed mechanisms and auxiliary parts of the machine.

Requirements for Safeguards

Safeguards must meet these minimum general requirements:

  • Prevent contact: The safeguard must prevent hands, arms, and any other part of a operator's body from making contact with dangerous moving parts. A good safeguarding system eliminates the possibility of the operator or another worker placing parts of their bodies near hazardous moving parts.
  • Secure: Operators should not be able to easily remove or tamper with the safeguard, because a safeguard that can easily be made ineffective is no safeguard at all. Guards and safety devices should be made of durable material that will withstand the conditions of normal use. They must be firmly secured to the machine.
  • Protect from falling objects: The safeguard should ensure that no objects can fall into moving parts. A small tool dropped into a cycling machine could easily become a projectile that could strike and injure someone.
  • Create no new hazards: A safeguard defeats its own purpose if it creates a hazard such as a shear point, a jagged edge, or an unfinished surface that could cause a laceration. The edges of guards, for instance, should be rolled or bolted in such a way to eliminate sharp edges.
  • Create no interference: Any safeguard that impedes an operator from performing the job quickly and comfortably might soon be overridden or disregarded. Proper safeguarding may actually enhance efficiency since it relieves the operator's apprehensions about injury.
  • Allow safe lubrication: If possible, workers should be able to lubricate the machine without removing the safeguards. Locating oil reservoirs outside the guard, with a line leading to the lubrication point, will reduce the need for the operator or maintenance operator to enter the hazardous area.

Safe Work Practices

Besides machine guarding, there are other safe work practices that can be followed to help prevent injuries associated with moving machinery, i.e. amputation type injuries.

  • Avoid loose clothing or jewelry and tie up loose hair to prevent it from becoming entangled in the moving parts
  • Use pushsticks and tampers for pushing stock or food into the point of operation. NEVER reach your hand toward the point of operation
  • Allow time for machine to stop moving once turned off. Some blades will take up to 15 seconds to spin down when powered down
  • Ensure the machine is unplugged or locked and tagged out before removing guards for cleaning or maintenance
  • Use the proper blades at the proper operating speeds as specified by the manufacturer of the equipment
  • Maintain blades and bits in good condition and replace when damaged