Understanding the risk factors of machinery operations and the general principles of machine guarding will help you complete your own evaluation process and in determining where additional safety controls are needed.
Understanding and controlling the hazards related to machinery operations is not only good business, it is required by law. Effective machine guarding is essential where the injury-causing hazards cannot be eliminated or reduced to a safe level. In order to ensure adequate guarding, it is important to know where the risk factors occur, relative to machinery operations, and to understand what hazards are created by the associated actions and movements.
Risk factors - Operations
There are five key operating elements to consider when evaluating the need for machine guarding:
The point of operation: This is where the primary mechanical work of the machinery takes place, such as cutting, grinding, bending, pressing and punching. It is a primary source of injury potential, especially for the machinery operator.
Power transmission: This encompasses all the elements that are used to mechanically transfer power from the source to the point of operation and related components. It may include belt drives, screw drives, gears, pulleys, rotating shafts, chains, flywheels, pistons and similar moving parts. Because these may be away from the point of operation, they are often the source of injury to others in the work area and may be overlooked.
Contact and emissions exposures: Some machines operate at high temperatures, have sharp surfaces, corners, or protruding parts, produce elevated noise levels, release steam or pressure, or may involve the use of chemicals, generate radiation exposures or produce unsafe atmospheres.
Release or ejection of materials or component parts: When high amounts of force, pressure or speed are involved in machinery operations, it can result in work pieces, waste or broken parts being dangerously projected from the machine.
Risk factors - Actions and motions
Actions: Tasks such as cutting, grinding, punching, bending, shearing, forming, or joining. The primary exposure typically occurs when the worker is inserting, holding or removing materials and often leads to a crushing injury, severe laceration or amputation. Actions that involve rotation, such as a saw, drill or lathe, have the increased risk of pulling the worker into the hazard. Actions that involve high speed or force can also result in materials being thrown from the machinery with enough power to cause a serious injury or fatality. In these situations, the guard should be capable of both preventing contact and containing possible projectiles.
Motions: Can be found in multiple operating areas of the machine and are generally grouped as rotating, reciprocating, and transverse.