Amputation is one of the most severe and crippling types of injuries in the occupational workplace, often resulting in permanent disability. The purpose of machine guarding is to protect the machine operator and other employees in the work area from hazards created during the machines normal operation by ingoing nip points, rotating parts, flying chips & sparks.
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.
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.
Hazardous Mechanical Motions and Actions
The basic types of hazardous mechanical motions and actions are:
|rotating (including in-running nip points)||cutting|
Requirements for guards
Guards must meet these minimum general requirements:
Prevent contact: The guard must prevent hands, arms, and any other part of a operator's body from making contact with dangerous moving parts.
Secure: Operators should not be able to easily remove or tamper with the guard. 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 guard should ensure that no objects can fall into moving parts.
Create no new hazards: A guard cannot create a hazard such as a shear point, a jagged edge, or an unfinished surface that could cause a laceration.
Create no interference: Any guard that prevents the operator from performing the job quickly and comfortably might soon be overridden or disregarded.
Allow safe lubrication: If possible, operators should be able to lubricate the machine without removing the guards.
Four approaches to machine guarding:
Guards are physical barriers that enclose dangerous machine parts and prevent employee contact with them. They must be strong and fastened by any secure method that prevents the guard from being inadvertently dislodged or removed. This is the preferred method of protection.
Safe Guarding Devices
Safeguarding devices are controls or attachments that usually prevent inadvertent access by employees to hazardous machine areas, when properly designed an installed. Examples include: Presence Sensing, Pullback, Restraint, Safety Controls, and gates.
These devices may perform one of several functions.
- It may stop the machine if a hand or any part of the body is inadvertently placed in the danger area.
- It may restrain or withdraw the operator's hands from the danger area during operation.
- It may require the operator to use both hands on machine controls, thus keeping both hands and body out of danger.
- It may provide a barrier which is synchronized with the operating cycle of the machine in order to prevent entry to the danger area during the hazardous part of the cycle.
Secondary Safeguarding Methods
Detection safeguarding devices, awareness devices, safeguarding methods and safe work procedures are secondary safeguarding methods. These methods provide a lesser degree of protection than the primary safeguarding methods as they do not prevent employees from placing or having any part of their bodies in the hazardous machine areas. These methods are acceptable only when guards or safeguarding devices cannot be installed due to reasons of infeasibility. Secondary safeguarding methods must not be used in place of primary safeguarding methods.
To consider a part of a machine to be safeguarded by location, the dangerous moving part of a machine must be positioned so that those areas are not accessible or do not present a hazard to a worker during the normal operation of the machine. A thorough hazard analysis of each machine and particular situation is absolutely essential before attempting this safeguarding technique.
Awareness Barriers (warnings)
Awareness barriers do not give complete protection from machine hazards, they may provide the operator with an extra margin of safety. An awareness barrier does not provide physical protection, but serves only to remind a person that he or she is approaching the danger area. Generally, awareness barriers are not considered adequate when continual exposure to the hazard exists.
29 CFR 1910 Subpart O
Good housekeeping practices, employee/student apparel, employee/student training and safe work practices are critical to promote safe working conditions around machinery.
- Ensure machines are equipped with appropriate safeguards.
- Provide personal protective equipment to operators, when necessary.
- Remove slip, trip, and fall hazards from the areas surrounding machines;
- Use drip pans when oiling equipment;
- Remove waste stock as it is generated;
- Make the work area large enough for machine operation and maintenance; and
- Place machines away from high traffic areas to reduce employee distraction.
- Enforce proper clothing requirements such as prohibiting loose-fitting clothing, jewelry, or other items that could become entangled in machinery, and long hair should be worn under a cap or otherwise contained to prevent entanglement in moving machinery.
- Provide machine specific training to operators
Ensure operators do not defeat machine safeguards.
Operate machines with all safeguards in place
Instruction in the safe use and care of machines and supervised on-the-job training are essential in preventing amputation injuries. Only trained employees/students should operate machinery.
Training should include:
- All hazards in the work area, including machine-specific hazards; Machine operating procedures lockout/tagout procedures and safe work practices.
- The purpose and proper use of machine safeguards.
- All procedures for responding to safeguarding problems such as immediately reporting unsafe conditions such as missing or damaged guards and violations of safe operating practices to supervisors.
Inspection and Maintenance
- Good inspection, maintenance and repair procedures contribute significantly to the safety of the maintenance crew as well as to the operators. To ensure the integrity of the machinery and machine safeguards, a proactive, versus a break-down maintenance program needs to be established based upon the:
- Manufacturer's recommendations
- Good engineering practice