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In almost all industries, we may work with or around machinery. 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. You must safeguard any machine part, function, or process that may cause harm. When the operation of a machine or accidental contact could injure the operator or others in the vicinity, the hazards must be eliminated or controlled.
OSHA’s machine guarding standards apply to employers having employees exposed to dangerous moving parts.
29 CFR 1910.212 General requirements for all machinery, which is OSHA’s general requirement for all machinery. It is a catch-all standard (like the General Duty Clause) requiring employers to protect employees from dangerous moving parts and to guard points of operation. OSHA also has some machine-specific standards, which you may need to know:
- 29 CFR 1910.213 Woodworking machinery
- 29 CFR 1910.215 Abrasive wheel machinery
- 29 CFR 1910.216 Mills and calendars in the rubber and plastics industries
- 29 CFR 1910.217 Mechanical power presses
- 29 CFR 1910.218 Forging machinery
- 29 CFR 1910.219 Mechanical power transmission apparatus
- Fixed guard:A fixed guard is a permanent part of the machine. It is not dependent upon moving parts to function. It may be 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 different types because of its relative simplicity.
- Interlock: When opening or removing this type of guard, the tripping mechanism or power automatically shuts off or disengages, and the moving parts of the machine stop. 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. Interlock all removable guards to avoid occupational hazards.
- Photoelectric (light) device: The photoelectric (optical) presence-sensing device uses a system of light sources and controls which can interrupt the machine’s operating cycle. Interrupting the light field stops the machine and will not cycle. This device must be used only on machines which can stop before the worker can reach the danger area. The design and placement of the guard depend upon the time it takes to stop the machine and the speed at which the employee’s hand can reach across the distance from the guard to the danger zone.
- Point of operation: The point of equipment at which work, such as cutting, boring, or bending, is performed. With a few exceptions, you must guard the point of operation.
- Power transmission apparatus/device: The power transmission apparatus are all components of the mechanical system which 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.
- Pullback: Pullback devices utilize a series of cables attached to the operator’s hands, wrists, or arms. One would use this type of device on machines with stroking action. When the slide/ram is up between cycles, the operator is allowed access to the point of operation. When the slide/ram begins to cycle by starting its descent, a mechanical linkage automatically assures withdrawal of the hands from the point of operation.
- Restraint: The restraint (hold-back) device utilizes cables or straps that are attached to the operator’s hands and a fixed point. The cables or straps must be adjusted to let the operator’s hands travel within a predetermined safe area. There is no extending or retracting action involved. Consequently, hand-feeding tools are often necessary if the operation consists of placing material into the danger area.
- Self-adjusting guard: The movement of the stock determines the openings of these barriers. 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 removing the stock, 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 plastic, metal, or other substantial material. Self-adjusting guards offer different degrees of protection.
- Two-hand control: The two-hand control requires constant, concurrent pressure by the operator to activate the machine. This kind of control needs a part-revolution clutch, brake, and a brake monitor if used on a power press. With this type of device, the operator’s hands are required to be at a safe location (on control buttons) and a safe distance from the danger area while the machine completes its closing cycle.
- Two-hand trip: The two-hand trip requires concurrent application of both the operator’s control buttons to activate the machine cycle, after which the hands are free. Usually one would use this device with machines equipped with full-revolution clutches. The trips must be placed far enough from the point of operation to make it impossible for the operator to move his or her hands from the trip buttons or handles into the point of operation before completing the first half of the cycle. The distance from the trip button depends upon the speed of the cycle and the band speed constant. Thus the operator’s hands are kept far enough away to prevent them from being placed in the danger area before the slide/ram or blade reaching the full “down” position. Locate both two-hand controls and trips must so that the operator cannot use two hands or one hand and another part of his/her body to trip the machine.
In general, you can use the following five steps to ensure safe machine operation in your workplace:
- Determine the types of machinery in the workplace. Then, determine if there is a machine-specific standard (e.g., 1910.213-.219), or if the equipment is covered under the “catch-all” guarding requirement of 1910.212. Follow the applicable standard.
- Provide one or more methods of machine guarding to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips, and sparks. Note: Some of the machine-specific standards prescribe specific safeguarding measures.
- Ensure the point of operation of machines is guarded.
- Ensure the necessary guards are affixed and secured.
- Anchor machines designed for a fixed location to prevent walking or moving.
These necessary steps will cover almost all of your machine guarding needs.
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