Machine Guarding

If safeguarding is not possible what must be used instead?

Distance and Location

The danger of cutting action exists at the point of operation where finger, arm and body injuries can occur. What things can be hazards?

Flying chips or scrap material can strike the head, particularly in the area of the eyes or face.

All that matters is that guards are used. Even those that don't meet all requirements are better than nothing. Is this true or false?

Guards must meet requirements in all cases.

A hazard occurs at the point of operation where stock is what?

Inserted, held, and withdrawn.

What motion involves a shaft that can easily grip hair and clothing?

Rotating

Which parts of a machine must be guarded?

1. Fan Blades 2. Abrasive Wheel Machinery 3. Revolving barrels, containers, and drums 4. Power transmission apparatus

If you are working with any of these machines listed, the point of operation MUST be guarded.

1. Guillotine cutters 2. Shears 3. Alligator shears 4. Power presses 5. Milling machines 6. Power saws 7. Jointers 8. Portable power tools 9. Forming rolls and calendars

What are the different types of guards?

1. Interlocked 2. Fixed 3. Self-Adjusting 4. Adjustable

What are the most common ways workers get hurt around machines?

1. Reaching in to clean equipment 2. Not using lockout tagout 3. Missing guards 4. Unqualified operators

All machines consist of three fundamental areas which are?

1. The point of operation 2. The power transmission device 3. The operating controls.

Such hazards are present at the point of operation in cutting wood, metal, and other materials. Examples of mechanisms involving cutting hazards include what?

Bandsaws, circular saws, boring and drilling machines, turning machines (lathes), or milling machines.

What is the criteria for a guard having to be used on a machine?

If operation exposes you to injury.

Easy Access - Allow Safe Lubrication

If possible, one 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 worker to enter the hazardous area.

Examples of machines used for shearing operations are what?

Mechanically, hydraulically, or pneumatically powered shears.

____________ are how the machine part moves, for example rotating, in-running nip points, reciprocating, and transversing. ________________ are operations the machine performs, such as cutting, punching, shearing, and bending.

Motions are how the machine moves and actions are operations it performs.

Motions

Motions which are how the machine part moves. Examples include rotating, in-running nip points, reciprocating, and transversing.

Abrasive Wheel Machinery

On abrasive wheel machinery, there must be an adjustable tongue guard to within ¼" of the wheel, a work rest with a maximum opening of 1/8 of an inch, and a cover spindle end, nut, flange projections.

What do guards do to protect the worker?

Places a physical barrier between the worker and the machine.

Punching action results when what happens?

Power is applied to a slide (ram) for the purpose of blanking, drawing, or stamping metal or other materials.

Bending action results when what happens?

Power is applied to a slide in order to draw or stamp metal or other materials.

Typical machines used for punching operations are what?

Power presses and iron workers.

Equipment that uses bending action includes what?

Power presses, press brakes, and tubing benders.

What is the type of safeguarding device that senses a worker in a certain area?

Presence Sensing

Pullback Device

Pullback devices utilize a series of cables attached to the operator's hands, wrists, and/or arms. This type of device is primarily used 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.

Revolving Barrels, Containers, and Drums

Revolving barrels, containers, and drums must be guarded by an enclosure interlocked with the drive mechanism, so the barrel, gun, or container cannot revolve unless the guard enclosure is in place.

Cutting action may involve what?

Rotating, reciprocating, or transverse motion.

Safety Trip Controls

Safety trip controls provide a quick means for deactivating the machine in an emergency situation. A pressure-sensitive body bar, when depressed, will deactivate the machine. If the operator or anyone trips, loses balance, or is drawn toward the machine, applying pressure to the bar will stop the operation. The positioning of the bar, therefore, is critical. It must stop the machine before a part of the employee's body reaches the danger area.

Secondary Safeguarding

Secondary safeguarding methods are acceptable only when guards or safeguarding devices (that prevent you from being exposed to machine hazards) cannot be installed due to reasons of infeasibility. Where it is feasible to use primary safeguarding methods, secondary safeguarding methods may supplement these primary control measures; however, these secondary safeguarding methods must not be used in place of primary safeguarding methods.

Shearing action involves applying power to what?

Slide or knife in order to trim or shear metal or other materials.

Gate Devices

The gate is a moveable barrier that protects the operator at the point of operation before the machine cycle can be started. Gates are, in many instances, designed to be operated with each machine cycle. To be effective, the gate must be interlocked so that the machine will not begin a cycle unless the gate guard is in place. It must be in the closed position before the machine can function. If the gate is not permitted to descend to the fully closed position, the press will not function. Another potential application of this type of guard is where the gate is a component of a perimeter safeguarding system. Here the gate may provide protection not only to the operator but to pedestrian traffic as well." (OSHA 2007)

Fan Blades

When the periphery of the blades of a fan is less than seven (7) feet above the floor or working level, the blades must be guarded. The guard must not have openings larger than one-half (½) inch.

Is Hazardous - No New Hazards

A safeguard defeats its own purpose if it creates a hazard of its own such as a shear point, a jagged edge, or an unfinished surface which can cause a laceration. The edges of guards. for instance, should be rolled or bolted in such a way that they eliminate sharp edges.

Actions

Actions which are operations that the machine part performs. Examples include cutting, punching, shearing, and bending.

Easy to Use - No Interference

Any safeguard which impedes a worker from performing the job quickly and comfortably might soon be overridden or disregarded. Proper safeguarding can actually enhance efficiency as it can relieve the worker's apprehensions about injury.

Self Adjusting Guard

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.

Operating Controls

The operating controls are the mechanical or electric power controls used by the worker to operate the machine.

Point of Operation

The point of operation is where work is performed on materials. Examples include cutting, shaping. boring, and, forming of stock.

Power Transmission

The power transmission apparatus is 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.

Restraint Devices

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 involves placing material into the danger area." (OSHA 2007)

Body Parts/Moving Parts - Prevent Contact

The safeguard must prevent hands, arms, and any other part of a worker'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.

Avoid Projectiles - Protect from Falling Objects

The safeguard should ensure that no objects can fall into moving parts. A small tool which is dropped into a cycling machine could easily become a projectile that could strike and injure someone.

Power Transmission Apparatus

The shafting, flywheels, pulleys, belts, chain drives, etc. of power transmission apparatus less than 7 feet from the floor or working platform must be guarded.

Two-hand Control

The two-hand control requires constant, concurrent pressure by the operator to activate the machine. This kind of control requires 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 at a safe distance from the danger area while the machine completes its closing cycle.

Presence Sensing Devices

There are three types of presence-sensing devices; photoelectrical, radiofrequency, and electromechanical. While they all work in slightly different ways, they all operate on the idea of the worker's presence in a certain area causing the machine to stop.

Adjustable Guard

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

Fixed Guard

This 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.

Primary Safeguarding

Two primary methods are used to safeguard machines: guards and some types of safeguarding devices. Guards provide physical barriers that prevent access to danger areas. Safeguarding devices either prevent or detect operator contact with the point of operation or stop potentially hazardous machine motion if any part of an individual's body is within the hazardous portion of the machine. Both types of safeguards need to be properly designed, constructed, installed, used and maintained in good operating condition to ensure employee protection.

Interlocked Guard

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. This guard may use electrical, mechanical, hydraulic, or pneumatic power or any combination of these. They 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.

The point of operation is the area on a machine where?

Work is actually performed upon the material being processed.

Not Easily Removed - Secure

Workers 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 firmly be secured to the machine.