Chapter 7 Machine Guarding

Slide 1: 

Chapter Seven Machine Safety

Accidents involving machines may not occur very often, but when they do, the results can be serious. Safety guards are installed on machines to prevent accidents. They are intended to protect people – not the machine. : 

Accidents involving machines may not occur very often, but when they do, the results can be serious. Safety guards are installed on machines to prevent accidents. They are intended to protect people – not the machine. Safety Guards

They are intended to protect people – not the machine. If machines could operate without moving parts, or if the moving parts could always be completely enclosed, there would be no need for safety devices. However, this is not always possible. : 

They are intended to protect people – not the machine. If machines could operate without moving parts, or if the moving parts could always be completely enclosed, there would be no need for safety devices. However, this is not always possible. Safety Guards cont’d

The parts of machinery and powered equipment that are considered hazardous and that require safeguards include point-of-operation components (cutting, drilling, shaving, grinding, and punching tools), control mechanisms, parts that transmit power, parts that retain stored energy (such as a spring), and miscellaneous moving parts. : 

The parts of machinery and powered equipment that are considered hazardous and that require safeguards include point-of-operation components (cutting, drilling, shaving, grinding, and punching tools), control mechanisms, parts that transmit power, parts that retain stored energy (such as a spring), and miscellaneous moving parts. Safety Guards cont’d

The illustrations in this chapter show a number of hazardous machinery parts before and after they have been safeguarded. : 

The illustrations in this chapter show a number of hazardous machinery parts before and after they have been safeguarded. Safety Guards cont’d

A close look will give you an idea of the many steps that machine designers have taken in their attempt to prevent accidents. Their goals include: : 

A close look will give you an idea of the many steps that machine designers have taken in their attempt to prevent accidents. Their goals include: Safety Guards cont’d

• Reduce shearing and crushing hazards by providing maximum clearance around and between moving parts, or enclosing them entirely. • Design the machine so that the operator does not need to work in an uncomfortable or awkward position or reach over or Around moving parts. Increasing the comfort of the operator increases productivity. : 

• Reduce shearing and crushing hazards by providing maximum clearance around and between moving parts, or enclosing them entirely. • Design the machine so that the operator does not need to work in an uncomfortable or awkward position or reach over or Around moving parts. Increasing the comfort of the operator increases productivity. Safety Guards cont’d

• Pad or reduce projections that someone can trip over or bump into. • Select the appropriate material for machine guards in instances where the failure of a part or a tool can cause pieces to fly about, or where the operator must be able to see through the guard to operate the machine properly. : 

• Pad or reduce projections that someone can trip over or bump into. • Select the appropriate material for machine guards in instances where the failure of a part or a tool can cause pieces to fly about, or where the operator must be able to see through the guard to operate the machine properly. Safety Guards cont’d

• Make sure that the guards will be secure. If someone bumps or falls against them, the guards must not give way.• Make the guards with hinges or cutouts, or make them removable, so that the machine can be adjusted, inspected, and serviced. Often the guard is interlocked with the machine, so that the machine cannot be started until the guard has been replaced properly. : 

• Make sure that the guards will be secure. If someone bumps or falls against them, the guards must not give way.• Make the guards with hinges or cutouts, or make them removable, so that the machine can be adjusted, inspected, and serviced. Often the guard is interlocked with the machine, so that the machine cannot be started until the guard has been replaced properly. Safety Guards cont’d

• Provide Danger, Caution, and other hazard warning signs on the machine where needed. Provide clear instructions for the proper operation of the machine. : 

• Provide Danger, Caution, and other hazard warning signs on the machine where needed. Provide clear instructions for the proper operation of the machine. Safety Guards cont’d

It is important that you understand the different kinds of hazards associated with the machinery. : 

It is important that you understand the different kinds of hazards associated with the machinery. Moving Parts Make Guards Necessary

Exposed rotating parts are extremely hazardous, including motor shafts, flywheels, pulleys, and drill spindles. : 

Exposed rotating parts are extremely hazardous, including motor shafts, flywheels, pulleys, and drill spindles. Safety Guards cont’d

Loose clothing, long hair, and jewelry can get caught in them, and you cannot pull free once you are entangled. : 

Loose clothing, long hair, and jewelry can get caught in them, and you cannot pull free once you are entangled. Safety Guards cont’d

You cannot always tell by looking at a part whether it is moving or not. Some rotating parts appear to be standing still when they really are moving at a very high speed. Look at the exposed gears in Fig. 7-1. : 

You cannot always tell by looking at a part whether it is moving or not. Some rotating parts appear to be standing still when they really are moving at a very high speed. Look at the exposed gears in Fig. 7-1. Safety Guards cont’d

Slide 15: 

719.07-01 Fig. 7-1. Enclosure around gears 15

Figure 7-2 and 7-3 show two kinds of dangerous rotating blades. : 

Figure 7-2 and 7-3 show two kinds of dangerous rotating blades. Safety Guards cont’d

Slide 17: 

719.07-02 Fig. 7-2. Enclosure around fan blades 17

Slide 18: 

719.07-03 Fig. 7-3. Enclosure around a saw blade 18

Figure 7-4 shows an unsafe belt drive. : 

Figure 7-4 shows an unsafe belt drive. Safety Guards cont’d

Slide 20: 

719.07-04 Fig. 7-4. Enclosure around a belt drive 20

All of these can appear to be standing still when they actually are moving at high speed. : 

All of these can appear to be standing still when they actually are moving at high speed. Safety Guards cont’d

Always make sure that you have shut off the power at its source and brought all parts of a machine to a complete stop before you remove the guards and start working on the machine. (You must be properly trained and have your employer’s authorization to perform this work.) : 

Always make sure that you have shut off the power at its source and brought all parts of a machine to a complete stop before you remove the guards and start working on the machine. (You must be properly trained and have your employer’s authorization to perform this work.) Safety Guards cont’d

The danger of being caught by a rotating part is increased if the part has a rough surface, spokes, or projections, such as a bolt or screw. You can see an example of such a hazard in Fig. 7-5. : 

The danger of being caught by a rotating part is increased if the part has a rough surface, spokes, or projections, such as a bolt or screw. You can see an example of such a hazard in Fig. 7-5. Safety Guards cont’d

Slide 24: 

719.07-05 Fig. 7-5. Enclosure around rotating parts 24

Other examples include the coarse surface of a grinding wheel, the spokes of a flywheel, and the nuts and bolts in a shaft coupling. A screwhead projecting from the hub of a shaft-mounted pulley can snag clothing, jewelry, hair, skin – almost anything that comes near it. : 

Other examples include the coarse surface of a grinding wheel, the spokes of a flywheel, and the nuts and bolts in a shaft coupling. A screwhead projecting from the hub of a shaft-mounted pulley can snag clothing, jewelry, hair, skin – almost anything that comes near it. Safety Guards cont’d

Well-designed guards prevent accidents without interfering with the operation of the machine. But you must do your share, too. Never remove or modify a guard without authorization. : 

Well-designed guards prevent accidents without interfering with the operation of the machine. But you must do your share, too. Never remove or modify a guard without authorization. Safety Guards cont’d

Never wear neckties, scarves, or loose-fitting clothing (dangling sleeves, etc.) when you are working around the moving parts of a machine. Rings, chains, and other jewelry should be removed. Long hair must be restrained. : 

Never wear neckties, scarves, or loose-fitting clothing (dangling sleeves, etc.) when you are working around the moving parts of a machine. Rings, chains, and other jewelry should be removed. Long hair must be restrained. Safety Guards cont’d

If you have ever closed a car door or a desk drawer on your fingers, you already know what a pinch point is. The rotating parts of machines create the same kinds of hazards where they meet or come near other parts. : 

If you have ever closed a car door or a desk drawer on your fingers, you already know what a pinch point is. The rotating parts of machines create the same kinds of hazards where they meet or come near other parts. Safety Guards cont’d

Examples include the points where belts meet pulleys, where chains meet sprockets, where two rollers meet, and where wheels or belts come near fixed objects. Most machine pinch points are guarded or enclosed during normal operation, and exposed only for special purposes – maintenance, for example. : 

Examples include the points where belts meet pulleys, where chains meet sprockets, where two rollers meet, and where wheels or belts come near fixed objects. Most machine pinch points are guarded or enclosed during normal operation, and exposed only for special purposes – maintenance, for example. Safety Guards cont’d

Linear motion also may go back and forth, like a punch press ram or a drill press spindle. If a part goes back and forth, the motion is called reciprocating motion. : 

Linear motion also may go back and forth, like a punch press ram or a drill press spindle. If a part goes back and forth, the motion is called reciprocating motion. Safety Guards cont’d

Again, the danger point is where the moving part meets a nonmoving part. You can see an example of such a danger point in Fig. 7-6. : 

Again, the danger point is where the moving part meets a nonmoving part. You can see an example of such a danger point in Fig. 7-6. Safety Guards cont’d

Slide 32: 

719.07-06 Fig. 7-6. Enclosure around a punch press 32

Avoiding this kind of danger is one more reason why it is so important for you to remember to shut off and lock or tag out the power before you begin working on a machine. : 

Avoiding this kind of danger is one more reason why it is so important for you to remember to shut off and lock or tag out the power before you begin working on a machine. Safety Guards cont’d

The point of operation of a machine is the place where the stock or raw material is processed – between the dies in a press, for example, or where the blade of a power saw meets the material being cut, or between the rollers of a rolling mill. : 

The point of operation of a machine is the place where the stock or raw material is processed – between the dies in a press, for example, or where the blade of a power saw meets the material being cut, or between the rollers of a rolling mill. Point-of-Operation Guards

These are danger zones – places where you can be caught, struck, cut, or otherwise injured. : 

These are danger zones – places where you can be caught, struck, cut, or otherwise injured. Point-of-Operation Guards cont’d

Point-of-operation guards cover, surround, or block the operator’s access to danger zones. Figure 7-7 shows such a guard. : 

Point-of-operation guards cover, surround, or block the operator’s access to danger zones. Figure 7-7 shows such a guard. Point-of-Operation Guards cont’d

Slide 37: 

719.07-07 Fig. 7-7. Fixed guard on a punch press 37

Each guard is designed for a specific machine. It is there mainly to protect the operator. But every worker in the plant should know what point-of-operation guards are and what their function is. : 

Each guard is designed for a specific machine. It is there mainly to protect the operator. But every worker in the plant should know what point-of-operation guards are and what their function is. Point-of-Operation Guards cont’d

Another device for guarding the point of operation is the wheel-and-blade cover used on abrasive cutting and grinding machines. Figure 7-8 shows such guards. : 

Another device for guarding the point of operation is the wheel-and-blade cover used on abrasive cutting and grinding machines. Figure 7-8 shows such guards. Point-of-Operation Guards cont’d

Slide 40: 

719.07-08 Fig. 7-8. Guards on cutting tools 40

Each cover shields the top and sides of the tool, leaving open only the part that cuts or grinds. Some saw guards are adjustable so that various thicknesses of stock can be cut while guards are on. : 

Each cover shields the top and sides of the tool, leaving open only the part that cuts or grinds. Some saw guards are adjustable so that various thicknesses of stock can be cut while guards are on. Point-of-Operation Guards cont’d

The guards for abrasive wheels are made strong enough to stop flying pieces if the wheel breaks apart. : 

The guards for abrasive wheels are made strong enough to stop flying pieces if the wheel breaks apart. Point-of-Operation Guards cont’d

Wheels and protruding shafts on bench and portable grinders require wheel guards similar to the ones shown in Fig. 7-8. Such a guard covers as much of the wheel as possible without interfering with its operation. : 

Wheels and protruding shafts on bench and portable grinders require wheel guards similar to the ones shown in Fig. 7-8. Such a guard covers as much of the wheel as possible without interfering with its operation. Point-of-Operation Guards cont’d

Most wheels guards are made of heavy metal that can contain the flying pieces of a broken wheel. The guards adjust so that they continue to fit as the wheel wears down. : 

Most wheels guards are made of heavy metal that can contain the flying pieces of a broken wheel. The guards adjust so that they continue to fit as the wheel wears down. Point-of-Operation Guards cont’d

The tool rest on a bench grinder should be positioned within 1/8 in. of the wheel surface to prevent stock from getting caught and jamming between the wheel and the tool rest. The tongue guard should be adjusted to within ¼ in. of the wheel surface to prevent pieces of a shattered grinding wheel from striking the user of the grinder. : 

The tool rest on a bench grinder should be positioned within 1/8 in. of the wheel surface to prevent stock from getting caught and jamming between the wheel and the tool rest. The tongue guard should be adjusted to within ¼ in. of the wheel surface to prevent pieces of a shattered grinding wheel from striking the user of the grinder. Point-of-Operation Guards cont’d

A movable shield must also be provided to protect the operator from flying chips or sparks. Even with point-of-operation guards and shields in place, be sure to wear personal protective equipment, including safety glasses. : 

A movable shield must also be provided to protect the operator from flying chips or sparks. Even with point-of-operation guards and shields in place, be sure to wear personal protective equipment, including safety glasses. Point-of-Operation Guards cont’d

There are two basic kinds of guards that can be permanently attached to a machine at the point of operation. Barrier guards limit the operator’s access to the danger zone. : 

There are two basic kinds of guards that can be permanently attached to a machine at the point of operation. Barrier guards limit the operator’s access to the danger zone. Fixed Guards

A barrier guard provides clearance for feeding materials to the point of operation, but not enough clearance for fingers or a hand to enter the danger zone. : 

A barrier guard provides clearance for feeding materials to the point of operation, but not enough clearance for fingers or a hand to enter the danger zone. Fixed Guards cont’d

Barrier guards are made from a variety of materials, including plastic, wire mesh, expanded metal, and closely spaced rods in a frame. When a guard has to contain flying chips or pieces of broken tools, it can be made of sheet, plate, or cast metal. : 

Barrier guards are made from a variety of materials, including plastic, wire mesh, expanded metal, and closely spaced rods in a frame. When a guard has to contain flying chips or pieces of broken tools, it can be made of sheet, plate, or cast metal. Fixed Guards cont’d

Enclosure guards completely surround and isolate a danger zone, thus preventing operator access altogether. Figure 7-9 shows a typical enclosure guard. : 

Enclosure guards completely surround and isolate a danger zone, thus preventing operator access altogether. Figure 7-9 shows a typical enclosure guard. Fixed Guards cont’d

Slide 51: 

719.07-09 Fig. 7-9. Barrier guards limit access 51

They admit stock, but not hands, into the danger zone. They are often adjustable or different sets of tools or dies. But once adjusted, they should remain at that setting. : 

They admit stock, but not hands, into the danger zone. They are often adjustable or different sets of tools or dies. But once adjusted, they should remain at that setting. Fixed Guards cont’d

Some automatic lathes, power presses, and milling or grinding machines have enclosure guards. A panel in the guard can be opened when tools must be changed or new material mounted, but the power is shut off automatically when the panel is opened. : 

Some automatic lathes, power presses, and milling or grinding machines have enclosure guards. A panel in the guard can be opened when tools must be changed or new material mounted, but the power is shut off automatically when the panel is opened. Fixed Guards cont’d

Total enclosures are most suitable for guarding power transmission mechanisms or other danger zones where access is seldom required. : 

Total enclosures are most suitable for guarding power transmission mechanisms or other danger zones where access is seldom required. Fixed Guards cont’d

Barrier and enclosure guards are called fixed guards, because they do not move when the machine is in operation. They offer protection only when they have been adjusted properly and attached securely. : 

Barrier and enclosure guards are called fixed guards, because they do not move when the machine is in operation. They offer protection only when they have been adjusted properly and attached securely. Fixed Guards cont’d

A fixed guard is shown in Fig.7-10. Note that the adjustable guard ha a thin wire mesh that makes it easier for the operator to see the point of operation. : 

A fixed guard is shown in Fig.7-10. Note that the adjustable guard ha a thin wire mesh that makes it easier for the operator to see the point of operation. Fixed Guards cont’d

Slide 57: 

719.07-10 Fig. 7-10. Fixed guards remain in place 57

Openings around or through guards should be too small for fingers to enter. But the size of the openings can vary according to the distance of the guard from the point of operation. For example, if a guard is within 1 ½ in. of the moving parts, the openings should b ¼ in. or less. : 

Openings around or through guards should be too small for fingers to enter. But the size of the openings can vary according to the distance of the guard from the point of operation. For example, if a guard is within 1 ½ in. of the moving parts, the openings should b ¼ in. or less. Fixed Guards cont’d

If the guard is 32 in. or more from the danger point, the opening can be as large as 6 in. At that distance, it is almost impossible for anyone to reach the moving parts through a 6 in. opening. : 

If the guard is 32 in. or more from the danger point, the opening can be as large as 6 in. At that distance, it is almost impossible for anyone to reach the moving parts through a 6 in. opening. Fixed Guards cont’d

Figure 7-11 illustrates the OSHA standard governing the size of openings in machine parts. : 

Figure 7-11 illustrates the OSHA standard governing the size of openings in machine parts. Fixed Guards cont’d

Slide 61: 

719.07-11 Fig. 7-11. OSHA standard for machine guard openings 61

When a fixed guard cannot be adapted to a particular point of operation, an interlocking guard is used. This guard is a movable barrier connected to the machine controls or power supply. : 

When a fixed guard cannot be adapted to a particular point of operation, an interlocking guard is used. This guard is a movable barrier connected to the machine controls or power supply. Special Guards Interlocking Guards

The connection can be mechanical, electrical, or pneumatic. The machine cannot operate if the guard is opened or removed. : 

The connection can be mechanical, electrical, or pneumatic. The machine cannot operate if the guard is opened or removed. Special Guards Interlocking Guards cont’d

When neither a fixed guard nor an interlocking guard is practical, an automatic guard may be used. Automatic guards push, pull, or sweep the operator’s hand out of the danger zone before the machine begins to operate, and keep them out until the operation is complete. : 

When neither a fixed guard nor an interlocking guard is practical, an automatic guard may be used. Automatic guards push, pull, or sweep the operator’s hand out of the danger zone before the machine begins to operate, and keep them out until the operation is complete. Automatic Guards

Some automatic guards work by means of cables connected to nylon straps (called pullbacks) that fit around the operator’s hands or wrists. The cables pull operator’s hands or wrists. : 

Some automatic guards work by means of cables connected to nylon straps (called pullbacks) that fit around the operator’s hands or wrists. The cables pull operator’s hands or wrists. Automatic Guards cont’d

The cables pull the operator’s hands away from the danger zone at the proper time (see Fig. 7-12). Never make modifications to this device. Follow the manufacturer’s recommendations, and keep a daily log of proper cable adjustment as required by OSHA. : 

The cables pull the operator’s hands away from the danger zone at the proper time (see Fig. 7-12). Never make modifications to this device. Follow the manufacturer’s recommendations, and keep a daily log of proper cable adjustment as required by OSHA. Automatic Guards cont’d

Slide 67: 

719.07-12 Fig. 7-12. Automatic guards pull hands away 67

Some machines are equipped with presence-sensing guards, including photo eyes, radio waves, or magnetic fields. These devices create a sensing area around the danger zone. When a hand or other object enters the sensing field, the machine automatically stops and will not resume operation until the object is removed. : 

Some machines are equipped with presence-sensing guards, including photo eyes, radio waves, or magnetic fields. These devices create a sensing area around the danger zone. When a hand or other object enters the sensing field, the machine automatically stops and will not resume operation until the object is removed. Presence-Sensing Guards

Figure 7-13 shows a machine that protects the operator by means of a sensing field. There is no physical barrier between the operator and the danger zone, so presence-sensing devices are used only on machines that can be stopped instantly, even during an operation. Other types of guards must be used if the machine coasts to a stop, or if it must complete an operation before shutting off. : 

Figure 7-13 shows a machine that protects the operator by means of a sensing field. There is no physical barrier between the operator and the danger zone, so presence-sensing devices are used only on machines that can be stopped instantly, even during an operation. Other types of guards must be used if the machine coasts to a stop, or if it must complete an operation before shutting off. Presence-Sensing Guards cont’d

Slide 70: 

719.07-13 Fig. 7-13. Presence-sensing device 70

Shafts, pulleys, gears, chains, and belts are examples of power-transmitting parts that must be covered to prevent accidents. Most power transmission guards are fixed barriers or enclosures. : 

Shafts, pulleys, gears, chains, and belts are examples of power-transmitting parts that must be covered to prevent accidents. Most power transmission guards are fixed barriers or enclosures. Power Transmission Guards

Remove them only to repair, service, or adjust a mechanism. Such guards prevent injury from contact with moving parts as well as from the breaking apart of the enclosed mechanisms. For example, a cast iron gear box prevents contact with the moving gears and is also strong enough to stop flying pieces if a gear breaks. : 

Remove them only to repair, service, or adjust a mechanism. Such guards prevent injury from contact with moving parts as well as from the breaking apart of the enclosed mechanisms. For example, a cast iron gear box prevents contact with the moving gears and is also strong enough to stop flying pieces if a gear breaks. Power Transmission Guards cont’d

Enclosure guards for power transmission equipment are made of wire mesh, expanded metal, perforated or solid sheet metal, or cast metal. The material should be free of burrs and sharp edges, and strong enough to withstand a worker falling, bumping, or leaning against it. : 

Enclosure guards for power transmission equipment are made of wire mesh, expanded metal, perforated or solid sheet metal, or cast metal. The material should be free of burrs and sharp edges, and strong enough to withstand a worker falling, bumping, or leaning against it. Power Transmission Guards cont’d

The guard must be positioned so that it does not touch the moving parts inside, and must be fastened securely. The guard should be hinged or bolted to provide protection during normal operation, and should be opened or removed only for inspecting, lubricating, or adjusting the parts inside. : 

The guard must be positioned so that it does not touch the moving parts inside, and must be fastened securely. The guard should be hinged or bolted to provide protection during normal operation, and should be opened or removed only for inspecting, lubricating, or adjusting the parts inside. Power Transmission Guards cont’d

Mechanical power transmission equipment is considered guarded if it is more than 8 ft above the nearest work level, or if the equipment is in an area enclosed by high walls with a locked entrance. : 

Mechanical power transmission equipment is considered guarded if it is more than 8 ft above the nearest work level, or if the equipment is in an area enclosed by high walls with a locked entrance. Power Transmission Guards cont’d

For safety, the enclosed equipment should be interlocked with the entrance so that it is disconnected automatically when the door opens. If you must enter an area with no automatic arrangement, shut off and lock or tag out the power first. : 

For safety, the enclosed equipment should be interlocked with the entrance so that it is disconnected automatically when the door opens. If you must enter an area with no automatic arrangement, shut off and lock or tag out the power first. Power Transmission Guards cont’d

Overhead line shafts, counterweights, V-belts, and other rotating mechanisms should be guarded regardless of height. There is always the possibility of maintenance workers or other employees being exposed to these “out-of-the-way” hazards. : 

Overhead line shafts, counterweights, V-belts, and other rotating mechanisms should be guarded regardless of height. There is always the possibility of maintenance workers or other employees being exposed to these “out-of-the-way” hazards. Power Transmission Guards cont’d

Guardrails and fences provide a little protection against coming into contact with the moving parts of equipment. : 

Guardrails and fences provide a little protection against coming into contact with the moving parts of equipment. Power Transmission Guards cont’d

A guardrail should have a midrail and toeboards and should be at least 42 in. high. It should be mounted securely and made of materials strong enough to support anyone who leans against it. : 

A guardrail should have a midrail and toeboards and should be at least 42 in. high. It should be mounted securely and made of materials strong enough to support anyone who leans against it. Power Transmission Guards cont’d

Still, it is never a good idea to lean against such a railing. Anyone who is foolish enough to sit on the railing risks falling into the danger area. : 

Still, it is never a good idea to lean against such a railing. Anyone who is foolish enough to sit on the railing risks falling into the danger area. Power Transmission Guards cont’d

Machine controls are not guards, but they can be designed, located, and interconnected in various ways to improve safety. For example, the switch may be so far away from a machine that the operator who starts it has to move entirely out of the machine’s danger zone. : 

Machine controls are not guards, but they can be designed, located, and interconnected in various ways to improve safety. For example, the switch may be so far away from a machine that the operator who starts it has to move entirely out of the machine’s danger zone. Other Safety Devices Controls

On large machines, where more than one worker is required, each should have a set of controls. They should be interconnected, however, so that the machine cannot start until everyone is out of the danger zone. : 

On large machines, where more than one worker is required, each should have a set of controls. They should be interconnected, however, so that the machine cannot start until everyone is out of the danger zone. Other Safety Devices Controls cont’d

A large press requiring six workers should have six separate sets of controls. The press will start only after all six sets of controls have been activated. : 

A large press requiring six workers should have six separate sets of controls. The press will start only after all six sets of controls have been activated. Other Safety Devices Controls cont’d

Presses are made with two-hand trip controls. The buttons are located so that the operator must remove both hands from the danger zone to reach them. : 

Presses are made with two-hand trip controls. The buttons are located so that the operator must remove both hands from the danger zone to reach them. Other Safety Devices Controls cont’d

The switches are interconnected – that is, both must be pressed at the same time to start the machine. They are placed far enough apart so that they cannot be tampered with. : 

The switches are interconnected – that is, both must be pressed at the same time to start the machine. They are placed far enough apart so that they cannot be tampered with. Other Safety Devices Controls cont’d

But some switches can be taped or bridged so that a worker can operate both with just one hand. This is a dangerous practice. You should never use it or permit it to be used on any job where you are working. : 

But some switches can be taped or bridged so that a worker can operate both with just one hand. This is a dangerous practice. You should never use it or permit it to be used on any job where you are working. Other Safety Devices Controls cont’d

Some machines have two or more switches that must be thrown in a certain order. Others have a time delay built into them so that the area can be cleared before the machine starts. Such controls are almost foolproof. : 

Some machines have two or more switches that must be thrown in a certain order. Others have a time delay built into them so that the area can be cleared before the machine starts. Such controls are almost foolproof. Other Safety Devices Controls cont’d

When materials are fed by hand, the operator may use a foot pedal to start a machine. Such machines have fixed guards that prevent the worker from operating the pedal accidentally. : 

When materials are fed by hand, the operator may use a foot pedal to start a machine. Such machines have fixed guards that prevent the worker from operating the pedal accidentally. Other Safety Devices Controls cont’d

Figure 7-14 shows such a guard. To push the switch, you must slip your foot inside the guard and then push the pedal down. : 

Figure 7-14 shows such a guard. To push the switch, you must slip your foot inside the guard and then push the pedal down. Other Safety Devices Controls cont’d

Slide 90: 

719.07-14 Fig. 7-14. Foot pedal protected by a guard 90

Special feeding and extracting tools, like those shown in Figure 7-15, can be used to place and retrieve stock at the point of operation. In the event that these special tools become caught in the dies of a machine, they are made of soft metal and will not shatter. : 

Special feeding and extracting tools, like those shown in Figure 7-15, can be used to place and retrieve stock at the point of operation. In the event that these special tools become caught in the dies of a machine, they are made of soft metal and will not shatter. Feeding and Extracting Tools

They do not replace other safety features, but they do eliminate the need for the operator to reach into the danger zone. : 

They do not replace other safety features, but they do eliminate the need for the operator to reach into the danger zone. Feeding and Extracting Tools cont’d

Slide 93: 

719.07-15 Fig. 7-15. Feeding and extracting tools 93

Such tools are required when the material is hot, delicate, or difficult to pick up. Examples of the tools include push sticks, tongs, pliers, suction cups, and magnetic pickup tools. : 

Such tools are required when the material is hot, delicate, or difficult to pick up. Examples of the tools include push sticks, tongs, pliers, suction cups, and magnetic pickup tools. Feeding and Extracting Tools cont’d

Make sure that the tool you are using is comfortable and does not require you to exert force or bend your wrist to use it. : 

Make sure that the tool you are using is comfortable and does not require you to exert force or bend your wrist to use it. Feeding and Extracting Tools cont’d

Some presses have automatic ejectors for removing processed material from the points of operation. Ejectors do not replace guards, but they too make it unnecessary for the operator to reach into the danger zone. : 

Some presses have automatic ejectors for removing processed material from the points of operation. Ejectors do not replace guards, but they too make it unnecessary for the operator to reach into the danger zone. Ejectors

Mechanical ejectors include springs, knockout pins, and lift out fingers. They can also work by gravity. On some presses, as air blows the material out of the point-of-operation area. : 

Mechanical ejectors include springs, knockout pins, and lift out fingers. They can also work by gravity. On some presses, as air blows the material out of the point-of-operation area. Ejectors cont’d

As a maintenance technician, you must realize that most safety equipment is there to protect the operator who works with the machine on a daily basis. You may need to remove that safety equipment because you are working on the machine. : 

As a maintenance technician, you must realize that most safety equipment is there to protect the operator who works with the machine on a daily basis. You may need to remove that safety equipment because you are working on the machine. Ejectors cont’d

You must learn what the safety devices are, where they are, and what they protect against. Always make sure to have a guard properly replaced once it has been removed. : 

You must learn what the safety devices are, where they are, and what they protect against. Always make sure to have a guard properly replaced once it has been removed. Ejectors cont’d

To service or repair a machine while the power is still on is to invite an accident. Throwing the main switch is not all there is to safe maintenance, however. Energy may remain stored in the machinery. : 

To service or repair a machine while the power is still on is to invite an accident. Throwing the main switch is not all there is to safe maintenance, however. Energy may remain stored in the machinery. OSHA Lockout/Tagout Procedures

It may be hydraulic energy, if the machinery uses fluid power. It may be pneumatic energy, if it uses air. Springs may be compressed or under tension. Chemicals can react. The force of gravity can move part of a machine and injure someone. : 

It may be hydraulic energy, if the machinery uses fluid power. It may be pneumatic energy, if it uses air. Springs may be compressed or under tension. Chemicals can react. The force of gravity can move part of a machine and injure someone. OSHA Lockout/Tagout Procedures cont’d

OSHA has established a lockout/tagout standard (29 CFR 1910.147) that helps safeguard workers from hazardous energy while they are performing maintenance on machines or equipment. The standard, which went into effect on January 2, 1990, not only states that equipment must be turned off and disconnected from the energy source prior to servicing. : 

OSHA has established a lockout/tagout standard (29 CFR 1910.147) that helps safeguard workers from hazardous energy while they are performing maintenance on machines or equipment. The standard, which went into effect on January 2, 1990, not only states that equipment must be turned off and disconnected from the energy source prior to servicing. OSHA Lockout/Tagout Procedures cont’d

It also requires employers to develop written lockout/tagout procedures, to train all those employees who could be injured by the accidental start-up or release of stored energy, and to carry out periodic inspections (at least annually) to ensure that the energy control procedures are being implemented properly. : 

It also requires employers to develop written lockout/tagout procedures, to train all those employees who could be injured by the accidental start-up or release of stored energy, and to carry out periodic inspections (at least annually) to ensure that the energy control procedures are being implemented properly. OSHA Lockout/Tagout Procedures cont’d

OSHA has developed guidelines for bringing about what is known as a zero energy state, which makes it impossible to activate a machine while someone is working on it. : 

OSHA has developed guidelines for bringing about what is known as a zero energy state, which makes it impossible to activate a machine while someone is working on it. OSHA Lockout/Tagout Procedures cont’d

You should not work on a machine, whether you are lubricating, cleaning, or unjamming a piece of production equipment, until you have brought it to this state. : 

You should not work on a machine, whether you are lubricating, cleaning, or unjamming a piece of production equipment, until you have brought it to this state. OSHA Lockout/Tagout Procedures cont’d

Bringing machinery to a zero energy state starts with locking out the power. Each worker should have an assigned lock, a key, and a lockout device. No two keys should it the same lock. : 

Bringing machinery to a zero energy state starts with locking out the power. Each worker should have an assigned lock, a key, and a lockout device. No two keys should it the same lock. Lockout

You initials or your clock number should be stamped on your lock. A lockout device is shown in Fig. 7-16. The procedure for locking out the power to a piece of equipment consists of the following steps: : 

You initials or your clock number should be stamped on your lock. A lockout device is shown in Fig. 7-16. The procedure for locking out the power to a piece of equipment consists of the following steps: Lockout cont’d

Slide 108: 

719.07-16 Fig. 7-16. Lockout device with warning tag 108

1 Notify the operator that you will be working on the machine.2 Turn the electric power off in two places (the stop button and the E-stop) and attach the lockout device to the energy-isolating device (that is, the circuit breaker or disconnect switch) in such a way that the power cannot be turned on. : 

1 Notify the operator that you will be working on the machine.2 Turn the electric power off in two places (the stop button and the E-stop) and attach the lockout device to the energy-isolating device (that is, the circuit breaker or disconnect switch) in such a way that the power cannot be turned on. Lockout cont’d

3 Place your own padlock on the lockout device. Anyone else who is working on the same equipment can add his or her own lock to the lockout device.4 Place an appropriate warning sign at the controls indicting that work is in progress. : 

3 Place your own padlock on the lockout device. Anyone else who is working on the same equipment can add his or her own lock to the lockout device.4 Place an appropriate warning sign at the controls indicting that work is in progress. Lockout cont’d

In order to bring a machine to a zero energy state, you must take the following steps after you have locked out the power and before you begin work: : 

In order to bring a machine to a zero energy state, you must take the following steps after you have locked out the power and before you begin work: Lockout cont’d

1 Make sure that all moving parts of the machinery have come to a complete stop. : 

1 Make sure that all moving parts of the machinery have come to a complete stop. Lockout cont’d

2 Check for pneumatic and hydraulic lines in the machinery. (They should be marked with labels or signs.) If they affect the area where you are going to work, bleed, drain, or purge them. This is the only way to eliminate the pressure, the contents, or both. : 

2 Check for pneumatic and hydraulic lines in the machinery. (They should be marked with labels or signs.) If they affect the area where you are going to work, bleed, drain, or purge them. This is the only way to eliminate the pressure, the contents, or both. Lockout cont’d

2 Air valves should be vented to the atmosphere. Surge tanks and reservoirs may be drained. You must do this to prevent any buildup of pressure in the lines. : 

2 Air valves should be vented to the atmosphere. Surge tanks and reservoirs may be drained. You must do this to prevent any buildup of pressure in the lines. Lockout cont’d

3 The valves controlling these lines then should be locked out. A lockout device on a valve is shown in Fig. 7-17. 4 Now check for mechanisms that are under spring tension or compression. Block, clamp, or chain them in position. : 

3 The valves controlling these lines then should be locked out. A lockout device on a valve is shown in Fig. 7-17. 4 Now check for mechanisms that are under spring tension or compression. Block, clamp, or chain them in position. Lockout cont’d

Slide 116: 

719.07-17 Fig. 7-17. Lockout device on a valve 116

5 Check for suspended mechanisms or parts that can drop to a lower position. Either lower them to their lowest position or block, clamp, or chain them in place so that they cannot fall. Some press rams are held by a brake when the power is off. Even so, place a sturdy brace or block under the ram (see Fig. 7-18). The brake might fail as you work on the machine. : 

5 Check for suspended mechanisms or parts that can drop to a lower position. Either lower them to their lowest position or block, clamp, or chain them in place so that they cannot fall. Some press rams are held by a brake when the power is off. Even so, place a sturdy brace or block under the ram (see Fig. 7-18). The brake might fail as you work on the machine. Lockout cont’d

Slide 118: 

719.07-18 Fig. 7-18. Safety blocks installed on a power press 118

6 Check for sharp or projecting parts or surfaces that can cut, tear, or gouge You. Either remove them or pad them, whichever is easier. : 

6 Check for sharp or projecting parts or surfaces that can cut, tear, or gouge You. Either remove them or pad them, whichever is easier. Lockout cont’d

When you have completed your work, inspect the work area to make sure that all tools and other items have been cleaned up and that all safety guards are in place. Check to be sure that no one is near any moving parts when you are ready to restore power. : 

When you have completed your work, inspect the work area to make sure that all tools and other items have been cleaned up and that all safety guards are in place. Check to be sure that no one is near any moving parts when you are ready to restore power. Lockout cont’d

When the inspection is complete, remove your own lock. The last worker to remove his or her lock also may remove the lockout device. Never remove anyone else’s lock or tag, and never allow anyone to remove yours for you. : 

When the inspection is complete, remove your own lock. The last worker to remove his or her lock also may remove the lockout device. Never remove anyone else’s lock or tag, and never allow anyone to remove yours for you. Lockout cont’d

If you lose your key, notify your supervisor at once and get a new lock and key. Finally, test the machinery for proper operation, and notify the operator that the machine is back in operating condition. : 

If you lose your key, notify your supervisor at once and get a new lock and key. Finally, test the machinery for proper operation, and notify the operator that the machine is back in operating condition. Lockout cont’d

In some cases, lockout may not be possible. Equipment then must be tagged out. Lockout is the preferred method, since no one can remove your lock without your key. Tags are not as safe as locks, because they can easily be removed, overlooked, or ignored. : 

In some cases, lockout may not be possible. Equipment then must be tagged out. Lockout is the preferred method, since no one can remove your lock without your key. Tags are not as safe as locks, because they can easily be removed, overlooked, or ignored. Tagout

In tagout applications, it becomes even more important for all employees to receive the proper training. Everyone must be aware of correct tagout procedures to ensure safe working conditions. : 

In tagout applications, it becomes even more important for all employees to receive the proper training. Everyone must be aware of correct tagout procedures to ensure safe working conditions. Tagout cont’d

Essentially, a tag or tagout device is a warning device that takes the place of a lock without providing the physical restraint of a lock. A tag simply identifies a source of potential danger and indicates that the equipment being worked on may not be operated until the tag is removed. : 

Essentially, a tag or tagout device is a warning device that takes the place of a lock without providing the physical restraint of a lock. A tag simply identifies a source of potential danger and indicates that the equipment being worked on may not be operated until the tag is removed. Tagout cont’d

OSHA makes the following requirements regarding tagout devices: • Tags, like locks, must clearly identify the employee who applies them. When a tag is attached to an energy-isolating device, it must not be removed except by the person who applied it. Tags should never be bypassed or ignored. : 

OSHA makes the following requirements regarding tagout devices: • Tags, like locks, must clearly identify the employee who applies them. When a tag is attached to an energy-isolating device, it must not be removed except by the person who applied it. Tags should never be bypassed or ignored. Tagout cont’d

• Tags must be readable and understandable by all employees. They must warn against the hazardous condition that will result if the machine or equipment is energized. Most tags have legends such as Do Not Start, Do Not Open, Do Not Operate, Danger, etc. (see Fig.7-16). : 

• Tags must be readable and understandable by all employees. They must warn against the hazardous condition that will result if the machine or equipment is energized. Most tags have legends such as Do Not Start, Do Not Open, Do Not Operate, Danger, etc. (see Fig.7-16). Tagout cont’d

Slide 128: 

719.07-16 Fig. 7-16. Lockout device with warning tag 128

• Tags must be made of materials that can withstand the environmental conditions in which they will be used. • Tags must be affixed securely to energy- isolating devices so that they cannot be detached accidentally during use. : 

• Tags must be made of materials that can withstand the environmental conditions in which they will be used. • Tags must be affixed securely to energy- isolating devices so that they cannot be detached accidentally during use. Tagout cont’d

It is easy enough to follow rules, especially when you understand that they are for your own protection. They are not for the purpose of slowing you down or making your job harder for you. : 

It is easy enough to follow rules, especially when you understand that they are for your own protection. They are not for the purpose of slowing you down or making your job harder for you. Tagout cont’d

But you must do more than follow the rules. For example, if your plant does not have lockout devices on valves, ask for them. Even if you feel that a project will take only a minute or so to complete, use the lockout system. : 

But you must do more than follow the rules. For example, if your plant does not have lockout devices on valves, ask for them. Even if you feel that a project will take only a minute or so to complete, use the lockout system. Tagout cont’d

You should never put up with someone else’s failure to follow the energy control procedures established in your plant. If the procedures are being bypassed, or if part of the procedure is lacking, report the situation to someone who can change it. Remember that you can be injured by someone else’s failure to follow safe working procedures. : 

You should never put up with someone else’s failure to follow the energy control procedures established in your plant. If the procedures are being bypassed, or if part of the procedure is lacking, report the situation to someone who can change it. Remember that you can be injured by someone else’s failure to follow safe working procedures. Tagout cont’d

Your only sure protection is to bring each machine you work on to a zero energy state. Maintenance workers who have not learned this are the ones who suffer the most serious injuries. : 

Your only sure protection is to bring each machine you work on to a zero energy state. Maintenance workers who have not learned this are the ones who suffer the most serious injuries. Tagout cont’d

Take no chances. Take no shortcuts. Do not depend on someone else to protect you from danger in the plant. Take those few extra moments to do the job right, and protect yourself. : 

Take no chances. Take no shortcuts. Do not depend on someone else to protect you from danger in the plant. Take those few extra moments to do the job right, and protect yourself. Tagout cont’d

Slide 136: 

Randy Gray, Adjunct Instructor, IS-100 President of Grayhawk Safety & Health Consulting Company 5795 Mayfield Hwy. Benton, Kentucky 42025-4749 270-703-8282 Cell 270-527-5680 Fax 270-205-0418 GM Hummer Onstar Cell Phone jgray0015@KCTCS.EDU OR randy@grayhawksafety.com www.grayhawksafety.com