Amputations are among the most severe and disabling workplace injuries that often result in permanent disability. They are widespread and involve various activities and equipment. The U.S. Bureau of Labor Statistics 2017 annual survey data indicated that there were 121,860 hand injuries and 6,090 non-fatal amputation cases – involving days away from work – for all private industry.
Approximately 60 percent of all workplace amputations were caused by machinery, such saws, presses, conveyors, milling machines, drill stands, bending, rolling or shaping machines, as well as from powered and non-powered hand tools, and other materials handling activities.
Understanding the mechanical components of machinery and the hazardous mechanical motion that occurs at or near these components in conjunction with machinery operation will help employees avoid injury.
Primary safeguarding includes control methods that protect (e.g., prevent employee contact with hazardous machine areas) employees from machine hazards through effective machine-guarding techniques.
In addition, a hazardous energy control (lockout/tagout) program needs to complement machine safeguarding methods in order to protect employees during potentially hazardous servicing and maintenance work activities.
Hazardous Mechanical Components
Three types of mechanical components present amputation hazards:
Point of Operation is the area of the machine where the machine performs work – i.e., mechanical actions that occur at the point of operation, such as cutting, shaping, boring, and forming.
Power-Transmission Apparatus is all components of the mechanical system that transmit energy, such as flywheels, pulleys, belts, chains, couplings, connecting rods, spindles, cams, and gears.
Other Moving Parts are the parts of the machine that move while the machine is operating, such as reciprocating, rotating, and transverse moving parts as well as lead mechanisms and auxiliary parts of the machine.
Safeguarding is essential for protecting employees from needless and preventable injury. A good rule to remember is: Any machine part, function, or process that may cause injury must be safeguarded.
Primary safeguarding methods refers to machine guarding techniques that are intended to prevent or greatly reduce the chance that an employee will have an amputation injury. Refer to the 29 CFR 1910, Subpart O for specific guarding requirements.
Machine safeguarding must be supplemented by an effective energy control (lockout/tagout) program that ensures that employees are protected from hazardous energy sources during machine servicing and maintenance work activities. Lockout/tagout plays an essential role in the prevention and control of workplace amputations. In terms of controlling amputation hazards, employees are protected from hazardous machine work activities either by: 1) effective machine safeguarding, or 2) lockout/tagout where safeguards are rendered ineffective or do not protect employees from hazardous energy during servicing and maintenance operations.
Additionally, there are some servicing activities, such as lubricating, cleaning, releasing jams and making machine adjustments that are minor in nature and are performed during normal production operations. It is not necessary to lockout/ tagout a machine if the activity is routine, repetitive and integral to the production operation provided that you use an alternative control method that affords effective protection from the machine’s hazardous energy sources.
The employer is responsible for safeguarding machines. The guards and devices used need to be compatible with a machine’s operation and designed to ensure safe operator use. The type of operation, size, and shape of stock, method of feeding, physical layout of the work area, and production requirements all affect the selection of safeguards. Also, safeguards should be designed with the machine operator in mind as a guarding method that interferes with the operation of the machine may cause employees to override them. To ensure effective and safe operator use, guards and devices should suit the operation.
The Performance Criteria for Safeguarding [ANSI B11.19-2010] national consensus standard provides valuable guidance as the standard addresses the design, construction, installation, operation and maintenance of the safeguarding used to protect employees from machine hazards. The following safeguarding method descriptions are, in part, structured like and, in many ways are similar to this national consensus standard.
The Performance Criteria for Safeguarding [ANSI B11.19-2010] defines safeguarding as the protection of personnel from hazards by the use of guards, safeguarding devices awareness devices, safeguarding methods, or safe work procedures. The following ANSI B11.19 definitions describe the various types of safeguarding:
Guard: A barrier that prevents exposure to an identified hazard.
Safeguarding device: A device that detects or prevents inadvertent access to a hazard.
Awareness device: A barrier, signal or sign that warns individuals of an impending, approaching or present hazard.
Safeguarding method: Safeguarding implemented to protect individuals from hazards by the physical arrangement of distance, holding, openings, or positioning of the machine or machine production system to ensure that the operator cannot reach the hazard.
Safe work procedures: Formal written instructions developed by the user which describe how a task is to be performed.
Primary Safeguarding Methods
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.
Criteria for Machine Safeguarding
Prevents employee contact with the hazard area during machine operation.
Avoids creating additional hazards.
Is secure, tamper-resistant, and durable.
Avoids interfering with normal operation of the machine.
Allows for safe lubrication and maintenance.
Guards usually are preferable to other control methods because they are physical barriers that enclose dangerous machine parts and prevent employee contact with them. To be effective, guards must be strong and fastened by any secure method that prevents the guard from being inadvertently dislodged or removed. Guards typically are designed with screws, bolts and lock fasteners and usually a tool is necessary to unfasten and remove them. Generally, guards are designed not to obstruct the operator’s view or to prevent employees from doing a job.
In some cases, guarding may be used as an alternative to lockout/tagout because employees can safely service or maintain machines with a guard in place. For example, polycarbonate and wire-mesh guards provide greater visibility and can be used to allow maintenance employees to safely observe system components. In other instances, employees may safely access machine areas, without locking or tagging out, to perform maintenance work (such as machine cleaning or oiling tasks) because the hazardous machine components remain effectively guarded.
Guards must not create additional hazards such as pinch points or shear points between guards and other machine parts. Guard openings should be small enough to prevent employees from accessing danger areas.
Types of Machine Guards
Safeguarding devices are controls or attachments that, when properly designed, applied and used, usually prevent inadvertent access by employees to hazardous machine areas by:
Preventing hazardous machine component operation if your hand or body part is inadvertently placed in the danger area;
Restraining or withdrawing your hands from the danger area during machine operation;
Requiring the use of both of your hands-on machine controls (or the use of one hand if the control is mounted at a safe distance from the danger area) that are mounted at a predetermined safety distance; or
Providing a barrier which is synchronized with the operating cycle in order to prevent entry to the danger area during the hazardous part of the cycle.
A. Types of Safeguarding Devices
Fixed: Barrier that allows for stock feeding but does not permit operator to reach the danger area.
Adjustable: Barrier that adjusts for a variety of production operations.
Self-Adjusting: Barrier that moves according to the size of the stock entering point of operation. Guard is in place when machine is at rest and pushes away when stock enters the point of operation.
Interlocking Shields: Shuts off or disengages power and prevents machine start-up when guard is open. Should allow for inching of machine.
These types of engineering controls, which either prevent the start of or stop hazardous motion, may be used in place of guards or as supplemental control measures when guards alone do not adequately enclose the hazard. In order for these safeguarding devices to accomplish this requirement, they must be properly designed and installed at a predetermined safe distance from the machine’s danger area. Other safeguarding devices (probe detection and safety edge devices) that merely detect, instead of prevent, inadvertent access to a hazard are not considered primary safeguards.
B. Types of Machine Guarding
Restraint Devices: Wrists are connected by cords and secured to a fixed anchor point which limit operator’s hands from reaching the point of operation at any time.
Presence-Sensing Devices: Interlock into the machine’s control system to stop operation when the sensing field (photoelectric, radio frequency, or electromagnetic) is disturbed.
Presence-Sensing Mats: Interlock into machine’s control system to stop operation when a predetermined weight is applied to the mat. A manual reset switch must be located outside the protected zone.
Two-Hand Control: Requires concurrent and continued use of both hands, preventing them from entering the danger area.
Two-Hand Trip: Requires concurrent use of both hands, prevents them from being in danger area when machine cycle starts.
Type “A” Gate (movable barrier): Applicable to mechanical power presses. Provides barrier between danger area and operator (or other employees) until completion of machine cycle.
Type “B” Gate (movable barrier): Applicable to mechanical power presses and press brakes. Provides a barrier between danger area and operator (or other employees) during the downstroke.
Secondary Safeguarding Methods
Other safeguarding methods, such as those described in the Performance Criteria for Safeguarding (ANSI B11.19-2010), may also provide employees with some protection from machine hazards. Detection safeguarding devices, awareness devices, safeguarding methods and safe work procedures are described in this section. These methods provide a lesser degree of employee protection than the primary safeguarding methods and they are considered secondary control measures as they do not prevent employees from placing or having any part of their bodies in the hazardous machine areas.
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 in-feasibility. 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.
Probe Detection and Safety Edge Devices
A probe detection device (sometimes referred to as a ring guard), such as that found on Rockford System’s Detect-A-Finger for Welders or Detect-A-Finger for Riveters, detects the presence or absence of a person’s hand or finger by encircling all or part of the machine hazard area. The ring guard makes you aware of your hand’s entry into a hazardous area and usually stops or prevents a hazardous machine cycle or stroke, thereby reducing the likelihood of injuring yourself in the point of operation. These types of detection devices are commonly used on spot welders, riveters, staplers and stackers because primary safeguarding methods are not possible. However, probe detection devices do not prevent inadvertent access to the point-of-operation danger area; rather, they serve as a warning mechanism and may prevent the initiation of or stop the machine cycle if an employee’s hand or finger(s) is too close to the hazard area.
A safety edge device (sometimes called a bump switch) is another type of safeguard that detects the presence of an employee when they are in contact with the device’s sensing edge. A safety edge device protects employees by initiating a stop command when the sensing surface detects the presence of a person; however, they do not usually, when used by themselves, prevent inadvertent access to machine danger areas. Therefore, additional guarding or safeguarding devices must be provided to prevent employee exposure to a machine hazard.
Awareness devices warn employees of an impending, approaching or present hazard. The first type is an awareness barrier which allows access to machine danger areas, but it is designed to contact the employee, creating an awareness that he or she is close to the danger point. Awareness signals, through the use of recognizable audible or visual signals, are other devices that alert employees to an approaching or present hazard. Lastly, awareness signs are used to notify employees of the nature of the hazard and to provide instructions and training information. OSHA standard 1910.145 provides design, application, and use specifications for accident prevention (danger, caution, safety instruction) signs and (danger, caution, warning) tags.
Safeguarding methods protect employees from hazards by the physical arrangement of distance, holding, openings or the positioning of the machine components to ensure that the operator cannot reach the hazard. Some safeguarding work methods include safe distance safeguarding, safe holding safeguarding and safe opening safeguarding. Requirements for these secondary control measures may be found in ANSI B11.19-2003. Proper training and supervision are essential to ensure that these secondary safeguarding methods are being used properly. Safeguarding work methods may require the use of awareness devices, including the use of accident prevention signs where there is a need for warning or safety instruction.
Safeguarding by safe distance (by location) may involve an operator holding and supporting a work-piece with both hands at a predetermined minimum safe distance or, if both hands cannot be used to hold the work-piece at a distance so that the operator cannot reach the hazard with the free hand. For example, the feeding process itself can create a distance safeguard if the operators maintain a safe distance between their hands and the point of operation. Additionally, where material position gauges are used, they need to be of sufficient height and size to prevent slipping of the material past the gauges.
Another example of a safe distance safeguarding method is the use of gravity feed methods that reduce or eliminate employee exposure to machine hazards as the part slides down a chute into the point of operation. Automatic and semiautomatic feeding and ejection methods can also protect the employee by minimizing or eliminating employee exposure with potentially hazardous machinery components. An employee places the part in a magazine which is then fed into the point of operation. Automatic and semiautomatic ejection methods include pneumatic (jet of air), magnetic, mechanical (such as an arm), or vacuum. Figures 18 and 19 illustrate different types of automatic feeding and ejecting methods.
Safe Holding Safeguarding (Safe Work-Piece Safeguarding)
Operator’s hands are maintained away from the hazardous portion of the machine cycle by requiring that both hands are used to hold or support the work-piece, or by requiring that one hand holds the work-piece while the other hand operates the machine. For instance, if the stock is several feet long and only one end of the stock is being worked on, the operator may be able to hold the opposite end while performing the work. The operator’s body parts are out of the machine hazard area during the hazardous portion of the machine cycle. However, this work method only protects the operator.
Safe Opening Safeguarding
This method limits access to the machine hazardous areas by the size of the opening or by closing off the danger zone access when the work-piece is in place in the machine. Operators are prevented from reaching the hazard area during the machine operation; however, employee access to the danger area is not adequately guarded when the work-piece is not in place. Refer to Rockford Systems’ OSHA Guard Opening Scale and ANSI/CSA Guard Opening Scale.
Safe Work Procedures
Safe work procedures are formal, written instructions which describe how a task is to be performed. These procedures should incorporate appropriate safe work practices, such as prohibiting employees from wearing loose clothing or jewelry and requiring the securing of long hair with nets or caps. Clothing, jewelry, long hair, and even gloves can get entangled in moving machine parts.
Complementary equipment is used in conjunction with selected safeguarding techniques and it is, by itself, not a safeguarding method. Some common complementary equipment used to augment machine safeguarding include:
Emergency Stop Devices
Emergency stop devices are designed to be used in reaction to an incident or hazardous situation and, as such, are not considered machine safeguarding. These devices, such as buttons, rope-pulls, cable-pulls, or pressure-sensitive body bars, neither detect nor prevent employee exposure to machine hazards; rather they initiate an action to stop hazardous motion when an employee recognizes a hazard and activates them. (See Figure 20.)
Work-holding equipment is not used to feed or remove the work-piece, but rather to hold it in place during the hazardous portion of the machine cycle. Clamps, jigs, fixtures, back gauges and holders are examples of work-holding equipment. This equipment may be used to reduce or eliminate the need for an employee to place their hands in the hazard area.
Feeding and Ejection Systems
A feeding and ejection system (e.g., a gravity fed chute; semi-automatic and automatic feeding and ejection equipment), by itself, does not constitute secondary safeguarding. However, the use of properly designed feed and ejection mechanisms can protect employees by minimizing or eliminating the need for them to be in a hazard area during the hazardous motion of the machine.
Operators can use tools to feed and remove material into and from machines so as to keep their hands away from the point of operation. However, this must be done only in conjunction with the guards and safeguarding devices described previously. Hand tools are not point-of-operation guarding or safeguarding devices and they need to be designed to allow employees’ hands to remain outside of the machine danger area. Using hand tools requires close supervision to ensure that the operator does not bypass their use to increase production. It is recommended that these tools be stored near the operation to promote their use.
Foot controls that are not securely fixed at a safe distance do not constitute machine safeguarding because they do not keep the operator’s hands out of the danger area. If you use foot-actuated controls that are not single-control safeguarding devices, they will need to be used with some type of guard or other safeguarding device.
Improperly used foot-actuated controls may increase productivity, but the freedom of hand movement increases the risk of a point-of-operation injury or amputation. Foot controls must be guarded to prevent accidental activation by another employee or by falling material. Do not ride the foot pedal. Ensure that the machine control circuit is properly designed to prevent continuous cycling. (See Figure 22 for an example of a properly guarded foot control.)
As an employer, you need to consider housekeeping practices, employee apparel, and employee training. Implement good housekeeping practices to promote safe working conditions around machinery by doing the following:
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.
Employees should not wear loose-fitting clothing, jewelry, or other items that could become entangled in machinery, and long hair should be worn under a cap or otherwise tied back or contained to prevent entanglement in moving machinery.
Adequate instruction in the safe use and care of machines and supervised on-the-job training are essential in preventing amputation injuries. Only trained employees should operate machinery.
Train Employees in the Following:
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; and
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.
In addition to employee instruction and training, employers need to provide adequate supervision to reinforce safe practices. Take disciplinary action to enforce safe work practices and working conditions.
OSHA’s lockout/tagout (LOTO) standard, 29 CFR 1910.147, establishes minimum performance requirements for controlling hazardous energy and it is intended to complement and augment machine safeguarding practices. The lockout/tagout standard applies only if employees are exposed to hazardous energy during servicing/maintenance activities. An employer may avoid the requirements of the LOTO standard if the safeguarding method eliminates your employees’ exposure to the machine danger area during the servicing or maintenance work by using Machinery and Machine Guarding methods in accordance with the requirements contained in 29 CFR 1910, Subpart O.
Additionally, because some minor servicing may have to be performed during normal production operations, an employer may be exempt from LOTO in some instances. Minor tool changes and adjustments and other minor servicing operations, which take place during normal production operations, are not covered by lockout/tagout if they are routine, repetitive and integral to the use of the machine for production and if work is performed using alternative effective protective measures that provide effective employee protection. For more information on this topic, read our blog HERE.
In short, a hazardous energy control program is a critical part of an overall strategy to prevent workplace amputations during machine servicing and maintenance activities, such as during the setting up of machines for production purposes, bypassing guards to clear jams or lubricate parts, and inspecting, adjusting, replacing, or otherwise servicing machine parts. Machine amputations occur when an employer does not have or fails to implement practices and procedures to disable and control a machine’s energy sources during machine servicing and maintenance work.
Specific Machine Hazards and Safeguarding Methods
The machinery listed below cause amputation injuries, and appropriate safeguarding and hazardous energy control (lockout/tagout) methods are addressed in this section. Employers need to consult the OSHA standard for specific machinery to ensure compliance with all requirements.
Machinery Associated with Amputations
1. Mechanical Power Presses
2. Power Press Brakes
3. Powered and Non-Powered Conveyors
4. Printing Presses
5. Roll-Forming and Roll-Bending Machines
6. Shearing Machines
7. Food Slicers
8. Meat Grinders
9. Meat-Cutting Band Saws
10. Drill Presses
11. Milling Machines
12. Grinding Machines
Machine safeguarding not only required by law, but it also helps reduce risk and keep employees safe at work. Proper safeguarding can be complex and any safeguarding project should always begin with a risk assessment.
For more information about machine safeguarding, please call 1-800-922-7533 or refer to our Machine Safeguarding Seminars, which provide 2.5 days of in-depth instruction on the topics covered above (and more).