Machine Safety Overview

Point of Operation: The area of the machine where it performs work includes mechanical actions like cutting, shaping, boring, and forming at the point of operation.

Power-transmission and exposed parts:  Components of the mechanical system that transmit energy, such as flywheels, pulleys, belts, chains, couplings, connecting rods, spindles, cams, and gears.

Safeguarding is essential: Protecting employees from preventable injuries and machine hazards is crucial for every business. Primary safeguarding methods are machine-guarding techniques designed to prevent or significantly reduce the risk of serious injuries at work. For detailed requirements, refer to OSHA (Occupational Safety and Health Administration) 29 CFR 1910, Subpart O.

Employers are responsible for the safeguarding of their machines: Guards and shields must be compatible with the machine’s operation and ensure safe use. Factors like the type of operation, stock size and shape, feeding method, work area layout, and production needs all influence safeguard selection. Safeguards should also be designed to avoid interfering with machine operation, as this may lead to employees bypassing them. To ensure safety, guards and devices must suit the specific operation.

ANSI (American National Standards Institute) B11.19-2019 guides the design, construction, installation, operation, and maintenance of safeguards used to protect employees from machine hazards. Some of the following safeguarding method descriptions are structured similarly to this national consensus standard.

ANSI B11.19-2019 defines risk reduction measures as protecting personnel from hazards through 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 piece of equipment that protects the user from the hazards of the machine.

Safeguarding Device:  A device that protects users from hazards by preventing or detecting exposure.

Awareness Means:  A barrier, signal, or sign that warns the user of an impending, approaching, or present hazard.

Safeguarding Method:  Risk reduction measures protect individuals from hazards by using distance, barriers, openings, or machine positioning to prevent access to the hazard.

Safe Work Procedure(s):  Formal written documentation created by the user that provides instructions for safely completing tasks where hazardous situations may arise or hazardous events are likely to occur.

Two primary methods are used to reduce risk on machinery, guards, and different types of safeguarding devices: Guards serve as physical barriers that block access to hazardous areas. Safeguarding devices prevent or detect operator contact with the point of operation or stop hazardous machine motion if any part of the user’s body is in or near the hazard. Both safeguards must be properly designed, built, installed, used, and maintained in good working condition to ensure employee safety.

Criteria for Reducing Risk

• Measures should prevent employee contact with hazardous areas during machine operation.
• Measures should not introduce new hazards.
• Measures should be secure, tamper-resistant, and durable.
• Measures should not interfere with normal machine operation.
• Measures should allow for safe lubrication and maintenance.

GUARDS

Guards are often the preferred control method because they serve as physical barriers that enclose hazardous machine parts and prevent user contact. To be effective, they must be strong and securely fastened to prevent accidental removal or displacement. Guards are typically secured with screws, bolts, or lock fasteners, requiring a tool for removal. They are generally designed to avoid obstructing the operator’s view or interfering with job performance.

In some cases, guards can be used instead of lockout/tagout, allowing employees to safely service or maintain machines while the guard remains in place. Polycarbonate and wire mesh guards, for example, provide visibility and let maintenance workers safely observe system components. In certain situations, employees can perform tasks like cleaning or oiling without locking or tagging out, as long as hazardous machine components remain effectively guarded. However, guards must not introduce new hazards, such as pinch points or shear points, and openings should be small enough to prevent access to dangerous areas.

Safeguarding Devices

Safeguarding devices help reduce hazards by preventing employees from accidentally accessing dangerous machine areas when properly designed, installed, and used. These devices enhance safety by:

• Stopping machine operation if a hand or body part enters a hazard zone.
• Restraining or pulling hands away from hazardous areas while the machine is running.
• Requiring both hands to operate machine controls, or one hand if the control is positioned at a safe distance.
• Using a barrier that moves in sync with the machine’s operating cycle to block access during hazardous phases.

A. Types of Safeguarding Devices

• Fixed: Allows material to be fed into the machine but prevents the operator from reaching the hazard zone.
• Adjustable: Can be modified to accommodate different production operations.
• Self-Adjusting: Moves according to the size of the material entering the point of operation. It remains in place when the machine is idle and shifts away as the material enters.
• Presence-Sensing Devices: Detects individuals or objects within a sensing field, area, or plane and triggers a response to stop hazardous motion.
• Shield: A physical barrier that contains or redirects materials, energy, or debris to reduce the risk of ejection from the machine.
• Interlocking Shields: Designed with an interlock switch that disengages power and prevents the machine from starting if the shield is not securely in place in front of the hazard.

These engineering controls prevent or stop hazardous motion and can serve as alternatives to guards or complementary devices when guards are impractical or insufficient. For safeguarding devices to be effective, they must be properly designed, installed, and maintained. Devices such as probe detection and safety edge sensors, which only detect rather than prevent accidental access to hazards, are not considered primary safeguards.

B. Types of Machine Safeguarding Devices

• Restraint Devices: Wrist straps attached to fixed anchor points limit an operator’s hand movement, preventing them from reaching the hazardous area.
• Presence-Sensing Devices: Detects individuals or objects within a designated sensing area and triggers a response to stop hazardous motion.
• Pressure-Sensitive Mats: Floor mats equipped with sensors that stop machine operation when a predetermined weight is applied. A manual reset switch must be positioned outside the protected zone.
• Two-Hand Control Device: Requires the operator to use both hands simultaneously to activate the machine and maintain contact during hazardous phases of the cycle.
• Two-Hand Trip Device: Requires both hands to be used at the same time to start a machine cycle, commonly used with full-revolution clutch machines.
• Type “A” Gate (Movable Barrier): Used with mechanical power presses, this barrier prevents access to the hazard area until the machine cycle is complete.
• Type “B” Gate (Movable Barrier): Designed for mechanical power presses, this gate blocks access to the hazard area specifically during the downstroke portion of the machine cycle.

A probe detection device, sometimes called a halo or ring guard, detects the presence or absence of a person’s hand or fingers by surrounding all or part of the machine’s hazard area. If interrupted, the device stops or prevents the machine cycle, reducing the risk of injury at the point of operation.

These devices are commonly used on spot welders, riveters, staplers, and stakers when other primary safety measures are not feasible. However, probe detection devices do not physically prevent accidental access to hazardous areas. Instead, they act as a warning system, stopping the machine from starting if a hand or fingers are too close to the danger zone.

Awareness devices help warn employees of potential or existing hazards.

• Awareness barriers allow access to hazardous areas but serve as a visual cue that employees are too close to a danger zone.
• Awareness signals use recognizable sounds or visual alerts to warn of an approaching or present hazard.
• Awareness signs provide information about specific hazards and include instructions or training details.

OSHA 1910.145 and ANSI Z535 1-4 outline design, application, and usage requirements for accident prevention signs (danger, caution, safety instruction) and hazard warning tags (danger, caution, warning).

Safeguarding Methods

Safeguarding methods protect employees from machine hazards by using physical distance, material handling techniques, controlled openings, or strategic positioning of machine components to prevent operator access to dangerous areas. Common safeguarding methods include safe distance safeguarding, safe holding safeguarding, and safe opening safeguarding. These secondary control measures are outlined in ANSI B11.19-2019. Proper training and supervision are critical to ensuring their effectiveness. Awareness devices, such as accident prevention signs, may also be necessary when warnings or safety instructions are required.

Safeguarding by Distance

Safeguarding by distance, also known as safeguarding by location, involves positioning the operator at a safe distance from hazardous machine components. One example is a gravity-feed system, where materials slide down a chute into the point of operation, reducing direct employee exposure. Automatic and semiautomatic feeding and ejection methods, such as pneumatic air jets, magnetic or mechanical arms, or vacuum systems, can also minimize or eliminate an operator’s interaction with hazardous parts.

Safe Work-Piece Holding

This method keeps an operator’s hands away from hazardous areas by requiring both hands to hold or support the workpiece or by ensuring one hand holds the material while the other operates the machine. For example, if only one end of a long stock piece is being worked on, the operator can safely hold the opposite end while performing the task. This method protects the operator but does not necessarily safeguard other employees nearby.

Safe Opening Safeguarding

This approach restricts access to hazardous areas by controlling the size of openings or by blocking entry to the hazard zone when the piece is in place. While this method prevents operator access during machine operation, it may not provide adequate protection when no piece is present. Guarding solutions, such as those outlined in Protech Systems OSHA Guard Opening Scale and ANSI/CSA Guard Opening Scale, help ensure compliance with safety standards.

Safe Work Procedures

Safe work procedures are written guidelines that outline how tasks should be performed safely. These instructions should include best practices, such as prohibiting loose clothing or jewelry and requiring long hair to be secured with nets or caps. Items like gloves, jewelry, and loose clothing can become entangled in moving machine parts, increasing the risk of injury. Proper adherence to these procedures helps maintain a safe working environment.

Complementary equipment is used alongside safeguarding methods to enhance worker safety but does not serve as a primary means of protection. Some commonly used complementary equipment include:

Emergency Stop Devices

Emergency stop devices respond to hazardous situations but do not prevent exposure to machine dangers. These devices—such as buttons, cable pulls, and pressure-sensitive body bars, are activated when an employee recognizes a hazard, stopping the machine’s motion to prevent injury. However, they do not detect or prevent access to hazardous areas.

Work-Holding Equipment

Work-holding equipment secures a workpiece in place during machine operation but does not feed or remove it. Clamps, jigs, fixtures, back gauges, and holders help reduce the need for an operator’s hands to be near hazardous areas, lowering the risk of injury.

Feeding and Ejection Systems

While feeding and ejection systems, such as gravity-fed chutes and automated or semi-automated feeders are not considered safeguarding measures on their own, they help minimize worker exposure to hazardous machine motion. Properly designed feeding and ejection mechanisms reduce the need for operators to be near the danger zone during machine operation.

Hand-Feeding Tools

Hand-feeding tools help operators keep their hands away from machine hazards when loading, unloading, or clearing jams. These tools should be used alongside other hazard reduction measures. To ensure compliance, supervisors must monitor their use, as operators may be tempted to bypass them to speed up production. Ideally, these tools should be made from “crushable” materials, such as aluminum, and stored near the work area for easy access.

Foot Controls

Foot-actuated controls, when not properly secured or positioned at a safe distance, do not reduce hazards and may increase the risk of injury by allowing unrestricted hand movement. To prevent accidental activation, foot controls should be equipped with guards and positioned to avoid unintended use by another worker or falling materials. When using foot controls that are not integrated into a safeguarding system, they must be paired with a primary hazard reduction method to ensure worker safety.

Employers play a crucial role in maintaining a safe work environment by enforcing housekeeping practices, proper employee attire, and comprehensive training. These measures help minimize workplace hazards and ensure safe machine operation.

Housekeeping Practices

Maintaining a clean and organized work area reduces the risk of accidents and promotes a safer working environment. Employers should:

• Remove slip, trip, and fall hazards around machines.
• Use drip pans when oiling equipment to prevent spills.
• Dispose of waste stock immediately after it is generated.
• Ensure work areas are spacious enough for safe machine operation and maintenance.
• Position machines away from high-traffic areas to reduce distractions.

Employee Attire

Proper work attire is essential to prevent injuries caused by entanglement in moving machinery. Employees should avoid loose-fitting clothing, jewelry, or accessories that could get caught in equipment. Long hair should be secured under a cap or tied back to prevent entanglement.

Employee Training

Thorough training is key to preventing workplace injuries, including amputations. Only employees who have received proper instruction should be allowed to operate machinery. Employers should provide training on:

• Workplace hazards, including machine-specific risks.
• Machine operation procedures, lockout/tagout protocols, and safe work practices.
• The purpose and correct use of machine safeguards.
• Proper responses to safeguarding issues, including immediately reporting missing or damaged guards and unsafe conditions to supervisors.

Supervision and Enforcement

Training alone is not enough—ongoing supervision is necessary to reinforce safe work habits. Employers should actively monitor employees to ensure compliance with safety procedures and take disciplinary action when necessary to enforce workplace safety standards.

The Occupational Safety and Health Administration’s (OSHA) lockout/tagout (LOTO) standard, 29 CFR 1910.147, sets minimum performance requirements for controlling hazardous energy. This regulation is designed to complement and enhance machine safeguarding measures, reducing the risk of serious workplace injuries.

In certain cases, employers may be exempt from LOTO requirements. Minor tool changes, adjustments, and routine servicing performed during normal production operations may not require lockout/tagout, provided that they are repetitive and integral to the production process, and alternative protective measures effectively safeguard employees.

A well-implemented hazardous energy control program is essential for preventing workplace amputations during machine servicing and maintenance. This includes procedures for setting up equipment for production, bypassing guards to clear jams or lubricate parts, and inspecting, adjusting, or replacing machine components.

Employers should implement proper safeguarding and hazardous energy control measures for machines known to pose serious risks of injury.

These include:

1. Mechanical power presses
2. Power press brakes
3. Powered and non-powered conveyors
4. Roll-forming and roll-bending machines
5. Shearing machines
6. Drill presses
7. Milling machines
8. Grinding machines
9. Slitters