What is Machine Guarding? Importance of Guards in Machine Safety

In many industrial settings, workers are required to operate heavy machinery and equipment. While these machines are necessary for producing goods and services, they can also be hazardous and pose a significant risk to the machine operator if proper safety measures are not in place. Machine guarding is one of the most important safety measures employers must implement to protect their workers from injuries caused by machine operation.

In this article, we will discuss the importance of machine guarding, why they are essential for safety, the dangers of not using them, OSHA requirements, and the best practices for implementing these measures in the workplace.

Machine guarding refers to the various safety measures implemented to protect workers from the hazards associated with machinery. These measures include physical barriers, safety devices, and other controls designed to prevent contact with dangerous machine parts, minimize the risk of accidents, and ensure safe operation. The primary goal of machine guarding is to protect operators and other employees from injuries caused by moving parts, flying debris, electrical hazards, and other potential dangers.

Machines and other heavy industrial equipment have different types of movements that post various risks to workers. The most common types of hazardous machine motions are:

Rotating Movement
This to any part of the machine that turns around an axis. This can include components like gears, flywheels, drums, or the spindle of a machine tool. Rotation can occur at various speeds, often high, and the motion can be continuous or intermittent depending on the machine's design.

Reciprocating Movement
This type of machine motion involves a part moving back and forth in a straight line. This action is typical in machinery like mechanical saws, shapers, and platen presses. The motion is generally regular and predictable, which can sometimes lead to complacency among operators.

Transverse Movement
Transverse motion refers to parts that move in a line from side to side, perpendicular to the direction of the operator. This type of movement is common in equipment where materials need to be positioned or shifted, such as conveyors or automated material handling systems.

Cutting Action
Commonly associated with tools with sharp edges or those moving to cut material such as circular saws, band saws, and milling machines. The cutting action can be powered by different mechanisms, usually involving a combination of rotating, reciprocating, or transverse movements.

Punching, Shearing, and Bending
Involves machines used in metalworking, such as presses and shears, involve punching, shearing, or bending actions. Punching involves a driving action into or through material to create holes. Shearing refers to cutting materials, while bending involves the deformation of material along a straight line, using a press brake or a similar tool.

Here are some of the key reasons why machine guarding are important in high-risk areas in industrial operations:

• Protection from Physical Harm: The most obvious reason for implementing machine guarding is to prevent machine operators from having any contact in the danger zone during a machine's operating cycle. This reduces the risk of crush injuries, amputations, and other physical harm to the worker. According to the Occupational Safety and Health Administration (OSHA), employees operating and maintaining machinery suffer an estimated 18,000 amputations, lacerations, crushing injuries, abrasions, and over 800 deaths per year. Implementing these guards is one of the most effective ways to reduce the risk of these types of accidents.
• Compliance with Regulations: Employers are legally required to implement machine guarding to protect their workers. OSHA sets regulations for machine guarding that employers must follow to ensure the safety of their workers. If an employer fails to comply with these regulations, they can be in violation and face fines and other penalties. In addition, non-compliance with OSHA regulations can also result in increased insurance premiums and decreased productivity.
• Increased Productivity: Implementing machine guarding can actually increase productivity by reducing the risk of accidents and injuries. Workers can perform their tasks more efficiently and with greater peace of mind, knowing that they are protected from the dangers of the machinery. When workers feel safe, they are less likely to make mistakes or experience work-related stress, which can result in increased productivity.
• Reduced Cost of Accidents: Accidents can be expensive, both in terms of human injury and financial costs. The cost of an accident can include medical expenses, workers' compensation claims, and lost productivity. Implementing these reduces the risk of accidents, which in turn reduces the cost of accidents for the employer.

Working with machinery and equipment without machine guarding and personal protective equipment presents serious risks to workers. These are some of the most devastating consequences that workers may face for not using these guards:

• Amputations: Amputations are among the most devastating consequences of not using machine safeguards. Workers who come into direct contact with hazardous machine parts without proper protection can experience serious injuries, including the loss of limbs. Amputations can result in permanent disability and can have a profound impact on a worker's quality of life.
• Crush Injuries: Crush injuries are another common consequence. Workers who are not protected by these safety measures are at risk of being crushed by moving machine parts, which can result in serious injuries, including broken bones and internal injuries. Crush injuries can be life-threatening and can have a long-lasting impact on a worker's physical and mental health.
• Burns: Burns are another potential injury that can result from not using machine guards. Workers who come into direct contact with hot machine parts or equipment can experience serious burns, resulting in pain, disfigurement, and permanent scars.
• Traumatic Brain Injuries: Traumatic brain injuries (TBIs) are a potential consequence of not using machine guards. Workers who are not protected by these safety measures are at risk of being struck by falling objects or other debris, which can result in serious head injuries. TBIs can result in long-lasting or permanent disability, including memory loss, speech problems, and mobility issues.
• Eye Injuries: Eye injuries are another potential consequence of not using machine safeguards. Workers who are not protected by these safety measures are at risk of being struck by flying debris or other objects, which can result in serious eye injuries, including blindness.
• Cutting and Shearing Hazards: These hazards involve sharp or moving parts that can cut or shear body parts. Cutting and shearing risks are prevalent in machinery such as saws, drills, lathes, and metal shears. The sharp edges and the force used in cutting actions pose a significant risk of laceration.
• Drawing-In or Trapping Hazards: These hazards happen when body parts are drawn into machinery by in-running nip points or the convergence of two parts. Drawing-in or trapping hazards are common in machines with rollers, gears, and belt drives and may result in crush injuries or amputation.
• Electrical Hazards: This include shocks, burns, or electrocution resulting from faulty wiring, exposed conductors, or improper grounding. Electrical hazards can occur in any machinery with electrical components, especially in environments with high humidity or where water is used and lead to minor to severe electrocution.

 

Machine guarding safety measures encompasses a range of equipment and devices essential to a comprehensive safety program and protocol. Here are the different types of machine guarding tools and devices and their specific functions:

Fixed machine guards are permanent parts of a machine. They are designed to be sturdy and non-moveable, providing a solid barrier between the operator and the hazardous parts of the machine. These guards are used where operator interaction with moving parts is unnecessary once the machine is set up.

Limitations:

• Fixed guards can make machine setup, maintenance, and clearing jams more time-consuming because tools may be needed to remove the guard.
• They may restrict visibility if not designed with a see-through material.

Interlocked Machine Guards

Interlocked machine guards are designed to shut off power automatically and halt machine operations when the guard is opened or removed. This ensures that the operator cannot access the dangerous parts of the machine while it is in operation and helps to prevent accidental startup during maintenance or inspection.

Limitations:

• More complex and costly than fixed guards due to the need for an interlocking system.
• Requires regular maintenance to ensure the interlock mechanisms function correctly.
• The risk of bypassing the interlock system, if not properly managed, can lead to safety breaches.

Adjustable guards are versatile protections that can be modified to accommodate various sizes of stock. They are particularly useful for machines that perform different kinds of operations requiring different configurations. However, they must be adjusted manually to ensure they provide adequate protection for each operation.

Limitations:

• The level of protection depends on the operator properly adjusting the guard, which can introduce human error.
• Requires training and diligence to ensure that adjustments maintain sufficient safety margins.
• Less secure than fixed guards, as they can be improperly set or left unadjusted.

Self-adjusting guards provide a barrier that adjusts automatically according to the size of the stock entering the danger area. These guards are typically designed around the principle of maintaining a minimal gap necessary for the stock and operation, providing protection while allowing for operation efficiency. For instance, in saw operations, the guard moves according to the thickness of the material being cut, offering protection while allowing for smooth operation.

Limitations:

• Complexity in design can lead to higher costs for installation and maintenance.
• Relies on mechanical parts that can wear out, necessitating regular checks and maintenance to ensure effectiveness.
• May not be suitable for all types of machinery, especially where the stock does not enter the machine in a consistent manner.

These are safety devices designed to prevent the operator’s hands or other body parts from entering hazardous areas. They typically involve cables, straps, or other forms of tethering that physically restrict the operator’s movement toward dangerous machine parts.

Limitations:

• Can be cumbersome and may reduce operator mobility and comfort, potentially affecting productivity.
• Requires proper fitting and adjustment to be effective, which can vary between different operators.
• Not a substitute for other guarding techniques but rather a supplementary safety measure.

These are movable barriers that operators can open or close manually or automatically (typically interlocked). Guard gates ensure that access to hazardous areas is controlled and safe, locking in place during operation to prevent exposure to dangerous conditions.

Limitations:

• Requires careful design to ensure that it provides adequate protection when closed and allows sufficient access when open.
• Interlocking mechanisms add complexity and need regular maintenance to function reliably.
• Depending on the design, it may require manual operation that could lead to safety compliance issues if not properly managed.

Two-hand control systems require the operator to use both hands to activate the machine, ensuring that hands are away from the danger zones during operation. This system is commonly used in press operations where precision and safety are paramount.

Limitations:

• Can reduce operational speed as the operator must always use both hands to operate the machine, potentially impacting productivity.
• Not suitable for all types of machinery, especially those requiring continuous hands-on adjustments during operation.
• Requires ergonomic consideration to prevent fatigue and ensure comfort during repeated use.

Similar to two-hand control, two-hand trip systems require both hands to be used to start a machine cycle, but this mechanism is generally used to activate the machine stroke, ensuring hands are free from the machine's operational components.

Limitations:

• Slightly less safe than two-hand controls because hands are free once the cycle starts, potentially leading to unsafe actions during the ongoing operation.
• Still requires ergonomic setup to ensure that the controls are appropriately placed to prevent strain or injury.

These controls are designed to stop machine operation immediately if they detect an issue. These controls can take various forms, including trip wires, safety bars, or emergency stop buttons strategically placed around the machine. Safety trip controls are widely used in heavy machinery, automated lines, and areas where quick cessation of machine operations can prevent accidents and injuries.

Limitations:

• Emergency stops or trip mechanisms can lead to sudden machine stops, which may cause mechanical stress or damage if not properly managed.
• Regular testing and maintenance are required to ensure reliability, as failure of these systems in an emergency could have catastrophic consequences.
• Does not replace the need for comprehensive guarding but serves as an emergency backup.

Pullback devices are attached to the operator's hands or wrists and retract hands from the point of operation when the machine cycle starts. They are typically used in operations where fixed guards would interfere with machine functionality.

Limitations:

• Can be restrictive and uncomfortable, potentially reducing operator dexterity and efficiency.
• Requires precise adjustment to ensure effectiveness without compromising comfort or safety.
• Regular maintenance and inspection are essential to ensure that pullback mechanisms function correctly.

Radiofrequency guards utilize a radio frequency field around the hazardous area of the machine. If this field is disrupted by any intrusion, such as a part of the operator's body, the machine automatically shuts down.

Limitations:

• More expensive and complex to install and maintain than physical barriers.
• Potential for false trips or failures, requiring regular calibration and testing.
• May not provide a visible deterrent like physical guards, potentially leading to complacency in safety practices.

Electromechanical guards use a combination of mechanical components and electrical sensors to monitor access points or dangerous areas. These guards typically require physical activation or contact to trigger safety mechanisms and are commonly found in machine doors, protective covers, or movable barriers where access to dangerous components must be controlled.

Limitations:

• Mechanical components can wear out or fail, necessitating frequent checks and maintenance.
• Can be bypassed if not properly integrated into the machine’s safety protocols.
• Requires careful alignment and setup to ensure effective operation.

Photoelectric guards use beams of light (infrared, visible, or laser) to create an optical barrier. If the light beam is interrupted by any object, the machine automatically stops operation. This is Ideal for perimeter guarding or for large areas where setting up physical barriers is impractical or restrictive.

Limitations:

• Vulnerable to environmental factors such as dust, smoke, or intense light, which can affect sensor performance.
• Requires regular cleaning and maintenance to ensure uninterrupted operation.
• Potential for non-visible beams (infrared or laser) to be unnoticed by operators, requiring additional safety training and signage.

Safety interlock switches are designed to ensure that a machine cannot operate unless certain conditions are met, such as a guard or door being in a closed and locked position. These switches can be mechanical, magnetic, or electronic, and they play a crucial role in ensuring that access doors or protective guards are properly secured before machinery can be operated.

Limitations:

• Requires correct alignment and installation to function effectively, as misalignment can lead to false readings or machine downtime.
• Mechanical switches are subject to wear and may require regular maintenance or replacement.
• Can be bypassed or defeated if not monitored or integrated correctly, leading to potential safety risks.

Safety mats are pressure-sensitive protective devices placed on the floor around hazardous areas. When stepped on, these mats detect the presence of a person and send a signal to stop the machine operation, thus preventing access to dangerous areas.

Limitations:

• Can be susceptible to damage from heavy objects or sharp tools dropping on them, which might cause false trips or failure to operate.
• Environmental conditions like moisture, dirt, or extreme temperatures can affect performance, requiring regular checks and maintenance.
• The visual presence of safety mats might not be enough to deter entry; additional signage and barriers might be needed.

The Occupational Safety and Health Administration (OSHA) has established strict requirements for machine guards to prevent injuries in the workplace. Under the OSHA CFR Section 1910.212, industries are mandated that all machines must have guarding equipment to protect workers from hazards. These guard systems must be designed, installed, and maintained to prevent injury to the operator or other workers who may be in the area. According to this standard, the criteria for machine guard requirements are:

• Presence of Hazardous Parts: Any machine part, function, or process that may cause injury must be safeguarded. If it’s possible that a body part can make contact with a hazardous area, guarding is necessary.
• Probability of Contact: The likelihood of a body part or clothing coming into contact with the moving parts of machinery determines the necessity for guards. This includes evaluating the machine's location and how frequently workers are near the machine during normal operation.
• Severity of Potential Injuries: Machines that have the potential to cause more severe injuries require more robust guarding solutions.
• Feasibility and Convenience: The guards should not impede workers from performing their tasks comfortably or efficiently, yet they must provide maximum safety.

The OSHA machine guarding standard also features a comprehensive guideline for machine safety and machine guarding. Compliance with this standard emphasizes the need to identify a machine’s point of operation, which is the area of the machine where work is performed on the material, to prevent contact with the implementation of appropriate machine guards. For safer operation, machine guards must not hinder the machine operator from performing the job quickly and comfortably. They should be designed to facilitate ease of use and good visibility.

This standard also requires that guards must be solidly constructed and securely fastened to the machine, or to the floor if not feasible on the machine. Furthermore, the openings of guards must not be larger than necessary to allow for the passage of material or tools, while ensuring safety. The applied mechanisms for feeding and ejecting materials should be designed to minimize the need for the operator to reach into the hazard area. Most importantly, operators need to be trained in the proper use and handling of the guards, including understanding why they are necessary and how they provide protection.

Employers have a responsibility to ensure that their workers are safe and protected from hazards associated with operating machinery. Implementing machine guarding in the workplace requires careful planning and attention to detail.

The first step in implementing machine guards is to conduct a risk assessment. This involves identifying all potential hazards associated with operating machinery and assessing the likelihood and severity of any potential injuries. A risk assessment should include input from workers who operate the machinery, as they may have unique insights into these hazards. This assessment will inform the selection and installation of appropriate machine guards.

The next step is to choose the right type of guarding restraint for the equipment being used. There are several types of machine guards available, including fixed, interlocked, adjustable, and self-adjusting. The type of guarding restraint chosen will depend on the type of equipment being used, the hazards associated with that equipment, and the level of risk identified during the risk assessment.

Aside from that, provide personal protective equipment (PPE) such as gloves, safety glasses, hard hats, and boots as a general safety measure against workplace hazards. However, some circumstances require more careful consideration with regard to the use of PPE. For some rotating equipment machinery, it may not be ideal for workers to wear gloves as well as loose fitting clothes as they may end up entangled in the machine.

Once the type of guarding restraint has been chosen, it must be installed properly. This includes ensuring that the guard is securely attached to the equipment and that there is no way for the guard to be bypassed or removed. The guarding restraint must also be properly positioned to prevent workers from coming into contact with moving parts or equipment.

All workers who operate machinery must be provided with adequate training on the use of machine safeguards. This training should include information on the purpose and function of guarding equipment, how to properly use and adjust them, and how to inspect them for defects. Workers must also be informed of the consequences of failing to use guards properly and be provided with personal protective equipment.

Finally, machine guards must be inspected and maintained regularly to ensure they are in good condition and functioning properly. This includes inspecting guards for any signs of damage or wear and tear, ensuring that guards are properly adjusted and positioned, and repairing or replacing guards as necessary.

The most common injuries caused by hazardous mechanical motions and working unsafely with machines include lacerations, amputations, and crushing injuries.

The three main areas of a machine are the point of operation, power transmission device, and operating controls.

Machine parts that always require guards include point of operation areas, ingoing nip points rotating parts, and flying chips and sparks producers.

The 7 foot rule for machine guarding states that if any part of a machine that operates over seven feet above the floor level must be guarded to prevent contact and protect from falling objects.

The three basic areas that require machine guarding to prevent severe workplace injuries are the point of operation, all moving parts, and any other parts of the machine where hazards such as in-running nip points exist.


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