Machine guarding is a safety feature on or around manufacturing or other engineering equipment consisting of a shield or device covering hazardous areas of a machine to prevent contact with body parts or to control hazards like chips or sparks from exiting the machine. Machine guarding provides a means to protect humans from injury while working nearby or while operating equipment. It is often the first line of defense to protect operators from injury while working on or around industrial machinery during normal operations. In the U.S., machine guarding is referred to in OSHA's CFR 1910.212;[1] in the U.K., machinery safety is covered mainly by PUWER."[2]
Point guarding refers to guarding of moving parts on a machine that present a hazard to the machine operator or others who may come in contact with the hazard. OSHA 1910.212(a)(2) requires these guards to be “affixed to the machine where possible."[1] Specifics for the type and construction of the guard are determined by the proximity of the guard to the hazard, and the type of hazard. Point of Operation Guarding refers to guarding the area of the machine where the work is performed. Construction of the machine and the guarding should “prevent the operator from having any part of his/her body in the danger zone during the operating cycle.”[3]
Fixed perimeter guarding
Fixed perimeter guarding with weld curtains
Perimeter or barrier guarding refers to a barrier placed around a work area where an automated piece of equipment-like a robotic arm-performs a function. This type of guarding is generally a wire partition system, but also can take the form of pressure sensitive mats or light curtains. Wire partitions systems used as machine guards must be fixed in place either on the machine or around its perimeter. These guarding systems may be configured with various sizes of wire mesh, solid sheet metal, or clear polycarbonate panels.[4] Use of these materials depends on the hazard being guarded and the distance between the hazard and the guard. Mesh opening size of the guard depends on the proximity of the guard to the hazard. If the guard is installed close to moving parts, the mesh openings must be smaller than if the guard is installed a greater distance away from the moving parts. Mesh opening sizes for specific distances from the hazard are defined in ANSI/RIA R15.06-2012.[5] Solid barriers such as sheet metal or clear view polycarbonate can be used to shield the hazard as well as control sparks or liquids. Size of the barrier (height and width) must conform to ANSI/RIA R15.06-2012.[5] Wire partition guards provide a means of access to the guarded equipment with doors, lift out sections, or other controlled openings.
Safety devices
Electrical interlock mounted on wire mesh machine guarding
Electrical interlocks or other devices tied into the equipment's control circuit are mounted on access points and are configured to stop equipment operations when opened. These access points should also incorporate hardware to comply with the OSHA lockout/tagout regulation 1910.147.[6] The lockout/tagout hardware allows the operator or maintenance person to lock the equipment in the stopped state while performing duties in the hazardous area.
Light curtain systems may be used alone or in conjunction with other guarding systems. The light curtain projects a field or beams of light between two points and, when the field is broken-at any point, the light curtain system interrupts the circuit it is wired into. These can be used in areas where an operator must interact with operating equipment to prevent movement of the equipment while the operator works a hazardous area.
Pressure sensitive mat for operator of laser cutter
Pressure sensitive mats that are wired into the equipment's control system can be placed in hazardous areas and be set to stop the equipment if stepped on. These devices can be used alone or in conjunction with other guarding devices, usually at operator interaction points.
Applications
Pallet wrapper without guarding
Packaging Equipment or pallet wrappers have a moving load and an arm that stretches plastic wrap around the load. Typically a three sided wire partition guard is placed around the wrapper, and a light curtain controls access to the open side where the wrapper is accessed by a lift truck.[7]
Machine guarding with weld curtains around a robotic weld cell
Robotic Welding Cells incorporate wire mesh fixed barriers outfitted with vinyl welding curtains and light curtains or pressure sensitive mats. The welding curtains mounted inside of the fixed barrier control exposure to welding flash, sparks and spatter from the welding operation. While the light curtain or pressure sensitive mats prevent welding operations while the operator is loading/unloading the weld fixtures.
In-Line palletizer with machine guarding
Robotic Material Handling for pallet pack or de-palletizing could use any of the aforementioned guarding systems. Light curtains or pressure sensitive mats around the perimeter of the work area that stop the robot when an operator enters. Wire partition could be used around the work area with an interlocked gate which stops the robot when opened.
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, electrical, heat, chemical, biohazards, and airborne particulate matter. Protective equipment may be worn for job-related occupational safety and health purposes, as well as for sports and other recreational activities. Protective clothing is applied to traditional categories of clothing, and protective gear applies to items such as pads, guards, shields, or masks, and others. PPE suits can be similar in appearance to a cleanroom suit.
An industrial robot is a robot system used for manufacturing. Industrial robots are automated, programmable and capable of movement on three or more axes.
A forklift is a powered industrial truck used to lift and move materials over short distances. The forklift was developed in the early 20th century by various companies, including Clark, which made transmissions, and Yale & Towne Manufacturing, which made hoists.
A confined space is a space with limited entry and egress and not suitable for human inhabitants. Alternative names for a confined space are enclosed space and dangerous space. An example is the interior of a storage tank, occasionally entered by maintenance workers but not intended for human occupancy. Hazards in a confined space often include harmful dust or gases, asphyxiation, submersion in liquids or free-flowing granular solids, electrocution, or entrapment.
Eye protection is protective gear for the eyes, and sometimes face, designed to reduce the risk of injury. Examples of risks requiring eye protection can include: impact from particles or debris, light or radiation, wind blast, heat, sea spray or impact from some type of ball or puck used in sports.
A safety barrier is a component which prevents passage into a dangerous area, and is commonly used to mitigate risk.
Lock out, tag out or lockout–tagout (LOTO) is a safety procedure used to ensure that dangerous equipment is properly shut off and not able to be started up again prior to the completion of maintenance or repair work. It requires that hazardous energy sources be "isolated and rendered inoperative" before work is started on the equipment in question. The isolated power sources are then locked and a tag is placed on the lock identifying the worker and reason the LOTO is placed on it. The worker then holds the key for the lock, ensuring that only that worker can remove the lock and start the equipment. This prevents accidental startup of equipment while it is in a hazardous state or while a worker is in direct contact with it.
A welding helmet is a piece of personal protective equipment used by welders to protect the user from concentrated light and flying particles. Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for others. OSHA and ANSI regulate this technology, defining shades based on the transmittance of light.
A light curtain is a safety device that detects when a beam of infrared light has been broken by a person passing through an area.
Pallet rack is a material handling storage aid system designed to store materials on pallets. Although there are many varieties of pallet racking, all types allow for the storage of palletized materials in horizontal rows with multiple levels. Forklift trucks are usually required to place the loaded pallets onto the racks for storage. Since the Second World War, pallet racks have become a ubiquitous element of most modern warehouses, manufacturing facilities, retail centers, and other storage and distribution facilities. All types of pallet racking increase storage density of the stored goods. Costs associated with the racking increases with increasing storage density.
A job safety analysis (JSA) is a procedure that helps integrate accepted safety and health principles and practices into a particular task or job operation. The goal of a JSA is to identify potential hazards of a specific role and recommend procedures to control or prevent these hazards.
A cobot, or collaborative robot, also known as a companion robot, is a robot intended for direct human-robot interaction within a shared space, or where humans and robots are in close proximity. Cobot applications contrast with traditional industrial robot applications in which robots are isolated from human contact or the humans are protected by robotic tech vests. Cobot safety may rely on lightweight construction materials, rounded edges, and inherent limitation of speed and force, or on sensors and software that ensure safe behavior.
Safety relays are devices that generally implement safety functions.
Engineering controls are strategies designed to protect workers from hazardous conditions by placing a barrier between the worker and the hazard or by removing a hazardous substance through air ventilation. Engineering controls involve a physical change to the workplace itself, rather than relying on workers' behavior or requiring workers to wear protective clothing.
A presence sensing device (PSD) is a safety device for press brakes and similar metal-bending machines. The device operator often holds the sheet metal work-piece in one place while another portion of the piece is being formed in the die. If a foreign object is detected, the PSD immediately retracts the die or stops the motion of the ram. PSDs protect the operator and other employees in the area.
Electrical safety is a system of organizational measures and technical means to prevent harmful and dangerous effects on workers from electric current, arcing, electromagnetic fields and static electricity.
Workplace robotics safety is an aspect of occupational safety and health when robots are used in the workplace. This includes traditional industrial robots as well as emerging technologies such as drone aircraft and wearable robotic exoskeletons. Types of accidents include collisions, crushing, and injuries from mechanical parts. Hazard controls include physical barriers, good work practices, and proper maintenance.
A safety sign is a sign designed to warn of hazards, indicate mandatory actions or required use of personal protective equipment, prohibit actions or objects, identify the location of firefighting or safety equipment, or marking of exit routes.
Hazardous energy in occupational safety and health is any source of energy that "can be hazardous to workers", such as from discharge of stored energy. Failure to control the unexpected release of energy can lead to machine-related injuries or fatalities. The risk from these sources of energy can be controlled in a number of ways, including access control procedures such as lockout-tagout.
A pinch point or pinch point hazard is a common class of mechanical hazard where injury or damage may be done by one or more objects moving towards each other, crushing or shearing whatever comes between them. A nip point is a type of pinch point involving rotating objects, such as gears and pulleys. Injuries can range from minor such as blisters to severe like amputations and fatalities. Examples of pinch point hazards include gaps in closing doors and objects swinging or being lowered near fixed objects.
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