This article will take an in-depth look at machine guards.
The article will bring more detail on topics such as:
This chapter will cover the definition of machine guards, their design, and their operational mechanisms.
A machine guard is a safety device designed to create a protective barrier between operators and machinery in environments such as manufacturing plants, factories, and warehouses. These guards also serve to restrict vehicle access to certain areas, manage traffic flow, and contain debris. Safety guards are essential for nearly all types of machinery.
Machines that pose safety risks due to impacts, shearing actions, rotating components, reciprocating arms, meshing gears, moving belts, or cutting tools require appropriate barriers to ensure safety.
Manufacturers usually make machine guards by combining CNC machining, extrusion, and post extrusion processes (rivet joining, bolts, nuts, screws, etc.) These methods are explained below.
Extrusion is the process of shaping material, such as aluminum, by forcing it through a shaped opening in a die. Extruded material has the same shape as the die opening and emerges as an elongated piece. The aluminum is pushed through the die by a powerful ram and resurfaces from the die's opening. When this happens, it emerges in the same form as the die and is pulled along a runout table. Aluminum extrusion is a relatively simple process to comprehend on a fundamental level.
Extrusion produces three primary shape categories: solid forms without enclosed spaces (such as angles, rods, or beams), hollow shapes with one or more voids (like rectangular or square tubes), and semi-hollow forms with partially enclosed voids (such as "C" channels with narrow gaps). These shapes are essential for manufacturing machine guards. The process is detailed in the following ten steps.
The malleable billet is now packed into the extrusion press, where it is subjected to up to 15,000 tons of pressure from the hydraulic ram.
The billet material is pushed into the extrusion press container as the ram applies pressure. The billet material increases in volume to fill the container's walls.
Post-extrusion refers to the process of continuously shaping a flat, hot, extruded sheet into a specific form. Typically performed during the extrusion process itself, this technique is commonly used with rigid PVC. It leverages the cost efficiency of extrusion while incorporating the forming benefits of injection molding.
CNC machining is a method of manufacturing that utilizes advanced computer programs to automate the design and creation of precise parts. This process is widely used across various industries, including the production of machine guards. CNC stands for Computer Numerical Control, highlighting its reliance on computerized systems to achieve accuracy.
This term encompasses a variety of CNC manufacturing techniques used to rapidly and efficiently produce parts, whether in small or large quantities, with consistent precision throughout the production process.
To select the most suitable CNC machine shop, it is essential to evaluate the specific processes required for designing and manufacturing the machine guard. Key considerations include dimensional capacities, material capabilities, production volume allowances, software compatibility, and the types of machines available. CNC providers vary widely in their material and dimensional capabilities. Diameter capacities are usually defined by a range of upper and lower limits, while volume requirements are similarly specified. Material capabilities should be precise, with metal often being preferred for machine guards, though plastic is also commonly used.
Once the appropriate facility, materials, and software are selected, control machining begins with collaboration between the client and the manufacturer. Using computer-aided design (CAD) and computer-aided manufacturing (CAM), along with advanced programming techniques like photo imaging, the product is conceptualized and designed in-house. These programs convert the product's schematics and measurements into code that guides the machinery. The raw material, typically metal or plastic in the form of billets or other stock shapes, is then loaded into the machine.
These materials can be pre-extruded and provided by either the machining shop or the customer. In shops with multiple machines, workers may manually transfer materials between different procedures, though this step can also be automated. Once the materials are in place, the software is activated. The code, regardless of the specific programming language, directs the machinery's operations.
The computer executes a series of commands in the required sequence, controlling the positioning, pressure application, depth, and all other movements of the automated equipment. This precise control allows for the rapid production of highly accurate duplicate parts, a process that would be significantly slower if done manually.
Machine guards are produced from various materials, with metal being the most commonly chosen option due to its durability and strength. They can be fabricated into different forms such as bars, pipes, wire mesh, panels, or sheet metal. For applications where visibility is important, polycarbonate is often used. This robust plastic material creates transparent panels that are shatter-resistant, capable of withstanding high impacts, and generally more durable than glass. Wood is used only in environments where there are no extreme temperatures or corrosive substances.
Industrial machine guards play a crucial role in protecting equipment through various methods. Examples include point of operation guarding, point guarding, and fixed perimeter guarding.
In the context of machine safety, "point guarding" refers to the protection of moving parts on machinery that may pose a danger to operators or other personnel nearby. According to OSHA standard 1910.212(a)(2), point guards should be securely attached to the machine whenever possible, or alternatively, positioned nearby if direct attachment is not feasible.
Machine guards designed for "point of operation guarding" are intended to protect the specific area where operators interact with the machinery. The primary objective is to prevent physical contact with the machine and keep workers out of the hazardous zone during operation.
Fixed perimeter guarding involves creating a complete enclosure or boundary around the entire machine workspace. This type of guarding ensures that the entire area is secured and inaccessible to prevent accidental contact with moving parts.
The considerations when choosing a machine guard are:
Risk factors and safety regulations can vary significantly between different organizations, even if they both use similar machinery. It's essential to assess the unique conditions of each workplace to ensure appropriate safety measures are in place.
First, measure the distance between the machine and the operator to identify potential hazards. This information will help in selecting the right type of machine guarding, whether it's wire mesh or solid panels. Additionally, review the safety standards set by organizations such as MSHA, OSHA, and CSA to fully understand the specific risks associated with the types of machinery in use.
While becoming an expert in the design and manufacturing of guarding panels isn't necessary, having some basic knowledge can be very helpful. Understanding key regulations from MSHA, OSHA, and CSA will also assist in distinguishing between high-quality and inferior products.
For instance, by learning more about the design and production process of wire mesh guards, you can identify the best materials, the most durable wire gauges, and the most effective weaving techniques, leading to better-informed decisions.
To adhere to existing regulations and safety standards, companies operating machinery must ensure proper installation of guards. Given the variety of machine sizes and configurations, it may be necessary to find manufacturers who can provide custom guards if standard sizes do not fit. Wire mesh guards often prove to be a flexible and effective option due to their adaptability.
Choosing the right machine guarding panels involves considering the level of support and customer service provided by the manufacturer. It's beneficial to collaborate with a reputable supplier who offers guidance throughout the purchasing process. Additionally, opt for a manufacturer that provides post-purchase support to address any questions or issues that may arise.
Machine guards come in four main types: fixed, adjustable, interlocked, and self-adjusting. These categories encompass various subtypes of machine guards, each tailored to specific safety needs.
Chuck guards are crucial safety devices designed to shield workers from flying debris such as shards, shavings, and tool bits produced during machining processes. Typically, these guards are curved panels mounted to machinery with brackets and screws. They are predominantly used on lathes, which operate at high RPMs (revolutions per minute) to shape various materials like metal, wood, and glass. The chuck, a clamping mechanism that secures rotating materials and tools, is a central feature of these lathes. Chuck guards are attached to the chuck itself, allowing them to be easily swung or lifted for convenient access to the lathe while providing protection.
Chuck guards are widely utilized in factories and manufacturing settings to enhance worker safety during processes like glass blowing, metal spinning, shearing, and sanding. These guards, along with protective clothing and goggles, help prevent injuries from debris ejected by high-speed lathes. Although the debris is typically small, its high velocity makes it a significant hazard. Chuck guards offer a straightforward and effective solution to mitigate these risks. Similar to chuck guards, other machine guards include milling machine guards, lathe guards, and drill press guards, each designed to address specific hazards associated with their respective machines.
Drill press guards are designed to shield operators from potential injuries during the use of drill presses. These guards help protect personnel from contaminants, moving parts, flying debris, and excessive noise generated by the equipment, ensuring a safer working environment.
Drill press guards, a subcategory of machine guards, shield operators' eyes and hands from cutting blades, cutting tools, hot chips, grease, splash coolants, and oil. Drill presses, according to the OSHA list, need guarding where work is done when the material is in an ongoing process. Drill press guards come in a variety of styles.
Fixed machine guards are securely attached to a machine or tool and do not have any moving parts, making them immovable during operation. These guards are typically employed to cover areas of the machine that pose hazards and do not require operator interaction, such as flywheels or fan blades. Since they are a permanent part of the machinery, they must be disassembled and removed before any maintenance or adjustments can be made.
Interlocking guards, also referred to as barrier guards, are designed to automatically cut off or disengage the power source when they are opened or removed. They are particularly beneficial in situations where operators need to access guarded machine components, such as for clearing jams, while ensuring that the machine is safely shut down during these activities.
Interlocking guards allow safe entry to the machine's interior without the need for complete disassembly. However, they can be inadvertently opened, so regular maintenance and careful adjustment are necessary to ensure their proper function.
A lathe guard functions as a protective shield or visor designed to safeguard operators and nearby workers from hazards associated with a spinning lathe. It helps prevent injuries from flying debris, chips, broken tool pieces, and shavings, and also keeps fingers clear of the high-speed rotating lathe.
Lathe guards come in pre-engineered sizes or are custom made to fit the particular dimensions of the machine. They are easily attached to the chuck or cross-slide by a bracket on screws, though others are attached to other lathe devices. Lathe guards can be curved and thus shaped as a half circle, or they can be flat and have three sides. The most common design consists of an aluminum die-cast frame and a big polycarbonate vision panel, a see-through plastic material which behaves like glass but is lightweight, has high impact strength, shatter resistance, and flexibility.
Milling machine guards are protective enclosures, typically consisting of two or three sides, designed to cover and protect dangerous milling machinery. They shield operators and machinists from hazards such as flying coolant, swarf, broken tools, and loose material fragments. These guards help maintain a clean work environment and enhance safety without compromising productivity.
Constructed from panels set within an aluminum frame or steel tubing, milling machine guards often feature transparent panels to allow visibility of the machining process. Milling machines are versatile tools used to cut and shape materials such as wood, plastic, and metals.
Milling machine guards are commonly found in manufacturing settings, workshops, and educational shop classes. Whether static (non-moving) or traversing (able to move without removal), these guards are securely locked in place whenever the milling machine is operating. They can either be pre-engineered in various standard sizes or custom-built to meet specific design requirements. Typically, milling machine guards are larger than other types of machine guards, reflecting the size of the milling machinery they protect.
There are two main types of milling machine guards: sliding and stationary. Both types are securely locked during operation to ensure worker safety. Sliding guards can move back and forth along a cross-slide, while stationary guards may need to be removed or swung aside to access the machining area. All panels used in milling machine guards are made from polycarbonate, a durable and shatter-resistant plastic that allows visibility while providing robust protection.
In industrial settings, safety barriers serve as physical partitions designed to prevent accidents and injuries. They protect operating personnel and employees from hazardous machinery, restrict vehicle access to designated areas, and manage traffic flow. These barriers enclose robotic and automated systems, safeguard heavy machinery that poses a risk of injury, and secure storage areas such as racks and shelving systems.
Safety barriers come in two main types designed to shield workers from injury and prevent costly vehicle accidents. Wire mesh and fencing barriers, for instance, restrict unauthorized access to dangerous areas and enclose automated machinery. Often equipped with interlocked electrical doors that shut off power when opened, these barriers are generally over six feet tall and easy to assemble. They are installed using a series of ground-mounted posts, and the doors can be customized as either panel or swing types to suit specific company needs.
Safety guards are physical barriers designed to encase potentially dangerous machinery and moving parts. They vary widely in size and shape, tailored to shield employees from preventable injuries related to machine operation. Many safety guards are custom-built to fit the specific safety needs of a particular machine or device. These guards can be made from various materials, including metals, wood, and plastics, with the choice of material depending on the type of machinery being protected.
The types of safety guards are self-adjusting, adjustable, fixed, and interlocked. Self-adjusting guards can automatically adjust themselves, whereas conventional adjusting machine guards should be shifted by hand. Fixed guards are permanently affixed to a part of the machinery, whereas interlocked guards are by electronic means connected to the machinery and thus capable of shutting down the machine if the barrier is crossed.
Self-adjusting machine guards automatically modify their positions when new materials are fed into the machines. Commonly used with saws, these guards move away from the cutting area to accommodate material entry and then cover the blade when it is not in operation, ensuring protection while maintaining accessibility.
In addition to the aforementioned types, there are numerous specialized machine guards designed for specific equipment. Examples include chuck guards, lathe guards, drill press guards, milling machine guards, wire guards, brake monitors, and safety light curtains, each tailored to address particular safety needs and machine types.
Wire guards are used to control traffic flow, establish secure areas, and contain large debris from escaping the work area. These guards are easy to install and are not reliant on electrical power, unlike safety light curtains. They are frequently employed to protect robotic systems, automated machinery, heavy equipment, tanks, spiral HVAC fans, and motors. Suitable for both indoor and outdoor use, wire guards are generally over six feet tall to deter individuals from climbing over them.
Wire guards serve to shield workers from accidents and injuries, prevent unauthorized access to restricted areas, and help reduce risks of tampering and vandalism. Unlike other machine guards, wire guards provide a visual warning of potential hazards. They are often brightly colored, such as yellow or orange, and are typically equipped with warning signs to enhance visibility and caution.
One widely used type of guard is the tiered guard, which attaches to the drill press's quill and encloses the rotating components. This design allows operators to maintain a clear view of the drilling process while ensuring safety. Although these guards generally do not pose significant issues, they can sometimes interfere with the task. In such cases, a safety protocol should be established to manage potential hazards, allowing the guard to be temporarily removed for task completion when necessary.
Safety guards come in various types, including self-adjusting, adjustable, fixed, and interlocked. Self-adjusting guards automatically modify their position, while adjustable guards require manual adjustment. Fixed guards are permanently attached to the machinery, and interlocked guards are electronically connected to the machine, enabling automatic shutdown if the guard is tampered with or removed.
This chapter will explore the applications and advantages of machine guards.
Machines such as presses, automated assembly lines, milling machines, roll formers, saws, feeders, and robotics have dangerous parts that require machine guards for safe operation. These safeguards are essential to prevent injuries like crushed hands, burns, blindness, limb loss, or fatalities. While many machines come with built-in guards, others may need custom-built guards tailored to specific operations. Proper machine guarding is also necessary for robotic systems.
Machine guards are crucial for ensuring worker safety, maintaining orderly operations, and promoting efficient workflow. They not only protect employees but also foster a sense of confidence and well-being in the workplace.
OSHA requirements for machine guards include:
Guards must be inspected regularly as part of the machine guard maintenance schedule.
A guard should be replaced if:
Guards should be cleaned using a non-abrasive plastic cleaner. Avoid cleaning products based on ammonia, such as glass cleaner. Yellowing of transparent guards is generally not a major issue since they are made from PETG plastic rather than polycarbonate.
A machine guard is a device whose role is to act as a safety barrier between a worker and machines used in manufacturing facilities, factories, plants, and warehouses. They are manufactured from extrusion, CNC machining, and post extrusion process. Metal is usually the preferred material for making machine guards though plastic and wood are used as well. Machine guards play a vital role in protecting operators and employees from workplace hazards.
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