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Posted by Sadia Waseem
Ergonomics is pivotal to the manufacturing sector considering the high chances of injuries and accidents that occur. According to the U.S. Bureau of Labor Statistics, 2.8 million work-related injuries were reported in 2022, 7.5% higher than in 2021. These injuries are mainly caused by poor workstation design, improper material handling, and tools that cause repetitive strains, which is why it is of utmost importance for the manufacturing sector to practice ergonomic principles when designing the factory to cater to the needs of workers and prevent injuries.
This article will explore ten ergonomics principles that you need to implement on your factory floor to create a safer, and more efficient work environment. From designing the workstation to material handling, and from tool selections to environmental factors, these ergonomic principles cover all you need for your workers’ wellbeing.
Now, we will dig deep into each ergonomics principle with detailed guidelines on how you can incorporate them into your daily operations:
Neutral posture is the working posture in which all body joints are aligned naturally and not in an awkward position, which reduces the risk of developing Musculoskeletal Disorders (MSDs). Characteristics of neutral posture are as follows:
Body Part | Body Posture |
Head | Centered and directly above shoulders and hips |
Back | Straight and not leaning backward or forward |
Neck | Relaxed and chin at a comfortable level |
Shoulders | Not lifted towards the neck |
Upper arms | Relaxed and close beside the body |
Forearms | Not in extended position |
Task-Specific Posture Consideration:
Different manufacturing procedures require different postures to maintain a neutral position:
Assembly line: While designing an assembly line workstation make sure that it allows workers to keep arms close to their bodies and elbows at a 90-degree angle for a comfortable position.
Machining Operations: Place work equipment in a position where it becomes easy for workers to access equipment without excessive bending and twisting.
Packaging Industry: Position your conveyor belt at a height that is within the reach of all workers and they can handle any product while maintaining a straight back.
You can also use a workstation positioner that can help workers do their jobs easily without additional strain. A study by Marras in 2000 concluded that the use of lift tables prevents workers from bending so that they spend less time in uncomfortable positions. You can use these designs to modify your workstation to maintain a neutral posture:
This ergonomic principle focuses on limiting force exertion during weightlifting as suggested by the Occupational Safety and Health Administration (OSHA). This reduces the physical effort required to perform a task and prevents the risk of injuries like strains or sprains. The best practice is to recognize heavy activities in your daily operation that require excessive force, and then think of a way to reduce or eliminate them. The suitable criteria defined to avoid overloading of muscles are:
Force Type | Criteria |
Dynamic Forces | Less than 30% of the maximum force a muscle can exert |
Dynamic Force | 50% if the duration of the force is 5 minutes |
Static Load | Less than 15% of the maximum force a muscle can exert |
Example to Reduce Forces:
Pulling a Heavy Cart: Pulling a heavy cart can cause excessive stress on the back. To avoid this, make sure your floor is in good condition with no bumps and potholes. Also, the cartwheels should be big enough to maintain a good grip, making it easier to push the carts. You can also include additional equipment like a power tugger to move the cart single-handedly.
Use of Hoist: You can use a hoist to lift heavy objects rather than lifting them with your own hands, which causes sprain on shoulders and upper arms. The hoist can be in the form of a lever or chain as per your requirement of the process.
Attaching Handholds on Boxes: Another thing you can do is add handhold on boxes, which reduces the force required to carry the same amount of weight.
The third ergonomics principle is about keeping everything within easy reach to avoid excessive bending or stretching and stress on lower back. The key to this ergonomic principle is to design your workstation in such a way that all necessary tools and materials are within arm’s reach.
Strategies to Keep Everything in Reach:
Reach Envelope: The “Reach Envelope” concept is an effective way to keep everything within reach. To implement it, first, draw a semicircle on the workstation till where your arms reach out. Keep the things that you frequently use within that semicircle. Now, again draw a semicircle till where your forearms reach. Keep any item or equipment that are not used frequently within that semicircle. Place items that are only used occasionally out of this zone.
Workstation Layout: Change the layout of a workstation to a U-shaped or semicircle to keep all materials that are needed within reach. You can also use adjustable shelves or bins to adjust workers of different heights.
Reduce the Size of Work Surface: Sometimes, work surfaces are too big, which makes it difficult for workers to reach across to get equipment. One way is to decrease the size of a work surface and the second option is to make a cutout, which makes it easy to reach things without compromising the size of a workstation.
Tilting of Boxes: Another common problem is that workers often get back injuries and strains while reaching the end of boxes. One common way to fix this is to teach them to tilt boxes, so it is easy to reach the end of the box.
This ergonomic principle emphasizes working at a proper height. In manufacturing industries, it is important to ensure work is performed at proper heights to reduce fatigue, improve labor efficiency, and prevent Musculoskeletal Disorders (MSDs). One of the effective ways to work at proper height is to work at about elbow height in a standing or sitting position .The optimum heights and dimensions for workstations as defined by the International Health Facility Guidelines are demonstrated in the figures below:
Strategies for Maintaining Proper Heights:
Adjustable Workstations: You can design adjustable workstations to accommodate workers of different heights. Workers can adjust the workstation by extending their legs to the table or use a platform.
Material Handling: You can also implement scissor lifts or tilters to adjust pallets and containers to the working height. When components are being taken from parts bins, use self-leveling spring platforms to keep retrieval height constant.
Periodic Assessment: Make sure to assess your defined height and position as a task or process changes. You can also seek feedback from your workers to find a comfortable height at which they can work without putting stress on the body.
The next ergonomic principle is to analyze and reduce motion throughout daily operations. The motion can be through arms, wrists, legs, or back. The first warning sign of excessive motion is pain or swelling in a particular body part. Due to frequent or repetitive motion, workers often face Cumulative Trauma Disorders (CTDs) which cause fatigue and inflammation. Here are some activities that you can teach your workers to avoid minimizing the risk of developing CTDs:
Strategies to Reduce Excessive Motion:
Use of Power Tools: One of the simplest ways to reduce repetitive motion is to use a power tool rather than a manual one. Power-driven tools will decrease hand and wrist movement and require less time to complete a job.
Re-design Workstation: You can also change the layout of a workstation to eliminate unnecessary movements. For example, during batch processing, a storage box can be kept closer to a workstation and in titled form, so that workers can easily slide products in it rather than picking and placing them.
Material Handling: You can use Automated Guided Vehicles (AGVs) or conveyor systems to minimize manual material handling. Also, make sure to eliminate any uneven surfaces or bumps in the way with flat surfaces to eliminate motion.
Some tasks require workers to hold the same position for a long period, a phenomenon called static load and the next ergonomic principle is to minimize this static load to reduce fatigue. These types of tasks affect muscles and workers often feel discomfort even when the task is complete. Some examples of static load include:
Strategies to Reduce Static Load:
Workstation Design: Design workstations in such a way that it allows workers to both stand and sit while performing a job. You can also use titled surfaces to reduce neck strain during precision tasks.
Use of Jigs and Fixtures: In the manufacturing environment, it is common to hold a workpiece in one hand and a tool in the other while performing an operation. For such situation, can use jigs and fixtures, so workers can clamp a part and easily perform any task.
Task Modification: You can re-design longer, repetitive tasks into shorter cycles by breaking them. In this way, workers would get a break for recovery, and they would not have to maintain the same posture for a longer duration.
The pressure point is where a part of the body is in contact with a hard surface or sharp tool during work. You must watch for these pressure points also called as ‘contact stress’ and minimize them. This ergonomic principle focuses on reducing these pressure points as they can cause numbness, discomfort and damage to tissues and muscles in that area even when the workers are not working.
Strategies for Minimizing Pressure Points:
Contouring Workstation: One way to reduce pressure point is by contouring the edges of a workstation, especially the spaces where workers usually lean or rest their arms. You can do contouring by rounding off the edges or padding it, which makes it a comfortable point for contact.
Personal Protective Equipment (PPE): To decrease pressure points while handling hard or sharp objects, make sure workers use cushioned gloves to avoid direct contact with hands. For tasks that require kneeling, you can use support like cushioned mats or knee pads.
Tool Modification: You can modify a tool handle to distribute pressure evenly over a wider hand area. You can make a tool handle larger or pad it for even pressure distribution. You can also use spring-loaded handle tools to reduce the grip force required to handle a tool.
In manufacturing, it is important to ensure adequate clearance is provided to workers for their safety. This ergonomic principle emphasizing on making movement easier for all workers. Work areas should be arranged in such a way that workers have enough space for their head, knees, and feet. The optimum work clearance for a standing position is mentioned below:
Strategies to Provide Clearance:
Pathway Design: You should maintain clear and wide aisles and pathways with a minimum of 4 ft. distance for one-way movement and 6 ft. distance for two-way movement. You can also use visual management techniques to mark the floor for safe movement without obstacles.
Material Handling: Provide enough space at a workstation to accommodate any temporary materials when required. Pathways should have enough turning radius to accommodate forklift and other material handling equipment.
Regular Assessment: During your Gemba walks, regularly assess any material that would be obstacle during movement. Take workers’ feedback to identify any areas with clearance issues.
It is important to change positions frequently, drink plenty of water, and maintain the fitness of your workers. This principle of ergonomics tells you to incorporate physical activities in daily operations to lessen the effects of repetitive tasks and static postures. There are three main types of physical exercise that you can tell your workers to do:
Tips to Maintain Fitness:
A study by the Department of Ergonomics at the University of São Paulo suggested that by optimizing environmental factors, you can promote human health, productivity, and worker’s well-being. So, you should also take into account lighting, temperature, noise, and air quality.
Strategies for Adequate Environment:
Thermal Comfort: Hot or cold, extreme temperatures can have adverse effects on individuals. While exposure to low temperatures can result in frostbite and hypothermia, heat stress can cause dehydration, heat exhaustion, and even heatstroke. So, make sure that the temperature is optimal.
Air Quality: To improve indoor air quality install appropriate ventilation systems, air filtering, and reduce the sources of pollution. Another crucial element that affects performance and well-being is lighting. Natural light is essential for maintaining a body’s biological cycle, which in turn influences mood, productivity, and sleep patterns.
Noise: Another environmental component that has a big impact on performance and comfort is noise. By using design interventions, soundproofing techniques, and urban planning tactics, you can create more peaceful and comfortable working spaces.
Follow these 10 ergonomics principles to create a safer, more efficient and productive workplace. By implementing small changes, you can significantly improve worker well-being and efficiency in operation. Emphasize on neutral postures, appropriate heights, reduced forces, minimized static loads, and a comfortable workplace. Remember, following ergonomic principles is not just a trend but a necessity for the manufacturing sector; it is an investment in your workers, which ultimately boosts your bottom line.
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