Adapted from an article in The Fabricator.
A serious, and often subtle, workplace safety hazard is lurking in many fabricating operations. It starts with employees hauling equipment, workpieces, and products around the shop, even when they’re already taking precautions and following OSHA’s lifting guidelines.
What might start out as a minor strain from pushing around the same cart or picking up the same material every day can develop into a debilitating condition, such as carpal tunnel or chronic back pain, resulting in a domino effect of physical suffering, financial liabilities, and work stoppage. Moderate physical exertion is so routine for employees in the fabrication industry that they sometimes fail to grasp the severity of their musculoskeletal disorder (MSD) risk.
To make matters worse, in high-product-mix, low-volume sheet metal fabrication environments, the most common material handling vehicle—the forklift—is often inadequate and unsafe to use. That doesn’t mean it’s time to throw in the towel and hope for the best. With a little homework and some expert input, fabricators can make workplace MSDs a thing of the past.
MSDs are a class of injuries caused by overexertion from lifting, pulling, or pushing a load, resulting in damage to muscles and tendons. MSDs can range in severity from minor sprains and strains to career-ending herniated disks. In manufacturing environments, MSDs of the wrist, elbows, knees, and back are typical.
In terms of understanding how MSDs impact the fabrication industry, most of the research has already been done. The Liberty Mutual Research Institute for Safety found that MSDs most commonly result from trauma accumulated over time during repeated tasks that require a low level of exertion. This is what makes MSD risks so difficult to detect. Workers may not realize that a load is too heavy to move safely on a regular basis until it’s too late, which also limits management’s ability to act preemptively.
Outside the purely moral argument—that is, companies should never put employees in a hazardous situation—poor ergonomics has both direct and indirect costs. Direct costs include workers’ compensation costs, time lost due to injuries, and subpar productivity. Indirect costs include low morale, which can lead to late deliveries, poor quality, and high employee turnover.
Poor ergonomics is a very real, though often hidden, safety hazard, and it can cost fabricators dearly every day. And like any other major cost, it should be analyzed, accounted for, minimized—and never ignored.
Precarious Pipes on the Move
Consider a large fabricator that had to move 20- to 40-foot-long pipes from the yard to inside the plant. In this situation, the pipes needed to move up a 5-degree incline into the plant through a corridor too narrow for a typical forklift. During the walk-through of the overall manufacturing operation, engineers also found that employees could not adequately gauge the weight of the materials they were moving, increasing the potential for injury.
In this case, the fabricator invested in a custom motorized transfer cart with a wireless control, so the operator could maintain a safe distance from the cart during the transfer. It also had an onboard payload scale to prevent overloading. This allowed the fabricator to move materials from outside to anywhere inside the plant, which in this situation was a better, safer solution.
The Big Picture
Ergonomics is about looking at the whole picture, not just a certain lifting load at one machine or workstation. Consider a press brake operator who forms parts and places them on a custom-fabricated mobile scissor-lift cart. The table’s large enough to accommodate large panels along with several smaller components and can be adjusted depending on who’s operating the brake that day.
Then the material handler pushes that scissor-lift cart to the powder coating department. There, a short employee needs to extend her reach to grasp a medium-sized part in the center of the large cart. She does that again. And again. And by the end of her shift, her back is aching. In this case, would two carts—large parts in one, smaller parts in another—have been a better solution? It could well have been, but not without extensive observation and analysis.
Because everyone’s physiology is different, what’s safe for one employee may not be safe for another. People’s height and weight have an effect, as do their reach and the frequency of particular movements. For instance, if a person (like the operator in the powder coat department) needs to extend his or her arms laterally beyond a comfortable distance when grasping an object, the employee might feel a brief ping in the back.
They do this repeatedly, and they’ll probably feel the pain and remember it. But people might not feel the pain all the time. Say someone needs to perform an awkward, “long reach” lift maybe once or twice a shift. She might feel a ping in her back, but it goes away, so she doesn’t complain. Still, over time it gets worse. And worse. Eventually she’s receiving physical therapy.
Because everyone’s body is different, we have to make some general assumptions when combatting MSDs. The same group of researchers at Liberty Mutual also discovered that when workplaces accommodate the physical ability of 75 percent of the female population, two-thirds of all back-pain claims can be avoided regardless of the gender makeup of a given workplace. Using this benchmark, they created tables for push, pull, and lifting limits that any industry can use. When first assessing MSD risk at any facility, engineers and ergonomics experts often start by referencing the Liberty Mutual tables.
When an operation chooses to begin addressing workplace MSDs, facing the music is nowhere near as time- and resource-consuming as ignoring the problem altogether. When accounting for medical care, employee turnover, work stoppage, increased insurance premiums, and regulatory fines, the consequences of overlooked MSD risks are steep. According to OSHA’s report on the financial impact of MSDs, a musculoskeletal injury can cost an employer anywhere from $48,000 to $67,000 per incident in both direct and indirect costs.
What Makes a Cart Safe?
After a company’s safety team identifies a workplace safety vulnerability, many well-intended fabricators will turn to material handling equipment to alleviate the overexertion their employees experience. Usually the equipment of choice will be a heavy-duty flatbed cart robust enough to carry a range of materials in high-product-mix environments. Unfortunately, some of these carts still will leave employees vulnerable to injury, particularly when they’re not adequately motorized. Especially creative fabricators might also put their welding skills to use and construct their own equipment to aid in the pushing, pulling, and lifting of essential materials, such as sheet metal, piping, and steel support beams.
Some mistakes fabricators make include using wheel casters that are too small for the load, piling too much material onto a single cart, and not realizing when it’s time to motorize a manual cart.
How do you identify these problems? Again, it starts with the plant walk-through. Are operators needing to lean and push excessively to give a cart momentum? That might mean the load is too heavy or the casters are too small, a particular problem for an uneven floor. Rolling those small casters over a crack in the floor creates a violent jostle, which in turn can throw a load off balance—not the safest of situations.
Put the right caster on these carts, and the situation might improve. Larger-diameter caster wheels make carts easier to push. The swivel action makes a difference too. A well-made caster, with precision-ground and sealed raceways, will add stability to turns. So too will the swivel lead, or the distance between the center of the wheel and the center of the swivel action. A long swivel lead increases the rotation distance and creates a mechanical advantage, making turns easier.
Determining the wheel size is just the beginning. Another factor is the center of gravity. A cart must be wide enough to be stable while carrying a variety of loads, but not too wide or it will be difficult to maneuver in tight spaces, whether or not it’s motorized.
There’s a reason that developing an adequate material handling solution is so difficult. Even following OSHA’s published lifting limit of 50 pounds doesn’t fully protect employees. This is because material weight alone is not the only factor that contributes to MSD risk, especially during physically awkward or fast-paced tasks.
Though many loads weighing less than 40 lbs. are safe to move manually, one OSHA study specifically analyzing the MSD risk of lifting tasks discovered that injury is still possible when transporting materials as light as 35 lbs. With such conflicting information, the confusion fabricators experience when trying to protect their employees is completely understandable.
Coming up with the right ergonomic motorized equipment for a specific application is a complicated process. In addition to load size and weight, engineers have to account for any inclines, rough surfaces, or outdoor conditions that could inhibit the proposed equipment’s ability to operate safely. Entire workplace processes and systems must also be looked at in-depth, because some safety risks go beyond transporting a load from point A to point B.
For example, shifting materials onto shelving or raising them up to work table height presents MSD risks that should not be overlooked. Facility layout and storage systems are another factor. Fabricators in particular can run into problems when trying to find a cart that is long enough to carry industrial shafts and sheet metal, but maneuverable enough to pass through tight workspaces.
Every fabricating environment is unique and can change with each new project, especially in low-volume, high-product-mix environments. Here’s where that all-important walk-through comes into play. Walk-throughs reveal how employees are operating and help identify any additional issues with workcell structures, storage systems, and operational logistics.
Quite often some type of motorized platform cart is needed to accommodate the lengthy or unusually shaped materials. Standard motorized carts can improve matters, as can scissor-lift carts with adjustable heights—especially helpful when tackling ergonomics for a group of employees with varying heights and body types.
Transporting exceptionally heavy or long materials often calls for a heavy-duty motorized transfer cart that can handle very large payloads. When designing these custom carts, a fabricator needs to consider the level of maneuverability. For example, in a facility with tight workcells and storage aisles, the cart might need to be engineered to rotate 360 degrees around its centerpoint.
Engineers can get creative in tailoring the final product to the needs of the fabricator by customizing the platform size, safety features, drive systems, and deck add-ons such as racks or shelving. Heavy-duty transfer carts can be designed to operate wirelessly, while the “driver” stands a safe distance away from the cart itself. Wireless control is ideal for a fabrication facility with space limitations or additional safety concerns that limit where employees can travel throughout the workspace.
Consider one fabricator that invested in a motorized transfer cart with side-mounted controls and steering to accommodate the length of the materials onboard. When beams, tubing, or extra-long components that will naturally extend beyond the platform of just about any motorized cart are transported, side-mounted controls help maximize platform space on both ends of the cart.
For appropriate applications, electric tuggers can be a versatile, cost-effective way to prevent MSDs. Tuggers operate similarly to an SUV towing a trailer, meaning pulling is usually easier than pushing or backing up. Though maneuverability is more limited with a tugger than a motorized cart, a tugger can pull multiple carts at once. With the proper hitching method, a standard tugger can hitch to and move a variety of manual cart types within its payload capacity.
Research, Education, and Engineering
Each of these ergonomic equipment categories is as diverse as the transport problems it is designed to fix, and it takes quite a bit of research, creativity, and expertise to find out which one is going to work for a specific application. Though every facility has its own challenges, one thing is clear about every fabricating operation: The most important step in combating musculoskeletal injuries isn’t simply going out and buying a piece of equipment. It’s the preliminary research, education, and engineering that allow fabricators to master the physics of their own workspaces.