Looking up for improved ergonomics
Overhead systems-such as work station cranes, manipulators, vacuum lifters, and others-can handle the tough, heavy jobs and help keep operators healthy and safe.
By Tom Feare -- Modern Materials Handling, 3/1/1999
The concept is rather simple: Good ergonomics = good economics. Minimize injuries to operators as a result of tough, heavy jobs they perform with poor ergonomics and possibly unsafe practices. And then regain the lost productivity and avoid the costs associated with workplace injuries and accidents.In many industrial settings where companies rely upon manual labor to get certain jobs done, improving the ergonomics brings big dollar savings down to the bottom line. Costs for workers compensation, lost workdays, insurance, and retraining other workers will fall.
Often, a manual handling task can be mechanized, or perhaps fully automated, to avert the health risk or injury potential. Frequently, overhead handling equipment and systems provide the solution to a problem of poor ergonomics.
In this article we have narrowed our focus to the types of materials handling systems which give operators an ergonomic edge or assist through the use of overhead equipment. In a feature last September (pp. 44-46) we examined a broader range of equipment categories.
Fitting the job to the worker
On its web site, www.osha.gov, the Occupational Safety and Health Administration provides more perspective on ergonomics and its approaches to ensuring worker health and safety.
"Ergonomics is the science of fitting the job to the worker," OSHA says. "When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, musculoskeletal disorders (MSDs) can result. Workers who repeat the same motion throughout their workday, who do their work in an awkward position, who use a great deal of force to perform their jobs, who repeatedly lift heavy objects, or who face a combination of these risk factors are most likely to develop MSDs."
According to the federal agency, MSDs are a class of workplace injury which is rapidly growing. Costs are high, too: direct costs of $20 billion in workers' compensation claims; with indirect costs possibly as high as $100 billion.
Simple and inexpensive changes in the workplace can prevent some of these MSDs, OSHA suggests. Adjust the height of work surfaces, for example, to better fit the individual worker. Reduce the size of items workers must lift. Or provide lifting equipment.
Seeing is believing
Overhead systems can provide capabilities for a lift from above motion and/or for a transfer while supported from above motion, along with performing some other motions, such as rotating a load on its horizontal or vertical axis.
In contrast, equipment such as a lift table primarily offers a lift from below capability, or a tilter/dumper a tilt motion, together with some degree of rotational motion about either of the axes just mentioned.
Seeing is believing, so we've included case study stories with illustrations. They should help you visualize how overhead equipment provides an ergonomic assist or edge.
Your overhead options
There are numerous instances for applying improved ergonomics in manufacturing, warehousing, and distribution jobs using an overhead system. Here's a brief description of the key features of each of the basic kinds of equipment. Often the equipment comes with standard end-effectors, but these can also be provided as custom attachments to fit your application.
Air balancer. Powered by air pressure, this device balances or suspends loads, tools, heavy fixtures, or other heavy or awkward items with little physical effort required by the operator. Some balancers function by mechanical, not pneumatic means.
Manipulator. Providing the operator with an extra, heavy-duty "arm," a manipulator offers the extra muscle power to lift, move, rotate, position, and transport a heavy load into place. Manipulators are hydraulically, mechanically, or pneumatically powered. Some are floor mounted, while others are tied into an overhead system. Custom or standard end-of-arm tooling is available.
Vacuum lifters. These lifters- or "hoists" as they are sometimes called-use the power of a vacuum against the flat or curved surface of the load to raise, lower, or move it. Suspended from bridge or jib cranes or track, the lifters require a reliable source of plant "air."
Workstation cranes. Overhead track and crane combinations-often used with a packaged electric hoist, or some other lifting and positioning device that directly connects with the load or item to be moved-also offer enhanced ergonomics. Typically, these workstation crane systems serve a specific plant area or work cell. They are generally made of a lighter-duty construction than the heavier-duty overhead traveling bridge crane.
OSHA's plans on ergonomics
Congress pulled the plug in June 1995 on OSHA's attempts to establish a final ergonomics standard, refusing to give the funds to continue with this effort. More recently, the agency has again begun standards development to limit the risk of MSDs. And the agency promises to continue its enforcement, citing any violations for poor ergonomics under existing law.
Smart managers will look closely, therefore, at the jobs they supervise with an eye to how they might match worker and work task for a greater ergonomic edge. Within materials handling, a key source for information is the Ergonomics Assist Systems Equipment (EASE) product section of the Material Handling Industry. Call 704-676-1190 or visit the web site, www.mhia.org for more details.
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