Ergonomic handling basics
Pallet positioners, workstation cranes and vacuum lifting devices are three leading ergonomic solutions that promote worker safety and productivity.
By Bob Trebilcock, Editor at Large -- Modern Materials Handling, 1/1/2007
When it comes to distribution and manufacturing, ergonomics is increasingly important as companies look for ways to get more throughput from their existing facilities yet protect their workers. The key to doing that with any workforce, let alone the aging one now in place, is to provide ergonomic equipment that makes the job easier.
"What we're really doing is designing products and processes that allow us to fit the job to the person," says Jim Galante, director for business development for Southworth Products (207-878-0700). He's also chairman of the EASE Council of the Materials Handling Industry, an association of manufacturers of ergonomic assist safety equipment and systems. "You can't change the person doing the job, but with ergonomic assist devices, you can improve the fit by creating an ergonomic zone."
Make no mistake about it, manual materials handling is stressful. By some estimates, manual materials handling represents an estimated 35% of total workers' compensation claims. Furthermore, back and upper extremities were involved in 44% of all lost time injuries.
Ergonomic assist devices like lifting and positioning devices, workstation cranes and vacuum handling systems can balance the scales between worker safety and worker productivity.
Determining which solution to use in a specific application is usually determined by pairing the solution to the application.
Positioning devices|
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| Pallet positioners respond to the weight of a load to keep a pallet positioned at a height that minimizes worker bending and stooping. |
Positioning devices are used where bottom-up movement of a load, product or worker is required.
The vast majority of pallets, for instance, are loaded and unloaded by hand. Lift tables rely on hydraulic or pneumatic controls to position a pallet so that the top layer of the load is always at a height to minimize the amount of lifting required by an operator to palletize or depalletize the load.
"A lift table works just like the device in the cafeteria that keeps the stack of plates level with the counter," says Galante. "Based on the weight of the load, it automatically raises or lowers the pallet to the right height."
While a lift table adjusts the height of the load to the worker, adjustable work platforms adjust the height of the worker to a stationary load.
Not all materials handling jobs require employees to lift heavy loads. Some jobs, like unloading parts from a container, require an employee to bend, twist and reach. These jobs can be improved ergonomically with devices that adjust the height and tilt the angle of the container for easier access. These can be mounted on the floor or a work table, and are available as mobile devices that move with the operator.
Workstation cranes
Positioning devices, like lift tables, move a load from the bottom up. Workstation cranes are used when a load has to be lifted and moved from above, especially in manufacturing applications.
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| Workstation cranes, like this free-standing jib crane, are used when a load has to be lifted and moved from above. |
"There are a multitude of applications for workstation cranes, but most tend to be in manufacturing, especially in assembly and machine areas," says David Butwid, vice president and general manager of Gorbel (585-924-6262). "In distribution, workstation cranes may be used in receiving or shipping, especially in conjunction with vacuum handling devices."
These cranes typically handle loads from 150 to 4,000 pounds. Most operate within enclosed tracks, which can be constructed from steel or aluminum. The enclosed track design keeps the surface clean, which makes it easier for an operator to push the load.
Three types of cranes are used at workstations.
- Floor supported, or free-standing, cranes are used when the ceiling isn't strong enough to support the loads that will be lifted. These units can also be mobile, so that an operator can move the load from one work cell to another.
- Ceiling-mounted bridge cranes are used for loading and unloading in assembly operations. With a bridge crane, an operator can cover a rectangular area, moving the load backward and forward as well as from side to side.
- Jib cranes rotate off an axis and can move a load in a circular area, either 180 or 360 degrees. They are wall mounted and floor mounted.
Intelligent assist devices
Intelligent assist devices, or IADs, are the next generation in overhead handling.They rely on sophisticated sensors, controls, and servo motor technology that allow operators to manipulate and position loads with speed, precision and ease. They also sense the actions of an operator, says Butwid. "Through the use of computers, sensors, and software, the unit adjusts to a changing force or a changing load without human interaction."
Because IADs are more expensive than traditional lifting devices, they have primarily been used in manufacturing applications requiring high throughput, a high degree of precision, or high value add.
Vacuum lifters and manipulators
Vacuum lifters rely on a vacuum of air to grip and lift boxes, pails, drums or sheets of material that would require two, three or four operators to lift manually. There are two types of vacuum lift systems.
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| Vacuum assist devices, including vacuum lift tube technologies, allow a worker to quickly palletize or depalletize boxes, pails, drums or sheets of material. |
A hard vacuum uses a compressor to create suction at the cup for the sole purpose of gripping a product that's hard to handle, like metal sheets. "In a hard vacuum solution, the vacuum grips the sheet and a workstation crane or other overhead hoist device does the lifting," says Tim Carney, president of Palamatic Handling USA (610-701-6350). Hard vacuum solutions are usually found at the front end of a manufacturing process.
The second type is vacuum lift tube technology, a type of vacuum technology that combines gripping and lifting in one solution. Powered by a regenerative blower, this equipment uses a tube to create a lower than ambient air pressure vacuum. The device can grip a variety of loads, including bags, pails and drums, and can lift them without a separate hoist or crane.
"The larger the tube, or the more tubes you have, the more weight you can lift," says Carney. "Properly designed vacuum tools can be used to lift or hold many tons."
In the shipping area, vacuum lifters are used for palletizing. In fact, vacuum lifters can also allow one worker to very quickly palletize or depalletize by moving a whole layer of cartons at a time.
Vacuum lift systems can handle loads of 1,000 pounds, but 300 to 500 pounds is the most common range.
Manipulators and extenders replicate the human arm to extend an operators' reach. Moving loads of up to 1,000 pounds, manipulators are used in the automotive industry to install car seats or doors. They might also be used to remove parts from a heating oven and insert them into a machine. "The technology only requires a pound or two of force to move a 150 pound object," says Carney.
| Company | Contact information | Lift tables | Container tilters | Overhead lift devices | Intelligent assist devices | Vacuum lifting devices | Manipulators | Work-stations |
| Advance Lifts |
www.advancelifts.com |
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| American Lifts | www.americanlifts.com 812-663-4085 |
X | X | |||||
| Autoquip Corp. | www.autoquip.com 405-282-5200 |
X | X | |||||
| Anver Corp. | www.anver.com 800-654-3500 |
X | X | |||||
| Bishamon Industries | www.bishamon.com 800-358-8833 |
X | ||||||
| BOSTONtec, Inc. | www.bostontec.com 989-498-0773 |
X | ||||||
| Dalmec, Inc. | www.dalmecusa.com 630-307-8426 |
X | X | X | ||||
| Dehnco | www.dehnco.com 847-382-1579 |
X | ||||||
| Demag Cranes & Components | www.demag-us.com 440-248-2400 |
X | ||||||
| Durham Manufacturing Co. | www.durhammfg.com 800-243-3774 |
X | ||||||
| ECOA Industrial Products | www.ecoalifts.com 800-433-3833 |
X | X | |||||
| Gorbel, Inc. | www.gorbel.com 800-821-0086 |
X | X | |||||
| Ingersoll-Rand Co. | www.irhoist.com 908-238-7360 |
X | ||||||
| Liftomatic | www.liftomatic.com 847-325-2930 |
X | ||||||
| Lift Products | www.liftproducts.com 877-543-8776 |
X | ||||||
| Palamatic Handling | www.palamatic.com 610-701-6350 |
X | ||||||
| Pentalift Equipment | www.pentalift.com 519-763-3625 |
X | X | |||||
| Positech Corp. | www.positech.com 712-841-4548 |
X | X | X | ||||
| Rousseau Metal | www.rousseaumetal.com 866-463-4270 |
X | ||||||
| Schmalz Vacuum Lifters | 919-713-0880 | X | X | |||||
| Serco | www.sercocompany.com 972-323-6730 |
X | X | |||||
| S.I.T. Indeva | www.SIT-indeva.com 704-357-8811 |
X | X | X | ||||
| Southworth International Group | www.southworthproducts.com 800-743-1000 | X | X | |||||
| Stanley Vidmar/Stanley Cobotics | www.stanleyvidmar.com 800-523-9462 |
X | X | |||||
| Unitech | www.unimove.com 610-826-7855 |
X | ||||||
| West Bend Division of Bushman Equipment | www.bushman.com 262-790-4200 |
X | X |
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