One Wrench Fits All


Until recently, industrial power tools were designed around what they did. Maximizing power and performance was the only goal. Workers were expected to adapt to the tools. The result? On the assembly line, 200-pound men and 130-pound women have been forced to use the same tools. Workers have wrapped handles in tape and used other ad hoc measures to make the tools more comfortable--and safer. Despite their efforts, cumulative trauma injuries (CTI), a category of repetitive-motion maladies, have become a growing health problem in the workplace.

Ingersoll-Rand Co., with help from Group Four Design in Avon, Conn., is building a new generation of power tools that could prevent some injuries. Working from the outside in, they're focusing on the operator as well as the tool. The "D" Series of Angle Wrenches, used in car, truck, or tractor assembly, is the second gold winner for the company. Last year, it won for the Cyclone Grinder, another ergonomic industrial tool used for polishing steel pipe and other metals.

Interdisciplinary teamwork was crucial to the success of the wrench. From the start, Phillip Federspiel, CEO of Group Four, joined with Ingersoll-Rand Project Manager Steven Thiry and representatives from the company's manufacturing, engineering, marketing, and purchasing departments. "When you start changing designs radically, as we did with the wrench, you have to change vendors for different materials and services, so getting purchasing in on the core team right away is very important," says Federspiel. "If you wait to the end, it's extremely difficult to find the parts and processes."

Group Four first surveyed assembly lines around the country, from Chrysler Corp. auto plants to Caterpiller Inc. factories. They found that one-third of the workers in these plants are now women. Even though the women have to use the same tools as men, their hands are as much as two inches smaller in length. Angle wrenches deliver torque to fasteners and, as a result, put a lot of force and pressure on the hand. Holding an object that is too big or too small makes gripping harder and can lead to CTI syndrome. Both men and women wanted lighter, easier-to-use fastening tools. No one, they said, had ever asked them how to fashion the tools they needed to do their job. At least not until members of Group Four came to their plant.

AMBIDEXTROUS. So Group Four fashioned a handle that can be adjusted for three hand sizes in just two seconds on the line. The handle is made out of soft polypropylene, which helps the operator's grip. The polypropylene acts as an insulator, keeping the hand warm as well. Previous angle wrenches were made out of steel, and assembly line workers had either wrapped the handles in tape or worn gloves. Finally, the design team increased the length of the wrench, which reduces "torque reaction."

To improve flexibility and balance, the team moved the power inlets to the top of the wrench. It also made the wrench ambidextrous--the forward/reverse controls were designed for both left- and right-handed people. Finally, the team switched from steel to composite materials to reduce weight. Reinforced nylon was used for the exterior motor housing.

The Angle Wrench comes in two forms: powered by compressed air or DC electricity. Ingersoll-Rand says Japanese auto makers are interested in the electric version because it allows the manufacturer to collect data, analyze it, and control quality. By tracking the information, a computer can tell the manufacturer what the acceptable quality range is for a product and when that range begins to be exceeded on the line. That means the system can warn assembly workers, for example, when their fastening is just at the point of crossing the line into "not acceptable," allowing them to make the correction without shutting down the line. With some complex computerized manufacturing systems, the computer will make the correction automatically, without consulting the workers. Japanese auto makers liked this aspect of the Angle Wrench as well as the adjustable handle, which provides a grip for the smaller Japanese hand.

The biggest fans so far of the Angle Wrench are at Chrysler. In fact, workers insisted on it at the company's showcase Jefferson Avenue factory in Detroit, where the new Jeeps are built.

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