Cool Tools: Tool Ergonomics
Published: October 2011
As indicated by hand tool advertising sales literature, toolmakers perceive ergonomics not only as a design feature but also a marketing strategy. Some identify ergonomic features and explain their benefits; other tools simply are characterized as “ergonomically friendly,” a description that can seem as ubiquitous relating to tools as “all natural” is to foods.
“Ergonomics is ‘the science of work’,” said Alan Hedge, Ph.D., CPE, director of the Human Factors and Ergonomics Laboratory, Cornell University. “It involves studying the design of tools and workplaces that fit the physical and mental abilities of people so that this maximizes their comfort, health and productivity.”
A simple, padded handle doesn’t necessarily make a tool ergonomic. The ergonomic design of hand tools, Hedge said, involves studying how workers will use a tool to perform a task, especially looking at the strength requirements and hand, arm, and body movements. Therefore, the tool can be used without a risk of injury and in such a way that optimizes the user’s ability to continue working with the tool for maximum work performance.
“For a tool design to be ergonomic, the essential starting point is consideration of what the tool is expected to do and how the tool will be used by different people,” Hedge said.
Using ergonomically friendly hand tools makes sense for tool users and employers. Poor hand tool design causes loss of productivity—slower work, more errors, and more accidents and injuries, which add to the cost of doing business from worker’s compensation claims and litigation.
Looking back to when each artist or craftsman had his or her own set of hand tools, ergonomics was embedded in the design of these tools because they were customized to the size and shape of each person, Hedge said.
“However, with the mass production of hand tools, this matching of the size and shape of the tool to the person was lost, and often the shape of the tool was for the convenience of manufacturers, rather than the needs of tool users. Some of the early studies on alternative tool design looked at tools like pliers, and one study showed that, by bending, curving and padding the grip of the pliers, a person could perform work with their hand in a more neutral posture (the hand is straight, not bent up or down or side to side), and this dramatically reduced the chance of a wrist injury and improved the performance of working with the tool,” he said.
Other studies followed, and manufacturers began to reshape tools. Research showed that bending the shaft of a hammer to a 19-degree angle puts the hand in a more neutral position when the hammer strikes the nail—the point at which maximum force is being exerted, reducing the risk of injury.
Ergonomic considerations vary with the type of tool and whether it is a manual or power tool. Basic factors to consider include size and weight; center of gravity; shape, diameter and length of handles; separation between handles, materials, and power tool triggers; vibration during operation; and the materials from which tools are made.
“Think about how the shape of an electric drill has changed since the 1950s,” Hedge said. “The first tools had large electric motors sitting above very short handles that were to the rear of the drill. Holding the drill put a large torque (rotational force) on the hand, and this made it unstable.
“These days, a good power drill has a much longer handle that passes all the way through the palm of the hand. The battery sits beneath this handle, and the handle is centered on the drill so that the tool is in balance in the hand. The tool can be operated with the hand in a straight power grip position. The material of the tool is not hard and cold. And the amount of vibration that is transmitted to the hand has been greatly reduced. All of these factors reduce the injury risk and improve the performance of using the tool,” he said.
Many of the tools electricians use today exhibit excellence of ergonomic design. However, Hedge said, the “fit” of the tool to the user remains an issue with mass-produced tools.
“A user with a large hand will find one tool comfortable to use while a user with a smaller hand might require a different tool,” he said. “Often, in industrial situations, a single tool size is provided for a variety of employees. Consequently, there is considerable interest in looking at how to develop hand tools where the size and angle of the tool has some adjustment so that this can better accommodate workers of different hand sizes and shapes.”
Reflecting on the continuing evolution of ergonomic tool designs, Hedge said that, as consumers become increasingly aware of the advantages of good ergonomic tool features, manufacturers will devote even greater effort to producing superior designs.
“There are numerous opportunities for future improvements,” Hedge said.
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at email@example.com.