Ohio State Tackles Assembly Line Ergonomics
Rising health care costs are one of the biggest challenges facing the American auto industry today. In fact, some OEMs and Tier One suppliers spend more on health care than on steel—as much as $2,000 per vehicle produced.
Reducing injuries on the assembly line and improving productivity are essential to reining in skyrocketing health care costs. That’s the goal of Ohio State University’s Center for Occupational Health in Automotive Manufacturing (COHAM).
“We design assembly tasks and processes that minimize occupational health risks and enhance productivity and quality,” says William Marras, COHAM director and a professor in the department of integrated systems engineering. “Our mission is to empower state-of-the-art technology and cutting-edge analysis methods to protect worker health, reduce worker injuries and optimize high-tech vehicle production.”
Many leading automotive manufacturers, such as BMW, Faurecia, Honda and Toyota, have turned to COHAM for assistance since the organization was created six years ago. Research projects have changed the way that air bags, bumpers, doors, headliners, instrument panels, wiring harnesses and other subassemblies are installed and attached in vehicles.
“We are the only university-based full-scale manufacturing operation in the world where automobile manufacturers and suppliers can test the effect of manufacturing systems on the health of workers,” claims Marras. “This approach provides quantitative cost-benefit information to manufacturers so that they can make production decisions based upon scientific evidence.”
Marras and his colleagues tap into basic ergonomic research techniques developed at Ohio State’s biodynamics laboratory. The 3,500-square-foot facility is equipped with a wide variety of tools that measure how the body works and how it responds to various types of muscle stresses and joint loads.
Engineers at the facility have developed several testing devices in-house. For instance, a wrist motion monitor measures how rapidly wrists move when performing various assembly tasks. A lumbar motion monitor studies back movement and exertion.
When tackling a new ergonomics challenge, engineers first visit the manufacturer’s assembly line to talk with operators and take basic measurements.
“However, there are limits on what you can do on the plant floor,” says Marras. “For instance, you can’t do MRIs or strap a bunch of electrodes onto assemblers. That’s where COHAM comes in.”
The center features 5,000-square-feet of simulated plant floor. It includes conveyors, parts bins, workstations, overhead hoists, zero-gravity arms, and a wide assortment of pneumatic, electric and battery-powered fastening tools.
“It’s designed to look like a real auto plant and it provides us with a lot of flexibility,” says Marras. “For example, we can easily change the speed of the assembly line to measure and monitor how operators react.”
Full-time line workers are typically involved in all COHAM research projects. In addition, Ohio State students are brought in to simulate new hires.
Several years ago, Marras and his colleagues conducted a research project for Honda aimed at reducing musculoskeletal injuries associated with DC-electric torque tools. The engineers tested a variety of right-angle fastening tools and evaluated how they affect the upper extremities of assemblers.
One of the most recent COHAM projects involved the development of a carriage that tilts cars sideways so assemblers can easily access interior areas while standing. As part of the study, the engineers had 12 people install components in a car’s interior, underbody and engine compartment while standing. They measured stresses on the people’s bodies when the car was tilted at different angles.
“Of nine different installation tasks, seven became much less strenuous when the car was tilted on its side 45 degrees,” says Marras. “The other two showed similar improvements when the car was tilted completely sideways at 90 degrees.”