COLUMBUS, Ohio, October 10, 2002 (ENS) - A process developed at Ohio State University (OSU) for shaping metal parts using magnetism may cut manufacturing costs and help preserve the environment. The process could also expand manufacturers' choice of available metals, and enable the use of aluminum parts in lighter, fuel efficient automobiles, the researchers said.
Glenn Daehn, OSU professor of materials science and engineering, and his colleagues pioneered hybrid electromagnetic metal forming in 1999, while collaborating with the "Big Three" automakers. With this process, a traditional tool and die stamps the general shape of a part out of sheet metal. Afterward, a magnetic field pushes at specific locations of the sheet metal to form fine details or complex shapes.
Now the Ohio State engineers have discovered that they can improve the process if they use the magnetic field to stretch certain portions of the metal during the stamping operation.
In tests, they were able to create an aluminum pan with a depth almost 1.5 times greater than possible before, without using the toxic industrial lubricants required for traditional stamping. Daehn described the improved process on Wednesday at the annual meeting of the Minerals, Metals, and Materials Society, now known as TMS.
Daehn calls the process "bump forming," because the magnetic field bumps against the metal in many short pulses - five to 20 times in less than one second - while the metal moves into the die.
As a sheet of metal bends to fit inside a tool and die, some parts of the sheet may stretch more than others, and may tear if the metal stretches too much. Lubricants are used to reduce tearing, and disposing of these lubricants can be expensive and hazardous to the environment.
With Daehn's technique, electromagnetic fields work against the parts of the sheet that would not normally stretch, causing them to bow out. With this extra amount of give in the metal, other portions of the sheet will be less likely to tear.
The process works well in electrically conductive metals, including aluminum. When exposed to a strong electro-magnetic field from a coil inside the punch portion of the stamping tool, a corresponding electrical current and electromagnetic field form inside the metal. The field in the coil and the field in the metal repel each other, pushing the aluminum away from the punch.
Bump forming could be useful in mass production, Daehn said. From the auto industry to aerospace and electronics, large manufacturing operations often need to stamp as many as 10 million copies of their metal components per year.
"We can enable the use of higher strength materials and aluminum alloys in manufacturing. We can reduce the amount of equipment associated with metal forming," Daehn said. "Parts that used to require multiple steps could be made with one set of tooling, which would mean a big cost savings. And we think we can eliminate reliance on these nasty lubricants.":
