Magnetic Metalworking

In their elegant laboratories near La Jolla, Calif., General Dynamics scientists are doggedly attacking a difficult problem: how to extract controlled power from hydrogen fusion. The pay off for their work is hidden in the future, but the powerful magnetic fields they have built to hold reacting hydrogen gas at 100 million degrees has already yielded a valuable practical "fallout." Those same magnetic forces used on a smaller scale have proved remarkably versatile for shaping metal.

Swift Action. At a Detroit meeting of the American Society of Tool and Manufacturing Engineers, engineers from General Dynamics' General Atomics Division demonstrated how the principle works in practice. Magneform -- a tool little larger than a home washing machine and using no more current than an electric range -- has no moving parts at all. Its essential part is a coil of heavy wire that can take var ious shapes, including a cylinder, a doughnut or a flat disk. When a massive electric current from a capacitor is shot suddenly through a coil, it creates an intense magnetic field in the space around it. If a piece of metal is near by, the magnetism starts currents flowing in the metal. These currents are surrounded by their own magnetism, and repulsion between the two fields drives the metal violently away from the coil. The action is over in microseconds, but it is powerful enough to push rigid metal into almost any shape.

The different coils do different jobs. When the end of a metal tube is inserted into the doughnut-shaped coil, it can be shrunk tightly around any insert such as a plug or a threaded fitting. To expand a metal tube, a cylindrical coil is pushed inside it. A flick of the switch, and the tube expands to bind itself solidly to whatever surrounds it. To stamp a flat piece of metal with a pattern, a trademark of elaborate lettering, the metal is placed between a flat coil and a die. When the coil is activated, the opposing magnetic field in the sheet shoves it away from the coil and presses it into the die.

Gentle Handling. Magneform is already doing many useful jobs: aluminum and copper are being joined to porcelain insulators for outdoor wiring; the metal bands around artillery shells are being fitted quickly without any fuss. The auto industry is using Magneform to produce ball-joint and seal assemblies for front suspensions. Magne-form's principal advantage over welding, pressing or stamping is its ability to shape metals without the rough handling that such operations ordinarily require. Automated assembly-line operation can be managed easily, and Magneform men are already looking toward the day when most subsidiary parts of an auto engine--carburetors, fuel pumps, etc.--are shaped and stuck together by Magneform.

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