Testing Without Breaking

In most U.S. companies, the quality-control department is apt to be a laboratory where technicians happily ruin a random sample of products by tearing, pulling, bending or melting them to see if they meet set standards. But in today's rapidly advancing technology, where the products are often too complex or too expensive to test by such methods, industry's scientists are turning to a new and promising science called nondestructive testing. They are using X rays, ultrasonics, magnetic pa ticles, dyes and tracer gases to spy out flaws and weaknesses that affect quality or safety -- and doing it without so much as scratching the products.

Right the First Time. The pioneers of nondestructive testing were the rail road brakemen, who used to tell if a steel car wheel was cracked by whacking it with a hammer to see if it rang true. United Air Lines technicians use basically the same principle today when they bombard jet turbine blades with electronically generated sound to see if the blades resonate at a frequency that indicates there is no danger of breakage. Westinghouse uses ultrasonics --super high-frequency sound waves -- to probe right through big forgings in the rotors of its giant $2 million turbine generators and detect air pockets or cracks inside the metal; since it began this test, Westinghouse has not had a single forging break on the job. An ultrasonic tester used by Republic Steel can measure the thickness of a coat of paint or locate an air pocket 40 ft. deep in solid steel.

Government buyers, insistent on the nearest thing to perfection in space components, have been the prime driving force behind industry's growing interest in nondestructive testing. Ever since loose solder balls of only a thousandth of an inch in diameter were found inside transistors in the Polaris missile, the Air Force has insisted that all the transistors in missile components be Xrayed. Companies have discovered that "preventive" testing produces safer and more efficient products, and also cuts costs by making it easier to detect and correct flaws. Manufacturers of machinery and airframes spend 13% of their production costs on nondestructive testing, are convinced that otherwise they would lose 45% of their production because of faulty quality. "Every time you have to do something over again," says Lockheed Aircraft Tester Harvey Christen, "you duplicate your original cost. Nondestructive testing helps you to make each part right the first time."

Dangerous Cracks. Republic Steel ensures that its seamless pipes are right before they leave the mill by using an electromagnetic testing machine that watches for breaks as the pipes rush by at assembly-line speed and determines whether they can be repaired. With such nonmagnetic metals as zirconium and tungsten, testers use penetrating oils to test products that are unresponsive to electromagnetic devices. Mixed with dyes that show up under ultraviolet light, the oils quickly reveal dangerous cracks in such important products as nuclear reactor components and power stations.

Despite the growing interest of business in nondestructive testing, Robert C. McMaster, a professor of welding engineering at Ohio State who has developed an X-ray method for testing metals that shows up flaws on a TV screen, complains that the new technology still "means little or nothing to perhaps 99% of U.S. industry." Considering the quality loss caused by less exacting standards, McMaster views industry's reluctance to take up nondestructive testing as "a major tragedy."

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