(2 of 3)
This week, for example, in General Electric's Schenectady plant great turbine castings for U.S. warships are being Xrayed. Special photographic films are taped inside the castings (see cut p. 7.5). Then the X-ray machine is lowered into place and the operators retire behind an 18-inch concrete wall.* From a remote-control panel the machine is turned on, and for a minute or two the rays fall upon the six-inch steel. The developed films reveal cracks and pores deep inside the metal. Defective 40-ton castings are not junked: their flaws are gouged out and the holes welded full of solid metal. Since 1936 the Navy has demanded that General Electric X-ray its turbines, so that no invisible engine faults will ever make its warships helpless in battle.
The use of X-rays has made possible improved industrial technology. Sturdier boilers for the Navy are insured by X-ray tests. Bent out of six-inch steel plate, boilers were formerly riveted because reliable welds were unattainable. But with the help of 1,000,000-volt and lesser X-rays, engineers and welders of Babcock & Wilcox have learned how to eliminate flaws so that welded seams can now be relied on.
Ford Motor Co., which is speeding production of Pratt & Whitney aircraft engines by casting instead of forging their crankshafts, recently got a 1,000,000-volt machine to X-ray the crankshafts. Ford's older 400,000-volters could X-ray 40 crankshafts a day; the new giant works six times as fast. Vital engine parts are all 100% Xrayed; at frequent intervals samples of other parts are X-rayed to make sure that quality does not fall off as it is apt to do in the furious pace of defense production. Founded in 1930, Ford's X-ray department soon expects to have industry's biggest collection of X-ray apparatus, to use many thousand films a day.
Principal use of big X-ray machines is to study castings and welds for flaws but there are hundreds of other uses for smaller machines ranging down as low as 5,000 volts, thousands of which have been turned out by Westinghouse, G.E., Picker X-Ray Corp. of Cleveland and Kelley Koett Corp. of Covington, Ky. For example :
> Inspecting tobacco, candy, nuts and canned foods for foreign objects. Usual method is by fluoroscopy. Instead of falling on photographic film the X-rays fall on chemically treated screens where they become luminous and form shadow pictures as the parade of examined materials goes by on conveyor belts. This inexpensive method is good where detail is not needed.
> Sorting fruits. In 1937 a frost-bitten California orange crop was ready to be thrown away completely when G.E. hurriedly developed X-ray machines which distinguished mottle-shadowed frozen oranges from the dark-shadowed good ones, saving fruit growers $10,000,000.
* World's biggest X-ray machine—a 1,400,000-volter—began operation last fortnight at the U.S. Bureau of Standards in Washington.