That Tin

Induction-heating by radio waves has come to the rescue of the tremendous program of tin-saving announced by U.S. Steel Corp. last spring (TIME, April 6). By electroplating tin on sheet steel, 1/2 lb. of tin may be spread over 100 lb. of steel. The old hot-dip process used 1 1/2 lb. So $15 million worth of tin electroplating equipment was built, on the expectation that much tin used for U.S. tinplate would be saved. Nowhere before has electroplating been done on such an enormous production scale. Some single tinning lines turn out a continuous sheet three-feet wide, passed through a furnace at 1,300 feet per minute--enough to cover an entire football field every 18 minutes. But the plated coating is not perfect. Dull grey, its porosity and corrosion resistance are not satisfactory. To complete the process it is necessary to remelt the thin skin of tin momentarily, so that it renews to make a smoother, tougher surface.

Last month Glenn E. Stolz of Westinghouse Electric & Manufacturing Co. announced an effective method of providing quick, localized heating by using a broadcasting set of enormous power that directs its energy at the surface of the sheet just where it is needed, melts the tin coating without affecting the steel base, and without any physical contact between the strip and the furnace to mar the tin.

At least one large induction-heat unit is already in operation with 1,200 kilowatt output--power equal to that of 24 of the largest radio broadcasting stations whose maximum power output is 50 kw.

This file is automatically generated by a robot program, so reader's discretion is required.