Radio age research, manufacturing, communications, broadcasting, television (1941)

"SEWING" BY RADIO SHOWN N^iu Elt'ctron/c Miicfiiiit' Deuelofeci Inj RCA Laborcitories for Use /n Faliricnt/iu] Plastic MiJtericils neitionstrntecJ to War Mauufactiirers AS electronic "sewing" machine L that uses radio-frequency cur- rent instead of needle and thread to join plastic materials was demon- strated to war equipment manufac- turers and members of the press for the first time June 2 at the Camden, N. J., plant of the RCA Victor Division of the Radio Corpo- ration of America. Although the new apparatus was primarily conceived as one of many post-war radio-electronic develop- ments, the demonstration was held to show its possible applications to war equipment production. An ex- perimental model was used, as de- veloped by C. X. Hoyler and R. A. Bierwirth, under the direction of Dr. George H. Brown, reseaixh sci- entist of the RCA Laboratories at Princeton, N. J. While the machine is still in the developmental stage and has not been placed in production, Fred W. Wentker, manager oi the electronic apparatus division of RCA, pointed out that news of its development has already attracted considerable notice among many war manufac- turers. Some of these war manu- facturers are hopeful, he said, that the new device will help break bot- tlenecks in production where con- ventional processing methods have been found inadequate to meet ur- gent war needs. Instead of needle and thread, the RCA Electronic "Sewing" Machine uses radio-frequency current; in- stead of ordinary woven cloth, it works on thermoplastics and ther- moplastic coated fabrics—the new synthetic materials that are finding wide application in the making of raincoats and caps, weather bal- loons, and in the packaging of many types of food and oils, to mention only a few. It "stitches" a thin solid seam that is air- and water-tight, creat- ing a bond that is stronger than the material itself. It does this simply and easily, thus promising to over- come many fabrication difficulties involved in usual processing meth- ods as applied to thermoplastics. The radio sewing machine was created to meet a definite need in the sheet plastics industry. Ther- moplastics, tough resilient material, can be rolled into large cloth-like sheets or can be used to form an air- and water-tight coating on RADIO-FREQUENCY CURRENT TAKES THE PLACE OF NEEDLE AND THREAD IN THE ELECTRONIC SEWING MACHINE (LEFT) AS DEMONSTRATED BY RCA LABORATORIES. THIS DEVELOPMENTAL MODEL (BELOW) OF THE ELECTRONIC MACHINE, WHICH IS BEING GIVEN NU.MEROUS PRACTICAL TESTS, LOOKS LIKE CONVENTIONAL TYPE. A TOBACCO POUCH MADE OF THERMO- PLASTIC MATERIAL IS "STITCHED" TO- GETHER IN A DEMONSTRATION OF RCA'S ELECTRONIC SEWING MACHINE. standard fabrics. When cut into patterns, the sections are usually put together by sewing with thread, by cementing, or by fusing with externally applied heat. None of these methods has been found to be entirely satisfactory. Heat fusing has always appeared to be the most desiralble method. The hot-iron methods which have been employed, however, have pioved far from satisfactory for many applications because of the difficulty in maintaining uniform temperatures, because the materials stick to the heating plates, and be- cau.se the materials tend to extrude when pressure is applied. By generating heat inside the material itself and by using a mini- mum of pressure, RCA's electronic sewing machine eliminates the.se difficulties, according to Dr. Brown. This is what happens. The mate- rial to be sealed, or "sewed," is fed across a table top through two small rollers which serve as the "needle." A small radio-frequency generator is connected to these rollers. As they i)ull the material along, they cause a concentrated beam of radio frequency current to pass through the material. Heat is generated by a dielectric loss, or, in other words, l)y the struggle of the current to get through the closely packed mole- cules of matter which compose the material. The heat, together with a very light pressure, causes ther- moi^lastics to fuse, or weld, in a tight bond. [RADIO AGE 25]