New New Ceramic Saves Defense Materials D K O B , .ILY tne vary best indication of the adaptability of porcelain to the changing needs of industry is the introduction, during a hectic year, of a wholly new process and plastic product. This material, "Prestite", was developed by Westinghouse Electric & Manufacturing < "o. as an answer in the race to release badly needed defense materials. In this rase the substitute in a number of instances out-performs the materials it displaces. T w o months after announcement, the new development was being produced in volume and a few months later temporarily outstripped available manufacturing capacity. Although Prestite is properly termed a new plastic because it is formed accurately to intricate shapes, it is actually a porcelain since it is made from exactly the same ingredients and is fired in the same kiln with it. Mechanically the plastic is as strong in compressions as wet-process porcelain. It retains its mechanical strength without deformation or warpage at temperatures that would completely destroy phenolic plastics. Electrically the material is the equivalent of w e t process porcelain. I t has the same dielectric strength, is completely impervious to moisture, m a y be subjected to repetitive flashover without surface charring, and otherwise behaves like the highest grade electrical porcelain.
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Recently the newly created Prestite has substituted for aluminum in the storage reservoir of water coolers. In that application, ease of forming, dimensional fidelity, and high mechanical strength were essential characteristics. Because porcelain is completely inert chemically, it has proved to be even more suitable than the previous metal reservoir. Distribution transformer tap changer plates have always been made of wetprocess porcelain because of the requirement for high dielectric strength. The economic and mechanical limitations in the production of these plates have always made a design compromise necessary. Normally, long leakage distance and close dimensional tolerances were prime requisites. Cast or pressed plastic bodies would n o t permit either, so designs were accommodated to the deficiencies in the manufacturing processes. Leakage distances were as long as possible but seldom adequate. Warpage caused a high
Top. Template turning of a 10-inch porcelain insulator ensures accuracy of assembly. W i t h a steel gage, workman checks d i mensions of the unit he has trimmed. Center. Insulators undergoing high-frequency, high-voltage test far in excess of the normal requirements. Bottom. Extruding blanks for largest one-piece wet-process porcelain part ever made. The blanks eventually will become a cylindrical coil form 1 7 . 2 5 inches in diameter by 4 6 . 2 5 inches long.
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