Publication: American Machinist
New York, NY, United States
A new material to take the place of hard fiber, glass, porcelain, hard rubber, built-up mica, pressboard, rawhide, molded compounds, etc., has been developed by the Westinghouse Electric & Mfg. Co., East Pittsburgh. Penn., and is known as "Micarta." It is used for commutator bushings and brush-holder insulation, noiseless gear blanks, conduit for automobile wiring, etc. It is a tan-brown, hard, homogeneous material having a mechanical strength about 50 per cent, greater than hard fiber. It can readily be sawed, milled, turned, tapped and threaded, if a sharp-pointed tool is used and the work is done on a lathe. It can be punched only in thin sheets and cannot be molded. "Micarta" is not brittle, and will not warp, expand or shrink with age or exposure to the weather; it takes a high polish, presenting a finished appearance.
Two grades of the material are made. The grade known as "Bakelite Micarta" will stand a temperature of 300 deg. F. continuously, or 500 deg. F. for a short time. It is infusible and will remain unaffected by heat until a temperature sufficient to carbonize it is reached.
It is insoluble in practically all of the ordinary solvents, and impervious to moisture. The other grade designated as "No. 53 Micarta," has the same mechanical and electrical properties as the "Bakelite Micarta," but differs in its chemical and thermal properties.