DEVELOPMENT AND FABRICATION OF A POLYCARBONATE EYESHIELD FOR THE U. S. ARMY FLYER'S HELMET
MINE SAFETY APPLIANCES CO PITTSBURGH PA
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The need to provide U.S. Army aircrewmen with increased eye protection saw a production technique developed to make optically acceptable, shatter- and impact-resistant eyeshields from polycarbonate resin. It was found that production quantities of optically transparent polycarbonate lenses can be manufactured with a great deal of reliability by injection-molding processes. Injection-molding of polycarbonate lenses employs standard equipment and techniques. These, however, must be adjusted to account for the idiosyncrasies of the resin, e.g., hygroscopic and flow characteristics. In this fabrication project, the mold used was end-gated and highly polished. Of three available grades of resin, the material with the lowest molecular viscosity provided the best results. The development molds produced about 75,000 acceptable eyeshields which were made available to U.S. Army and Air Force airmen for immediate tactical use. The polycarbonate resin characteristics and molding techniques that influenced the design of the eyeshield, and the development of the fabrication technique are discussed. Also discussed are factors that governed the selection of material type, mold design, and quality assurance considerations.
- Protective Equipment