Process for molding thin thermoset resin plates in an inverted cavity

Abstract

The mold described herein comprises an upper and a lower portion in which the upper portion comprises an inverted cavity flash land mold section and the lower portion comprises a readily removable steel plate. By having the cavity flash land mold portion inverted and in the upper portion of the mold, the molded product is more easily separable by gravity from this upper mold portion which avoids the necessity to use means for lifting the molded product from the cavity and thereby avoids the distortions and stresses previously caused in the product by such lifting means. To aid in separating the product from the inverted cavity upper portion as the upper portion is separated from the lower flat sheet portion of the mold, releasing means, such as air from poppet valves in the upper area of the cavity mold, may be used to facilitate separation of the product from the upper cavity portion and deposition of this product on the lower flat sheet portion of the mold. This permits removal of the product while still retained on and supported by the lower flat sheet portion of the mold. This prevents out-of-place deformations and stresses in the molded product. This mold design is particularly suitable for the molding of very thin flat plates of considerable length and width.