Precision investment casting with blocks - providing reservoirs for molten metal and so eliminating air inclusions

摘要

Precision investment casting of small parts by the lost wax method, ensuring freedom of air inclusions, is achieved by using a transversely bored, rectangular heat-destructible, reservoir blocks within which are received on an elongated heat destructible sprue pin. The patterns are secured to the end of each sprue pin and each block is secured to its respective sprue pin at a point adjacent but spaced from the pattern. The free ends of the sprue pins are secured to a base and placed within a flask so forming a hollow body to receive investment material which hardens around the patterns and their supporting structures. The investment is then heated, allowing the blocks, sprue pins and patterns to melt, and flow out having a metal pouring cavity with adequate reservoirs close to the casting cavities. Method provides the simultaneous casting of several small parts, ensuring freedom of shrinkage or air voids by the use of adequate reservoirs for the molten metal. Used for casting of small dental restorations and other small parts e.g. rings, buttons, settings, etc.