Measurement Technique of Setting Expansion of Phosphate-Bonded Investment for Lost-Wax Casting

Abstract

Several measurement techniques were investigated on the setting expansion of a phosphate-bonded investment for lost-wax casting. Measuring the vertical expansion of a cylindrical investment molded in a vessel which was internally lined with an appropriate buffer material, gave a high expansion value. The friction or restriction by the vessel wall accompanied by the progress of the expansion, influenced the expansion value. In the case of measuring the expansion with a differential transformer, an expansion suppressing effect was generated by the load from the sliding-tip of the differential transformer. However, the load was reduced by modification of the differential transformer, which has enabled us to obtain values nearly equal to those by a non-contact type LASER displacement measuring apparatus.