Development of an Integrated System for the Automatic Viscosity Correction of a Ceramic Slurry for the Investment Casting Process

摘要

Background: Starting from a wax model of the mold, which is later discarded, investmentcasting is used to make almost finished metal cast parts. The term "investment casting" is derived fromthe use of a ceramic liquid mixture (slurry), in which the model is repeatedly immersed (invested) toform, layer by layer, the shell which has to be filled with molten metal. The liquid of the slurry tends toevaporate so that the viscosity of the former increases and a correction is needed.Objective: The study aimed to investigate the simplest way to measure slurry viscosity and automaticallycorrect it.Methods: Numerical and experimental tests have been implemented to correctly assess the proposedmethod. An integrated system for the automatic correction of slurry viscosity is realised which comprises:a reservoir of slurry including means for mixing it; a transducer which continuously measuresthe slurry viscosity; a pump that gradually feeds the diluent into the slurry to keep its viscosity constant;and a device, governed by the continuous viscosity measurement, that operates the pump.Results: It has been proved that the developed system is able to integrate the slurry viscosity continuousmeasurement with gradual addition of diluent into the slurry, so as to have a fully automated operationthat can make corrections, whenever necessary, on the basis of the transducer output.Conclusion: The developed system works properly by keeping the slurry viscosity within a fixed range.A patent has been recently deposited to protect the integrated system for the automatic correction ofslurry viscosity.