Fluid Bed and Rain Fall Sanded Shells-An Investigation Into Fundamental Structural and Mechanical Property Differences

摘要

Investment casting research has been carried out by the University of Birmingham, sponsored by E.P.S.R.C. and a consortium of industrial companies. The programme was aimed at developing an in-depth understanding of all aspects of the process, with a view to routinely producing sound, net shape castings. The investment technique itself has tremendous advantages in the production of quality components and key benefits of accuracy, versatility and integrity. As a result the process is one of the most economic methods of forming a wide range of metal components. Environmental and economic pressures have, however, resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Optimisation of the mechanical and physical properties of the ceramic shell, whilst reducing process/material costs, will be elemental to achieving these aims. The mechanical performance of the ceramic shell is fundamental to the quality of the finished component. The properties of the ceramic are completely dependent upon the materials and method used in the production of the shell itself. Two main techniques are used in the casting industry for the application of stucco material: rain fall sanded and fluid bed. Choice is a matter of preference and experience for individual foundries but the two methods produce a significantly different ceramic structure. This paper reports on the work carried out to characterise the fundamental difference in physical structure and properties of shells produced by both techniques. Practical suggestions as to the applicability of use will be presented.