Gating Systems for Sizeable Castings from Al Alloys Cast into Ceramic Moulds

I Stachovec,M Horáček,L Zemčík,J Horenský,V Kolda

doi:10.2478/v10266-012-0038-5

Abstract

Gating Systems for Sizeable Castings from Al Alloys Cast into Ceramic Moulds In contrast to casting to conventional non-reusable "sand" moulds, for which calculating technique for an optimum design of the gating system is comparatively well-developed, a trial-and-error method is applied mostly for casting to ceramic shell moulds made by the investment casting technology. A technologist selects from gating systems of several types (that are standardized by the foundry mostly) on the basis of experience. However, this approach is not sustainable with ever growing demands on quality of castings and also the economy of their fabrication as well as with new types of complex sizeable castings introduced to the production gradually (by new customers from the aircraft industry above all) any more. The simulation software may be used as a possible tool for making the process of optimising gating systems more effective.

Highlights

The investment casting technology is a progressive technology that facilitates a production of very complex thinwalled castings of dimensional and shape stability
An example of the gating system solution of a specific thin-walled sizeable casting from the viewpoint of optimising the metal flow in the cavity of the shell mould above all is given in this article
Simulations made have shown that air gets enclosed in certain places of the casting at the solidification, in the area of ribs in the main so that there is a risk of porosities creation

Summary

Introduction

The investment casting technology is a progressive technology that facilitates a production of very complex thinwalled castings of dimensional and shape stability. This technology belongs to a group of technologies working with non-reusable sand moulds, which show considerable differences as compared with common technologies of this category They express themselves at designing shapes and dimensions of gating systems. An example of the gating system solution of a specific thin-walled sizeable casting from the viewpoint of optimising the metal flow in the cavity of the shell mould above all is given in this article This optimisation is very important because the air may be enclosed at filling the shell by metal in consequence of an unsuitable construction of the gating system (of the shape and position of gates) and may cause the origin of defects such as shrinkage porosities, blow-holes, and porosities [1, 2]

Main principles of assembling gating systems for precision casting

Simulation of a sizeable casting

Findings

Conclusion