Advanced inline measurement and control tools for sand filling and compaction in lost foam casting

Abstract

Lost Foam Casting (LFC) enables metal casters to produce complex parts by making foam patterns having the same geometry as the desired finished parts. Among the greatest strengths of LFC process is that it allows designers to consolidate parts, reduce machining and minimize assembly operations. One of the key steps in the LFC process takes place in the compaction box, where the foam pattern is suspended in a steel container that is vibrated while sand is added to surround the pattern. The sand provides the mechanical support to the pattern as molten metal is poured into the mold. Discussed in this paper will be the development of an advanced sensor array for the measurement and control of the sand compaction stage. Compaction of the sand is key in controlling casting distortion and is instrumental in the efficiency rating of the LFC process. Too much compaction can cause the foam part to distort or even get crushed. Too little compaction can lead to a defective final product due to inadequate support of the foam part or lack of sand flow into small cavities in the foam part. To understand and control the behavior of the sand compaction stage, the key parameters that must first be measured are: (1) Energy imparted on the compaction box, sand and foam part, (2) compaction of the sand in the casting box, and (3) distortion of the foam part. The sensor array is to be placed inline in order to give direct feedback that can then be used in both passive and active process control.