Early castability evaluation using analytical hierarchy process

Abstract

Design for manufacture usually implies applying various guidelines derived from previous experience to improve part design so it is more compatible with the capabilities of the selected process, resulting in better quality and lower cost. The guidelines can be formulated as dimensionless criteria, enabling quantitative evaluation of a particular aspect of part design. There is, however, no good way to compare two or more designs for all aspects, considering that they may not be equally important. In this work, we employ analytical hierarchy process to determine the relative weights of various criteria for castability evaluation. The criteria are categorised in a three-level hierarchy, with the middle level comprising mould, feeding and gating groups. The prioritisation of criteria along with consistency checking of pair-wise comparisons enables a systematic evaluation of alternative product designs for manufacturability. The methodology is illustrated by modifying the product and tooling design of a grey iron bracket casting and estimating the improvement in manufacturability. The results are supported by experiments.