AUTO-REGRESSIVE TIME SERIES MODELLING OF STOCHASTIC SURFACES

摘要

Roughness profiles of EDM surfaces were obtained from a perthometer and digitized through AUTO CAD. Fortran program was developed for fitting ARMA (n, n-1) models. A significant observation was that for the sinking electrode type. EDM generally AR (1) or AR (2) models were adequate but for wire cut EDM higher order models, generally ARMA (3,2) and ARMA (4,3) were required. The higher order models indicate additional factors like wire vibration influencing the dynamics of wire EDM process.