A Theoretical Model for Optimization of SALD Parameters

Abstract

This paper addresses the need to conduct theoretical work concerning an economical way of Solid Freeform Fabrication rendering by using selective Area Laser Deposition (SALD). The part in SALD rendering process is formed layer by layer that, in turn, is composed of stripes of material produced in the path of a laser. There are three situations in which such a stripe can be rendered: a) alone, b) with one neighbor on one side, and c) with neighbors on both sides. Residual thermal stresses in the part are expected to be affected by how a stripe is rendered. Furthermore, the residual thermal stress and the mechanical property of the part are also dictated by other processing variables such as laser scanning patters, laser input power, scanning speed, scanning spacing, deposition temperature, gas precursor pressure, intrinsic thermal conductivity and mechanical properties of the rendered material. A theoretical approach is proposed to address the minimization of residual thermal stresses and rendering times and the maximization of the strength of the part. It is proposed that such multiple optimizations that are dictated by many decision variables can be solved by minimizing and/or maximizing object functions dePending on the design criteria for each attribute of the rendered part