Motion planning for coating process optimisation in electron beam physical vapour deposition

Electron beam physical vapour deposition (EB-PVD) is used mainly in a variety of coating and surface engineering applications. The present research focuses on coating process optimisation using EB-PVD for turbine blades, which are widely used in industrial, marine and aircraft applications. More specifically, the present research identifies the five most important objectives for the EB-PVD coating process and then proposes metrics to quantify such objectives. In addition, a heuristic for EFB-PVD process optimisation is developed to control workpiece motion systematically to reduce coating thickness variance, providing a uniform coating for turbine blades. The heuristic developed is an iterative algorithm which uses a finite element model of the rotating workpiece to determine the translation motion. The finite element model can be readily generated using standard computer aided design (CAD) of the workpiece, which makes the method applicable to workpieces with complex three-dimensional geometry. These computational developments are illustrated using a simulation of a turbine blade coating in which the coating thickness variance is reduced significantly. The proposed method could eliminate dedicated tooling/fixtures used in the traditional coating process and improve the cost effectiveness of the process, especially for low volume production.