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Rapid manufacturing of rhenium components using EB-PVD Vittal V. Prabhu Indraneel V. Fuke Sohyung Cho Jogender Singh Article information:To cite this document: Vittal V.If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to provide insights for understanding the relationship between rapid manufacturing process for rhenium components in jet nozzle fabrication using electron beam-physical vapor deposition (EB-PVD). Specifically, to develop a methodology to characterize and improve this new process through motion planning for maintaining uniformity in the deposition thickness. Design/methodology/approach -This research first identifies several important objectives for the process, and then develops an optimized heuristic method based on a look-ahead approach to generate motion plans for uniform thickness objective. In this heuristic, the surface of the workpiece is modeled using finite element method and the accumulated thickness of each layer on each element is computed based on its location in the vapor plume using a ray casting algorithm. Findings -Computational experiments show that the proposed algorithm can potentially provide significant improvements in the uniformity of the layers and cost savings in manufacturing compared to prevailing practice, especially for low-volume production such as aerospace applications.Research limitations/implications -In this research, net-shaped jet nozzle has been fabricated using a graphite mandrel. Therefore, the mandrelbased approach can be limited to producing hollow components. Practical implications -The proposed method is very generic and thus can be applied for multi-material manufacturing process identifying the sweet spot of the intersecting vapor plumes. Originality/value -This research can help the EB-PVD process for rapid manufacturing which has been considered as financially expensive to be accepted in real practice by providing a relationship of the process-to-product transformation through the developed motion planning methods.

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.

The present paper presents an intelligent automation of the electron beam physical vapour deposition (EBPVD) process to achieve high quality and cost efficient coatings for low volume part production, using realtime feedback control. A computational model of EBPVD for predicting coating thickness is used with an optimisation heuristic for reducing coating thickness variance and feedback control approaches for substrate temperature control and melt pool control. The computational model can be readily generated using a standard computer aided design (CAD) model of the workpiece, which makes the method applicable to workpieces with complex threedimensional geometry. Based on this model, an optimisation heuristic for the EBPVD process is developed to control workpiece motion systematically with the objective of reducing coating thickness variance, i.e. providing a uniform coating. These computational developments are illustrated using a simulation of a turbine blade coating in which the coating thickness variance is reduced significantly. Process level intelligence is incorporated using realtime feedback control for substrate temperature and melt pool control using an open architecture control system. Results using thermocouple based temperature control and realtime vision for melt pool control are presented. Video images of the melt pool are analysed on a block by block basis, using a technique to identify critical regions of the melt pool. Simulation results demonstrate the feasibility of automating the electron gun beam steering sequence. The proposed methods offer the prospect of eliminating dedicated tooling/fixtures and improving the cost effectiveness of the process, especially for low volume production.