Interactive online visualization for cold spray additive manufacture of titanium walls and square corners

Cold spray is a solid-state deposition process that is well suited to oxygen-sensitive materials such as titanium. Cold spray has been widely considered as an additive manufacturing technique, but systematic study of how to control the process to produce 3D objects has not been published. The purpose of this paper is to determine the influence of tool path planning strategy and robot kinematics on geometry and porosity distribution of a 3D object. The capacity of the cold spray technique to produce straight, vertical walls and features that require 90 turns is demonstrated. Square titanium frames were manufactured using a continuous tool path planning strategy in which the contour spray angle, traverse speed and corner smoothing radius (zone data) were varied selectively. The geometry of the samples was analysed by 3D laser scanning, and the porosity distribution by metallographic analysis and X-ray computed tomography. The straightness of the titanium walls depends on the contour spray angle while the shape of the square corner is affected by the traverse speed and corner radius. Best geometry control was achieved using a low traverse speed and small corner radius. Some level of geometry control can be achieved at higher traverse speed by increasing corner radius at a constant powder feed rate. Porosity is distributed layer by layer creating a fishbone structure in cross-section with higher porosity between the layers and near the lateral edges of the walls and corners. The thickness of the porous section at the edges must be considered for post-deposition machining if required.