Conformal additive manufacturing using a direct-print process

In conventional additive manufacturing, most processes for creating the layers of a part are performed on a horizontal plane. In contrast, a conformal additive manufacturing process has been suggested in order to build a real 3D structure on a freeform surface using a direct-print process based on material extrusion. A new algorithm was developed that is able to use the standard 3D printing file format that includes both a 3D model to be printed and a 3D model of a freeform substrate along with the desired printing parameters as input, and it returns G-code instructions for the 3D printing process as output. A slicing surface was generated to slice the 3D model by offsetting the surface of a freeform substrate model by a discrete amount (i.e., layer thickness) for each layer. The perimeters of each layer (including the internal features) were extracted based on the intersections between the slicing surface and the 3D model, and infill toolpaths were created by projecting 2D patterns reflecting the features to be printed with a desired fill factor (in the x-y plane) onto the slicing surface to create 3D patterns. Two printing methods, complete conformal printing and a hybrid methodology that combines conformal printing with conventional horizontal printing, were presented. Several 3D models were sliced and printed on a freeform surface to validate the developed algorithm.