Helical slicing method for material extrusion-based robotic additive manufacturing

The purpose of this article is to introduce a nonplanar helical slicing method for additive manufacturing (AM) which forms a single continuous three-dimensional tool path and removes seam defects. In the proposed method, the geometry is initially sliced into planar slices. Afterwards, using two consecutive planar slices, direction vectors from the current layer to the next layer are constructed. These vectors are used to generate helical slices in-between planar slices. Repeating the process for all the planar slices results in a single helical sliced tool path. With the direction vectors, geometric improvements over the existing spiralization methods are obtained. With the helical slicing method, the seam defects which are found in the extrusion start–stop points of the planar slices are removed. The switching control of the extruder is simplified, and non-extrusion movements of the extruder are eliminated. The generated tool path is tested using a material extrusion-based robotic AM setup. Manufactured models are investigated in detail under the scanning electron microscope. The method is applicable for additively manufacturing complex freeform shell type, genus zero models with no infill and minor overhangs. This helical slicing method removes the form errors found in those of previously developed solutions.