Robotic additive turning with a novel cylindrical slicing method

Abstract

The turning process used from ancient times to today's modern turning centers is based on material removal. This article presents a new work to integrate additive manufacturing into the turning process and generate complex free-form additive turning part geometries. The conventional slicing method used in AM is the planar slicing method. In the planar slicing method, the computer-aided design (CAD) model is sliced using planes, and as a result, two-dimensional toolpaths are formed. A new slicing method is required to achieve additive turning parts. This work proposes a generalized, cylindrical slicing method that generates nonplanar toolpaths wrapped around a cylinder. The model is sliced by cylindrical layers, with increasing radii at each layer. As a result, three-dimensional toolpaths that are suitable for additive turning are generated. In conventional AM, lower tensile strength is observed in the build orientation of the part where the layers bind. Additive turning increases the low tensile strength observed in conventional AM. Additionally, it reduces and, at times, even eliminates the support structures required for certain CAD models. The cylindrical slicing results are verified by additively turning different CAD models using a six-axis robotic serial manipulator fitted with a fused filament fabrication end effector and an external turning axis. Tensile tests are conducted on conventional AM and additive turning models to verify the improvement in tensile strength.