A framework for tool-path airtime optimization in material extrusion additive manufacturing

Building time is an important issue in material extrusion-based additive manufacturing because in such a process head repositioning is always required between deposition segments (contours and rasters). The length of head repositioning, usually referred to as tool-path airtime or non-productive time, can be minimized by applying optimization algorithms. A particular issue in this area is the size of the problem to be solved. In this work, this problem is detailed and a framework for its decomposition and simplification is presented. The framework was divided in four (4) main steps and was designed to be used with different optimization methods. The first step was designed with some innovative methods to reduce the problem size. Hybrid mixed integer linear programming (MILP) models were implemented to solve steps two (2) to four (4). Three cases of different complexities were analyzed and compared with the solution from a classic greedy optimization algorithm. The results show that the framework was effective in dealing with this problem and, particularly for the cases analyzed, it was possible to reduce the repositioning distance considerably over a non-optimized route and by greedy optimization (with the best case reaching 69% and 17.8%, respectively).