HotFill: cooling time constrained raster-fill planning algorithm for extrusion 3D printing

Abstract

The flexibility offered by additive manufacturing when fabricating complex parts, compared to traditional methods, makes it an attractive tool for many applications. However, the decisions made in the process planning stage influence the properties and cost of the final part. In the case of additive manufacturing technologies based on thermoplastic extrusion, the definition of the route to be followed during the construction of a layer has a direct impact on the quality of the part. The route created directly influences the adhesion between adjacent filaments of the same layer, one of the factors responsible for the mechanical strength of objects manufactured by thermoplastic extrusion 3D printers. This, in turn, depends on the time lapsed between their deposition. In this work we describe HotFill, an algorithm that finds a tool-path for solid raster infill that keeps the cooling time intervals between depositions below user-specified limits. The algorithm, based on the dynamic programming technique, was implemented in Python and tested on several representative slices of 3D models. The results show that HotFill is fast and produces tool-paths that have low fabrication time while respecting the cooling time constraints.