Experimental measuring of printing speed in FDM

Abstract

Fused Deposition Modeling (FDM) technology, based on material extrusion, helps additively manufacture, using cheap printers, stable mechanical parts in different materials. The dimensional deviations and staircase effect are the main drawbacks of this approach and limit its use to prototypes. The linear interpolation used to define the hot-end movements is responsible for continuous speed changes along the tool-path, contributing to dimensional and surface errors. In that sense, the study of the speed profile can help to improve the process. This work explains two printing speed estimation approaches an out-process measurement method, which estimates the average speed as a function of the interpolation segment length and direction, and an in-process method based on encoder measurements. We applied these solutions and an analytical approximation based on a trapezoidal speed profile to a printed 3D Archimedean spiral. All approaches detect abrupt speed changes, potential candidates to produce extrusion-movement synchronization problems, and, therefore, part errors.