Algorithm for Detecting and Solving the Problem of Under-Filled Pointed Ends Based on 3D Printing Plastic Droplet Generation

In this paper the problem of under-filled pointed ends is introduced and mathematically defined. To tackle this problem, we present a new algorithm that detects and fills the critical areas, which arise at the 3D printed plastic parts. While printing the contours and/or infill lines, due to the limitations based on the width of the extruded material, narrow edges and pointed ends remain improperly filled. This eventually results in 3D printed objects with the final geometry that differs greatly from the initial geometry. This paper presents the fundamentals for solving the problem of 3D printing of geometries which contain narrow pointed ends. The critical area of the pointed ends is mathematically defined and, depending on the angle, the formulae for the calculation of under-filled and over-filled areas are given. The newly developed algorithm, based on the 3D Printing plastic droplet generation process, assures that the droplets of the repeating contours are placed at the edges of the contour-segments and by that minimises the potential under-fills. Furthermore, an additional number of droplets is defined, that are either printed in or removed from the under-filled areas in the angle bisector. The proposed algorithm is applied on parts, whose geometry describes pointed ends. The final 3D printed parts are very appealing and their shape resembles the original geometry more than the final shape of the parts without applying the algorithm.