Next week in Vancouver, SIGGRAPH 2018, the world’s largest computer graphics and interactive techniques conference, will kick off five days of interesting programming and exhibitions. Many research teams from around the world showcase the results of their latest projects, ranging in topics from 3D shapes and augmented reality to topology optimization and 3D scanning, at the annual conference, and this year, the Delft University of Technology (TU Delft) is doing the same.
A research team led by Charlie C. L. Wang, PhD, a Professor and Chair of Advanced Manufacturing in the Department of Design Engineering at TU Delft, has had their latest research achievement published in a paper, titled “Support-Free Volume Printing by Multi-Axis Motion,” for the conference. The paper will also be published in the ACM Transactions on Graphics journal.
The paper, which TU Delft researchers collaborated on with researchers from Tsinghua University in China and the French Institute for Research in Computer Science and Automation (INRIA), explains how the team developed a new robotic 3D printing technique that’s able to automatically create toolpaths for fabricating a solid 3D model without the use of support structures.
The abstract reads, “This paper presents a new method to fabricate 3D models on a robotic printing system equipped with multi-axis motion. Materials are accumulated inside the volume along curved tool-paths so that the need of supporting structures can be tremendously reduced – if not completely abandoned – on all models. Our strategy to tackle the challenge of tool-path planning for multi-axis 3D printing is to perform two successive decompositions, first volume-to-surfaces and then surfaces-to-curves. The volume-to-surfaces decomposition is achieved by optimizing a scalar field within the volume that represents the fabrication sequence. The field is constrained such that its isovalues represent curved layers that are supported from below, and present a convex surface affording for collision-free navigation of the printer head. After extracting all curved layers, the surfaces-to-curves decomposition covers them with tool-paths while taking into account constraints from the robotic printing system. Our method successfully generates tool-paths for 3D printing models with large overhangs and high-genus topology. We fabricated several challenging cases on our robotic platform to verify and demonstrate its capabilities.”
Professor Wang explained that the collaborative research team has developed the world’s first algorithm able to supervise a robotic system that’s fabricating a general solid model through the use of curved, 3D toolpaths.
The paper goes on to say that most commercial 3D printing systems actually use 2.5D fabrication, where materials are accumulated layer upon layer in planes along a fixed direction, which lowers development costs and complexity but makes it necessary to use supporting structures.
No one really wants to have to deal with support structures – it’s a pain to remove them once your 3D printed object is off the print bed. But robotic 3D printing systems have additional degrees of freedom in motion, and can actually change the direction in which the material accumulates during printing.
In the paper, the researchers wrote, “In this paper, we present a new methodology to tackle the challenge of multi-axis AM tool-path generation. Our technique is based on the observation that the dimensionality of the problem can be successively reduced by first decomposing the volume into sequences of curved surface layers, and then decomposing each surface into curved tool-paths. Our algorithm searches for an accumulation sequence, which is collision-free, ensures always supported material deposition, and can print all regions as much as possible. Curved surface layers are covered with tool-paths taking into account hardware constraints.”
Co-authors of the paper include Chengkai Dai and Professor Wang from TU Delft, Chenming Wu from Tsinghua University, Sylvain Lefebvre with INRIA, Guoxin Fang from TU Delft, and Yong-Jin Liu with Tsinghua University.
To see the team’s multi-axis robotic 3D printing system in action, check out the video below.
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[Images: TU Delft]