Purdue University researchers have developed two software algorithms for trimming time and material, reducing 3D-printing time by up to 30 percent and the amound of support material by up to 65 percent.

The new PackMerger algorithm works by printing a project in segments that can fit into the printing tray and later be glued together.

Maximum packing density

The algorithm determines how to pack the most elements into the smallest possible space using the same principle used by the Tetris tile-matching puzzle game, in which tiles are manipulated with the aim of creating a horizontal line of blocks without gaps.

Such improvements are likely to result in lower overall printing costs, said Bedrich Benes, a Purdue associate professor of computer graphics, co-author of a paper on the algorithm published in the journal Computer Graphics Forum.

Benes and Purdue doctoral students also developed another algorithm, detailed in a paper also published in the journal Computer Graphics Forum, that results in smaller support structures, reducing printing time by an average of 30 percent and the quantity of material by an average of 40 percent.

Before printing the object, a geometry-based method determines how it should be oriented on the printer tray so that the overhanging area requiring support is minimized. “The computer automatically rotates the object in all possible orientations before printing to find the orientation that has the smallest overhang area,” Benes said. Then supporting structures are built only at certain points within this area, resulting in a scaffoldlike structure that effectively supports the overhangs.

---

Abstract of Clever Support: Efficient Support Structure Generation for Digital Fabrication

We introduce an optimization framework for the reduction of support structures required by 3-D printers based on Fused Deposition Modeling (FDM) technology. The printers need to connect overhangs with the lower parts of the object or the ground in order to print them. Since the support material needs to be printed first and discarded later, optimizing its volume can lead to material and printing time savings. We present a novel, geometry-based approach that minimizes the support material while providing sufficient support. Using our approach, the input 3-D model is first oriented into apposition with minimal area that requires support. Then the points in this area that require support are detected. For these points the supporting structure is progressively built while attempting to minimize the overall length of the support structure. The resulting structure has a tree-like shape that effectively supports the overhangs. We have tested our algorithm on the MakerBotR ReplicatorTM 2 printer and we compared our solution to the embedded software solution in this printer and to Autodesk RMeshmixer TM software. Our solution reduced printing time by an average of 29.4% (ranging from 13.9% to 49.5%) and the amount of material by 40.5% (ranging from 24.5% to 68.1% ).

---

Abstract of PackMerger: A 3-D Print Volume Optimizer

We propose an optimization framework for 3-D printing that seeks to save printing time and the support material required to print 3-D shapes. Three-dimensional printing technology is rapidly maturing and may revolutionize how we manufacture objects. The total cost of printing, however, is governed by numerous factors, which include not only the price of the printer but also the amount of material and time to fabricate the shape. Our PackMerger framework converts the input 3-D watertight mesh into a shell by hollowing its inner parts. The shell is then divided into segments. The location of splits is controlled based on several parameters, including the size of the connection areas or volume of each segment. The pieces are then tightly packed using optimization. The optimization attempts to minimize the amount of support material and the bounding box volume of the packed segments while keeping the number of segments minimal. The final packed configuration can be printed with substantial time and material savings, while also allowing printing of objects that would not fit into the printer volume. We have tested our system on three different printers and it shows a reduction of 5–30% of the printing time while simultaneously saving 15–65% of the support material. The optimization time was approximately 1 min. Once the segments are printed, they need to be assembled.