New 3-D printing algorithms speed production, reduce waste

October 21, 2014  


Benes support

New software algorithms reduce the time and material needed to produce objects with 3-D printers. Here, the wheel on the left was produced with conventional software and the one on the right with the new algorithms. (Purdue University photo/Bedrich Benes)
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WEST LAFAYETTE, Ind. – New software algorithms have been shown to significantly reduce the time and material needed to produce objects with 3-D printers.

Because the printers create objects layer-by-layer from the bottom up, this poses a challenge when printing overhanging or protruding features like a figure's outstretched arms. They must be formed using supporting structures - which are later removed - adding time and material to the process.

Now, two software algorithms have been created to address the problem. Researchers from Purdue University have demonstrated one approach that has been shown to reduce printing time by up to 30 percent and the quantity of support material by as much as 65 percent.

Such improvements are likely to result in lower overall printing costs, said Bedrich Benes, a Purdue associate professor of computer graphics.

"The total cost of printing is governed by numerous factors, including not only the price of the printer but also the amount of material and time to fabricate the shape," he said.

Two research papers detailing the new algorithms have been published in the journal Computer Graphics Forum. One paper was authored by Purdue doctoral students Juraj Vanek and Jorge Galicia; Benes; and Adobe researchers Radomir Mech, Nathan Carr, Ondrej Stava and Gavin Miller. Vanek is now working at Samsung USA. Stava earned a doctorate in computer graphics technology from Purdue.

The new PackMerger algorithm works by printing a project in segments that can be glued together. For example, Benes said, printing a model of the Gateway Arch is completed by first dividing the arch into segments before printing.

“Our algorithm cuts the project into small elements that will fit into the printing tray,” Benes said.

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

"To the best of our knowledge this is the first fully working 3-D volume-packing algorithm," Benes said.

The algorithm prints the segments so that they are spaced as closely together as possible in the printer tray. Because they are packed together, there is little supporting material between them, saving both time and material. The segments can then be separated and assembled. The algorithm sometimes instructs the printer to produce items nested within each other to save space.

Benes and Purdue doctoral students also have developed another algorithm 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. Research findings are detailed in a paper also published in the journal Computer Graphics Forum. The paper was authored by Vanek, Galicia and Benes.

Before printing the object, the algorithm 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. The algorithm uses a “geometry-based” method that does not need to consider structural or physical properties when determining how to reduce the supporting elements.

"The main advantage of it being geometry based is that it saves time and money and printing material," he said.

Writer: Emil Venere, 765-494-4709, venere@purdue.edu 

Source: Bedrich Benes, 765-496-2954, bbenes@purdue.edu 

Note to Journalists: The research papers are available from Emil Venere, 765-494-4709, venere@purdue.edu.


ABSTRACT

Clever Support: Efficient Support Structure Generation for Digital Fabrication

J. Vanek, J. A. G. Galicia and B. Benes

Purdue University

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

PackMerger: A 3-D Print Volume Optimizer

J. Vanek1, J. A. Garcia Galicia1, B. Benes1, R. Mech2, N. Carr2, O. Stava2 and G. S. Miller2

 1Computer Graphics Department, Purdue University, West Lafayette, IN, USA {vanek, garci191, bbenes}@purdue.edu


, 2 Adobe Research
 {rmech, ncarr, ostava, gmiller}@adobe.com 

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.


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