Sep.23, 2013

Material costs are still one of the reasons why 3D printing might not be the best method for production. When you get your 3D model printed at 3D printing companies, the price is calculated based on which 3D printing material is chosen and how much this material is used.

To minimize the cost of material you can either hollow out your designs, or uniformly hollow the 3D object by extruding the outer surface and creating a scaled-down version on its inside, as the most commercial printers do.

Researchers at University of Science and Technology of China have designed an automatic and practical method to generate a skin-frame structure for a given 3D model for minimizing the material used in printing and the number of struts in the structure. The frame structure generated by their algorithm, which is geometrically approximate to the shape of input model, is guaranteed to be physically stable, geometrically approximate, and 3D printable.

Teaser: Given an input Horse model (a), our method generates a skin-frame structure (b). The frame structure is designed to meet various constraints by an optimization scheme. In (b) we remove the front part of the skin in order to show the internal structure of frame. (c) is the photo of an printed model by removing part of its skin to see the internal struts. (d) is the photo of the printed model generated by our method. A small red drawing pin is put under the object as a size reference in (c) and (d) respectively. The material usage in (d) is only 15.0% of that of a solid object.

Frame structure is a typical light weight structure which is widely employed in architecture, engineering, and building construction. The key idea is to 'hollow' the object by creating a lightweight frame structure, made of a mesh of nodes and thin cylindrical struts with large voids among them inside the object. And the frame is also expected to have simple topology structure with minimal number of struts.

Frame structures benefit 3D printing in two aspects. First, the mass of object could be significantly reduced through the use of frame structures while maintaining its strength and stiffness, which is cost-effective for 3D printing. Second, frame structures provide sufficient flexibility and variability, which make them possible to meet a variety of constraints in 3D printing.

Researchers develop an optimization scheme to minimize the frame volume subject to various constraints such as stiffness, stability, geometrical approximation, self-balance, and printability.

Check out the following examples:

Overview of our algorithm. Given an input model (a), an initial frame structure (b) is generated. Our algorithm runs alternatively the topology optimization (c) and the geometry optimization (d). The struts in (b), (c), and (d) are shown with color visualizations of their radii. Note that the frame in (c) is much sparser than that in (b). The frame volumes of (b) and (d) are 3.790e4 and 2.875e4 mm3 respectively. The saving ratio of the frame volume is about 24%. In this example, an external force of 5N is loaded vertically downside on top of the model.

The Hanging-Ball model in the lower row has a smaller base than the one in the upper row. For the model with a smaller base, our algorithm produces thicker struts on the vertical pillar in the right part than the counterparts in the upper row due to the balancing constraint. Photos of the printed naked frame and the printed objects using the power-type printer are shown in (b) and (c), respectively.

Printed objects using powder-type printers produced by our algorithm. From left to right: Fighter, TV-Alien, Fishing-Frog, and Buddha-Head. The upper row shows the rendering results with half skin and half frame. The lower row shows photos of the printed objects. The largest edge length of the bounding box of each object is 200mm. A small red drawing pin is put beside each object as a size reference.



Smart Design of Support Material

In addition, the researchers have also studied the design of support material and proposed a scheme to design the structure of support by adding some extra struts to make the frame printable with minimal use of support material. Check out the examples below:

FDM 3D printers need to add extra supporting structures to print the objects. Left: the printed result with supporting structure generated by commercial software; Right: the printed result with supporting structure generated by researchers' algorithm.

Researchers' paper, "Cost-effective Printing of 3D Objects with Skin-Frame Structures" was accepted by SIGGRAPH Asia 2013 Conference which will be held in Hong Kong at the Hong Kong Convention and Exhibition Centre from 19 to 22 November 2013.

According to Zhouwang Yang, Associate Professor in Mathematics and also co-author of the paper, this method reduces the weight of the design and creates material saving of up to 70%.



Posted in 3D Printing Materials

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Mr R Syer wrote at 1/9/2019 11:48:54 PM:Looking at your web site showing a picture of a horse printed out on yur 3d printer, i assume you could also print out other animals, such as dogs, you picrure does not give a size, i would like to make them say 80cm long?can that be done. Mr R Syer, i am as you see new to 3d printing, i used to run a commercial print business some years ago, so 3d printing is of interest. Mr R SyerTARIK wrote at 7/23/2017 8:54:10 PM:which software do you use ?TARIK wrote at 7/23/2017 1:40:28 PM:Hi, Which software do you use ?Chris wrote at 5/27/2014 1:06:54 PM:How much and where can I buy it?



