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Importance of Design for AM

July 1, 2017

Filed under: 3D printing,additive manufacturing,CAD/CAM/CAE — Terry Wohlers @ 08:35

Note: The following was authored by Olaf Diegel, associate consultant at Wohlers Associates.

Lasertech, a metal additive manufacturing (AM) company in northern Sweden, asked me to design something that showcased metal AM, so I chose a small still. The company wanted to use it as a special gift for executives. I designed the barrels of the still to measure 117 x 58 mm (4.6 x 2.3 inches).

One of the largest obstacles to broad adoption of metal AM is the significant amount of post-processing that is required. Premium AEROTEC, Daimler, and EOS agree that about 70% of the cost of metal AM is related to pre- and post-processing. For metal parts, support structures are used to anchor them to the build plate when printed. These structures are used to transfer heat to the build plate and prevent features of the parts from warping and distorting.

After the build process, the support structures must be removed—a process that often requires labor, skill, tools, and equipment. After removal, the surfaces of the parts require smoothing, such as hand filing and/or milling. I treated the small still as a design challenge, with the goal of using little or no support structures, other than what is required to attach the still to the build plate.

In general, it is important to avoid overhanging features with a surface area of more than a few square millimeters. Also, it is helpful to avoid features that are produced at angles greater than 45 degrees from vertical because they will require support material. The exact angle can vary depending on the material being used. For this project, I chose aluminum and made certain that features did not exceed a 45-degree angle.

The design resulted in no support structures whatsoever. The still was cut off the build plate and shot-peened and then was ready for use. The design shows that it is possible to reduce or entirely eliminate the need for these structures. It can dramatically reduce the time and cost in producing metal parts by AM.

Click here to see a series of nine images related to this project.