The following was authored by Olaf Diegel, associate consultant at Wohlers Associates.
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.
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).
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.
One of the largest obstacles, in my opinion, to the wide-scale adoption of metal AM is the large amount of post-processing that can be required if a part is not designed for metal AM.
Some companies estimate that up to 70% of the cost of a metal AM part can be in pre and post-processing. In particular, with metal additive manufacturing support material is used to anchor the component to the build platform during printing, to help support overhanging features and, most importantly, to transfer heat away from stressed areas of the component to minimize heat distortion. This support material has to be removed, which is often a laborious manual process, and all the surfaces with which the support material makes contact need to be filed or machined smooth.
So, in a perfect world, we always want to try and design our parts to use as little support material as possible in order to avoid the labor of having to remove the supports, to produce a better surface finish, and to avoid wasting material on support material that cannot be reused.
I, therefore, treated this as a design challenge to try and design the little still to use no support material at all, other than what was required to weld it to the build plate.
Rapid 3D are running a 2-day ‘Design for Additive Manufacturing’ Workshop for Experienced CAD users, to be held on the 13th and 14th of September 2017 in the Kemtek Center of Excellence in Johannesburg.
In this workshop we’ll take you through the following steps:
As this workshop is aimed at experienced CAD designers, we have to insist on the following requirements to ensure we can focus on the workshop goals and material:
- You will need to bring your own laptop with a working MCAD software installation (don’t forget your charger).
- Working proficiency in your CAD software.
- For practical reasons, we have to limit the seats to 25 CAD designers, on a first come first served basis.
Sign up for the workshop – seats are limited
Call Leanette Mtsweni on 011 624 8048 to secure your booking or complete the online booking and payment form below.