Page 12 - 3D Metal Printing Summer 2016

3D INSIGHTS IN METAL PRINTING BY TERRY WOHLERS AND OLAF DIEGEL
Aluminum Guitar—A Study in Design and Post-Processing
This unique project underscores the importance of designing to make post-processing as efficient as possible.
TERRY WOHLERS
Editor’s note: Olaf Diegel, associate consultant at Wohlers Associates, has designed, manufactured and sold many guitar designs in poly- mer. This is his first design in metal.
Metal additive manufactur- ing (AM), around since the early 1990s, often was accomplished by fusing polymer- coated metal particles and then infiltrating the parts with bronze. Most of today’s metal AM systems can fuse metal powders into 99-percent or more dense parts. Examples include lightweight aero- space parts, complex biologically inspired jewelry and medical implants.
Fig. 1
To investigate these post-processing steps, co-author Olaf Diegel tackled a new project that pushed the limits of metal AM and provided an opportunity for hands-on experience with post-processing, as well as with designing for additive manu- facturing (DfAM). The project: design and manufacture an alu- minum guitar.
Terry Wohlers is president of Wohlers Associates, Inc., an independent consulting firm based in Fort Collins, CO; 970/225-0086, www.wohlersassocaites.com. The firm provides technical and strategic consulting on the rapid-product-development and additive-manufacturing industries. Wohlers is a principal author of the Wohlers Report, a publication that provides data on all facets of additive manufacturing, including business, product, market, echnology and application.
We see countless metal-AM
parts displayed at conferences and
exhibitions, but they usually are displayed in a finished, ready- to-use state. This leads many to falsely believe that metal-AM systems magically produce finished parts at the push of a but- ton. However, the steps required after the build process are just as important as the build process itself.
A Complex Design
10 | 3D METAL PRINTING • SUMMER 2016
3DMPmag.com
The journey began by developing a sufficiently complex guitar design that would be impossible to produce using conventional methods of manufacturing, while symbolically representing metal (e.g., barbed wire). The inspiration was a Fender Telecaster design, modified by replacing the outer body with a diamond tread-plate design. The front and back surfaces were created (using SolidWorks, Fig. 1) with crisscrossing strands of barbed wire. To soften the design, a few roses were added to the inside of the guitar to counteract the hardness of the outer design.
From a DfAM perspective, the thickness of the outer body and the strands of barbed wire must be strong enough to with- stand the abuse that guitars often encounter. A 10-mm-dia. curved pipe allows wires to run from the main body to the elec- tronic cavity, under the assumption that it could be printed without the use of support material on the inside. (It was known that the limits were being pushed because most pipes with a diameter larger than 6 mm require support material,