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When “Good Enough” is No Longer Enough
Posted on November 9th, 2016 by Ken Klapproth in New Materials & Applications
Engineering is about approximation – knowing what phenomena you can and cannot ignore to sufficiently model your problem. For additive manufacturing, it appears the approximation of triangles have lost their usefulness.
As an engineering student you quickly realize that if you would never be able to solve any problems without some form of idealization. In order to simplify complex systems with nonlinear relationships you would selectively “ignore” reality. Materials become homogeneous and non directional, friction goes away, thermal properties are non-directional. Using this technique, the problem could be reduced to something mathematically solvable.
The same technique was used during the evolution of 3D parametric CAD models. Fully precise NURB surfaces represented the geometric design intent, but using those complex representations either in downstream applications or simply displaying large assemblies on the screen quickly became too computationally complex. Enter the STL (STereoLithography) file format.
The STL format simplified complex NURB surface models as tessellations – a mesh of triangles approximating the shape. STL files had a variety of uses including digital mockup and became the defacto representation for rapid prototyping and 3D printing. While lightweight and quick to render, the format has no embedded intelligence.
According to a recent article published by Advanced Manufacturing Media, it appears the trusty old STL file is reaching the end of its useful life with respect to additive manufacturing. High end 3D printers are becoming increasingly precise. Hod Lipson, professor of mechanical engineering at Columbia University and chair of the AM data interchange committee for ASTM, one of the largest international standards development organizations notes, “For the first time in history, manufacturing is more advanced than design. With additive manufacturing, you can make almost any shape you can imagine. The challenge is the software design tools are not keeping pace. We can build anything but we can’t design it.”
The concept of design being limited by current software is also something being promoted by Autodesk through their philosophy of Generative Design. Through their Dreamcatcher research project, Autodesk enables designers to describe the forces or constraints acting on an object, then the software iterates on a variety of solutions satisfying the design criteria. To better understand the Generative Design approach, watch the following video:
The industry and standards bodies are hard at work developing viable replacements for the lowly STL file. Both the AMF and 3MF formats have the capability to represent geometric shapes in addition to triangles such as arcs. Both can also include extensions of other critical data such as material, texture, and colors extending its utility to broader application. Whether you consider the evolution of engineering to be design limited or manufacturing limited, there are certainly exciting developments in the works to keep watching.
What’s your experience with STL files? Tell us about your quest for unconventional knowledge and what it could mean for the future of your products or companies. Share your thoughts in the comments section below and don’t forget to follow us on your favorite social media channel.
All opinions shared in this post are the author’s own.
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