As anyone reading this publication can attest, additive manufacturing is no longer a novelty. It is now a platform for mainstream innovation. But as common as it has become, AM still suffers from at least one technological barrier: a vicious cycle of increasing design complexity, ballooning file size, and slowing output. However, a forthcoming development promises to eliminate this bottleneck, and it is expected to be adopted as an AM industry standard.
Implicit interoperability—an outgrowth of implicit modeling developed by nTop (formerly nTopology)—streamlines the additive manufacturing of highly complex geometries. Representing intricate designs in an implicit format reduces file size exponentially and makes the export to AM build preparation software much quicker.
Whereas traditional mesh-based files can be as large as tens of gigabytes, the exact same highly complex part, when represented in this new implicit data file format, could be just a few kilobytes. This could yield up to a 10,000 times reduction in file size as well as drastically cutting file generation, transfer, loading times, and ultimately, time to manufacture.
Of course, to achieve interoperability, both the design and the AM build preparation software must be compatible with this new implicit format. Many independent AM build preparation software developers and 3D-printer manufacturers have already pledged to adopt the new format following a preview of implicit operability last November at a trade show in Frankfurt.
Among them is EOS, a leading technology provider for industrial 3D printing of metals and plastics. EOS recently added implicit interoperability capabilities to its native EOSPRINT AM build preparation software.
Moreover, even broader adoption of the implicit interoperability technology will be spurred by the 3D Manufacturing Format (3MF) Consortium, which is working to incorporate the new file format in a future standard update.
Since the 1980s, manufacturing has grown far more advanced. Today, automated systems can create products at higher throughput and better quality. Yet, CAD software utilized by engineers to develop those products has largely remained the same. And while advanced engineering design software such as nTop enables vastly greater design freedom, the file formats used to exchange data between design and manufacturing also need to advance. These formats were developed in an era when subtractive manufacturing was the norm. They’re not optimized for the additive manufacturing of objects that, by their nature, can contain exponentially more intricate features than what is feasible with traditional manufacturing processes.
When scaled to meet current engineering product development needs, the current generation of data exchange mechanisms have the potential to bring many projects to a halt. They rely on huge files that require hours of high computing power to generate, open, and process. Most importantly, they are merely approximations of the actual design.
By contrast, implicit interoperability is the direct transfer of implicit geometry between design, build preparation, CAD, computer-aided engineering (CAE), product lifecycle management (PLM), and visualization software.
Implicit modeling is a method of simulating 3D objects by representing them as a zero-level set of a mathematical function. In other words, instead of representing an object’s geometry with explicit shapes, such as triangular meshes or non-uniform-rational-basis spline (NURBS), implicit modeling represents the object as the boundary where a certain mathematical function is zero. This approach provides a powerful and flexible way to represent and manipulate shapes, especially when it comes to generative design.
When passing a design in an implicit format to manufacturing, there is no loss of geometric precision or design intent. Simply put, it removes frictions related to generating, transferring, and processing large and intricate mesh files, an issue that has bedeviled the AM industry in recent years. The underlying design files are compact (only a few kilobytes), precise—not mesh approximations—and can be generated in a few seconds. They also are intelligent—supporting full parametric editing, not solely replicas of “dumb solids.”
An excellent proof-of-concept displayed last Fall was a previously unprintable large industrial heat exchanger designed by Siemens Energy. Manufacturing this complex design had been halted due to bottlenecks stemming from its immense file size. Yet, it was 3D printed via a direct implicit connection between nTop software and EOSPRINT.
“With the industry’s advancements regarding topology optimization, generative design, and design for additive manufacturing (DfAM), part geometries are becoming increasingly complex. As a result, exchanging such complex geometries with traditional data formats is becoming more challenging, severely hindering thermal management innovation,” explained Ole Geisen, head of AM engineering services at Siemens Energy.
This particular heat exchanger’s intricate internal structure and enormous size would necessitate weeks of processing time for mesh generation, build preparation, and slicing, yielding a massive data file that demands immensely time-consuming processing. It contains a core consisting of wavy surfaces that promote heat transfer and an external gyroid-based rib grid to increase the design’s stiffness while keeping it lightweight.
To produce the demonstration unit, Siemens Energy began by designing, in nTop, a full-sized version measuring about one meter long, then reduced the size for manufacturing by 75% (at 220 x 150 x 160 mm) to match the build volume capacity of the 3D printer employed, an EOS M290. When saved in the implicit data format, the full-sized and scaled design files were generated in seconds and occupied less than 1 MB of storage space. Using EOSPRINT, the design was sliced at the optimal accuracy of the AM system and manufactured on the EOS M290.
Of course, the upside potential of implicit interoperability extends well beyond manufacturing esoteric industrial parts. The opportunity ultimately is anything that is engineered. Implicit modeling opens up the space of what’s possible, allowing more performative products to be engineered.
Functional mass customization of consumer products is just one possibility. A footwear company, for instance, may offer a consumer the option to design a running shoe with a 3D-printed mid-sole that conforms to the person’s physiology, being softer or firmer where the person needs more bounce or more support. Managing the enormous database of unique designs would be an IT nightmare, but it becomes a lot more manageable in terms of computational resources if using the implicit data file format.
Another area where the implicit data format could make an impact is advanced product design. Today, the advanced design processes enabled by AM, such as generative design, are primarily used to design individual parts or components, not whole systems. For example, these tools can be used to engineer a lightweight motor casing for an aircraft.
However, the entire aircraft is still designed using decades-old CAD and CAE software that technically lags behind modern engineering design tools. Implicit interoperability opens new opportunities for connecting and augmenting existing software stacks and enriching current processes with cutting-edge engineering design tools, enabling larger organizations to continue evolving using the best tools available for the job in decades to come.
Connect With Us
