Life Sciences & HealthcareJuly 15, 2020

How Virtual Twins Can Overcome the Challenges of Additive Manufacturing

We don’t think about it much, but there is a considerable amount…
Avatar Randall Newton

We don’t think about it much, but there is a considerable amount of culture wrapped up in our engineering and manufacturing processes. In North America, product design traditionally delivers project data to the manufacturing engineers with a “here, make this” attitude. Other nations and cultures give more power in this dynamic to the manufacturing engineers. In these cultures, design becomes an artifact of available fabrication processes, to be interpreted by the manufacturing engineers. The Japanese even have a word for it, “monozukuri,” which roughly translates into “the thing and the act of its making.”

The rise of additive manufacturing (AM) brings new challenges to manufacturing cultures. When materials can be assembled into products at the micron level, easy buildability becomes a seductive but deceptive notion. The western attitude of “here, make this” turns into “here, print this” when AM is available. Yet manufacturing engineers with 3D printing experience know the process is as much art as it is technology. Tacit knowledge about what processes and materials work in any given situation is hard won and not quickly taught. The result is that “CAD the Master” too often becomes “CAD the challenge” in AM.

The challenges that make additive manufacturing an art as well as a technology can be summarized into four broad areas:

  • Stress: AM methods use constant rapid heating and cooling to build up the part layer by layer. These stresses affect both the new material and the existing form of the part. If the stresses are extreme enough, the stress of production may exceed the strength of the part.
  • Build orientation: AM machines build from the bottom up. There are times when build orientation within the chamber can create unforeseen problems in surface finish, build time, and the if-and-how of using support structures.
  • Support structures: AM equipment manufacturers tell their customers it is bad form to rely on supports to overcome orientation issues. “Excessive reliance on supports is an indicator of marginal part geometry,” says 3D printer manufacturer Renishaw.
  • Part optimization: The use of geometry and topology optimization is becoming more common, thanks to a variety of new software tools using various artificial intelligence routines. Internal lattice structures, in particular, are becoming popular as a way to reduce weight while maintaining part integrity. The problem comes when topological optimization is assumed to be functional optimization. Not every path to a lighter part makes for an optimal part.

Virtual twin models (also known as digital twins) are becoming an important technology for capturing and reusing the tacit knowledge behind additive manufacturing. And by  “important” we mean bringing calculable value to the project.

As noted researcher Michael Grieves (Chief Scientist for Additive Manufacturing, Florida Institute of Technology) says, the core premise for the virtual twin is that “information is a replacement for wasted physical resources of time, energy, and material.” Any manufacturing task, Grieves says, can be represented quantitatively as “the sum of the cost of all resources required to complete the task.”

As virtual twins and additive manufacturing reduce the total amount of time, energy, and materials invested in a project, the savings accumulate. Grieves says value can be captured by the use of virtual twins throughout the product lifecycle. In design, the ability to simulate both form and behavior makes it possible to save wasted material resources, save energy, and save the time it takes to create and test physical prototypes. In production, manufacturing can be simulated before it occurs, reducing trial and error. Collecting as-it-is-built information for the virtual production twin — from any process, additive or otherwise — becomes a virtuous cycle that reduces time and improves quality each time it is used.

For virtual twins to truly replace wasted resources with information, the cost of acquiring the information needs to be less than the cost of wasted resources every time a task is performed. The more repetition, the greater the value of creating the virtual twins. This becomes the bedrock notion of today’s smart manufacturing movement, using virtual twins to drastically reduce the use of time, energy, and materials.

Successful use of virtual twins will require companies to place as much value on the creativity of manufacturing engineers as they do on designers.

In explaining the notion of monozukuri, manufacturing expert Kentaro Kiziki notes, “this creativity at the production side is what strengthens the foundations of the Japanese manufacturing process. It is the invisible competitive edge created by innovation of design and production processes.”

The result is a subtle but valuable shift from process-centric to product-centric engineering practices, with every participant contributing and benefiting in equal measure in a true collaborative fashion.

Editor’s Note: Interested in learning more about additive manufacturing? Join Dassault Systèmes for 3DEXPERIENCE: A Virtual Journey, launching via live-stream on July 29th at 1:00 PM Eastern Time. 3DEXPERIENCE: A Virtual Journey will deliver thought-provoking and actionable content presented by a powerful line-up of industry influencers, customers and Dassault Systèmes experts.

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