Predicting behaviour inside machine is critical to part success.
I was during a talk by software company, Volume Graphics on the TCT Introducing stage at formnext a couple of years ago that I had a mini existential crisis about the validity of additive manufacturing (AM). I wondered whether this entire burgeoning industry that kept thousands of people, including myself, in work, was built on a lie.
Volume Graphics’ Business Development lead, Gerd Schwaderer, was discussing how the company’s software was able to take CT Scan data and detect defects in internal lattice structures. ‘Defects in lattice structures?’ I thought. Lattice structures are the crux of many an AM sales pitch. Walk past any stand at an AM trade show and, at some stage, you’ll hear something along the lines of, “by using lattice structures the weight of this aerospace part can be reduced by 50%.” If the internal channels of our topologically optimised designs could have defects, how could anyone in their right mind adopt this technology?
Added to this particular crisis in faith, a few months previously I had found myself questioning the validity of AM at the International Conference on Additive Manufacturing and 3D Printing in Nottingham. Manyalibo J. Matthews of Lawrence Livermore National Laboratory (LLNL) was discussing the problem of spatter in selective laser melting (SLM) 3D printing. LLNL’s research suggested that spatter from the energy source can randomly land anywhere in the build area, potentially contaminating an entire job.
It’s the spatter phenomenon and other variables such as material contamination, energy drops and inconsistent scanning that lead to a widespread distrust of additively manufactured parts. The likes of Volume Graphics and Wenzel America exist in the additive world to ease those worries and to validate parts. However, if AM is to truly head into certified series production, it surely isn’t viable for the majority of companies, both in terms of time and cost, to CT scan every single part?
“Today, a company like GE does take every part and run it through a CT Scanner,” Dr Brent Stucker, Director of Additive Manufacturing at ANSYS (at the time of writing Brent Stucker was CEO of 3DSIM) tells me. “That only works if you’re building jet engines and have those high margins.”
Brent is a veteran of the additive manufacturing industry, having first been involved in additive academia over 25 years ago. Like anybody engaged in those early days of 3D printing back when it was called things like Rapid Prototyping or Time-Compression Technologies, the majority of Brent’s work was trial and error. Unlike many of his peers, Brent was keen on documenting those experiments.
“I was trying to understand how changes to the machine, changes to the material, changes to the process parameters, or changes to the geometry resulted in different properties or accuracies,” explained Brent. “I joined forces with the guy who is now our chief scientist, Deepankar Pal, and we decided to tackle this issue of trial and error. By developing a whole new set of simulation capabilities, this would allow us to predict from process parameters what is going to happen to your part.”
ANSYS Inc - Additive Print
Simulation results from ANSYS Additive Print showing displacement for a heat exchanger part.
Part courtesy of Additive Industries.
The pair joined forces in 2009 and by 2014 had formed the company, implementing years of research and resulting algorithms into an additive manufacturing software platform called 3DSIM.
3DSIM developed two software tools; exaSIM, allowed engineers to predict residual stress, distortion and build failure; and FLEX, which allowed users to dial in the best process parameters for a particular additive manufacturing machine and material combination thus predicting both part integrity and microstructural formations.
In November 2017, the world’s most renowned engineering simulation software company, ANSYS, acquired 3DSIM. Shane Emswiler, ANSYS vice president and general manager, said at the time: “By bringing exaSIM and FLEX onto our Workbench platform, ANSYS can off er customers the only end-to-end additive manufacturing simulation workfl ow available. That will spark innovation, speed time to market and reduce manufacturing costs for our customers across industries.”
The way Brent saw it at the time of the takeover was that 3DSIM plugged some holes in ANSYS’s already world-class software that made it the complete simulation for AM and for 3DSIM, ANSYS gave access to a previously untapped worldwide market. In April this year, ANSYS announced the full integration of the 3DSIM platform with two products, Additive Suite and Additive Print.
Risk Mitigation
Additive Print will demonstrate to engineers the exact printing process, informing them before the part goes to print whether it will fail or not. If a part is going to fail, the software will detail exactly how, where and why it will fail. Part failures in industrial applications aren’t your messy spaghetti on a Yoda head, it can mean life or death for a company.
“People think software is expensive,” says Brent. “But if you think of how much money is wasted in just one failed build of those new large metal machines, we’re talking tens of thousands of dollars in a single build failure based on wasted material, time and cost. The cost could be even higher if you’re missing a deadline on something like a satellite launch.”
Autodesk Generative Design Tools were used for a previous TCT cover star; The Lighning Motorcycle Swingarm.
For the likes of a metal AM service provider, simulation software could be critical and not only in regards to preventing costly jobs from failing part the way through.
“With software, you don’t need an expert to build a part anymore,” stated Brent. “You can have software to tell me; this is the orientation, this is where I need supports, this is how I’m going to get distortion, with that you eliminate the need for years of built up intuition. We’re seeing people in the service bureau market also use it as a risk mitigation tool, saying, ‘if I get the software, make sure I’ve got it proven for my process, my machines, and my materials, then if somebody comes and takes my people away from me I’ve some way to continue my operations.
Generation Simulation
When one pictures simulation software, you might conjure up an image of a CAD file on screen with a primary coloured heat map that indicates load stresses. In the ANSYS case, it is their software that gave birth to this vision of digital simulation, but simulation is no longer a tool used after a part has been designed, it is playing a crucial role in the technology many claim to be the “future of design”.
“With generative design, simulation is a driving technology underneath,” says Ravi Akella, Director of Product Management for Simulation and Generative Design at Autodesk. “Instead of simulation in a traditional process where you propose a solution then you go and validate that solution, what generative design is doing is using simulation to propose functionally valid solutions from the get-go.”
Generatively designed parts are like nothing we’ve seen in the world of human-made manufacturing before; these organic meshes of metals and plastic that are lighter, stronger make motorcycles faster, planes lighter and cars stronger. Designers give generative design tools the required constraints and conditions and the software will virtually mimic the physical forces and create the optimal shape. Designs can be mind boggling, Ravi says that at first many users will go down traditional validation steps using simulation tools but once they realise the generatively designed part does its job, this provides generative design’s aha moment.
“Our goal is to make simulation integrated with the design process and not make it this additional step,” stated Ravi.
What ANSYS and Autodesk are doing may seem like opposing strategies but at the core of those strategies is simulation. A combination of generative design, sensors and simulation together can predict what should happen during a build, measure whether it did happen and then if it does happen we can begin to say that parts are certified. Once that is the case, additive’s shackles are off and my existential crisis banished.
