Industry Information | 2018-04-05 119
We've reported before on the work of innovative UK 3D printing service provider MTC (Manfuacturing Technology Centre), and the company has now created a new app that could prove to be extremely useful for a huge number of manufacturers in the 3D printing eco-system. The team has been using simulation software in order to test designs for components for a while, and it recently started developing apps that enable multiple different departments to simulate the performance of fabricated parts over time. This encourages multi-disciplinary collaboration in order to improve parts at the design stage and to streamline workflows.
The MTC is primarily involved with aerospace companies, providing them with designs as well as prototypes, and also researches new 3D printing techniques to optimize its clients operations. DLM 3D printing, a form of laser powder-bed fusion, is one of the techniques most commonly used. Despite the obvious advantages that this boasts in terms of resolution and accuracy, defects are relatively common. Thermal cycling due to the high temperature gradient and quick cooling can cause residual stresses during deposition, and this gradually alters the microstructure, which causes distortions in the final part.
It’s difficult to avoid these deformations without completely overhauling the manufacturing process, but the MTC devised an ingenious way around it, in order to maintain the necessary precision and quality standards in parts manufacturing. The team uses physical simulations to predict how the deformation will happen, and then works backwards from it. This allows designers to adjust their initial designs accordingly.
According to Borja Lazaro Toralles, team leader of MTC’s Physics Modelling department “We created a simulation that predicts the stresses and deformation during a part build to give us a clear understanding of how it will distort during printing,” Toralles says. “Once we have this information, we can invert the distortion in the part’s design, which allows us to account for the warping ahead of time so that the final product distorts into the shape we actually want.”
The team normally uses the COMSOL Multiphysics software environment, for virtual design testing, validation, and performance prediction. Within this platform, there is an option to develop smaller apps, based on the COMSOL models. The app they developed is capable of predicting distortions in structure using physical simulations, and it can be used by designers, researchers and engineers without them having to understand the original simulation model or having to know everything about the manufacturing process.
“Traditional additive manufacturing models are very detailed, down to the microstructure. But these are not suitable for simulating large part builds because of the computational cost,” Toralles explains. “They take forever. But we still need to understand how an entire part will behave during printing. To circumvent this, we lump the layers of the print build and impose an analytical temperature field based on experimental data. This reduces solving time but still gives an accurate solution.”
Inputs into the COMSOL model were parameterized for the app, including things like material properties, lumped layer thickness, build plate fixturing on the part, mesh element size. This means that the same model can be used for a variety of different materials, from aerospace-grade titanium to stainless steel, and parts of any shape or size can be tested.
The app is available online, and designed to be use for analysis by simulation engineers as well as part designers. In order to bridge the gap between different departments, features were built into the app that blocked certain types of changes, preventing any inadvertent errors. This means that everyone involved with the part can access the same predictive models, and easily share information with each other without getting their wires crossed. This increased accessibility has led to the whole prototyping workflow being optimized, for a number of different clients.