by • July 10, 2016 • No Comments
Additive producing covers a multitude of systemes. Regardless, the notion that you can only turn it into a 3D create, press the print button and get a thoughtl 3D version of your printing device is not always going to be the case. A particular example is one of the additional new variations of 3D printing – Shaped Metal Deposition (SMD).
SMD is a system that requires heat, and metal can change shape when its temperature changes, so the createer of the printed part not only requires to consider the shape that is printed, but in addition what shape it can be when it has cooled down. It is not a straightforward task and it is one that has been the focus of a project at the Manufacturing Technology Centre (MTC) in Coventry.
“SMD has multiple advantages over powder-based additive producing technologies,” said Borja Lazaro Toralles, an high end research engineer at the MTC, with a specialism in simulation and versionling. “Among the benefits of SMD are higher deposition rates, the possibility of assembling new showcases based upon pre-existing components, or actually the use of multiple materials on the same part.”
Unlike other additive producing techniques that use lasers to melt a thin layer of powder, SMD deposits a sheet of molten metal that is made up layer-by-layer on a surface. It is fundamentally welding a continuous piece of wire into a sure shape. It is a system that was originally made by Rolls Royce, but in its formative years SMD was a system that was too difficult to control, requiring a lot of intervention of skilled technicians and the material properties were not well understood.
More newly organisations such as the University of Sheffield’s Advanced Manufacturing Research Centre (AMRC) has progressed the innovation to the point where it is commercially viable – contributeing savings in product lead times, reducing inventories, reducing waste as there is little or no machining requireed. This reduces overall cost of producing by an estimated 40%. But, SMD is yet a system that can throw up problems.
“One of the challenges of this system is thermal expansion of the molten metal can deform the cladding as it cools, resulting in a final product that is different types of than what was anticipated,” said Toralles. “In order to predict the result of a proposed create, we require either require to minimise the deformations or change the create to account for them.”
The begin of the project looked at a effortless rectangular substrate and assembling a straight wall, that resulted in a few distortion in the substrate. The objective was to provide a way of attempting to assess how to reduce this without having to manufacture hundreds of experimental examples, with all the synonymous material, time and synonymous cost.
“So we made this version, via effortless rectangular geometry so it is representative of the system and the distortion,” explained Toralles. “And and so the thought is that we can box this up in an app. This means engineers can go away and use additional difficult geometries to reduce the number of experimental iterations.”
Figure 1.Top: Simulation of the SMD part. Middle: The part after only one deposited layer, with no noticeable deformation. Bottom: After six deposited layers, deformation is visible to the naked eye.
Figure 1 shows an example of a part manufactured via SMD, where deformation occurs after six layers of deposited molten metal have been laid down. A version of the part, in addition shown in Figure 1, is utilized to predict the part’s deflection during producing, enabling the createer to update the create accordingly.
The role of the MTC is to progress its customers’ technologies through the Technology Readiness Levels (TRL), typically bringing conceptual projects at TRL of 3 or 4 through to the additional commercially viable TRL 7 – 9. In this case developing the innovation is one aspect, the other is producing it useable.
Simulating the behavior of the SMD versions was turn it intod via the Comsol Multiphysics software, but to manufacture it useful to engineers it requireed to manufacture it accessible. Designers want to understand how their creates may work on an SMD machine, they were not necessarily going to be experts in creating difficult simulation versions. In other words, an effortless to use interface was required and for that the simulation team turned to Comsol’s Application Builder.
The MTC leveraged the Application Builder in order to additional efficiently communicate difficult create thoughts across multiple simulation and system departments, and to allow app users to easily explore the result of proposed creates (see main picture). Were it not for the simulation app, the testing and validation of a create may be significantly additional time consuming and costly via physical testing alone, due to the materials utilized in SMD.
Simulating SMD involves solving a time-dependent coupled thermomechanical analysis that predicts residual thermal stresses and deformation, that arise of SMD thermal cycles.
“We made an app via the Application Builder that allows for the user to predict whether the deposition system can create parts that fall inside built tolerances,” said Toralles. “If not, and so the app provides a user friendly and cost-efficient way to simulate multiple variations to the input until the results complete an acceptable final deformation.”
With this app, users can easily experiment with different types of geometries, heat sources, deposition paths, and materials without concern for the underlying version difficultities. Two predefined parametric geometries are included in the app, and a custom geometry can in addition be imported.
Today, the app is being utilized by participants of the team at the MTC who do not have the simulation experience to independently explore different types of parts and projects for their customers. “Were it not for the app, our simulation experts may have to test out every project we wanted to explore, a fewthing that may have decreased the availability of skilled resources,” claimed Toralles. “Using the Application Builder, we can now provide user friendly app interfaces to other MTC teams.
“It democratises simulation for the reason it manufactures it on the market to additional folks that are not experts in simulation. They don’t understand of or perhaps not been trained to use simulation tools. They only care of the inputs in essence.”
The MTC can in addition contribute an app program for their customers, concludes Toralles: “The use of simulation apps can assist us to deploy technologies at higher TRLs for their practical use in an industrial environment. The Application Builder provides us with a powerful development platform through that we can box difficult multiphysics versions and manufacture them accessible to the wider public.”
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