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3D printing, technically known as additive manufacturing (AM), has gained a lot of use as both a novelty technique to be used at home to print ‘cool things’ and as a manufacturing tool to fabricate architecturally complex parts for various industries. As techniques advance, certain parts of the production process become more important than first thought. The use of simulation software in 3D printing has slowly become an integral part of the 3D printing workflow and helps the operator to understand and visualize many of the thermo-mechanical phenomena taking place during the manufacturing of parts. In this article, we delve into why and where simulation software is used in 3D printing processes.
Why Are Simulations Used in 3D Printing?
Shortly put, computer simulations enable the operator to observe the many phenomena that can occur during the fabrication process. This allows the operator to see if there are any potential issues with the current set up and ultimately leads to the creation of high quality and highly accurate parts. Computer simulations are there to help predict the outcome the printing process—be it on a layer-by-layer basis or under certain conditions—and shouldn’t be confused with another type of simulation, known as mechanical FEA, which evaluates the mechanical performance of a part.
What can be seen with simulations, and what issues can be avoided?
There are five general areas where added benefits can be seen by using computer simulations. The first point to consider is a reduction in the number of print failures. By performing a simulation, parts that would conventionally fail due to geometric issues can be reduced, as any issues can be identified beforehand, and this helps to save time and reduce the overall cost of the manufacturing. The second general area where simulations provide added benefit is in the evaluation of potential risks of different of different production processes, and this leads to information that can reduce the overall probability of failure.
The other areas that can be realized with simulations are a better understanding of the physics during the manufacturing process, a greater understanding (and prediction) of the microstructural characteristics of the finished product, and the ability to optimize production through increasing the manufacturing speed, reducing post-processing operations and increasing the accuracy of the print. From a property and structural point of view, the deformation, temperature distribution, recoater interference, and the thermo-mechanical phenomena that occur during post-processing can all be simulated and evaluated.
When Are Simulations Performed?
Simulations can be performed before any printing has occurred, or after the support structures have been put in place. If the simulation is performed before any printing has occurred, it can be used to identify if there are any areas of internal stress or mechanical deformation prior to them being physically realized. The print can then be modified and extra support structures, or geometrical changes, can be added to the design to produce a higher quality product.
If the simulations are performed after the support structures are in place, they can help to minimize the risk of product failure by ensuring that the dimensions of the finished product are within a defined tolerance range and if any other parameters may have a positive effect on the final product. In either case, the use of simulations helps to improve the quality of the product, reduce the risk of failure, save on production times and save on development and production costs.
Which 3D Printing Process Can Be Simulated?
Simulations are often used in high-value and high-precision 3D printing processes, ergo, all the main 3D printing processes can be benefitted from the use of simulations. However, the most popular simulation packages revolve around metal welding simulation solvers and are therefore used in a lot of metal 3D printing process. If we look at some of the main printing processes, namely Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Fused Deposition Modeling (FDM), Stereolithography (SLA), Direct Light Processing (DLP), and Selective Laser Sintering (SLS), in a bit more detail, then we can see why simulations are beneficial for all these processes.
Because they are the oldest technologies, most of the software packages out there focus on the SLM and DMLS printing methods. These are often used in metal 3D printing methods, where the fusion temperatures are higher, and simulations help to evaluate the thermo-mechanical constraints during these fusion processes.
Compared to more established methods, EBM is relatively new, so there are only a handful of simulation packages which are available for these methods. However, the packages that are available can be used to simulate any area that accumulates a lot of localized heat from the electron beam.
The main issue with FDM printing methods is warping, and this occurs because of the different cooling rates of extruded thermoplastic materials. SLA and DLP methods undergo a similar issue known as curling (shrinkage of materials under cooling). Whilst there are more simulation packages available for FDM methods than SLA and DLP, simulations can help to check if any parts require a brim to increase adhesion throughout the part, or whether a full redesign is required. The last method is SLS, and simulations can be used to see where the accumulation of heat might occur, and where poor surface smoothness and high degrees of warping may occur.
In terms of the actual software programs that can perform these simulations, there is a vast number, and many are only suitable for certain printing processes. Anyone who is interested in performing simulation in their 3D printing research should seek out which one would be best for them and work out the relevant advantages and disadvantages towards their own printing process needs.
Sources and Further Reading
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