Introduction to Rapid Prototyping (SLM, DMLS & EBM)
Once again, thank you everyone for joining us in our 3rd installment of Introduction to Rapid Prototyping. First off this week, I’ll be jumping into SLM and DMLS (selective laser melting and direct metal laser sintering) which work on the same principles while utilizing lasers. As stated last week, this technology is an off-shoot of SLS. And to wrap things up, I’ll close out with EBM and EBW (electron beam melting and electron beam welding) which work on very similar principles as well.
SLM (Selective Laser Melting) & DMLS (Direct Metal Laser Sintering)
First off, SLM, DMLS, and SLS all stem from the original patented technology and process by Carl Deckard back in 1988¹. DMLS and SLS are closer related than the SLM technology because of their inherent “sintering” aspect versus “melting”. To-may-toe, to-ma-toe right…well just don’t try to argue with an Engineer about these two technologies doing the “same thing”. SLM and DMLS prints are created by using high powered fiber-optic lasers to fuse and melt together layers of powdered metals and alloys. The only difference being, SLM can actually achieve a full material melt and create a solid end piece/component whereas sintering is a fused, yet semi-porous structure. Nonetheless, these two technologies build their prints by fusing together a series of consecutive, super-thin layers of powdered metals and alloys.
The obvious and clear advantage of these two technologies is in the materials. No other 3D printing technology previously mentioned can execute rapid prototyping with metals and alloys. Also, just like SLS 3D printing, there is no support structure needed SLM rapid prototype components. Last but not least, almost 100% of the leftover powder metal/alloy can be recycled and reused unlike that of the SLS 3D printing. However, SLM sets itself apart by surpassing DMLS rapid-prototyped components in strength because of the melting aspect². SLM 3D printing is also favored for the more exotic metals such as Nickel-based super-alloys, Titanium, and pure metals³. In summary, both technologies can produce production equivalent metal components for any engineering application and even in the medical realm where biocompatibility is crucial, but are pretty cost-prohibitive still and have slower build times than their counterparts.
EBM (Electron Beam Melting) & EBW (Electron Beam Welding)
As for EBM and EBW (Electron Beam Melting and Electron Beam Welding), the electron beam technology was first commercialized in 1997 by a Swedish company, Arcam⁴. EBM rapid prototyping is the youngest technology in the 3D printing world, the next closest is material jetting. As for EBW, this clearly isn’t a rapid prototyping technology, however, welding and sintering are very similar in the fact that they bond/fuse metals together. Electron beams are used in both applications and the main difference lies within the intensity of the beam itself which is stronger for melting.
EBM prints are created identically to that of an SLM rapid prototype. Layers of metal and alloy powders are melted together. Once again, consecutive layers of super-thin metal powder are fully melted together creating a solid end piece/component. EBM definitely crosses over into the realm of SLM as far as material selections go. Recently, EBM development work has documented the successful use of exotic metals such as Inconel, Titanium, and Cobalt chrome much like SLM⁵. EBM prints also have the ability to be production equivalent within aerospace and medical markets but have a greater disadvantage in the cost aspect when compared to SLM. The extra costs associated with EBM are due to the need for creating a vacuum and the robust chambers/enclosures that are required.
1 – https://www.asme.org/topics-resources/content/infographic-the-history-of-3d-printing
2 – https://en.wikipedia.org/wiki/Selective_laser_melting#:~:text=The%20DMLS%20machine%20uses%20a,watt%20Yb%2Dfiber%20optic%20laser.&text=The%20technology%20fuses%20metal%20powder,using%20layers%2020%20micrometers%20thick
3 – https://en.wikipedia.org/wiki/Selective_laser_melting#:~:text=The%20DMLS%20machine%20uses%20a,watt%20Yb%2Dfiber%20optic%20laser.&text=The%20technology%20fuses%20metal%20powder,using%20layers%2020%20micrometers%20thick
4 – https://amfg.ai/2018/05/16/electron-beam-melting-introduction/#:~:text=Electron%20beam%20melting%20(EBM)%20is,durable%20and%20dense%20end%20parts
5 – https://en.wikipedia.org/wiki/Electron-beam_additive_manufacturing