Metal 3D Printing Overview and the Best SLM/DMLS 3D Printers on the Market
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Hi everyone! This is Top 3D Shop, and in this video, we will tell you about SLM 3D printing and the most prominent equipment based on this technology.
Selective laser melting, or SLM, is the technology behind most 3D printers using metals as consumable. DMLS, DMLM, LMF, LPBF, SLM are different names for the same printing method. Some terms have developed historically, while others are trademarks. Referring to the inventors of the technology from the Fraunhofer Institute in Germany, the most appropriate term would be LPBF - Laser Powder Bed Fusion. In our guide, we are going to use the term SLM as the most common name for the technology today.
So, what is the essence of this additive method? In short, potent lasers selectively fuse metal powder layer by layer. The required volume of powder is placed on a platform, which, after fusing a layer, is lowered to a predetermined height, equal to the layer thickness. The next layer of material is applied on top and the procedure is repeated until the part is finished.
SLM refers to additive methods that do not require special support structures. On the one hand, the whole volume of powder in which the model is formed acts as support. On the other hand, supports are needed since the difference in temperature between the melt zone and the surrounding powder can lead to certain deformations. In this method, supports are used to remove excessive heat from the work area.
Today, SLM 3D printers use both pure metal powders and metal alloy ones. The most common consumables are aluminum, cobalt-chrome, copper, nickel (Inconel), stainless and tool steel, titanium, and precious metals.
Compact budget-friendly SLM printers can be equipped with low-power lasers. Usually, the larger the size of the device, the more power and number of lasers it features. Some units are engineered with dozens of lasers 1 kilowatt each. As a result, the efficiency and productivity grow significantly, but so does the cost of the machine.
SLM 3D printers have an array of characteristics that should be taken into account when choosing proper equipment: power and number of lasers, diameter of laser spot, scanning algorithms and speed, layer thickness (usually from 20 to 120 microns), cooling system, etc.
When printing, the build chamber of an SLM printer is filled with inert gas - nitrogen or argon.
Upon completion of the process, the finished part can be removed from the build chamber after cooling. The latter can take up to several hours in case of large objects. The unused metal powder is collected, cleaned, and used for further printing.