3D printing services use a variety of materials in order to manufacture products for their clients. Of course, it depends on the customer which material the service will actually use. For example, the client might want its three dimensional model to be made out of a plastic filament. On the other hand, metal 3D printing is possible as well. This brings so many new possibilities to businesses and technologies. For example, it allows automation. This is the case since 3D printers are able to develop parts automatically, they just need the design files to do their job. What the metal 3D printing process looks like will be explained below in three steps.
How does metal 3D printing work?
The basic fabrication process for SLM and DMLS are very similar. Here is how it works:
- The build chamber is first filled with inert gas (for example argon) to minimize the oxidation of the metal powder and then it is heated to the optimal build temperature.
- A thin layer of metal powder is spread over the build platform and a high power laser scans the cross-section of the component, melting (or fusing) the metal particles together and creating the next layer. The entire area of the model is scanned, so the part is built fully solid.
- When the scanning process is complete, the build platform moves downwards by one layer thickness and the recoater spreads another thin layer of metal powder. The process is repeated until the whole part is complete.
When the build process is finished, the parts are fully encapsulated in the metal powder. Unlike polymer powder bed fusion processes (such as SLS), the parts are attached to the build platform through support structures. Support in metal 3D printing is built using the same material as the part and is always required to mitigate the warping and distortion that may occur due to the high processing temperatures.
When the bin cools to room temperature, the excess powder is manually removed and the parts are typically heat treated while still attached to the build platform to relieve any residual stresses. Then the components are detached from the build plate via cutting, machining or wire EDM and are ready for use or further post-processing.
If you want to use 3D printing to produce a metal part you need to use CAD, this is where you design the product. After this is done you can export it to a STL file, which then has to be sliced. There are many different programs available for this. Eiger is an example of this, but there are more options. Often this software monitors the metal item’s progress through each step of the process. After the model has been prepared, you can move to the metal 3D printer. Again, there are a lot of options when it comes to the 3D printers that can create metal objects. They do essentially all work the same, though. After the product has been printed, it will be in the so-called green form.
Green form essentially means that the 3D printed item needs to be placed into the wash, this has to be done for the debinding process. The first stage of the binding material will be removed during the washing. The metal part is taken from the 3D printer and put into a wash basket. Subsequently, it will be lowered into the solvent. After the washing has been done, you will have a brown part.
A brown part still is not a fully metal piece, this is done by sintering. The temperature will be ramped up slowly in order to burn away the trace amounts of the binding material that still remained on the product. The temperature will rise slowly but surely and eventually come close to the melting point of the metal. This is when the metal particles will fuse together, which will create a strong metal part.