We have talked about the surface finish, the cost factors, the materials and now let me explain to you how the actual process works.
Are you familiar with SLA (stereolithography)? Well is very similar to that but does it in metal...
Thats it. The end.
What makes SLA and DMLS similar is that fact that both build with supports, SLA builds with supports and so does DMLS. This means that any bottom surface must be supported to the build plate. The easiest way to explain this is that if you were to slice the part into a bunch of layers then take those layers and start from the bottom and work your way to the top, you then have to stack these layers one on top of the other right? So, you have to build from something, one layer must build on top of something else whether it be a support or another layer it just cannot be free floating in air like the SLS process is.
I hear a lot well isn't it like SLS and it doesn't require supports? Nope, this is much different, the reason being is that there is stress involved, just like traditional machining there is some warping and stress. Each layer is melted locally using a fibre optic laser, so that layer can become very hot and the laser isn't zapping the whole part at once (which may be worst).
Here is how the whole DMLS process starts;
- You start with a CAD file that is sliced into 20 or 40 micron layers using a specialized software called Magics. There is a lot more that goes into just taking the CAD file, for instance each part must be orientated to build the best way. I can't give away all the secrets right?
- Take the sliced file and input it into the EOS software and depict the best angle for this part to be facing the recoater blade (the blade that sweeps new powder over each layer).
- Output job file.
- Add powder and level build plate inside the equipment.
- Install Job parameters for the EOS equipment via the EOS software.
- Input job file to the EOS equipment computer.
- Let oxygen levels get to a safe amount.
- Hit GO!
- Take build plate out of EOS equipment.
- Cut parts off the build plate (typically a 2-4 mm support structure under the part is cut close to the plate).
- Remove support material with a variety of tools and/or CNC equipment.
- Finish said parts to desired finish level.
- Pack and send.
V.P. NBD / Marketing Manager
GPI Prototype & Manufacturing Services, Inc.
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