With the release of Desktop Metal’s new Studio System, we wanted to publish some highlights of the design guidelines developed by Desktop metal in order to ensure success on your new metal printing system. By following these guidelines, you will be creating part designs that are best suited to utilize the strengths of the Studio System while at the same time minimizing the impact of the process limitations inherent to the tech behind the Studio System. All these design guidelines and more can be found online in Desktop Metal’s knowledge base, located here https://knowledge.desktopmetal.com
Maximum Shell thickness: 6mm
The studio system process has a maximum shell thickness limitation due to the nature of the debinding process. When parts are submerged in debinding chemical, the fluid begins to penetrate the part surface and remove the binding agent laid down during the printing process. The more solid the part is, however, the more difficult it is for the fluid to penetrate in a timely manner. To ensure total debind a limit of 6 mm shell thickness has been established. This means we can have a 12mm or thinner part printed completely solid, or a 6mm solid wall, followed by honeycomb infill and another 6mm wall.
Minimum Wall thickness: 1mm
If you are familiar with FDM design, this is a very similar guideline. The goal here is to ensure a minimum of two toolpaths are printed for any geometry to created stable features and give enough surface area to bond to the previously printed layer. Here with the studio system, toolpaths are 0.48mm wide, so 2x that gets us 1mm.
Aspect Ratio for Tall Parts: 8:1
For tall, thin parts we need to keep aspect ratio in mind. These parts may print totally fine during our first stage, but during our final sintering stage is where issues can come up. Because the parts are heated to a semi-liquid state in order for the metal particles to properly bond, this also means that part geometry can begin to warp under its own weight if not properly supported. If parts are too tall and thin, they will begin to sag under their own weight and come out of the furnace with undesirable warping.
Self Supporting Angle: 40 degrees
Again, FDM veterans should know this concept well. With layer-based extrusion 3d printing, it is possible to print out into unsupported air as long as the deviation from the last layer isn’t too far. Think of it like building an arch or an igloo. Each block is still touching the block beneath it, but it is also hanging over the edge by a fair margin as well. This allows us to print certain geometries at a gradual enough angle using no support structure. This is great in FDM because by printing fewer supports, we save on both time and material. With DM though, you get three times as much out of this design trick because we have three different processes (printing, debinding, and sintering) that benefit from the reduced part mass.
Clearance for as-printed Assemblies: 0.3mm
In extrusion 3d printing, there is always the chance for over-extrusion to happen. These appear on parts as small globs on the surface where the over extrusion occurred. In plastic printing, this is a non-issue as they can be broken very easily by hand. With metal, however, those parts are now welded together and are much more difficult to separate after sintering. With a clearance of 0.3mm or more, we are helping ensure none of those globs contact both part surface and render our as-printed assembly useless.
Application Engineer, Manufacturing Solutions
Computer Aided Technology, LLC