The issues in designing a part for filament-type metal 3D printing, including orientation and support, are a bit different from the equivalent techniques for plastic, but there are many similarities in design constraints.
- [Instructor] Designing for 3D printing requires that you think about the geometry of your part, the physical limitations of the materials you're working with, and whether your printer is using a powder or a filament. In this movie we'll focus on the issues related to the geometry of your part and the practicalities of printing with the filament like materials. For the filament like materials, the printing process is pretty much the same as it would be for plastic. However, formulations of materials used as binders aren't likely to be pure forms of common 3D printing plastics. Most of these binders are proprietary mixtures and optimized for the overall process. The key thing to remember is that you're melting the binder, not the metal, during the 3D printing process. In fact, you're never actually melting the metal particles entirely even during during sintering. This allows the use of tool steel alloys in these mixtures that might be challenging in DMLS. The usual considerations of getting filament to stick to a build platform apply. For example, you want to be sure you have as large a contact area between your part and the print bed as possible. - [Narrator] Manufacturers of printers or materials will make suggestions, and you should start there. The integrated systems have other solutions like removable or single use flexible print beds that make taking parts off easier. Other constraints come in to keep parts stable during the sintering process. Some of these constraints are intended to limit how delicate the part becomes during its brown state or to ensure that it doesn't droop during the sintering process. The debinding and sintering process requires that solid sections be small and walls be relatively thin. Otherwise, the debinding and sintering may take too long to be feasible or variations in thickness can lead to local over or under sintering. After printing, the green part should be removable from the platform just like a plastic filament print would. DMLS parts, on the other hand, are welded to the platform during printing and need to be removed with metal cutting tools. - [Instructor] The ideal Infill settings will depend on the rest of the process. You should read what your particular vendor suggests and understand why they suggest that. Exactly what happens to the green and brown part will likely play a role. Desktop Metal and Markforged both use a triangular grid infill for their integrated systems. BASF, on the other hand, suggests printing solid in order to more closely match the behavior of a metal injection molded part when you vend out the debinding and sintering. Similarly speed, retraction, and extrusion multiplier recommended profiles vary, and you should read carefully what the manufacturer suggests. Some of these filaments are brittle, and they may benefit from being warmed before being printed on a conventional printer. Support material is generated the same way as it is for other single material filament prints. The supports are removed at the green parts stage because the part will be supported by a refractory material during debind and sintering. On the other hand, some end to end printing, debinding, and sintering proprietary systems lay down a ceramic interface layer between support and the print. This allows the user to relatively easily remove external supports from the completed part so supports are kept in place all the way through the brown part stage and sintering. Supports inside concave parts might be very challenging to remove however, as is extensive support needed for complex internal geometries. Part design will need to be carefully managed to eliminate support or to be certain it can be removed if it's internal. For example, Desktop Metal has an anti mold lock feature in its software that breaks up support structures to ensure that each piece is removable for situations where a monolithic structure wouldn't be. - [Narrator] There's a lot of energy in the generative design space which uses algorithms to create different suggested 3D printable parts that only put material where it is needed to resist a force. These tools will evolve and get backed up with more experience and testing as time goes on. Meanwhile, unless you're sure that your software is simulating parts made by techniques like this accurately, it would be advisable to back up part strength simulations based on bulk material averages with some testing. One caveat in all this is that tools designed to simulate the stresses in a traditional bulk metal part may not accurately model the 3D printed or sintered metal parts. The sintered parts should be reasonably isotropic since sintering should largely merge together the layer intersections, but healthy caution should still be used when using software that assumes other fabrication techniques to analyze a part's likely failure. - [Instructor] We've covered the basic practicalities of 3D printing with high metal content filament here. If you want to know more about debugging prints created with a filament based printer, you might also look at our courses Additive Manufacturing: Optimizing 3D Prints and Additive Manufacturing: Troubleshoot 3D Prints. The advice in those courses might need a little tweaking in detail, but in general will give you ideas of things to try if you're having issues.
- Process introduction
- Materials considerations
- Debinding and sintering
- Resolution, shrinkage, and isotropy
- Post-sintering treatment
- Outsourcing vs. in-house manufacturing
- Metal 3D printing alternatives