Slicing For Metal Paste Deposition
What is slicing?
Slicing is the name for the process that takes a digital 3D shape file and converts it into a printing tool path. The process is analogous to computer-aided manufacturing (CAM) software used for generating CNC machining programs. The name slicing alludes to how the slicing software cuts a 3D part model into many layers and builds a path for making the part layer by layer. Slicer programs output gcode files, the software language used by 3D printers to direct print head movement and extrusion.
What is Rapidia’s slicing solution?
Our Conflux 1 printer is an open platform in that it will accept gcode from any slicer. In fact, the drying lamp code is added by the printer itself, so slicing principles from any plastic filament slicer can be made to function with Metal Paste Deposition.
To make printing easier, Rapidia offers an open-source, modified release of one of the most popular slicers: Rapidia Cura.
Rapidia Cura is configured with printing profiles tailored to work well with our Conflux 1 metal 3D printer. Our built-in printing profiles provide a shortcut to successful prints, without locking users out of any settings that might allow them to optimize slicing for a fringe project. The profiles also provide a convenient ‘reset’ point if you get deep into setting tweaking and need a clean state.
Importantly, Rapidia Cura has built-in material profiles to automatically scale parts to correct for shrinkage in sintering.
Rapidia Cura adds features for support material generation which allow for both metal and evaporative support to be printed at the same time. This is crucial for providing metal sintering support to parts that would otherwise deform during sintering while avoiding creating metal support with interlocking geometry.
Why did Rapidia make a modified Cura release?
We chose to create Rapidia Cura because it’s the slicer we really wanted to use. For one, Ultimaker’s standard Cura is familiar and has many powerful features. To us, there’s no reason to make users learn a new software interface if the core functionality is the same.
Secondly, Cura is open source, so users can audit our changes, provide direct feedback or make feature requests through github, and even contribute to the codebase. Open-source software aligns with our vision to making metal part manufacturing more accessible to everyone.
Why are the added slicing tools needed?
As powerful as existing slicers are, they were not designed with sintering in mind. Polymer printing only needs support structures to act as support during in printing. Furthermore, plastic supports are easily removed, usually just by tearing them out.
At sintering temperatures, metal parts have similar stiffness to warm plasticene and require support to prevent sagging. We wanted it to be easy to add the necessary sintering support without having to spend time designing support shapes in CAD, as is required for other metal additive manufacturing processes.
The reason we had to create a modified release of Cura was to allow the creation of support from two different materials. If the support material was all metal it would have to be cut off with metalworking tools after sintering. Moreover, using metal supports everywhere would often lead to interlocked pieces that can’t be separated by hand.
Our Rapidia Cura release allows you to put metal sintering support where it’s needed and use evaporative support elsewhere so that sintered parts can be lifted off the support structures and are within tolerance specs.
What’s next?
Rapidia Cura is currently built on Cura 4. Ultimaker™ released Cura 5 in 2022 with an updated slicing engine called the ‘Arachne’ Engine that allows for variable line width printing. This next generation slicer provides a leap forward in printing quality. We are currently completing our porting of Cura 5 and will be releasing it in the first half of 2023.