Material
The powder used for the metal binder jetting process consists out of very small particles in a range of <20µm formed by gas or water atomization. The powder is designed to enable a rapid and consistent layer spreading during the printing process step.
Printing
Two major steps are repeated to produce the parts in the printer
- Spread powder - The build job starts with the recoater applying a thin layer of powder in the working area. At both ends of this area the recoater is refilled from storage containers. This enables bidirectional recoating for increased productivity.
- Print agent – Thousands of nozzles in the print heads precisely place binding agent droplets at those locations in the powder bed that define the geometry of the part
Curing
After completing the build the powder bed with its printed parts is heated to evaporate liquid components from binding agent Polymers are cured to increase strength in the green parts to enable safe handling.
De-powdering
After the powder bed has been cooled down, the green parts can be de-powdered or decaked. In this process step the loose powder is removed from the surfaces of the part. Remaining powder can be processed and reused for further printing.
Sintering
The green parts need to be sintered in a furnace During the sintering process at temperatures below the melting point, atomic diffusion at the surfaces of the metal particles binds them in a matrix that can exceed up to 98% solid density. Any remaining binding agent decomposes.
Finishing
Finally, the parts may undergo any machining and surface treatment that is common for solid steel parts.