Binder Jetting (BJ)
A binder jetting machine will distribute a layer of powder onto a build platform. A liquid bonding agent is applied through inkjet print heads bonding the particles together. The build platform will be lowered and the next layer of powder will be laid out on top. By repeating the process of laying out powder and bonding, the parts are built up in the powder bed.
Binder Jetting does not require any support structures. The built parts lie in the bed of not bonded powder. The entire build volume can therefore be filled with several parts, including stacking and pyramiding of parts. These are then all produced together. Binder Jetting works with almost any material that is available in powder form.
Advantages / disadvantages
Binder Jetting works with almost any material that is available in powder form. The process is fast, simple and cheap as powder particles are glued together (as compared to e.g. laser melting where material is melted under protective gas environment). Certain binder jetting machines can print colors along with the binding agent creating full color parts.
Parts produced with the technology are basically particles glued together resulting in fragile parts with limited mechanical properties (if not further processed).
- Prototypes are produced in full color for visual and form / fit testing by binder jetting.
- Green parts are produced to be further processed with other manufacturing techniques. For instance metal parts are sintered in an oven process and then infiltrated.
- Casting patterns are produced as models to create molds for casting.
- Molds and cores for casting can also be directly produced in specialized casting sand
Characteristics / restrictions
- Maximal build envelope: 4’000 x 2’000 x 1’000 mm3
- Minimum feature size: 0.1 mm
- Typical tolerance: +/-0.13 mm
- Minimum layer thickness: 0.09 mm
- Fast build speed
- Full color parts
Characteristics are only indicative, as there are different types of machines available.
Binder jetting parts are often the starting point for further processes like infiltration, sintering or casting. Read more
The production of parts is planned in a build preparation software. One or several parts are placed in the build, using the digital 3D files (typically in the STL file format). These can be arranged to fill the entire volume of the build envelope.
- Remove excess powder: First step is to remove all excess powder from the parts. This is usually straight forward, however might require some extra effort for parts with complex geometric features (e.g. trapped powder).
- Infiltration: Parts might be infiltrated with a resin to increase mechanical properties, durability and finish.
- Oven processes: Green parts, for instance out of metal, can be sintered in an oven process.
- Casting: Binder jetting is used to produce casting patterns or molds and cores directly out of casting sand.