Binder jetting

The binder Jetting (also 3-D printing ) is an additive manufacturing process , wherein the powdered starting material at selected locations with a binder is bonded, so as to produce workpieces.

The process is standardized in VDI guideline 3405 under the name "3D printing" and is based on developments by the Massachusetts Institute of Technology (MIT). A machine was built there in the early 1990s that was based on an inkjet printer and instead of ink on the paper, the binder shot onto the powder. MIT also received a patent on the process. However, the term “3D printing” is also often used as a generic term for all additive manufacturing processes, especially in marketing and in public media. In contrast to this, in the specialist literature this mostly refers to the procedure standardized in VDI 3405.

Several companies bought licenses from MIT and developed their own printers. These include ExOne , Z Corporation (Z Corp.) , which was acquired by 3D Systems in 2012, and Voxeljet .

technology

Layered construction of a colorful object (here flower blossoms) with a ProJet-4500 from 3D Systems

With 3D printing, the workpieces are built up in layers. The geometry to be generated for each individual layer is calculated from 3D data (e.g. CAD data). In 3D printing, a layer of powder or granulate is applied to a height-adjustable table and bonded to the areas that are part of the workpiece using a binder. Similar to a conventional inkjet printer, a printhead is used for this purpose, which applies the binder instead of ink. Then the table is lowered one layer thickness and a new layer of powder is applied. This is repeated until the workpiece is completely created, which is then completely hidden from the surrounding powder. The excess powder is then returned for further use, the workpiece is removed from the printer and powder residues are removed.

The process principle is thus similar to selective laser melting , in which a metal powder is locally melted by a laser .

Advantages and disadvantages

In theory, all materials can be used as long as they can be glued to the binder. In particular, food or temperature-sensitive substances such as pharmaceuticals can also be processed. It is also possible to use different binders within a single workpiece and thus create areas with different mechanical properties. Numerous substances can be used as binders, e.g. B. those based on water, synthetic resin or living cells . In principle, the powders do not have to be identical in every layer.

In addition, similar to laser sintering , binder jetting does not require any support material, as the workpiece is carried by the powder during the production process.

However, 3D printing does not provide a particularly strong workpiece. Especially when using metals as materials, the workpieces must be subsequently freed from the binder and sintered in order to ensure sufficient strength. This leads to shrinkage, so that the final geometry is difficult to set in advance, but this can be managed with sufficient experience.

Individual evidence

1. ↑ Engelbert Westkämper, Hans-Jürgen Warnecke: Introduction to manufacturing technology. 8th edition. Vieweg-Teubner, Wiesbaden 2010. ISBN 978-3834808356 , p. 265.
2. ^ Albert Herbert Fritz (author), Günter Schulze (ed.): Manufacturing technology. 11th edition. Springer Vieweg, Wiesbaden 2015. ISBN 978-3662465547 , p. 120.
3. ↑ Fritz Klocke: Manufacturing Process 5 - Gießen, Powder Metallurgy, Additive Manufacturing , Springer, 2015, 4th edition, p. 131
4. ↑ Gibson, Rosen, Stucker: Additive Manufacturing , Springer, 2015, 2nd edition, p. 205.
5. ↑ Gibson, Rosen, Stucker: Additive Manufacturing , Springer, 2015, 2nd edition, p. 205.
6. ^ Andreas Gebhart: Generative Manufacturing Processes , Hanser, 2013, 4th edition, pp. 73f.
7. ↑ Gibson, Rosen, Stucker: Additive Manufacturing , Springer, 2015, 2nd edition, p. 205.
8. ^ Andreas Gebhart: Generative Manufacturing Processes , Hanser, 2013, 4th edition, pp. 74f.