Binder Jetting

Parts of the following article are a piece of writing that is published on the WZR ceramic solutions GmbH?website and is property of the company.

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Is it possible to produce ceramic parts fast and cost-effective?

Conventionally, ceramic parts are produced by extrusion, pressing or injection molding. All of these manufacturing methods do have one problem in common: Tools are needed to produce parts. When the production of only one part or a small batch is desired, tooling costs skyrocket. Furthermore, the geometry of the parts to be produced is limited – not every part is manufacturable, especially fragile structures break during demolding. Therefore, adjustments and sometimes compromises in the geometry are required, which also increase time-to-market and costs.

The additive manufacturing process Binder Jetting combines the advantage of no tooling costs with the geometrical freedom of additive manufacturing processes.

Binder Jetting is a 3D printing method, often referred to as powder bed based 3D printing. The process is based on inkjet technology where a liquid binder is used to bind the powder particles, following the CAD file of the component.

Building the component layer by layer

A rotating roller transports the powder from the storage container into the building space. The print head prints the first slice of the print file on the powder surface. Then the building space is lowered by the height of one slice, the storage container is moved up accordingly and the next powder layer is placed by the rotating roller. Usually, the layer thickness is between 50 – 200 μm. The steps are repeated until the last slice is printed. Thus, the component is built up from bottom to top, with the remaining, unbound powder taking on a supporting function during this process.

Ink and powder

The interaction between ink and powder is of great importance. If the binder saturation is too low, the layers will not bind together strongly enough to give the green body sufficient strength. If the binder saturation is too high, the geometry will be irregular because too many powder particles are bound. The decisive factor here is the wetting of the powder with the ink.

Powder and ink choice

In general, any ceramic raw material (aluminium oxide, zirconium oxide, silicon carbide and many more) can be processed with Binder Jetting. The particle size distribution, particle shape, density and specific surface of the powders are critical as these properties indicate the flowability and compactability of the powders while ensuring sufficient reactivity during the sintering process.

The ink is typically a simple liquid binder. To lower the relatively high porosity of Binder Jetting components or to add another chemical component to the system, ceramic particles can be added to the ink. Important properties for the ink are the viscosity, surface tension and time-dependent stability (phase separation, sedimentation).

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