3D printing by stereolithography enables rapid forming of workpieces with complex shapes which is not possible with the traditional methods used in the ceramics industry (e.g. pressing, injection, casting, extrusion). This technique makes it possible to produce ceramic objects from a digital model by superimposing thin layers of material.
There are several 3D printing techniques using stereolithography but the most commonly used is by stereolithography using photopolymerisation. The process is based on the specific properties of certain resins under the effect of light and/or heat. This technique consists of several stages:
- Acquisition of a digital model using CAD software or digital acquisition of an existing model
- Digital cutting of the 3D model into layers of equal thickness (2D models) and print sequencing
- Preparation of a paste containing a ceramic filler, organic binders and a light-curing resin
- Production of a part by adding paste layer by layer and polymerisation of the paste according to the shape of the layer as defined by the computer
- Cleaning by eliminating the monomer surplus (green part)
- Debinding to remove binding agents and resin and sintered to densify the part.
Ceramics are not naturally printable materials and so they are mixed with binders/resins which are eliminated during the various heat treatments. The materials printed by the members of the association are: glass/quartz, glass-ceramics, zirconia, alumina, porcelain, hydroxyapatite, tricalcium phosphate, alumina-zirconia composites, cordierite, silicon nitride, aluminium nitride, spinel.
Advantages and disadvantages of this process
- Complex geometry and customised
- Flexibility of production/no tools
- Low initial investment.
- Cost of parts
- Production output
- Limitation of the thickness of workpieces
- Problem of "trapped volumes".