Photopolymer Jetting (PJ)
Photopolymer jetting machines utilize inkjet print heads to jet a liquid photopolymer which is immediately cured by a UV lamp. By adding layer on layer, the part is built. Several materials can be jetted at the same time. Photopolymer jetting requires support structures for overhangs, which is usually built in a different material.
Advantages / disadvantages
Through utilizing print heads, several materials can be processed at the same time. This allows multi-material and/or multi-color parts. Through mixing materials in different proportions, functionally graded materials can be built (e.g. different shore hardness at different locations of the part). The technology can achieve good accuracy and surface finishes.
As stereolithography, photopolymer jetting is working with UV-active photopolymers. Therefore, parts are not durable over time and have limited mechanical properties.
- Prototypes can be built in multiple materials with multiple colors and good surface finish. Further, transparent materials are available. Therefore, photopolymer jetting parts are often used for visual and form / fit testing.
- Casting patterns are built with photopolymer jetting as good accuracy and surface finish can be achieved.
- Tools for injection molding of very small series / prototypes are produced with photopolymer jetting due to the good surface and accuracy.
Characteristics / restrictions
- Maximal build envelope: 1’000 x 800 x 500 mm3
- Minimum feature size: 0.15 mm
- Typical tolerance: +/-0.025 mm
- Minimum layer thickness: 0.016 mm
Characteristics are only indicative, as there are different types of machines available.
Multi-material and multi-color parts need to be specially planned beforehand. After the build, the support structure can be removed with water. Often parts are not further processed, as good surface finish and accuracy can be achieved. Read more
The production of parts is planned in a build preparation software. One or several parts are loaded from digital 3D files (typically in the STL file format). Different materials and colors can be defined for different parts.
- Remove of support material: Support material is removed with water.
- Surface finish: The surface can be changed through adding material (e.g. painting, coating), which can also improve durability.