With Sand Binder Jetting devices, these are low-cost types of 3D printing technology for producing parts from sand, e.g. sandstone or gypsum.
For full color models, objects are fabricated using a plaster-based or PMMA powder in conjunction with a liquid binding agent. The printhead first jets the binding agent, while a secondary print head jets in color, allowing full color models to be printed.
Once parts have fully cured they are removed from the loose unbonded powder and cleaned. To enhance mechanical properties, parts are often exposed to an infiltrant material.
There are a large number of infiltrants available, each resulting in different properties. Coatings can also be added to improve the vibrancy of colors.
Binder Jetting is also useful for the production of sand cast molds and cores. The cores and molds are generally printed with sand, although artificial sand (silica) can be used for special applications.
After printing, the cores and molds are removed from the build area and cleaned to remove any loose sand. The molds are typically immediately ready for casting. After casting, the mold is broken apart and the final metal component removed.
The big advantage of producing sand casting cores and molds with Binder Jetting is the large, complex geometries the process is able to produce at relatively low-cost. Plus, the process is quite easy to integrate into existing manufacturing or foundry process without disruption.