Three-dimensional printing and laser micromachining became the core technologies for The ExOne Company, which currently supplies services, systems and solutions for manufacturing in the digital age, including three-dimensional printing in sand, metal and glass, and laser micromachining.
Furan Resin Binders in 3D printing Applications (picture).
Digital part materialization for the sand printing business began in 1999 when a group of engineers at a start-up company called Generis in Augsburg, Germany, developed the prototype 3D printer for making sand casting molds and cores. The first printing system was sold to BMW AG in 2001. Generis was focused on the development of machines and processes for sand and investment casting before it was divided in 2003 into ProMetal RCT for sand and Voxeljet for investment casting. As a division first of Extrude Hone Corporation and then ExOne, ProMetal RCT developed a worldwide market for sand printing with dozens of machine installations. The development and production facility in Augsburg, Germany has been renamed ExOne GmbH. ExOne’s 3D sand printing business has grown from a handful of engineers to a worldwide team with operation and support facilities in Germany, the United States and Japan.
ExOne offers digital part materialization in various combinations of sand casting media and chemical binders, depending on desired strength and level of detail:
- Silica sand
- Synthetic sand
- Other casting media
Digital production of sand molds and cores eliminates the need for hard tooling and drastically reduces lead times. The process uses three-dimensional printing technology to produce the molds and cores layer by layer from a CAD file. A binder catalyst is coated on the sand which is then spread in layers. The print head jets a second component of the binder system selectively onto the spread sand layer. The use of furan resin binders allows for optimized low gas emissions and high part strength. When this component meets the catalyst coating on the sand, a polymerization reaction occurs which bonds the sand particles together. Curing occurs in the air without the need for external heat.