ExOne offers a binder system for washout tooling that can be used to create one-piece composite parts with trapped geometries such as bottles, aircraft ducting, pressure tanks, struts and mandrels. Washout tooling is said to eliminate the expense and long lead time associated with manufacturing multi-piece metal breakdown tooling, and avoid the need for multi-piece molds needed to make castable washout tooling media. According to the company, the ExOne binder system is also faster than other 3D-printed soluable tooling.
The system has been formulated to be water-soluble up to 350°F to enable high-temperature curing of many composite materials. Silica and ceramic sand are available as printing media. After printing, a sealant coating is applied to the surface of the tooling to prevent resin migration into the tool from the composite part. Coating options include a spray-on coating system based on the binder chemistry, which is also water-soluble, or a Teflon tape wrap.
When the composite layup is completed and cured, tap water is applied to the mandrel ends to begin the washout process. The washout is completed within minutes and leaves no residual material behind, ExOne says.