Water Wash Out Tooling Process Developed

ExOne’s Materials Applications Laboratory (ExMAL) has developed a process to produce water wash-out tooling via additive manufacturing to produce varying composite parts designs. Using ExOne’s printers, the company created 3D-printed cores that can simply be washed out of a part after manufacturing. Intended for the production of hollow parts, typical of mandrel or clamshell molding, ExOne’s water wash-out tooling process involves 3D printing a core in sand, ceramics or carbon, applying a composite lay-up, and curing. The final core is then washed out with only the structural composite part remaining.

The dimensionally stable process enables easy prototyping for part evaluation, and can be used with polyester, vinyl ester or epoxy resins. The system is fully capable of autoclave pressures to 125 psi and can withstand process temperatures ranging to 375°F. According to the company, the process has a short lead time requiring no machining, and the print media can be chosen to optimize coefficient of thermal expansion (CTE), thermal connectivity, and density.

To fully realize the capabilities of the application, ExMAL developed a new surface coating process that is applied to the printed core and said to eliminate the porousness of printed media and provides extremely smooth surface finishes. According to the company, the water wash-out tooling process allows all of the print material to be recovered and reused for future print cycles, reducing inventory requirements and removing molding steps.

The process is ideal for printing mandrels for filament winding, tape placement or hand lay-up; plugs and source tools; styling and design models; hollow or trapped shape fabrication; and one-off parts for part validation.