Development of a Low Coefficient of Thermal Expansion Composite Tooling via 3D Printing

Abstract

The use of additive manufacturing (AM) provides an opportunity to fabricate composite tooling rapidly and cost effectively. This project appears to have demonstrated the use of an additive technology for the production of composite processing tools. In particular, this work has addressed tooling that is functional in the range of autoclave temperatures around 300–350°F. This has led to the use of Invar and ceramic materials for use in composite molding tools because of their relatively low coefficient of thermal expansion (CTE) performance, which is in range to that commonly displayed by carbon fiber reinforced composites during their solidifying-curing process. In this project, two main approaches have been considered. The first approach consisted on using binder jetting for 3D printing sand molds to cast molten Invar to produce the composite tooling. Indeed, 3D sand printing offers the ability to cast complex geometries without the geometric limitations associated with conventional pattern making. The second innovative approach was based on printing a mold based on silica sand and infiltrating it with a polymer to yield a robust ceramic composite tooling. An additional technology using a Hybrid Direct Energy Deposition (DED) System for cladding Invar upon a steel molding structure has also been considered for producing potential composite tooling. Indeed, this unique approach could represent a promising technology for producing low cost composite tooling since only a small layer of Invar would be printed upon a non-expensive substrate. The results have shown that the aforementioned processes have successfully resulted on low CTE composite tooling molds. This work presents innovative AM processes by initially investigating 3D ceramic systems for composite tooling.

The fracture properties of metal‐ceramic composites manufactured via stereolithography

“…61 These results could be associated with the presence of cracks in the sintered samples, which could have interfered with the CTE analysis. 36 These IPCs appear to produce robust and stable carbon fiber reinforced epoxy parts as reported by Cortes et al 38 . A feasible approach to overcome this disadvantage is the incorporation of a coating with high temperature thermoset resins as performed on other 3D printed ceramic systems used for manufacturing composites.…”

“…37 In contrast, the CTE of the transformed parts resulted in an average value of 11.02x10 -6 K -1 , which is two times lower than the aluminum alloy used on current composite tooling molds. 36 These IPCs appear to produce robust and stable carbon fiber reinforced epoxy parts as reported by Cortes et al 38 . Indeed, these IPCs have been subjected to ten cycles of thermostability at 180°C, and no presence of configurational deformation was reported 38 .…”

“…Tian et al 30 investigated the production of silicon carbide (SiC) components using SLA technology with carbon precursors. 36 Indeed, one critical property that needs to be addressed on the production of fiber reinforced thermoset composites is the dimensionally stability during the curing process. They reported a full silicon-carbon transformation process with flexural strengths close to 130 MPa.…”

“…35 A new application of these IPCs has been on the area of composite tooling due to their low coefficient of thermal expansion. 36 Indeed, one critical property that needs to be addressed on the production of fiber reinforced thermoset composites is the dimensionally stability during the curing process. 37 A preliminary work performed by Cortes et al 38 showed that composite tooling based on IPCs yielded stable and well consolidated high temperature carbon fiber reinforced epoxy composites.…”