Enhancing part demolding characteristics of additively manufactured fiber-reinforced polymer composite tools via surface coating

The influence of a surface coating on the demolding characteristics of an additively manufactured fiberreinforced polymer composite tool was investigated. An experimental setup was developed to measure the reaction force developed as a part was demolded from an additively manufactured tool. The tool used in the demolding experiments consisted of a cylindrical geometry and was additively manufactured with 50% by weight of carbon fiber reinforced polyphenylene sulfide (PPS). A commercial thermoset-based liquid coating was applied, and a composite laminate was laid on the surface of the tool and cured in an autoclave process. The force was recorded as a function of the displacement during the part demolding process of both the coated and noncoated tools. The demolding test results showed that the initial force required to demold the part and the kinetic friction coefficient between the tool and the part decreased substantially with the application of the coating. Further, the stick-slip behavior developed during the demolding process of the part was significantly reduced with the coating. Stereoscopic images of the tool surface revealed that the coating filled voids initially present at the surface of the tool, thereby producing a smoother and more homogenous surface texture than the non-coated tool. Although a significant reduction in the part demolding force was obtained with the application of the coating, the coating started to chip off upon multiple part manufacturing cycles which compromised the part demolding characteristics of the coating.