Investigating the Effects of Release Coating on Tool-Part Interaction and Process-Induced Deformations in Composites Manufacturing

Abstract

Although modern-era composites manufacturers possess advanced processing capabilities, several production challenges remain prevalent. One such challenge is mitigating residual stresses and process-induced deformations (PIDs) in composite parts while maintaining a cost-efficient manufacturing workflow. For example, applications and touch-ups of release coatings are labor-intensive process steps and generate high recurring production costs, yet are critical to minimize tool-part interaction and PIDs. One intuitive approach to reduce the frequency of disruptive tool coatings or cleanings may be to apply greater quantities of fresh release coats to a tool surface before completing successive cure cycles. However, the consequential effects of such an approach on tool-part interaction and PIDs are currently undetermined and neglected. This paper first investigates the relationship between release coating quantity and tool surface physicochemical properties using laser microscopy and contact angle goniometry. Then, a novel test fixture installed in a Dynamic Mechanical Analyzer (DMA) is presented and used to quantify tool-part stress developments as a function of fresh release coating quantity applied on a tool surface. Lastly, findings from tool surface characterization and DMA testing were validated by curing long symmetric laminates on tools treated with different release coating quantities in an autoclave and measuring warpages. The results in this paper can be used to expand the current understanding of tool-part interaction and improve the efficiency of tool preparation in composites manufacturing.