Minimizing Surface Porosity in Vacuum-Bag-Only Prepreg Processing

Surface porosity, also known as pinhole porosity or pitting, is a type of defect that often occurs on the tool-side surface of composite laminates produced from out-of-autoclave (OOA) or vacuum-bag-only (VBO) prepregs. The current methods of correcting this problem require surfacing films prior to cure and/or rework after cure. Both solutions are costly in time and weight. A systematic investigation of the factors causing surface porosity in VBO composite laminates has identified both probable root causes and potential cost and weight-effective solutions that significantly influence the surface quality of laminates. Multiple processing adjustments are investigated, including RT vacuum hold time, tool roughness (Ra), tooling material, moisture content, and surface release methods, among other variables. Presented at: Composites Manufacturing 2014, SME, April 8-10, 2014, Covington, KY.