ENHANCEMENT OF OVEN-VACUUM BAGGING PROCESS FOR MANUFACTURING SANDWICH PANELS

Vacuum Bagging Oven (VBO) process is widely used in the aerospace and construction industries. Manufacturing induced defects on the panels during manufacturing could decrease the mechanical properties and reduce their aesthetic values. Therefore, the objective of this study is to investigate the effect of pressure and vacuum bagging method on external surface porosity and internal voids for the sandwich panel using VBO while supported with MATLAB, profilometer, 3-D scanner and compaction test. Hence, various researches were carried out to identify the best parameter values to get fewer void content. Factors affecting the defects of the specimen are pressure and temperature but, in this paper, the pressure will be highlighted, and temperature will only be used as constant for all specimens. The materials that are used for producing sandwich panels are carbon-epoxy prepreg for the skin and Nomex honeycomb for the core. The out-life prepreg time must be 4 hours minimum at room temperature. It is necessary to do pre-curing after taking the prepreg out of the freezer to prepare it in room temperature for a more ideal outcome. The temperature has two stages based on manufacturer’s recommendation cure cycle (MRCC) which are pre-curing and curing where each has its own reasoning to make fewer defects with suitable temperature. There are three different pressure values, 30 kPa, 60 kPa and 90 kPa of pressure factors. Pressure was constant throughout the vacuum hold time for SVB while DVB has an additional 100 kPa for the outer layer bag. Other than that, MATLAB software gives image analysis of the components’ microstructure, resulting in data that will quantify the evolution of impregnation and porosity due to resin flow from pressure. Finally, compaction test will be held onto the specimen until breaking point to analyse the mechanical properties it could withstand.