Effects of the Vacuum Moulding Process on the Mechanical Properties of Cotton/Epoxy Composite

A study on the effect of the vacuum assisted resin transfer moulding (VARTM) manufacturing process on the mechanical properties of cotton/epoxy composite is presented in this investigation. Woven cotton was used as reinforcing material embedded in epoxy resin. The woven cotton was treated with sodium hydroxide for one hour at concentrations of 0% to 20%. The tensile test showed that the untreated material had the highest ultimate strength and Young’s modulus. Observation of the fracture surface by scan electronic microscopy (SEM) was compared to the hand lay-up process as well as the results of the tensile test. The comparison showed that the VARTM process presents better mechanical properties than the hand lay-up process due to the reduction in discontinuities observed by means of optical microscopy.

Manufacturing of thermoplastic composite sandwich structures

Composite sandwich structures show promising lightweight properties for the aviation industry. Nowadays time-consuming manufacturing methods still prevent an extensive application of composite sandwiches, which can be overcome by the use of thermoplastic polymers in skins and core. During manufacturing of thermoplastic composite (TPC) sandwich structures, the joining of skins and core is a critical step. Therefore, several skin–core joining methods have been under investigation and development in the published literature, which can be categorized into adhesive bonding or fusion bonding. Fusion bonding by means of vacuum moulding, compression moulding or in situ foaming shows great potential for joining sandwich skins and core. Although various phenomena such as core collapsing or skin deconsolidation challenge the processes. This article aims to present an overview of research that has been done in the area of manufacturing TPC sandwich structures and will serve as a baseline and aid for further research and development efforts.

Surface roughness improvement of cast components in vacuum moulding by intermediate barrel finishing of fused deposition modelling patterns

In this work, investigations have been made for surface roughness (Ra) improvement of vacuum moulding (VM) components by introducing barrel finishing (BF) on fused deposition modelling patterns at preliminary stage (i.e. before being used as master patterns). The Ra improvement will help to avoid/reduce post machining/finishing operations for green manufacturing. The VM master patterns were prepared using P-430 grade acrylonitrile butadiene styrene material on commercial fused deposition modelling setup. Further, Ra of VM master pattern prepared was improved by using BF process (as intermediate process). The controllable parameters of BF and VM process (namely, media weight, cycle time, vacuum pressure and grain size of refractory sand) were studied at three levels by using Taguchi L9 orthogonal array to explore their affects on Ra of the final cast components. The results of study suggest that media weight of BF and sand grain size of VM process contribute significantly for improving Ra.