Wednesday, 16 September 2015

Manufacturing Techniques of Fibreglass Reinforced Composites

IJSRD found Good research work on Mechanical research area.

Abstract— Combining a high strength fibre with a polymeric matrix produces a composite material with higher stiffness and strength. There are many techniques to produce composite materials, among which few techniques are discussed here based on its process, capabilities and application of composite parts. Among which hand lay-up, vacuum infusion, resin transfer molding and sheet molding compound are widely used. The prepreg is widely used for manufacturing composite parts.

Key words: Fibreglass Cloth, Fibre Reinforced Composites, Prepreg, Vacuum Infusion, Sheet Molding Compound


The global nature of today’s reinforced plastics industry creates a demand from all over the world. To produce a composite item, two basic components are required, these being a synthetic resin and a strong fibre [1]. The resin, which can be in the form of a polyester, epoxy or vinyl ester, is normally supplied as a viscous liquid, which sets to a hard solid when suitably activated [1]. The fibre may be glass, carbon, or a combination of some or all of these. What makes composites unique is the fact that the material of construction and the end product are produced simultaneously. Using a suitable mould, layers of fibre are impregnated with activated resin until the required thickness is achieved [1]. After completion, the mould is removed, which further can be used to produce more no. of identical items. These products are FRP cylinders, FRP sheets, FRP components for Transformers, and switchgears products. In the manufacturing of the Fibreglass epoxy sheets are more difficult tasks as it has many intermediate processes to manufactured sheets. The sheets are the combination of the fibreglass cloth and resin matrix that bond with the fibreglass cloth to make highly strength composites. Glass fibres fall into two categories: low-cost general-purpose fibres and premium special-purpose fibres. Over 90 % of all glass fibres are general- purpose products. These fibres are known by the designation E-glass. The remaining glass fibres are premium special-purpose products [2]. Specialpurpose fibres, which are of commercial significance in the market today, include glass fibres with high corrosion resistance (ECR-glass), high strength (S-, R-, and T Eglass), with low dielectric constants (D-glass), high-strength fibres, and pure silica or quartz fibres, which can be used at ultrahigh temperatures[2].

Fig. Schematic Illustration of the Vacuum Enhanced Resin Infusion Technology (Verity)

Vacuum Infusion:

The most popular term to describe vacuum infusion processes are Vacuum Assisted Resin Transfer Moulding (VARTM), Vacuum Assisted Resin Infusion Moulding (VARIM) etc, basically the same technology, and describe methods based on the impregnation of dry reinforcement by liquid thermoset resin driven under vacuum, and this technique made to reduce the void content inside the molded composites. With vacuum bag moulding, the bags are used to evacuate the air from laminate and to generate the atmospheric pressure required for compaction over the mold [7]. Infusion processes are plagued by limitations such as lower fibre volume fraction, lack of uniform resin distribution, higher porosity, control on thickness of part, clogging of resin and vacuum feed lines. CSIR-NAL has developed a proprietary infusion process called VERITy (Vacuum Enhanced Resin Infusion Technology), Kundan et al. (2013), to overcome the above limitations. The process is designed in such a way that it is scalable from a laminate level to a complex cocured primary structure like the wing of a transport aircraft. A schematic of the VERITy process is shown in Fig

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