We use vacuum infusion for the majority of our composite production. Although the Vacuum Infusion Process (“VIP”) is one of many closed mould processes, it is the only process that solely utilizes atmospheric pressure to push the resin into the mould. The mould is usually one-sided, with bagging film being utilized for the counter side. The process is highly controllable, as the resin flow is affected only by the viscosity of the resin, permeability of laminate and pressure differential.
VIP has the environmental advantage of lower VOC emissions as the resin is cured in a closed environment. It allows for an excellent glass-to-resin ratio and the superior application of core materials, with minimal to no voids in the finished laminate leading to one of the strongest composite laminates available.
Standard composite tooling can be utilized for VIP as long as it will hold a vacuum and the flange is wide enough to seal the bag, meaning lower investment in tooling compared to other closed mould processes.
3D VACUUM INFUSION
3D Vacuum infusion is a cost effective technology solution, which enables the merger of two independent elements in one piece. The base laminate structure can be reinforced with core foam 3D shapes, bulkheads, stringers or beams, thereby creating an even stronger overall structure.
This not only allows for simplified production, but also very high strength-to-weight ratios without the need for additional reinforcement bondings.
Light Resin Transfer Moulding, or Light RTM, is a process by which composite products are manufactured using a closed mould system consisting of two halves: a base mould and counter mould, which are sealed using vacuum pressure. Resin is drawn into the mould via a vacuum-assisted injection pump, which also draws the air out of the mould. Once the part is cured, the counter mould is removed and the part is demoulded.
Light RTM is a very versatile manufacturing process offering many advantages such as high productivity count, class-A surfaces on both sides of the part, enhanced dimensional stability, improved process control and a better work environment (almost completely eliminates VOC emissions).
Reusable Bag Moulding is often described as a hybrid process that borrows desirable features from both LRTM and VIP. Reusable Bag Moulding is especially useful in applications where part geometry is complex, with high glass-to-resin ratios required, and where parts are made in a medium to large series.
Silicone Bag Moulding (SBM) is similar to VIP, as it also relies solely on vacuum pressure. However, it is a more efficient process for serial production as silicone bags (if cared for properly) can be reused for hundred’s of cycles, meaning that unlike VIP, with SBM there are very few disposables. SBM also allows for the elimination of virtually all VOC emissions.
PRE-PREGS AND AUTOCLAVE
Complex parts with high structural and optical properties can be achieved via the use of pre-impregnated composite fibers, usually with epoxy resin (“pre-pregs”), cured in an autoclave. All pre-pregs are cut to dimension, moulded and bagged in a clean room lamination area to ensure quality.
After lay-up in the mould, the pre-pregs are vacuumed and hardened in a controlled manner under heated high pressure in a digitally controlled autoclave. This enables the effective and reliable production of complicated and mechanically resilient parts.
Elan is currently in the procurement phase of acquiring a complete autoclave system.