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Jäger - Vacuum infusion of a rotor blade in detail

JÄGER relies on vacuum infusion for large-area fiber composite components

Vacuum infusion offers manufacturers from the wind power, automotive, aviation and many other sectors a manufacturing process that is particularly well suited for small series or manufactures, but also for very large-area components. JÄGER has various specialists for fiber composites in its partner network and has already successfully completed several projects. This is
in line with the trend towards ever larger components as well as the expansion of the manufacturing processes used for this purpose.

An alternative to injection molding
Injection molding processes are ideal for large-scale production of plastic components. Once the mold has paid for itself, the unit costs are relatively low. However, this manufacturing technique is often unprofitable for small batches, since mold construction often represents a disproportionately high share of the manufacturing costs for small quantities. Fiber composites, which are usually manufactured by vacuum infusion, offer an alternative for large-area parts.

How does the process work?
Injection molding and vacuum infusion processes are based on different principles. In injection molding, the liquid material is pressed into the mold under high pressure, while vacuum infusion sucks the material in by negative pressure. In practice, a laminate mold, which determines the subsequent shape of the component, is first coated with a layer of gelcoat. Precisely cut fiber mats are then inserted into the contours of the mold, forming the core of the composite. The composition of these mats depends on the application. Most common are glass and carbon fibers, but aramid fibers (e.g. Kevlar) or various mineral (basalt) or vegetable (jute, flax, cotton) fibers can also be used. For infusion, infusion tubes are placed at predefined locations and the mold is sealed all around with a film.

As soon as the preparation is complete, the air is sucked out from under the foil so that a vacuum is created. Liquid resin is now fed into the mold via the hoses, which is “pulled” into all corners and free spaces by the vacuum. The compound is therefore not actively pressed into the mold, but is pushed into the evacuated mold by the ambient pressure. To ensure that no dry spots remain, a little more resin is pumped in than necessary. The excess material is collected and recycled if possible. The resin mixture then cures under vacuum and combines with the fiber mats to form a fiber-reinforced material.

Jäger - Vacuum infusion of a rotor blade in detail    Jäger - Vacuum infusion of a rotor blade in detail

Outlook
Vacuum infusion is a common process for the production of fiber composite components. It is particularly suitable for small series or manufactures, as the investment costs for molds and tools are comparatively low and the properties of the material can be tailored to the individual application. Even very large-area components are no problem. However, this manufacturing approach is less suitable for large-scale production because it involves a high number of manual work steps. The automation potential is therefore limited and scales poorly for large series. For small batches, however, vacuum infusion is very well suited. The process should always be considered for appropriate projects.

You can read the entire article on the vacuum infusion process in the JÄGER Business Blog:

https://www.jaegergroup.com/en/blog/vakuuminfusion-fuer-grossflaechig-faserverbundbauteile-eine-alternative-zum-spritzguss.

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