By adopting a new approach KraussMaffei Reaction Process Machinery strives for a whole new level of performance in pultrusion, the continuous moulding process for the manufacture of high-filled fibre-reinforced plastic components.

A new efficient system solution lies at the heart of the development: the new iPul pultrusion machine. KraussMaffei will present the initial results at JEC World in Paris from March 14 to 16, 2017, using the example of select applications in the wind energy and construction industries. Partners for the projects include Covestro (polyurethane), Evonik and Huntsman (both epoxy), as well as Thomas GmbH + Co. Technik + Innovation KG (Thomas Technik).

Unique combination

The new pultrusion machines from KraussMaffei combine the direct injection of the matrix material and the radius pultrusion process in a unique way. “The direct injection of the matrix material using a metering machine and an injection chamber offers clear technical and economic advantages compared with the typical market practice where impregnation is generally effected by pulling the reinforcement through a bath”, states Josef Renkl, Head of Pultrusion Development at KraussMaffei.

The machine is more compact; the production speeds are higher. “To date the speeds are generally 0.5 to 1.5 m/minute. With the new KraussMaffei iPul machines we are aiming for decisively higher production speeds with more than 3 m/minute. This opens up completely new markets for pultrusion. In addition, the machines are able to manufacture not only straight but also curved profiles in the radius pultrusion process”, adds Renkl.

An important component of the new machine is the metering technology which has been optimised especially for the pultrusion process. It injects the matrix material directly and continuously into the injection chamber. This means the matrix systems can work with a higher reactivity, which in turn can be specifically coordinated to the property patterns of the end product. Another advantage: The current open resin bath where impregnation of the dry fibres must take place with the use of additional guide panels is omitted.

Furthermore, the injection chamber supports the higher speeds required in production and is much more flexible and precise. For instance, the injection points can be easily and individually set and adjusted specific to the product.

Following the injection chamber the impregnated fibres are pulled through a heated stationary die. The component is cured in several individually selectable heating zones to achieve the desired hardened state. A profile pulling unit transports the pultruded profile continuously through the machine at constant speed before it can be cut and assembled. All machine components can be operated centrally via a control system.

High flexibility and global service

Another advantage of the new iPul pultrusion machines is their flexibility. They are suitable for processing diverse matrix materials such as epoxy, polyurethane or in the future also polyamide 6. Fibres made from glass, carbon, basalt, or aramid are mainly used as reinforcement fibres.

It is also possible to directly work in additives such as mineral fillers, pigments or flame retardants. With the new iPul pultrusion machines both linear profiles with complex cross-sections, as well as 2D and 3D curved profiles, can be manufactured in the patented radius pultrusion process. KraussMaffei is working closely with Thomas Technik, the inventor of radius pultrusion and an experienced supplier of pultrusion machines, which complement the metering machines from KraussMaffei perfectly.