Light and stable

09 / 2012 - The aeronautics is just one of the industries where weight reduction is a central focus today due to the constantly increasing pressure to save fuel. With the goal of making aircraft lighter, manufacturers have been making more and more use of carbon fibre-reinforced plastics (CFRPs) in recent years.  For example, the fuselage of the new Airbus A350 XWB is made entirely of CFRP composites.
The outer skin is connected to the frame assemblies and stringers by means of “clips”. Traditionally made of aluminium, the clips for this project are made of CFRP composite sheet. The fully automated production system, including the tools for manufacturing the complex structurally loaded CFRP components, was developed by FRIMO and delivered to the customer Premium Aerotec.
The “self-stabilizing” clips are basically flat elements with different geometries made of three surfaces oriented at right angles to each other which join the outer skin, frame assemblies and stringers to one another.
Composite sheets made of carbon fibre mat with a thermoplastic matrix serve as the starting material. Depending on the load requirements, manufacturers use semi-finished products with different numbers of layers and either polyphenylene sulphide (PPS) or polyether ether ketone (PEEK) as matrix materials.
Pre-milled sections of the semi-finished product are laid into a tenter frame with a special folding mechanism and laid into an infrared heater by a robot. Following the required heating time at the corresponding temperature, depending on the matrix material and number of layers, the pre-form must be moved from the oven to the press. This complex task, whereby the robot lays the heated section, already folded with the tenter frame, into the press for final consolidation within 5 seconds, was a major challenge.
Due to the large variety of clip geometries, more than 1600 tools were were constructed and built, which are changed by means of a fully automated tool changing system. This tool changing function is integrated into the customer’s PDA, so that the machine parameters are adjusted accordingly, together with a plausibility check.  
It was important to Premium Aerotec that FRIMO could supply the complete tenter frame technology, robot, press and all tools and tool changing with clearly defined interfaces, all from a single source. The system from FRIMO can produce thousands of clips with different geometries with extremely short cycle times, and without folds or pores, while guaranteeing the highest levels of quality and reproducibility.

Contact for further information and documentation

FRIMO Group GmbH
Martina Schierholt
Hansaring 6
D-49504 Lotte

Phone.: +49 (0) 54 04 / 8 86 - 1 57
Fax: +49 (0) 54 04 / 8 86 - 51 57
E-Mail: schierholt.m[at]frimo.com