Multiaxial reinforcement manufacturer Formax is tailoring lightweight materials to automotive needs
If you think of carbon fibre you more than likely envision the familiar woven sheet, but there is more to this high-tech, lightweight material – as a visit to multiaxial reinforcement manufacturer Formax reveals. Based in Leicestershire, UK, the company uses an intricate and highly technical process to produces sheets of what it calls 'multiaxial reinforcement'. These differ fundamentally from woven materials in the way they are produced.
The carbon fibre strands are arranged in parallel across a machine table, at a diagonal angle that varies according to the performance requirements of the finished material and its application. Each strand is positioned by a pin at either side of the table in an automated process, with these locators running the length of the table. The threads are fed from individual spools at one end of the machine, and the composition of the thread varies depending on the application.
Once a run of strands has been placed, a second layer is added at an opposing angle to the first. The layering process continues according to the application and performance requirements. When the final layer is in place, the material is stitched together to create a strong, highly flexible sheet. This method of production offers a highly drapable fabric which can be engineered to fit complex moulds. [sam_ad id=17 codes='true']
Formax develops and produces multiaxials for a wide range of industries and applications, including automotive, and managing director Oliver Wessely is keen to highlight the company’s ability to deliver relatively short runs. This very flexible approach to manufacturing, while serving customers well, presents some challenges for maintaining production flow. In particular, changeover from one specification to another is an extremely involved operation and can take several hours to complete. This results in a level of downtime that would would not be tolerated in high-volume automotive manufacturing, but in this high-tech field the need for flexibility is key – and something Formax prides itself on.
The company employs a variety of stitch-bonding, weaving, and laminating machines, from narrow width weaving looms through to 2.5 metre-wide multiaxials. The multiaxial machines are manufactured by Karl Mayer Malimo, and include 50" and 100" biaxials, 50" and 100" multiaxials, plus the latest generation of carbon cut-and-lay machines. Formax's woven UD fabrics are manufactured on re-engineered Dornier and F2001 weaving looms. However, the company does not simply buy off-the-shelf machines; a team of experienced engineers develops the machines by refitting them to improve efficiency and to accommodate new customer requirements.
Installed in a new 5,000 sq.m automotive facility at the company’s UK headquarters, the new cut-and-lay machine will be dedicated to the production of tailored Non Crimp Fabrics (NCFs) specifically optimised for high-volume automotive programmes.
The machine is equipped with three axes, capable of laying ply angles from 20° through to 90° with both in-line and off-line spreading technology, allowing engineers to specify larger, lower-cost, carbon fibre tows, with ply weights starting from just 50gsm. An additional feature of the machine is that it is equipped with electronic pattern cams. This allows the creation of fabric specific stitch patterns, which, together with Formax’s extensive research into simulating drape, provides the capability to tailor fabric for specific parts.
One recent client was Lamborghini, for which Formax developed a range of balanced materials combining drapeability and robust structural properties, and using an innovative method of binding the materials in a preform structure prior to injection. The resulting quadaxial structures, stitched with Formax’s "tacky-stitch” which is specifically designed for preform applications, were refined many times before the final, optimised version was used by Lamborghini to reinforce the chassis for its new carbon supercar, the Aventador.