Advanced Composites Group (ACG), a member of the Composites Division of Umeco plc, and GrafTech International Ltd, one of the world's largest manufacturers of graphite and carbon-based products, have strengthened their partnership with the aim of providing a strong alliance that will see the proliferation of composite tooling technology into exciting new areas.

After nearly two years' research and development at ACG's Technology Centre, the processing and performance requirements of ACG GRAFOAM FPA-20 Carbon Foam Tooling System have now been fully characterised. It is now hoped that the carbon foam product, combined with associated novel technologies, will enable exciting new concepts in low CTE, low mass composite tooling.

ACG GRAFOAM® FPA-20 Carbon Foam Tooling System not only exhibits an extremely low CTE (2.3 x 10-6/°C), but it also has a thermal resistance that exceeds composite processing requirements.

Furthermore, it can be rapidly machined to near-finished size and then fully encapsulated in ACG's proprietary, patented, compliant interface technology and a tooling laminate skin, typically ACG's Low Temperature Moulding (LTM®). However, the inherent thermal qualities of the carbon foam also allow the application of higher temperature resin systems from ACG's medium (MTM®) and high (HTM®) temperature tooling laminate ranges.

Once cured, the final tool profile is created with a second machining operation, overcoming many of the problems encountered with the usual master model approach, such as shrinkage, spring-in/spring- out, and pattern/laminate CTE mismatch. Any further tooling modifications can be achieved with additional local lamination and subsequent re-machining.

Tools manufactured from ACG GRAFOAM® FPA-20 Carbon Foam Tooling System are fully self- supporting, and are suitable for traditional and emerging composite process methods, particularly tape placement and filament winding, where low weight is a major benefit when manipulating extremely large tools, the latter of which is a major issue with Invar or other metallic tooling.

Large development tools, manufactured at ACG's facilities for a major aircraft manufacturer in North America, have achieved dimensional accuracy of 0.2mm on particularly complex surface profiles, but with the vast majority falling within +/-0.1mm.

The high thermal resistance of the ACG GRAFOAM® FPA-20 Carbon Foam Tooling System offers significant advantages and cost savings when manufacturing high temperature (BMI) tooling. With no requirement for a master model, ACG BMI prepreg can be cured directly onto the foam core in a single operation, without the need for a heat-resistant intermediate splash tool, and then machined to the requisite final profile.

GRAFOAM is a registered trademark of GrafTech International Holdings Inc.