JEC COMPOSITES MAGAZINE - Issue #39 - March/April 2008 - 108

KNOW-HOW Composite Tooling Conclusive preliminary test for HexTOOL® Producing quality tooling while keeping costs under control is a major challenge that must be addressed if one is to keep up with the demand for carbon-based parts, especially in the civil aviation industry. This article provides an important return on experience about the use of HexTOOL® in composite tooling. More information LOÏC ALIRAND PRODUCT MANAGER HEXTOOL®, HEXCEL T he project presented below involves the design and fabrication of composite moulds for manufacturing fuselage panels for the future Airbus A350 XWB. One of the moulds to be made is four metres wide by five metres long; the other is four metres wide by eight metres long. Among other things, the specifications indicate a surface tolerance of ± 0.5 mm, a surface roughness of Ra<0.8, tightness of < 10-4 atm.cm3/sec and polymerizability in autoclave (7bar/190°C). CNIM is a group with turnover of €522 million, facilities in 21 countries and 2,789 employees. It works in crucial industries like energy, the environment and mechanics (defence and transport sectors), with activities that cover the entire product life cycle, from R&D to engineering, manufacturing, installation, operation and after-sales services. CNIM is a prime contractor for complex systems and a developer of materials and technologies; its overall objective is to become a major partner in aircraft structure production. It proposes technologies like filament winding, lay-up and automatic fibre placement, liquid resin infusion, automatic stringer forming machines (ASFM) and composite tooling. tooling was chosen for the master mould, with lay-up of the HexTOOL® over an infused epoxy skin (Figure 1). The mould was autoclave cured at 190°C under a pressure of 7 bar, then post-cured in an oven to complete the fabrication cycle for the rough mould (Figure 2). At this stage, the mould is ready for machining and its operating temperature is 218°C (maximum Tg, 250°C). Machining was done on a 5-axis machine. Following a trial and error period to determine the right setting parameters and tools, the mould machining and finishing operation progressed without any major problems. Achieving the right final surface finish is an important aspect and a determining Modifiable geometry After examining all the technologies likely to meet the specifications, CNIM chose HexTOOL®. A crucial factor in the technological choice was the compromise between the time constraint and the need to adapt to potential changes in mould definition. One of HexTOOL® material’s major characteristics is that it can be machined without losing its quasi-isotropic structure in the end part, meaning that its geometry can be modified over time. CNIM validated its technological choice on two demonstrators (lay-up on a real section, helium tightness test and definition of machining parameters) before starting the fabrication process. Machined Fig.1: Mould in preparation Fig.2: Rough surface mould after curing JEC Composites Magazine / No39 March - April 2008

JEC COMPOSITES MAGAZINE - Issue #39 - March/April 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #39 - March/April 2008