Addev Materials’ aerospace & defence projects director, Jim Rowbotham discusses the company’s distribution partnership with Solvay for the production of tool and mould products.
Addev Materials is the official distributor of the Solvay range of composite materials. This comprises a range of prepregs in carbon and glass fibre, as well as aramid, nylon, polyester, etc. Solvay also produces film adhesives, sealants and compounds required for related processes.
Up to now, we’ve been focusing on composites used to produce strong, lightweight structures for aerospace, defence, industrial and automotive components. The next phase of our development sees us introducing similar prepreg materials used in making tools and moulds.
Material selection is similar to that used for product manufacture, with various metals and composites used for tool production. Selection is based on cure temperature, the material that components will be made from, their size and the number of impressions made. We will be concentrating on carbon and glass fibre prepreg with Solvay’s low temperature cure resin LTM350 and for specific aerospace applications, bismaleimide (BMI) resin Duratool DT450. These BMI materials are selected for higher temperature applications with curing up to 6 hours at 440°C. The life expectancy of this type of tool is extremely long and suitable for the lifecycle of aerospace projects.
Our partnership means that customers can access Solvay’s range of materials, avoiding non-approved supply chains - and still obtain a flexible service, including cutting material to size and kitting with other products.
Our West Yorkshire composites centre has >260m3 of freezer capacity for composites stored at -20°C, a cutting room for resizing rolls of prepreg and film adhesive, and in Q2 this year we will be installing a new flatbed cutting machine which will allow us to create design files of customers’ patterns, nest them for maximum efficiency and cut to any shape and size up to a width of 1.6m. Although the main demand will come for kits of prepreg to make components, we also expect to cut tooling materials to size. We have AS9100/9120 approval at this location and we’re members of aerospace trade associations and Composites UK, which is a great resource for us.
We have a dedicated technical sales manager for our composites business and a range of additional products, such as adhesives, sealants, coatings and surface treatments that complement our composites range to differentiate us from competitors.
Carbon composite tools are made by forming multiple plies of prepreg around a master model, which is a full-size equivalent to the component made of aluminium or epoxy syntactic block. The first ply applied to the master model is a surface ply of LTM prepreg in a 2x2 twill weave with a weight around 220gsm. This forms the surface layer of the tool and provides the side which the components will emerge from. A neat job is required with tidy overlaps, balanced layups and good fibre orientation.
Traditionally, we would then apply eight plies of a heavier weight prepreg (around 650gsm) and then a final light ply of the same 220gsm material. This is referred to as a 1-8-1 system based on the number of plies. Our new system is based on a heavier 995gsm ply for the middle section and is referred to as a 1-5-1 system, as we can dispense with three of the eight plies while still achieving the same result. This reduces the labour time applied to the tool and the elapsed time, as there are numerous additional processes involved in applying each ply. The layup will then be cured in an autoclave between 60-130°C, depending on process requirements. Such a tool can be used repeatedly up to 220°C and should produce well over 1,000 impressions if maintained correctly.
To offer both ply options, we’re stocking the LTM350 in all three weights and will cut the material to size for customers in the exact format they need. By concentrating on LTM350, we hope to keep a good stock and eliminate supply chain issues, which are exacerbated by using different materials. We also supply mould release materials and stock Tedlar PVF release film which we can cut to size to match the tool.