Where chemistry meets component

A new, automated cure tracking tool from Hexion is set to increase efficiency and quality in composite processing. Mike Richardson travelled to the company’s Segensworth, Hants-based headquarters to find out more. Offer any manufacturing company the chance to own an ‘all singing, all dancing’ piece of equipment that makes composite components at the press of a button, and I’d imagine most of them would bite your arm off for the chance. And yet this is exactly what the Hexion business unit, Combined Composite Technologies (CCT) seems to have achieved with the launch of a programmable logic-controlled (PLC), automated resin curing and moulding system. The Optibox* tool is a self-contained system which utilises closely tracked data on resin filling and curing to optimise resin processing cycles for greater productivity and better quality laminates in composites manufacturing. In a typical composite manufacturing process, once a resin infusion tool is closed, there’s no way of monitoring what is actually happening inside. Processing steps are arbitrarily timed according to the resin manufacturer’s suggestions even though, in actual practice, the optimal timing of these steps can vary. What the Optibox tool system does is allow composite manufacturers to automatically track and adjust each step’s timing and heating precisely and trigger the next step as soon as the composite is ready. This responsive technology can improve efficiency through faster cure cycles and help reduce product flaws in preforms, prepreg moulding, and resin infusion processes, including vacuum-assisted resin transfer moulding (VARTM). The Optibox tool system is a portable, self-heating, single- or double-sided, mould tool with a LCD readout. Interchangeable upper tool configurations enable flexible, rigid, heated and multi-cavity functionality. Once loaded with fibre reinforcement, the Optibox tool enables cycle time optimisation by tracking resin filling and curing through a variety of sensors, logging the data for quality assurance. Variables monitored include resin flow, temperature profile up to twenty zones, the extent of mould-filling, gelation, vacuum level, and degree of cure. Multi-zone heat controls respond to sensor feedback, promoting optimised curing to achieve desired part tolerances and finish. The fully programmable cure cycles combined with integrated pre-set or selectable vacuum settings afford the user complete process control. “The Optibox tool system is where chemistry meets component,” begins Hexion Combined Composite Technologies’ managing director, Paul Collier. “As we start to characterise the many prepreg resin systems, we acquire a lot more understanding in this area. It allows us to create a database of what actually happens to the material and what it looks like when it’s inside the tool system. “The Optibox tool is aimed at companies manufacturing large volumes of preforms, educational establishments that can use it to see what happens when process variables are changed and the effects on material properties, and smaller companies looking to avoid huge financial outlays for large ovens or different sets of tools, yet still want the advantages of a PLC and continuous production.” In terms of component size and extending the Optibox tool’s appeal to the largest group of potential users possible, Hexion CCT needed to establish the average size of the parts being produced in prepreg, preform or in this case, resin infusion. “Yes, there are physical limits to the size of part that the Optibox tool can manufacture, but our focus is more concerned with its monitoring and sensing capabilities; everything else inside the tool is expandable,” Collier explains. “This is the result of what we’ve been looking for over the years as we migrate from heated tools. If we can build something that allows us to measure everything, what else can it do? If we can measure it, we can control it and if we can control it then we can ultimately manufacture parts more efficiently. If we achieve all this, the manufacturing process will become more repeatable and the skill levels required won’t need to be as high. “One of the novel things about the Optibox tool is in its ability to measure the viscosity of resin infusion. As infusion takes place, the resin starts to thicken. If it becomes too viscous, the user simply increases the heat to make the resin run again. Once a gel point has been reached, the user applies the vacuum system. We’ve removed much of the guesswork of traditional processes.” Clearly the Optibox tool system is a pretty cool invention, but what does the rest of the world think? Collier adds that at last year’s JEC Europe Paris show and the Advanced Engineering UK show in Birmingham, The Optibox tool was well-received and it appears to be filling a niche in the marketplace. “As increasingly more people try and understand what composites are all about and how they can actually get the most out of it, the Optibox tool is one way of ensuring that at least the cure cycle, the ejection cycle and everything else that has to do with cure is measurably constant,” adds Collier. As part of a commitment to its skills development programme, Hexion CCT has opened a training centre in partnership with Consuta Training’s Chris Little to develop and deliver training courses. The Optibox tool enables groups of students attending Hexion CCT’s training centre to actually ‘make’ something as opposed to just learning about the theory from books. “The Optibox tool has been specifically designed to reduce the amount of equipment required to actually undertake the process,” states company sales manager, Rob Collinson. “There’s no real difficulty in laying up the component in the mould tool, closing the lid and pressing the button. Users can monitor the entire process: the amount of infusion, where the resin is going and what the temperature is at a certain stage of production. Everything is fully-automated and designed to be quick and easy for use.” Collinson believes that the Optibox tool is not restricted in its size; the only restriction is in the users’ imagination and what they perceive the process can be used for. “The Optibox tool is the culmination of the knowledge our company has gained over the last three years and how it can benefit the end user,” he concludes. “For example, users may require a stable and repeatable process, reduced lead-times, constant component quality and avoid the necessity of employing fully-skilled operators to use it. Take all of these things into consideration and the Optibox tool system offers the end user exactly what they are looking for, all at the push of a button.” *Footnote: The Optibox tooling system is a trademark of Combined Composite Technologies. www.hexion.com