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Vitec and Composite Integration Develop High Volume RTM Process

For its new lightweight, fast-deployment Flowtech camera tripod, Vitec Production Solutions Division worked with Composite Integration to develop a manufacturing process for the tubular carbon fibre legs.

The structure consists of accurately moulded composite tubes which allow rapid telescopic deployment and include a unique internal brake system. The manufacturing process needed to produce consistently moulded tubes in varying sizes with a fine cosmetic carbon finish on the outside and a relatively complex cross section. The challenging geometry coupled with the high production numbers demanded meant that the conventional manufacturing processes (such as pultrusion or filament winding) were not applicable.

After much research Vitec carried out small-scale tests with Composite Integration that indicated that resin transfer moulding (RTM) was a possible route and then carried out extensive trials in-house to mould parts to assist in the development of the manufacturing process and to support the development of the Flowtech tripod. Scaling-up these lab-scale trials to achieve consistent high-volume production would be a huge step. With automation as the main focus, Vitec worked with a number of suppliers to integrate the entire system and to specify and install the necessary robotic systems to operate the work-cell.

Composite Integration helped with the design of machined metal moulds which would be fitted into hydraulic clamping presses. The moulds are heated and use removable inner steel mandrels which form the internal surfaces and are removed automatically once the moulded component is demoulded from the outer mould.

Vitec integrated a radial maypole braider to automatically deposit triaxial carbon fibre onto the mandrel with the handling and positioning being entirely robotically controlled.

Composite Integration was tasked with building the injection and vacuum equipment that would automatically inject the snap-cure epoxy resin system.

The machine is required to inject and mix the resin and hardener at a precise mix ratio and at relatively high pressure. The three component machine is also designed to introduce precise levels of internal release agent (IMR) at the mix-head. The resin and hardener are accurately temperature controlled and continuously agitated. The Ciject Two based machine then routes the mixed resin into the correct mould cavity via an injection valve and maintains a precise dwell pressure at the end of each cycle before automatically flushing and preparing for the next cycle. The mould cavity is evacuated down to a precise level before each cycle to achieve optimum laminate quality. The entire process is controlled by the on-board PLC and data (pressures, temperatures, material quantities etc) is monitored and recorded.

The end result of this development is a highly automated manufacturing process with a cycle time for each moulding of 2 minutes with a current annual production rate of 90,000 components per year.

Industries: Automation, Consumer Goods

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