Fast parts breakthrough

Aerospace and automotive components, and even replacement hip joints, could be made in a fraction of the time and for half the cost using a technique developed by Rolls-Royce and Nottingham University.

Researchers at Rolls-Royce’s University Technology Centre (UTC) at Nottingham have developed a process called shaped metal deposition, which allows components to be built up from scratch using CAD images.

The technique, which has already been used by Rolls-Royce to produce parts for its Trent 800 engine, used in the Boeing 777, significantly reduces the cost of making parts, said Richard Harvey, Rolls-Royce’s manufacturing technology UTC co-ordinator. ‘It is great for rapid prototyping, or for one-off parts such as hip joints, and can also be used to build prototypes such as a new gearbox for a Formula One car, without the need to create moulds or castings,’ he said.

The technique uses metal deposition technology to make the part from scratch, starting from a base plate and building upwards, said Steven Jones, researcher atNottingham.

A CAD image of the component to be built is produced and processed by software, which divides the design into a number of grids and decides on the movements the robot will need to take to make the part. This information and the 3D design are sent through to a simulation system, which is pre-programmed with the robot’s capabilities. The robot, equipped with welding technology, then begins depositing metal on to the base plate in the desired shape. ‘A designer sends a CAD model to the engineer, the design is programmed into the software, which checks the route, and the system can start depositing metal straight away,’ said Jones.

The system can cut the time taken to build parts by up to 80 per cent, claimed Rolls-Royce. The research team recently built a large component for the Trent 800 engine, which would normally take seven months to complete using traditional casting methods, in just 40 days. As the process works at such a fine level, it also allows the properties of the materials to be manipulated more closely to meet individual needs, such as improved fatigue resistance, said Jones.

The robot can move on a range of axes depending on the complexity of the part, and as a result can produce shapes that would be virtually impossible using any other method, such as closed, hollow components. The system can be used with a range of materials such as titanium and nickel alloys, steel, and some aluminiums.

The technique uses existing Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW) processes to deposit the metal into the required shape, said Jones.

‘The team has cleverly modified off-the-shelf technology to meet the mechanical and physical material properties needed, and to produce a part at substantially reduced time and cost.’