With global sales in excess of $30 billion, net shape (NS) and additive manufacturing (AM) of metal powders are the fastest growing metalforming technologies. But in order for the UK’s high value manufacturing sector to realise the benefits of NSAM processes, effort is required to translate the research being conducted in the country’s university network into robust, mature manufacturing processes that are ready for commercial exploitation.

To address this, the National Centre for Net Shape and Additive Manufacturing (NCNSAM) has been established at the Manufacturing Technology Centre (MTC) in Coventry. Backed by initial funding from the Aerospace Technology Institute and Innovate UK, it will attempt to bridge the gap between market requirements and process reality.

More specifically, the centre will enable potential end users, supply chain companies or equipment providers to assess and develop the end-to-end capability of NSAM processes, from design and powder processing to fully inspected, high integrity components and their post-processing. Areas within the facility include powder atomisation, powder characterisation, EBM (electron beam melting) and laser melting AM, NDE (non-destructive evaluation), isostatic pressing and powder recycling. The latter is vital as powder represents up to 33% of product costs. Titanium powder for EBM, for example, costs circa €160/kg, and is even more expensive in the case of laser melting.

EQUIPMENT ROLL-CALL
Within the EBM area, the equipment roll-call sees machines from Arcam CAD to Metal (01926 491 300) well represented. As well as three A2XX models – the largest standard EBM machine available from Arcam – an A2WT (wide and tall) model, commissioned specially by the MTC, can also be found within. This features a build chamber of 350 mm diameter by 380 mm high and can accommodate up to 200 kg of Ti64 powder.

Also in the EBM area is the latest Arcam Q20, which is purpose-designed for aerospace parts such as turbine blades and structural airframe components. It supports the production of large components, as well as the stacking of smaller ones. It includes LayerQam, Arcam’s camera-based melt pool (see also p25) monitoring system for inline part quality verification, and a powder recovery system for closed-loop powder handling.

Indeed, size appears to be a rapidly disappearing limiting factor of AM, particularly in light of the fact that engineers from the MTC recently played a key role in producing the largest ever civil aero engine part made using EB-based AM. The component – an aero engine front bearing housing the size of a tractor wheel – has been produced by Rolls-Royce. What’s more, it has already been ground-tested on the Trent XWB-97 engine, which will power the in-development Airbus A350-1000. The part will take to the skies later this year, when Rolls-Royce tests an XWB-97 engine on its Boeing 747 flying test bed.

Engineers from Rolls-Royce at Derby worked closely with AM specialists from the MTC and the University of Sheffield, as well as machinery supplier Arcam. The 1.5 m diameter Ti64 part contains 48 aerofoils that were also produced by AM. Rolls-Royce has been using AM to repair components for more than five years and is now using its expertise to build bigger and more complex component parts.

Explains the MTC’s chief executive, Dr Clive Hickman: “The project has been a key step in proving the industrial viability of the process, shortening manufacturing lead-times in this application by more than 30%, compared with developing components of this type using conventional manufacturing methods.”

Next door to the EBM machines at the National Centre for Net Shape and Additive Manufacturing is the laser melting area. Here, an Eosint M280 from EOS (01926 623107) sits side-by-side with an AM250 from Renishaw (01453 524524). According to the MTC, both laser melting and EBM have advantages and disadvantages. While laser melting offers superior surface finish and a wider selection of materials, there are some in-built stresses, while deposition rates are typically slower. Conversely, EBM offers higher deposition rates, thanks to its higher power and ability to better articulate the beam. The caveat, however, is poorer surface finish.

The laser melting area also hosts the latest version of a hybrid manufacturing system (offering both additive and conventional subtractive processes) that was first developed as part of a four-year UK-based research project named RECLAIM (REmanufacture of high value products using a Combined LAser cladding, Inspection and Machining system). The latest machine is based on a 5-axis vertical milling machine fitted with the AMBIT multi-task system developed by Hybrid Manufacturing Technologies (www.hybridmanutech.com), a company that spun out from the project.

AMBIT is a patent-pending series of heads and docking systems that allows virtually any CNC machine (or robotic platform) to use non-traditional processing heads in the spindle. Changing from adding metal to cutting simply requires an automated tool change (as the laser cladding head fits into the toolchanger). The HMT system is coupled to a fibre laser and powder feeder system that is capable of delivering four different materials to the cladding head, allowing a wide range of metals to be deposited in graded compositions (see also ‘Adding and subtracting,’ Machinery June p14-16).

The MTC’s chief technologist, David Wimpenny, an acknowledged expert in the field of additive manufacture, says: “AM is clearly giving designers unrivalled freedom, unlocking their creativity and fostering a new generation of entrepreneurs able to explore new market opportunities without the high barriers to entry associated with conventional manufacturing. Moreover, it is possible to make a single part composed of several materials, each printed precisely where required to give the desired properties. This ability to design the material at the same time as designing the shape is a unique characteristic of AM, which will keep the best material scientists in the UK busy for decades to come.

“Ultimately, it’s no exaggeration to say that almost every field of human endeavour, from how we travel, what we make and use in everyday life, to what we eat and how we treat injury or illness, is likely to be touched by this technology,” he continues. “The strength and integrity of components and products made by AM often exceeds that of conventionally produced parts. Complex shapes and structures can be made with no joints or weaknesses. Imagine a bicycle made as a single structure with no welds or brazed joints – just a seamless tubular structure.”

Opened officially by Anna Soubry MP, Minister for Small Business, Industry and Enterprise, it’s clear that the new National Centre for Net Shape and Additive Manufacturing has a big role to play in ensuring that UK manufacturing industry benefits from these latest technologies.

Centre facts in brief
- The NCNSAM’s priorities include fast tracking innovative process development, powder production, part design, inspection and validation, materials research and the establishment of robust, cost-effective production processes.
- The NCNSAM was funded jointly by the Aerospace Technology Institute and Innovate UK, drawing on the £60 million of government and industry funding announced in January 2014 for the development of new aerospace technology at the MTC. This figure is part of a £2 billion joint government and industry package to be invested in aerospace research and development over seven years.
- The NCNSAM currently employs 30 highly skilled engineers; that will increase to 50 by the end of 2016.