AMRC furnace puts UK at forefront of titanium casting

Some of the biggest titanium aerospace components in the world can now be produced in the UK, thanks to the launch of a new castings facility.

The newly-operational furnace, at the University of Sheffield Advanced Manufacturing Research Centre, has three interchangeable crucibles with the capacity for melting 250kg, 500kg and 1000kg of metal.

AMRC Castings Titanium Caster, showing (top to bottom) the electrode delivery and power supply system, melting and casting chambers

This allows it to produce titanium components weighing between 60-500kg.

There are only a few furnaces in the world capable of producing titanium castings of up to 500kg, which requires a molten mass in excess of 1000kg, according to AMRC Castings research and development manager, Mark D’Souza-Mathew.

To produce complex, near-net shape components, the titanium is first melted and then poured into a mould representing the intended part.

But titanium is highly reactive when exposed to atmosphere, so the process must be carried out in a vacuum to prevent explosions, said D’Souza-Mathew.

“There are many safety and cost considerations when casting titanium, and it is for these reasons that foundries don’t tend to go above the 100kg poured mark,” he said.

The researchers are studying the risks and benefits of casting large-scale near-net shape components in titanium. They are also planning to improve the casting process by reducing the amount of material wasted, said D’Souza-Mathew.

“When you cast titanium it’s so reactive that even under vacuum it reacts with the mould, so you have a 300 micron interaction layer that develops all over the surface, which is essentially unusable,” he said.

The researchers hope to reduce the size of this interaction layer by up to one third, using a previously developed technique.

Casting titanium produces near-net shape components, which in itself reducing wastage considerably when compared to traditional forging techniques. The so-called buy-to-fly ratio, or the amount of purchased material that is eventually used in the finished component, can be improved from 5:1 with forging down to 1.5:1 using casting, he said.

The technology can also produce improved material properties, such as the use of enhanced cooling to better control the material microstructure.

The new furnace is being supported by the UK’s Aerospace Technology Institute; Innovate UK; and the High Value Manufacturing Catapult. It will be available for industrial access by summer 2017.

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