New aerospace casting milestone for UK’s sole titanium caster

Castings Technology (Cti) has reached a new milestone by producing the first large-scale, centrifugally-manufactured, high-integrity component.

The UK-based specialist – a supplier of difficult to- source, low volume castings to the high value manufacturing sector – used its considerable expertise to produce a demonstration inter casing by pouring 250kg of molten titanium into moulds rotating at 200 rpm.

The 600mm diameter, near net shape casting is similar to those used in engines powering large turboprop aircraft and short-haul commercial jets.

Cti’s success builds on its previous experience of making safety-critical, centrifugally-cast titanium components and is a major step towards its goal of making the largest centrifugally cast titanium aerospace components in Europe.

Cti Manager Director Richard Cook and Technology Development Manager Will Jeffs showcased the company’s capabilities for ‘supersize’ shell casting to a global audience at the 65th Annual Technical Conference and Expo in Kansas City, USA, hosted by the Investment Casting Institute.

Attendees at the yearly event benefit from presentations covering all aspects of the investment casting process and it is there where Will presented his paper ‘Supersize My Shell’ on a system designed to be able to manufacture a shell envelope of 6ft 6ins in diameter and 8ft 2ins long with a maximum shell weight of 5,510lbs.

Cti’s expertise already includes making the largest ceramic shells in Europe using proprietary technology that enables it to create greener, cleaner near net shape castings with improved surface and micro structural properties.

Unlike other ceramics, the material Cti uses to make shells does not need heating to withstand the thermal shock when the molten titanium is poured in under the high g-forces produced by spinning the moulds. That radically reduces the thickness of the alpha case – a hard and brittle, oxygen-enriched surface layer that forms on titanium castings.

As a result, large castings made using Cti’s process are near net shape, require less finishing and avoid having to make over-sized castings which need significant chemical milling using highly corrosive materials that are difficult to dispose of safely.

Furthermore, unlike Cti’s materials, other ceramics have a density close to that of titanium, which makes defects difficult to detect using x-rays.

Cti MD, Richard Cook, said it was a major step forward for Cti’s expertise and for the capability of the European aerospace sector.

“Aero engine companies are understandably protective of their Intellectual Property, which is why we could only make an illustrative part.

“However, those who have seen it have been impressed by the complexity, the as-cast surface finish, internal quality and improved mechanical properties we have achieved, as well as the reduced ‘buy-to-fly’ ratio offered by our processes.

“We will now be scaling up the size of centrifugally cast aerospace components we can make, so that we can take full advantage of the capacity of the 1200kg titanium caster at our site on the Advanced Manufacturing Park.”