High Temperature Superalloy Prototype Castings Substitute for Forgings

Honeywell Hymatic design and manufacture precision engineered systems and equipment for the aerospace, defence and industrial markets. Honeywell Hymatic is at the forefront of the development and implementation of pneumatic and hydraulic technology solutions for these key industries.

One of their products – a high temperature air control valve – was developed for use during the testing phase of an aero engine for the Airbus A380. The valve is part of the gas control circulation system on the aero engine. Honeywell Hymatic wanted to investigate producing a casting rather than a costly forging.

When Honeywell Hymatic approached Cti, the valve was still in the early stages of development. This gave the opportunity for the two companies to work closely together utilising Cti’s expertise to optimise Honeywell Hymatic’s design for casting. To aid the casting process, features on the valve were modified using the latest Catia V5 software.

Once the design had been finalised, a computer casting simulation was carried out on the parts to predict how the molten metal would fill and solidify. The results of the simulation were used to assist in the design of the production method for the casting – ensuring that the parts were rightfirst- time with no casting related defects. When the overall casting design was complete, a prototype was made within nine days by Cti’s in-house rapid prototyping facilities.

Jamie Preece, the Engineer who is responsible for developing the valve explains, “The valve is an extremely high profile project for Honeywell Hymatic; it is a brand new product, meaning we have a completely blank sheet of paper to work from. The valve is one the largest of its type that we have developed; our standard manufacturing methods have been challenged further than usual by this valve, especially when discussing overall lead-times. This led us to investigating the casting route. When we saw the excellent prototypes so soon, we were confident that we made the right choice.”

The material used for the valve needed to be stable at temperatures of around 500°C for long periods and, because of this, the obvious candidate was a nickel-based alloy. This alloy requires vacuum melting conditions, which is where Cti’s facilities come to the fore again. The commercial scale vacuum melting system housed at Cti’s Sheffield headquarters can melt titanium, superalloys and other reactive alloys, and has been used for applications in industries as diverse as aerospace and Formula 1.

The parts were cast in production grade material to ensure a comparison to the production parts. These castings were used to prove everything from the casting process to product suitability and even gave the Honeywell Hymatic machining programmers an opportunity to prepare before any production parts were made. Jamie Preece commented, “The two castings exceeded our expectations, we believe we have saved time and money by using Cti’s near-netshape prototypes”.

The successful development of the valve resulted in Honeywell Hymatic being awarded a contract to produce 30 castings. Despite the stringent timescale placed on the project by the aero engine development team, the time saved by Honeywell Hymatic through collaborating with Cti ensured that the castings were delivered ahead of schedule. In addition, it rapidly became clear that the savings in terms of material usage and machining time meant that the chosen production route offered significant advantages over the alternatives. Having proved the capabilities of rapid prototyping technologies in the development of a cast component, the techniques will undoubtedly see greater use in the foundry industry in the future.

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