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Product category: Machinery and Production Equipment
News Release from: StarragHeckert UK | Subject: Hermle C800U five-axis machining centre
Edited by the Engineeringtalk Editorial Team on 29 June 2000

TWR turns to Traub-Heckert for machining
centre

To produce the key components for such finely tuned power units calls for quality engineered machine tools and here, TWR has installed a Hermle C800U five-axis machining centre

Since its formation in 1976 by Tom Walkinshaw, TWR has designed some of the world's most outstanding performance cars, such as the futuristic-looking Jaguar XJ220, the stunning Aston Martin DB7, the Volvo C70 Coupe and the Arrows Formula One Grand Prix racing car Powering these and many more TWR-designed road and race cars are engines manufactured by TWR Engines at its Kidlington plant near Oxford

To produce the key components for such finely tuned power units calls for quality engineered machine tools and here, the company has installed a Hermle C800U five-axis machining centre supplied by Traub-Heckert UK of Brackley, Northamptonshire, which is used principally to precision machine cylinder heads for the Arrows F1 cars and Volvo BTCC cars.

The Kidlington machine shop of TRW was originally set up in 1990 to produce components for the Jaguar XJ220 but has been re-structured over the past five years to allow previously sub-contracted work to be brought in-house.

This has meant buying more, but smaller and more flexible machine tools that now include 12 CNC milling machines and lathes and three co-ordinate measuring machines, manned by a staff of 16.

These machines now produce some 80 per cent of the company's machine shop output valued at around ?4 million.

Apart from the cost savings and quality improvements from the latest technology machines, bringing the work in-house also protects the confidentiality of TWR's designs for its partners and sponsors, an area that is vitally important on cylinder heads.

Around 100 cylinder heads for the Arrows F1 engines are required each year and feature compound angle valve guides and seats, for which five-axis milling and drilling is the most viable method.

The component also demands a machine capable of high precision and to produce the heads against a short lead time.

Simon Lockwood, Manufacturing Manager at Kidlington, comments: "I was impressed with the C800U when I first saw it and as Traub-Heckert were able to satisfy our short delivery time, I had no hesitation in placing the order.

Its accuracy is phenomenal, which has much to do with the basic machine design and its mineral cast bed." Another benefit derived by TWR on the Hermle C800U is the trunnion mounted table axis.

This enables the cylinder heads to be fixtured below the swing centreline and rotated about the axis of the cutting tool, thus minimising the degree of swing and developing excellent cutting dynamics.

"It is a feature that helps us to further reduce cycle times and ensure accuracy," maintains Simon Lockwood.

He follows on saying: "Lead time to produce a new revised F1 cylinder head is very critical with timescales within four weeks of initial production engineering to final machining.

The machining methods employed on the Hermle, coupled with its fast 30 position tool changer and 35 m/min rapid traverse rates with acceleration of 5 m/sec2 help reduce non cutting times.

Quality is not compromised because it gives us an excellent surface finish within 0.8 micro metres and has a positioning accuracy within 0.008 mm.

While the C800U was originally justified for the FI cylinder heads, it can now also be applied to any 3-D surface work that requires a high quality finish.

It is often used for wind tunnel models as well as other components from wheel nuts to axles.

TWR Engines has a highly skilled workforce and, in general, each technical machinist is responsible for creating his own programs.

Programming of the cylinder heads is carried out directly at the machine using the interactive dialogue and simulation graphics that are a feature of the Heidenhain TNC 430 CNC control.

In the case of the 3-D surface work carried out on the Hermle, data is extracted from the TWR's CATIA CAD system and downloaded direct to the TNC control.

The Hermle C800U has axis travels of 800 mm by 600 mm by 500 mm and a 25 kW high torque spindle developing 156 Nm.

Direct scale positioning provides a resolution of 0.0001 mm and all linear movements are performed by the cutting tool.

The dynamic behaviour of the machine is totally independent from the weight of the workpiece and its fixturing.

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