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Walter’s ability to provide customers with an holistic approach to problem-solving tooling solutions has led to a continued success in the power engineering sector, according to Andreas Elenz.

‘Power generation manufacturers commission us to develop end-to-end concepts for the production of individual parts or components, consisting of pre-machining and finishing processes,’ said Elenz, who is responsible for power engineering at Walter.

‘This involves an intense amount of process support and a high ratio of special tooling solutions, which in these cases accounts for 60 to 70 per cent of our work.

‘As a turnkey supplier, we are able to offer a package of optimum cutting tool material, high-precision tool bodies, engineering knowledge and customer service,’ he added.

Gas and steam turbines dominate the Walter order books – with components such as runners, blades, housings and generator shafts as well as wind energy plant gear components (housings, bearings, gear wheels), shafts and housings.

Milling tools are the most frequently required, both solid carbide types and those with inserts.

Other important technologies are drilling, including deep-hole drilling, threading and turning (including a lot of grooving).

One niche application is the machining of crude oil conveying tools, for which Walter primarily supplies turning inserts.

The components are invariably of high-cost, difficult-to-machine materials, which according to Elenz often means there are no test workpieces and the possibilities for experimentation are therefore extremely limited.

Tests, therefore, are predominantly conducted on ‘living components’, often between roughing cuts, or dimensionally within a tolerance range during which no permanent damage can occur.

Such test cuts require both the customer’s trust and a corresponding level of experience from Walter.

Such is the case at Alstom, a manufacturer of gas and steam turbines, where Walter provides around 60 per cent of the tooling required for rotor manufacture.

These are mainly milling and drilling tools, including special form mills for rotor grooves and special tools for coupling systems.

With turbines operating at 700C, highly heat resistant nickel-based alloys are increasingly being used for the required high-pressure blades, and rotors and housings are invariably cast iron with steel/steel casting also being used for high-stress applications.

Some components measure several metres long and weigh several tons.

Over the years, Walter has constantly monitored material trends in every industry sector and is developing appropriate tooling and cutting solutions to meet ever-evolving demands.

Its Tigertec range, for example, now includes grades with a PVD aluminium oxide coating (PVD Tiger) to deal with applications involving ISO-S and ISO-M materials.

Other Walter specialities include solid carbide form mills up to 50mm diameter, mills with soldered collets and HSS form mills.

Other examples concern the development of fir tree cutters complete with inserts for the semi-finishing and finishing of blade base profiles and rotor groove profiles.

With four or more teeth and five or more steps, each insert seat also offers repeatability in the micron range.

Developing optimum tools and machining technologies for blade production – usually on five-axis machines – is an area that Walter has been working closely on with the Institut fur Produktionstechnik (Institute for Production Engineering) at the University of Zwickau in Western Saxony.

One example of a recent joint project is the testing of Walter’s modular Conefit mill, a system that consists of interchangeable solid-carbide milling heads screw fitted to a variety of different shanks via tapered precision threads.

The main advantages are a high degree of flexibility and low tooling costs.

As tests on turbine blade finish prove, no reductions in performance are caused by the thread interface – the performance of the tools in unstable machining conditions prone to oscillation suggests certain absorption characteristics in the Conefit design.

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