Wind power: a fresh wind for tool technology

Tools as the key to profitability

If we are to satisfy the world's hunger for energy in the future, the question of whether the installations are in fact profitable is crucial. The parts that transmit the kinetic energy extracted from the wind – the gears, the toothed wheels and the shafts – play a key role here. The lower the friction, in a quite literal sense, between the individual engineering components, the more efficient the installation is. As a specialist in gear-cutting tools, LMT Fette offers a range of tools particularly tailored to match these requirements. Innovative gear hobs and involute gear cutters permit high productivity in the manufacture of large-modulus live rings and gearboxes. Tap drills and tap formers guarantee the highest quality to the threads. Turning tools with indexable inserts from group partner Boehlerit for the fabrication of shafts and flanges, along with drills and cutting tools, handle other phases of the manufacturing process.

Hochleistungsgewindeformer von LMT Fette.

The right tool for every application:

• Cutting large gear teeth: involute gear cutters are used in the manufacture of the large gear teeth on live rings. They are fitted with carbide indexable inserts whose substrates and coatings are matched to the particular requirements. Small cutting forces allow low-vibration running, resulting in optimum workpiece surfaces and long tool lives. These tools are also available with internal cooling. The ecologically beneficial dry machining process, cooled predominantly with air, has a favorable effect on the generation of flying chips, thereby avoiding adhesion of the chips to the workpiece. At the same time, the current of air emerging from the chip space significantly reduces heating of the tool and the workpiece, and this helps achieve the long life that is wanted from these components. The segment gear hobs fitted with indexable inserts also make a significant contribution to the economical manufacture of large gears. LMT Fette has recently introduced a double-start segment gear hob whose particular advantages consist firstly in the improved surface quality of the workpieces, and secondly in halving the machining time through correspondingly increased feed rates.
• Thread manufacture: the wind exerts large forces on the equipment. The internal threads of the components therefore not only need to be made to high precision, but also need to be particularly tough. High-performance tap drills are used for the larger thread dimensions, as well as high-performance tap formers from the HPF (High Performance Forming) product family for the smaller threads. Process reliability demands that the sensitive cutting edges of the tap drills can withstand the stresses – particularly when backing the tap drill out – without being deformed or fracturing. The toughness of the cutting material in the tool is therefore particularly important. For this reason, something like 90 percent of all tap drills still consist of high-speed cutting steel. The powder-metallurgical version is capable of providing enormous improvements in performance. Thanks to the development of carbide substrates comprising finer and finer carbides (ultra-fine-grained carbides), tap drills and formers made from this cutting material continue to find new applications.

A massive shield for the tool

Innovative coatings are the key to further improvements in the performance of cutting processes. Coatings such as TiCN, TiAlN or AlCrN with nano-structured layers allow longer service lives and greater cutting or feed rates. In combination with HSS or carbide base materials, they protect the micro-geometry of the tool from being damaged by the extreme thermal and mechanical stresses.
The new Nanotherm coating provides an example of the performance of this technology. The carbide indexable insert gear hobs from LMT Fette coated with this material are already in use with a company in the wind power business in the south of Germany. In dry machining, the tool operates at a cutting speed of 158 meters per minute with a feed rate of 300 millimeters per minute. The tool life is increased by 100 per cent. The Nanotherm structure, with a layer thickness of 6 µm, is critical for this improved performance, providing significantly increased productivity in comparison with the titanium-aluminum-nitride coatings used formerly.