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CNC multi-axis grinding machines featuring NUM’s Numrotoplus 3D simulation and control software are helping Miller Prazisionswerkzeuge make Mapal solid-carbide twist drills.

The new drill tools employ complex optimised profiles to accelerate cutting speeds.

The Numrotoplus software allowed Miller Prazisionswerkzeuge to visualise and optimise the complex machining process required to produce the new drills in 3D, before putting the new drill range into volume production.

Ulrich Krenzer, technical director of Miller Prazisionswerkzeuge, said: ‘The Numroto features helped during the development of our latest Mapal drill products and we made extensive use of the advanced 3D simulation capabilities of Numrotoplus software, including its tool collision monitoring procedures, to optimise our manufacturing process.

‘We have used NUM’s CNC software for a number of years and are now in the process of running it out across all our machines.

‘By effectively standardising on this one package, with a consistent user interface, we will reduce our personnel training costs and help maximise productivity, while maintaining the product quality for which we are renowned.’ To cope with demand, Miller Prazisionswerkzeuge recently doubled the size of its research and development and manufacturing operations at Altenstadt in Germany, culminating in the opening of a new 7000m2 factory in November 2008.

The facility contains more than 40 CNC grinding machines equipped with the Numrotoplus software – which operates for three shifts per day, 365 days of the year.

It is widely acknowledged that more than 30 per cent of productive machine time is taken up by drilling operations.

Typically, these include pilot drilling and pre-centring, drilling, reaming, countersinking, boring out, de-burring and thread cutting.

Combining some of these operations in a single step makes it possible to significantly decrease machine time, but only if the drilling tools feature task-optimised profile geometries: factors such as chip removal, heat dissipation and tool stability are critical.

The new Mapal ‘Mega Speed Drill’ is designed for high-speed drilling of steel and iron.

It features an asymmetric tip, with reinforced cutting edges.

The three margins are designed in such a way that the drill slightly oversizes the holes and the friction between the margin lands and the workpiece is minimised.

This geometry makes the drill relatively insensitive to high cutting-edge temperatures and corner wear.

The specific, polished flute geometry guarantees a free flow of chips.

The drill can be applied with a very high cutting speed of about 200m/min when machining steel, enabling drilling times to be reduced by as much as 70 per cent compared with conventional products.

For example, when used to drill annealed 42CrMo4 under these high-performance cutting conditions, the tool has a typical lifetime of 60 to 70m, reducing the production cost per bore by as much as 50 per cent.

Miller Prazisionswerkzeuge has also just developed a twist drill that produces a bore with a flat 180-degree bottom.

Normally, this would require two machining operations, one to drill the bore to the required depth and one to perform counter-boring.

A special tip profile on the new ‘Mega Drill 180’ effectively combines the two operations in a single machine cycle.

The drills are ground with an S-shaped point thinning, which delivers good chip control and a profiled concave flank to produce a flat-bottom hole.

The tool can also be applied for piloting at inclined surfaces.

The flat point here reduces the radial forces compared with conventional drill points with a 140 degree point angle.

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