Zecha milling cutters master demanding hard processing operations

By Niraj M Wanikar, Chief Editor, CNCTimes.com, 2018-10-12 15:05:00

Polished chipping spaces give heat no chance

Robust high-performance tools for materials up to HRC 67

 Zecha's high-performance milling cutters in its  581P, 583P, and 597P series have been specially designed for the HSC processing of highly alloyed and hardened steel up to 67 HRC, for example like the material especially encountered in mold-making. The reliable tools in the PEACOCK range are available in diameters ranging from 0.2 to 0.8 mm and boast extremely strong cutting edges. The polished chip spaces mean that swarf and heat are rapidly removed from the processing area, which also enables the reliable production of difficult contours at the micro level.     

The cutting of steels up to HRC 67 used to be a laborious and virtually uneconomical task just a few years ago, but can now be ably mastered using the right tools. However, if the machine operation involves cutting fine contours in such hard materials the entire process becomes considerably more difficult - and not just for the machine operator, for the tool, too. 

For example, the high-speed cutting in hardened tool steels calls for exceedingly strong milling cutters with optimised cutting geometries that can process at low vibration levels. These have been manufactured by Zecha Hartmetall-Werkzeugfabrikation GmbH in Königsbach-Stein and have been successfully employed in numerous applications for many years now. The tried-and-tested PEACOCK high-performance milling cutters in the 581P, 583P, and 597P series now come in new dimensions and with innovative WAD coating. This makes the tools ideally suited for HSC processing of materials up to HRC 67. It is Zecha's way of enabling users, especially in the automotive and aerospace industry, model and tool making as well as mechanical engineering, to process such materials with even greater accuracy.

PEACOCK – when things get hard

Their specially adapted shaft geometries with gentle radius transitions mean that PEACOCK milling cutters also produce the finest surfaces, high dimensional and geometric precision plus excellent efficiency. Also, the especially fine cutting edge structure, the sophisticated groove design to ensure the necessary stability, as well as the ideal facing edge geometry do their bit to ensure the reliable removal of chips. These characteristics all combine to produce the optimum tool for the machining of materials such as powder metallurgical steels, tungsten copper, Ni-Cr alloys, and cobalt chromium.

The PEACOCK 581P double-fluted ball cutters are available in diameters of 0.2 to 12.00 mm. The new three-edged tools come in diameters of 1.0 to 8.0 mm. If machine operators need to fall back on four-edged ball cutters, they can now choose from the new diameters of 3.0 - 8.00 mm. There are likewise double-fluted torus cutters in the PEACOCK range: Series 583P comes in the diameters 0.2 to 6.00 and cuts with great precision, just like the ball cutters. Coming in diameters of 0.8 to 6.00 mm and having a helix angle of 30°, the four-fluted VHM torus cutters in the 597P series with free lengths prove to be reliable standbys for nearly every micro application. All the milling cutters - irrespective of whether double, triple or four edged - boast precise cutting performance right down to the centre of all cutting edges.

High performance cutters brave high loading

Arndt Fielen, sales manager at Zecha: "In order to be capable of reliably mastering the hard processing of materials up to HRC 67 it is necessary to run the tools at high feed and cutting speeds. The HSC cutters save a great deal of machining time and produce superb surface qualities. Nevertheless, this very efficient strategy has a downside - the extreme temperatures that make the whole operation more difficult!  This is because the heat normally generated during demanding hard machining translates into a lot of stress for the tools."

The robust PEACOCK cutters avoid this stress by heat, virtually in its entirety, because the easy-cutting design and the smooth WAD coating result in hardly any high temperatures being generated during machining. Smoothly polished chip spaces swiftly remove chips from the tool so that the process temperature can be easily verified. The strong shaft and cutting geometry greatly prolongs service life.

Precision is also called for in hard machining - and this is why the four-fluted micro cutters have a geometric and concentric accuracy of 0.005 and 0.003 mm respectively. The cutters can also be used for dry and wet cutting. This means the tools used in conjunction with KSS emulsions also achieve excellent surface qualities in the cutting of chromium-containing, high wearing superalloys.

When the going gets tough...

Although Zecha developed its PEACOCK range specifically to deal with hard materials, tests have shown that its highly abrasive properties also make it eminently suitable for "softer" and tougher materials. One and the same double-fluted ball cutter with a diameter of 1.5 mm was employed both for pre-finishing as well as fine finishing of tool steel. The very smooth and constant milling action during the processing produced a very good smooth surface. In addition, the predefined tolerances were observed. The same cutter, admittedly in a somewhat longer variant, was used to cut the material 1.2343 with 56 HRC, a hot work steel (vc= 118 m/min; vf= 700 mm/min; fz= 0.014 mm/z; ap= 0.050 mm). The desired 3D contours could be achieved in 240 min per operation without any apparent wear of the tool.

"A customer who processed the material 1.2379, tough, compressively strong cold work steel with 57 HRC in 2.0 mm diameter was equally impressed," said Arndt Fielen. "The cutter with WAD coating was used for finishing and fine finishing." The coating displayed superb adherence properties even after prolonged use - its high density and hardness in combination with the geometry of the tool guarantee long service times and very smooth surfaces!"

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