The advantages of wet-milling electrodes

Author / Editor: Andreas Weck / Rosemarie Stahl

Cooling lubricants are often used to prevent stubborn graphite dust when milling electrodes. This means that it is not necessary to acquire an additional milling machine for graphite machining. Cooling lubricants help to extend tool life and to improve dimensional accuracy.

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The Seagull milling tools are perfectly suited for the wet machining of graphite.
The Seagull milling tools are perfectly suited for the wet machining of graphite.
(Source: Zecha Hartmetall-Werkzeugfabrikation)

The numerous advantages mean that graphite electrodes are indispensable in spark erosion – no manual work, no deburring, hardly any burning, even intricate geometries are possible and the electrode comes out of the milling machine ready to use for erosion. However, as before, graphite dust is the spectre that haunts production. Milling electrodes with cooling lubricants offers a good alternative to dry machining. A comprehensive comparison test with Seagull tools from Zecha shows the many advantages of wet-milling: greater cleanliness, more flexible machine utilisation, higher dimensional accuracy and less tool wear.

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Because of stubborn graphite dust, machining graphite and copper on one machine has hardly been worth considering up to now. Dry machining also creates additional financial obstacles, particularly for small and medium-sized enterprises, since another milling machine has to be purchased for the eroding machine for graphite machining. The use of cooling lubricant allows the milling machine to be used flexibly. The graphite dust produced during milling is washed away by the cooling emulsion and then filtered from the emulsion by special equipment. This keeps lines and machines clean and free of graphite deposits. But what effect does this have on the tools, the electrodes and the finished component? A comparison test with Seagull milling tools produced amazing results.

With Seagull milling tools, the finest ridges and most delicate electrode geometries can be produced to an excellent finish. The reason? The patented short cutting – only 0.6 mm at a diameter of 2 mm – and the coordinated combination of high-quality hard metal, diamond coating and a special geometry with the tightest tolerances of only 5 µm ensures minimal cutting pressure and cutting forces. This allows for excellent surface quality and maximum tool life. Zecha offers the Seagull milling tools in two quality levels: The Quality line – divided into the 568 series (ball milling tool) and 578 series (torus milling tool) – provides an optimum price-performance ratio for standard applications and targets the price-conscious user, who nevertheless relies on quality results – even in the wet-milling process. The tools have proven diamond coating concentricity of 0.005 mm and diameter tolerances of 0/-0.015 mm. For excellent surface finish and narrow tolerances (in diameter of 0/-0.010 mm and concentricity of 0.003 mm), the High End line, with ball milling tools of the 567 series and torus milling tools of the 577 series, is the right choice. Thanks to the 10µm-thick high-performance diamond coating, the tools also shine with long tool lives. In both the High End and the Quality lines, each tool is measured individually and the actual size is noted on the packaging. This always guarantees the same narrow tolerances and highest process safety in the manufacture of the delicate graphite electrodes. All Seagull milling tools are available from 0.3 to 12 mm. Arndt Fielen, sales manager of Zecha Hartmetall-Werkzeugfabrikation, says: “The Seagull tools have made a significant contribution to the further improvement of dry graphite machining. We wanted to go a step further and see what was possible with wet processing.”

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