Technology Exploring high speed cutting for ultra-hard materials
How will ultra-hard materials be defined in the future, and can they be milled today with reliable processes? Union Tool wanted to find out, so it worked with partners to test the limits of its cutting tools.
Union Tool asks, “Should 90 HRa be classified as ultra hard, hard or simply easily machinable?” It said the answers and how they were found are all the more interesting since testing was conducted not at a research institute, but at a company that has to offer competitive prices every day.
Making it work on the floor
Gebr. Bräm AG, in Dietikon, Switzerland, has been machining tungsten carbide for decades. Since purchasing its first erosion machine in 1968, it has been using mostly wire and die-sinking erosion. It later added grinding and polishing.
According to Union Tool, the problem of negative effects on microstructures could only be significantly reduced when erosion machine manufacturers offered clean-cut generators or optional hard metal packages. Nevertheless, use of this special equipment requires much skill and ability. Thus the desire to not only erode, grind and polish hard metals, but to also mill them is a dream that has long been impossible to realise.
Bräm manufactures carbide stamps and dies for punching tool and carbide tools for forming. Wear has always been an important issue for customers since the service life of these expensive hard metal tools had to be significantly higher than those of hardened steels or those produced with powder metallurgy. In any case, tool breakage had to be avoided since it would lead to faulty machining.
In 2011, Bräm purchased a high-accuracy milling machine from Kern Mikro- und Feinwerktechnik. The shop said its manufacturing professionals eventually machined hardened steels up to 70 HRc. Then, since the Kern machine drove tools very smoothly around the contours, the company considered machining hard metals. Shop Manager Martin Bräm said the use of hydrostatic axes and drives is essential for this kind of machining, but further steps were required.