New performance reduces costs and increases efficiency

Innovative companies are continuously engaged in the holistic optimization of processes. Ideally, such efficiency increases are approached in cooperation with the respective suppliers. TVB GmbH in Murnau therefore does not purchase tools as catalog goods, but works out new efficient strategies or solutions together with the tool manufacturers.

In cooperation with the company Schreurs Tools, TVB GmbH in Murnau has succeeded in making the production of electrode holders with the new Performance Line milling tools more cost-effective, faster and more sustainable.

With the investment in fully automated production including a 5-axis machining center, the company took this step at the beginning of 2020. However, with the different materials to be machined, such as aluminum, brass and chromium-containing stainless steels like 1.2083 and 1.2085, the milling tools used quickly reached their limits. At that time, Schreurs was still in the development stage with the new "Performance Line" torus and end mills.

However, this was reason enough for Volker Jünger, Sales Manager Key Account Customers at Schreurs, to involve Andreas Rauchenberger in the test phase: "We already ran prototype tests with these milling tools in mold making and parts production at the beginning of 2020. The results showed that the tools are not overbred and that the cutting edge lengths of 3, 4 and 5 x D would be ideal for machining at TVB. The problem with these holders is when the machine accelerates with a 16 mm dia. cutter on these holders, the toolpath is already over. However, due to the available cutter lengths, we were able to reduce the cutter diameter to 12 mm, which also allowed us to use a different strategy."

Constant precision from January to December

The cost factor mentioned plays an important role for Andreas Rauchenberger. But a fundamental factor for him is process reliability: "In automated production, constant quality is an absolute must. In my opinion, this already begins with the manufacture of the tools. Fluctuations in substrates, coatings or even dimensional accuracy are an absolute no-go, because we have to reliably manufacture precision with a corresponding repeatability. We are therefore not necessarily looking for the second, but I have to be able to call up this precision from January to December. Of course, that also applies to the sister tools."

The primary objective in changing the milling tools, that the tool life and process reliability be maintained, and ideally improved, compared to the Ø 16 mm cutters, has been achieved, because the Performance Line, as a 4-flute HPC tool for roughing and finishing operations, also scores in terms of quality. With a much lower cutting pressure compared to the larger tools, the Ø 12 mm cutter runs smoother. This in turn has a positive effect on the cutting data, tool life and also the resulting better surfaces, especially when milling the 1.2085.

This is one of the reasons why Murnau now relies on Performance Line milling tools not only for milling electrode holders, but also for slides, inserts, etc. For Benjamin Hintz, CNC operator at TVB, this is a logical consequence: "First of all, it is the case that no other supplier was able to reproduce this machining with a smaller tool because the cutting edges were simply too short. But I see a really big advantage in the all-round properties of the milling tools. Whether it's aluminum, plastics, non-ferrous metals or steel up to 55 HRC, it works."

The attitude that you don't look for the second, you find especially in the tool and die industry, yes often. But it is also a fact that TVB, as a service provider, mills about 30,000 graphite electrodes per year. Between 80 and 85 percent of these electrodes are supplied to customers on a loan basis for 30 days as a packaging unit with a holder including a clamping spigot. So costs certainly do not play a minor role with these batch sizes.

"Werkzeug Technik" magazine, No. 194, February 28, 2021, Author: Dr. Michael Haas