Dead Hard - New Experts for Machining Steel and Cast Iron from Hofmann & Vratny

The Bavarian manufacturer presents its new EXPK1 series.

A├čling, Germany, November 04, 2021 --( The steel and cast iron material group is a challenging one for milling tools to handle, not least because of the variety of alloys that can be used and all the different properties they have. On the one hand, the tools need to be able to withstand huge amounts of strain, for example due to the high tensile strength of steel (up to 1400 N/mm2) and the unequal structure of cast iron. Yet on the other hand, very soft alloys require geometries that are favourable for cutting in order to ensure that the material can be machined effectively.

The H&V EXPK1 Series has been developed specially with these requirements for cutting steel and cast iron in mind. The manufacturer has already received initial positive reactions from various industries, such as mold and die making, machine and plant construction and the automotive industry.

Optimization to the smallest detail

For its new generation of milling cutters, the manufacturer has made it its mission to make no compromises. In order to meet its claim of "the right tool for every application," a product portfolio consisting of a total of 800 individual articles (48 article groups) was created. In this process, not only the geometries were perfected, but also a special fine-grain substrate with proven hardness and increased fracture toughness was selected, as well as the tolerances were optimized for maximum accuracy (± 0.003 mm or ± 0.005 mm depending on the tool type and radius).

Maximum performance is achieved by using the latest coating technology. In addition, they have made it their mission to solve the problematic differences between wet and dry machining and have created specific experts where it is most important. Further to comprehensive technological updates, the eight new milling cutter types in the series also fit into the new H&V naming. These are: Performmaker (end mill cutter), Slotmaker (roughing cutter), Chipmaker (trochoidal cutter), Mirrormaker (finishing cutter), Formmaker (torus cutter), Blademaker (face torus cutter), Rowmaker (full radius cutter).

One highlight of the new series are the new chipmakers (trochoidal cutter) with optimized positioning and groove shape of the chip chambers, which impress with ideal chip disposal in trochoidal volume machining and thus prevent "chip nests." This avoids the repeated milling of chips that have stayed in or accumulated so that the development of microbreakouts on the cutting edges are effectively prevented. Furthermore, the lower pressure angle of this geometry reduces the generated heat during the milling process and thereby also the thermal load. Process reliability and tool life are significantly increased. In order to offer the right tool for every application, the manufacturer has designed both a five- and a seven-flute milling cutter for trochoidal machining on purpose.

The five-flute chipmaker is preferred for high lateral infeed due to its number of flutes and the chip space groove size. Therefore, the machine mechanics are subjected to a lower load, which makes it ideally suitable for machines with lower dynamics.

The powerful seven-flute chipmaker, for its part, achieves higher feed rates with better dynamics and at the same time less load on the milling spindle.

The competitors' tools could not keep up with these tool lives.

The fact that the tools of the EXPK1 series are literally "tough as nails" is reflected in in-house tests carried out at Hofmann & Vratny's research and development center as well as in comprehensive field tests. The new Performmakers (end mill cutters) score particularly well when machining with high radial cutting depths even with full slot milling. These cutters also master ramping and helical immersion with high process reliability. Despite the longest tool life, the new chipmakers (trochoidal cutters) had not yet reached their limit of wear by a long way compared to the tools of the competitors and also convinced the customers above all with regard to spindle load, chip removal and milling noise.

The new Rowmakers (full radius cutters) achieved the highest tool life not only in dry machining but also in milling with cooling lubricant.

Radial and axial as well as thrusting and tensile loads were tested on the tool. Selected mold making customers who have already tested the tools thoroughly are convinced in terms of tool life, dimensional accuracy and surface quality.

Alpha Ferro Platin X – new high-performance coating

The standard coatings for machining steel, such as TiAIN coatings, have become so well-established on the market thanks to their characteristically solid properties when used for universal machining. In order to achieve this level of suitability for universal use in all steel and cast iron alloys while improving even further on the performance of the TiSiN-Alpha coating previously used by the manufacturer, the new Alpha Ferro Platin X was built on a novel concept consisting of AlCrTiN (aluminum chromium titanium nitride). The main advantages of the new coating are characterized by its increased temperature stability during dry machining as well as its thermal resistance when wet machining, higher wear resistance and maximum stability of the cutting edges. In addition, a new finishing method has been developed which is characterized by its achieved smoothness and thus prevents microbreakouts. Furthermore, the finishing ensures a permanently optimal chip removal and even wear.
Hofmann & Vratny OHG
Isabell Bodmayer