Chatter-free endmill for highly alloyed steels

New grades of stainless steel and super alloys are constantly being developed for a range of  industries where it is important that corrosion and contamination is minimised. However, as new materials with better characteristics are developed, the very properties that make them suitable for use in demanding applications also make them progressively more difficult to machine.

Sutton Tools Export Manager, Jeff Boyd, explains how the company’s latest addition to its Harmony Endmill range provides the solution for high-quality milling of emerging hardwearing super alloy materials being developed for the aerospace, oil & gas, food & beverage, medical and marine industries.

To keep pace with the advancement of materials technology, this Australian company based in the northern Melbourne, has long-standing partnerships with local universities and with the Defence Materials Technology Centre (DMTC) to develop and test combinations of base materials, coatings, cutting geometry and edge-preparation micro-geometry to optimise new tools to effectively and efficiently machine each new super alloy as it is adopted by the market.

The company’s latest product breakthrough is its VA-Harmony EndMill, which has been engineered specifically for milling stainless steels and super alloys—such as austenitic grades 304 and 316, duplex grades, as well as inconels 718 and 725.

Sutton Tools’Harmony family is a range of endmills that is constantly being expanded to enable component producers supporting a broad spectrum of industries to successfully mill new materials as they are introduced. The Harmony line-up is primarily designed for use in CNC machining equipment, and the latest addition—the VA-Harmony EndMill—is aimed at those companies producing equipment for the oil & gas, aerospace, food & beverage, medical and marine industries.

Available in diameters from 6mm to 20mm, the VA-Harmony EndMill complements the existing range, furthering Sutton Tools’ aim to ensure its Harmony endmills include milling options that are optimised for any modern alloy material.

Hot hardness
The VA-Harmony EndMill has been in development by the Sutton Tools’R&D department at Thomastown  for the last six months. During this period, every aspect of the VA-Harmony Endmill’s design—from its base material, the cutting geometry, the advanced coating technology and the edge preparation micro-geometry—has undergone exhaustive testing to ensure the finished tool delivers the best possible combination of performance and durability to the end user.

The VA-Harmony EndMill features an ultra-fine micro-grade carbide base material, which offers the best wear resistance for high-performance milling applications. However, even using such an advanced base material, heat build-up during machining operations can result in damage to the toolunless a suitably advanced coating is applied to act as a thermal barrier between the work-piece material and the drill substrate.

Sutton Tools employs a Balzers Oerlikon Helica multi-layer coating for the VA-Harmony EndMill, as this has been designed specifically to work with the characteristics of carbide tools. The outstanding oxidation resistance and hot hardness that this coating delivers contributes greatly to the stability at the severely loaded cutting edges, while improving the toughness of the multi-layer structure to significantly reduce the possibility of cracking.

The cutting geometry of each Harmony endmill is specific to the materials on which it will be used. Through its meticulous design process, Sutton Tools has identified that the VA-Harmony EndMill requires a 40-42°unequal flute helix to efficiently mill the tough grades of super alloys and stainless steel for which has been designed. Extensive testingNew Balance