Sutton Tools develops VA-Harmony optimised endmill for highly alloyed steels

Available in diameters from 6 to 20 mm the VA-Harmony complements the existing Harmony range of endmills which are primarily designed for use in CNC equipment manufacturing components for the oil and gas, aerospace, food and beverage, medical and marine industries. Development has seen Sutton Tools working in collaboration with local universities and the Defence Materials Technology Centre (DMTC) to develop and test combinations of base materials, coatings, cutting geometry and edge-preparation micro-geometry. The VA-Harmony endmill features an ultra-fine micro-grade carbide base material for wear resistance in high performance applications. A suitably advanced coating is applied to act as a thermal barrier between the workpiece material and the drill substrate. Balzers Oerlikon Helica multi-layer coating was selected as it has suitable oxidation resistance and hot hardness to maintain the stability of the severely loaded cutting edges. The toughness of the multi-layer structure also reduces the possibility of cracking. The cutting geometry of each Harmony endmill is specific to the materials on which it will be used. In the case of the VA-Harmony a 40 to 42º unequal flute helix was established through extensive testing to reduce the harmonic build up in the workpiece to provide smooth operation with suppressed chatter using various milling techniques. The edge preparation, or micro-geometry, incorporates 45º corner chamfering edge protection to provide additional strength and resistance to cracking, particularly in semi-roughing and roughing applications. The gash grind of the end-teeth blends with the outer corner of the chamfer for further strength in this area. The post-grind treatment of the edges comprises polishing before and after the application of the coating. This has been fine-tuned to deliver the best results in a broad spectrum of milling operations on Inconels and austenitic materials. Lower cutting forces and minimised vibration not only extends tool life, but also permits faster feedrates. A further production gain by using VA-Harmony is achieved as it has been designed to undertake multiple operations with one tool, so the workpiece does not have to be moved from one machine to another. The endmill is also available with a neck reduction option for extra cutting reach.