Helical Cutter Delivers High Metal Removal Rates, Low Cutting Forces
Kennametal’s Harvi Ultra 8X helical milling cutter was designed to meet high metal removal needs in aerospace machining as well as to provide machinists with a tool that can withstand higher cutting speeds but generate lower machining forces.
Kennametal’s Harvi Ultra 8X helical milling cutter was designed to meet high metal removal needs in aerospace machining as well as to provide machinists with a tool that can withstand higher cutting speeds but generate lower machining forces. According to the company, the Harvi Ultra 8X can predictably remove 20 cubic inches (328 cm3) of Ti-6Al-4V per min. while attaining 60 min. of tool life per cutting edge.
Several design features enable the cutter to accomplish this. A double-sided yet positive rake insert that delivers the lowest cost per edge possible and simultaneously reduces power consumption by up to 50 percent. The AlTiN+TiN PVD coating provides robust resistance to thermal fatigue, while Kennametal’s high-performance KCSM40 carbide grade provides longer tool life. The cutter body is constructed of a higher-quality steel for improved stiffness and rigidity under high cutting forces. A BTF46 (bolt taper flange) connection provides high deflection resistance compared to traditional shell-mill type holders. The variable helix design breaks up the harmonics that lead to chatter, further improving tool life, part quality, and throughput. Using 12- and 10-mm inserts also reduces vibration, as their smaller size means more inserts in the cutter body, more inserts engaged in the workpiece and more inserts to absorb the pounding of a heavy machining operation.
Precision through-tool coolant nozzles direct cutting fluid where it is needed most. An enhanced flute design promotes maximum chip evacuation. Oversize M4 Torx Plus screws provide greater insert stability. The option of a KM4X adapter brings greater toolholding stability. Specially-prepared insert edges optimized for the KCSM40 grade are said to extend tool life. Corner radii from 0.8 to 6.4 mm are said to expand the number of possible cuts the Harvi Ultra 8X can make.
The right choices in tooling and technique can optimize the thread turning process.
To make the transition to hard turning, you'll need to switch from carbide to CBN inserts, but that is easier (and more economical) than you might think. It's making the jump to much higher surface speeds that might scare you off. It needn't. Here's why.
One of the most common methods of tapping in use today on CNC machines is 'rigid tapping' or 'synchronous feed tapping.' A rigid tapping cycle synchronizes the machine spindle rotation and feed to match a specific thread pitch. Since the feed into the hole is synchronized, in theory a solid holder without any tension-compression can be used.