| The Iscar ChatterFree endmills are designed varying helixes: two flutes have a 35° helix angle and the other two ascend at 37°. |
Claiming a new level of “built-in asymmetry,” Iscar reports that its EC-H ChatterFree solid-carbide endmills advance the speed and process security of slotting and shoulder milling of ferrous metals. On alloy and stainless steel, it continued, users report 20-25% longer tool life than with ordinary variable-pitch endmills.
Familiar variable-pitch flutes have proven their vibration-dampening characteristics in solid carbide endmills, and Iscar improves that design by varying the helixes. Two flutes have a 35° helix angle and the other two ascend at 37°.
Iscar explained its design theory that more asymmetry in a solid carbide tool will increase its resistance to harmonic vibration and chatter. The variable helix adds a dampening influence against harmonic vibrations, a principal cause of tool fracture in hard but brittle solid carbide endmills. By the same mechanism it also further minimizes chatter marks in the workpiece, it said.
EC-H ChatterFree endmills are available in the diameter range of 6-25 mm, with either Weldon (relieved) or cylindrical (straight) shanks. All have corner radii and are made of IC900, the most versatile PVD coated grade available today.
In addition to defeating vibration, Iscar EC-H ChatterFree endmills feature a free-cutting edge geometry that improves chip evacuation and reduces cutting forces, suiting them ideally for low power machines with ISO 40 or BT40 adaptations. With such improved control over vibration and cutting forces, they can safely be used on slots up to 2.5×D in alloy and stainless steel.
Four-flute EC- H ChatterFree endmills are offered in three types: standard lengths with cylindrical shanks, standard lengths with relieved shanks and extra long 4×D mills with cylindrical shanks.
Iscar described two early applications that it said underscore the improved performance of the variable-helix/variable-flute endmill versus a standard variable-flute tool. In rough shoulder milling of an austenitic stainless steel workpiece, the material removal rate improved to 20.05 cm3/min., from 9.17 with the tool change, and tool life improved to 45 pieces versus 30, before flank wear necessitated replacement. The main improvement with the EC-H cutter stemmed from doubling the depth of cut, which would have snapped off the competing tool. Also, in the case of a rough slotting operation with X6CrNiMoTi17-12-2, the EC-H ChatterFree endmill lasted through 60 pieces under identical conditions that had snapped off the competing endmill at 45 pieces.