Tech Talk
What is a "Roughing Cutter"?
Standard end mills also include heavy-duty end mills designed for heavy "hogging" cuts in tough steels and for machining of titanium, high-nickel alloys and the other high-performance metals coming into increased usage. Heavy-duty end mills, are used primarily for rough cutting applications. They come in large sizes (2-diameter and up), and in 2,3,4, 6 and 8-flute configurations. These tools are generally made up of cobalt and high speed steel and are of more rigid construction than the "general purpose" end mills described to this point. Their high web-to-diameter ratio provides a stiffer core which is better able to resist deflection. The overall design of the tool puts more metal behind the cutting edges to improve breakage resistance. The combination of premium material and rigid construction enables the heavy-duty end mills to operate at 10 to 20 percent higher speeds and feeds than the general purpose tool.
Heavy-duty end mills can usually be recognized by their shanks which are machined to fit bayonet lock-type holders. This provides the grip needed to withstand the high torque generated in the machining of some of the more difficult materials.
The roughing end mill is one of the newest members of the end mill family. Instead of uniformly straight cutting edges, the roughing end mill has chip-breaker cutting edges which take the form of a repeating sine wave. The "peaks" on each cutting edge proved the cutting action, producing short, fat chips instead of the longer and thinner chips generated by the cutting edge of a conventional end mill. The waveform on succeeding theeth of the roughing cutter is offset to overlap the cut made by the preceding tooth, which results in a relatively smooth milled surface.
For given cutter feed rate, the roughing end mill has a much higher effective feed per tooth than a conventional end mill. This type of end mill can zip through a roughing cut using 20 percent less power than a conventional end mill. Alternately, this type of tool enables the user to get improved performance from low-horsepower machines.
The short, fat chips generated by the "nibbling" action of the roughing end mill do a better job of absorbing heat in the cutting zone. This enables the roughing end mill to run cooler in heavy cuts, particularly in high-tensile steels. This tool offers the end mill user an impressive array of advantages:
1.Unmatched performance as a roughing tool. It removes more metal in less time than any other type of end mill-and requires less machine horsepower to do it.
2.The roughing end mill can take heavier cuts at higher speeds with less chatter and vibration.
3.The roughing end mill can remove metal at the same rate as conventional end mills with considerably less deflection - even in longer lengths.
4.The tooth form of the roughing end mill provides excellent heat dissipation during heavy cutting operations, making the tool especially effective for cuts on high-tensile steels.
5.The sine wave tooth form produces small, controllable chips.
6. Finally, the roughing end mill is form relieved, which means simplified resharpening with no change in tooth profile.
