A rotary cutting tool has a plurality of circumferentially spaced grooves, each having a plurality of cutting inserts mounted. Each cutting insert has a wave-shaped major cutting edge, a corner cutting edge, and a minor cutting edge. The cutting inserts are arranged such that, the phases of the waves of the rotational trajectories formed by the cutting inserts that are adjacent to each other in a direction along the tool rotational axis coincide with each other in one groove. Also, the rotational trajectories of at least part of cutting edge portions of at least some cutting inserts are overlapped with each other in the direction of the tool rotational axis. Accordingly, even when the cutting edge portion is used as a major cutting edge and as an inner cutting edge, it is still possible to reduce cutting load and suppress breakage.

A method of milling an engine bore is disclosed. The method may include inserting a milling tool having a plurality of cutting edges along a longitudinal axis into an engine bore, rotating the milling tool about the longitudinal axis and moving the milling tool around a perimeter of the engine bore to remove material from the engine bore, and rough honing the bore. The milling may generate a tapered bore (e.g., frustoconical). The rough honing process may increase a minimum diameter of the tapered bore by at least 60 m. A total time of the milling and honing process may be less than 60 seconds. In one embodiment, the honing step may include using a grit size of at least 200 m and/or using a honing force of at least 200 kgf. The method may reduce the cycle time and tooling requirements of forming engine bores.

A tool center path is compensated so that the number of collisions with a workpiece in positions on cutter tips complies with use frequencies in cutter tip information, based on tool information including the diameter of a tool and the number of cutter tips attached to the tool, a tool center movement path specified by a machining program, workpiece shape data, and cutter tip information.

A cylindrical tool body has a peripheral surface provided with one or more spiral grooves extending from a base end side to a leading end side. The grooves each have a plurality of insert seats which are shifted relative to one another from the base end side toward the leading end side. The insert seats each have a bottom surface, a first side surface of length L1, and a second side surface of length L2. The first side surface faces the tool body's base end side, and the second side surface faces the tool body's leading end side and is located on the base end side with respect to the first side surface. In at least one insert seat located closer to the base end side than an insert seat located closest to the tool body's leading end side, the first side surface is longer than the second side surface.