A machining apparatus machines a surface of a workpiece by feeding, relative to the workpiece, a cutting tool having a plurality of cutting edges A to D with tips of the cutting edges A to D arranged at equal intervals. The machining apparatus performs a cutting process of cutting the surface of the workpiece with the plurality of cutting edges A to D and a feeding process of feeding the cutting tool relative to the workpiece by a predetermined feed amount to form a plurality of grooves on the surface of the workpiece. The predetermined feed amount is set to a length that is not an integral multiple of the interval between the tips of cutting edges.

A machining apparatus machines a surface of a workpiece by feeding, relative to the workpiece, a cutting tool having a plurality of cutting edges A to D with tips of the cutting edges A to D arranged at equal intervals. The machining apparatus performs a cutting process of cutting the surface of the workpiece with the plurality of cutting edges A to D and a feeding process of feeding the cutting tool relative to the workpiece by a predetermined feed amount to form a plurality of grooves on the surface of the workpiece. The predetermined feed amount is set to a length that is not an integral multiple of the interval between the tips of cutting edges.

A fibre-reinforced polymer component is provided which comprises a main portion comprising fibre-reinforced polymer and at least one surface and at least one raised feature extending from said surface. The at least one raised feature consists of non-reinforced polymer and is shaped to incur visually perceptible damage when the component is subject to an impact with an energy above a predetermined impact energy threshold and to resist an impact with an energy below the predetermined impact energy threshold. The at least one raised feature thus provides a clear visual aid as to when a component has experienced an impact with an energy above the impact energy threshold. Because the raised feature consists of polymer without fibre reinforcement, it is more fragile than the fibre-reinforced polymer main portion 204 and thus reduces the energy at which impacts may be detected.

A fibre-reinforced polymer component is provided which comprises a main portion comprising fibre-reinforced polymer and at least one surface and at least one raised feature extending from said surface. The at least one raised feature consists of non-reinforced polymer and is shaped to incur visually perceptible damage when the component is subject to an impact with an energy above a predetermined impact energy threshold and to resist an impact with an energy below the predetermined impact energy threshold. The at least one raised feature thus provides a clear visual aid as to when a component has experienced an impact with an energy above the impact energy threshold. Because the raised feature consists of polymer without fibre reinforcement, it is more fragile than the fibre-reinforced polymer main portion 204 and thus reduces the energy at which impacts may be detected.

A turning process method for processing a step-shaped workpiece includes: feeding a tool in a rotation axis direction and/or a radial direction of a workpiece while rotating the workpiece; using a tool that includes an insert with a main cutting edge having a straight portion and a machine tool having a pivot shaft of the tool in the machine side; processing a peripheral surface of the small diameter portion by turning the pivot shaft so as to have a cutting edge angle of less than 90°, the cutting edge angle having an angle between the straight portion of the main cutting edge and the rotation axis direction; and processing an end surface and a peripheral surface of the large diameter portion by turning the pivot shaft so as to have the cutting edge angle of 90° or more at a front of the large diameter portion.

A turning process method for processing a step-shaped workpiece includes: feeding a tool in a rotation axis direction and/or a radial direction of a workpiece while rotating the workpiece; using a tool that includes an insert with a main cutting edge having a straight portion and a machine tool having a pivot shaft of the tool in the machine side; processing a peripheral surface of the small diameter portion by turning the pivot shaft so as to have a cutting edge angle of less than 90°, the cutting edge angle having an angle between the straight portion of the main cutting edge and the rotation axis direction; and processing an end surface and a peripheral surface of the large diameter portion by turning the pivot shaft so as to have the cutting edge angle of 90° or more at a front of the large diameter portion.

A boring tool holder has a base member and a cutting insert holding member. The base member has a first main surface and a second main surface opposite to the first main surface. The cutting insert holding member is contiguous to the base member on the first main surface, and disposed in a circumferential direction of the base member as viewed in a direction from the first main surface toward the second main surface. A cross-sectional area of the base member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the base member is larger than a cross-sectional area of the cutting insert holding member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the cutting insert holding member.

A boring tool holder has a base member and a cutting insert holding member. The base member has a first main surface and a second main surface opposite to the first main surface. The cutting insert holding member is contiguous to the base member on the first main surface, and disposed in a circumferential direction of the base member as viewed in a direction from the first main surface toward the second main surface. A cross-sectional area of the base member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the base member is larger than a cross-sectional area of the cutting insert holding member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the cutting insert holding member.

An indexable cutting insert has a central mounting portion and two cutting portions. The central mounting portion has opposing upper and lower surfaces. The lower surface has two abutment elements associated therewith, each abutment element having two diverging abutment surfaces forming two abutment angles. The two cutting portions extend away from the central mounting portion, have distal cutting edges, and are entirely located in diagonally opposite imaginary quadrants of four quadrants defined by two mutually perpendicular quadrant planes. Two abutment bisector planes bisecting the two abutment angles and one of the quadrant planes are parallel or coincident. In a top view, the two cutting portions extend away from the central mounting portion in opposite directions. Two cutting bisector lines parallel to the two directions and bisecting the two cutting edges are mutually offset. A cutting tool has an insert holder and the cutting insert removably retained therein.

A composite machining tool includes a tool body with at least one cutting edge and at least one grinding region. The grinding region is located adjacent to the cutting edge such that there is a gap between the grinding region and the cutting edge and such that when the tool performs a machining action the cutting edge and the grinding region act together on a material surface.