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1). For some cutters, with long, helical, cutting edges, the axial rake angle is further called the helix angle. The cutting speed, as in turning, is pDW. 3, the cutter is shown rotating clockwise and travelling through the work so that a cutting edge A enters the work at a and leaves at e. A chip is then formed from the work with an uncut chip thickness increasing from the start to the end of the edge’s travel. If the cutter were to rotate anticlockwise (and its cutting edges remounted to face the other way), a cutting edge would enter the work at e and leave at a, and the uncut chip thickness would decrease with the edge’s travel.

2 shows four examples of a chip being machined from the flat top surface of a parallel-sided metal plate (the work) by a cutting tool, to reduce the height of the plate. It has been imagined that the tool is stationary and the plate moves towards it, so that the cutting speed (which is the relative speed between the work and the tool) is described by Uwork. In each example, Uwork is the same but the tool is oriented differently relative to the plate, and a different geometrical aspect of chip formation is introduced.

4(a) and (f)) by a sharp, plane rake face tool. 1) will be considered. The role of mechanics is to show how the force and velocity boundary conditions at the chip – tool interface and the work material mechanical properties determine the flow of the chip and the forces required for cutting. For continuous chip formation, determining the flow means at least determining the thickness of the chip, its contact length with the tool and its curvature: none of these are fixed by the tool shape alone. In fact, determining the chip shape is the grand challenge for mechanics.