OVERVIEW

The contour of a part - also known as a profile - is normally programmed for milling applications by establishing the depth in the Z axis first, then moving the cutting tool individually along the X axis, Y axis, or both axes simultaneously. For turning applications, either the X axis or the Z axis, or both axes can be used to face, turn or bore a contour. For both types of machining, each contour element contour requires one block of cutting motion. These motions between contour change points can be programmed in inches or millimeters and they can use an absolute value position or an incremental distance. In either case, keep in mind that this type of programming uses the center line of the spindle as the X and Y or X and Z tool movements. Although the center line programming is a very convenient method for program development, it is also a method unacceptable for machining. During contact with the material, the edge of the cutting tool must touch the programmed part contour, not its center line.

The tool path for all contouring operations is always equivalent to the cutting tool motion. Whether used on a CNC machining center or on a CNC lathe, the cutting tool edge must always be tangent to the contour, which means the tool motion has to create a path where the center point of the cutter is always at the same distance from the contour of the part.