Knurling is widely used in industry for many applications. Some of these include: decorative and "grip" surfaces, repair of undersized shafts and oversize bores, and driving serrations and splines. The word "knurling" applies to both the method of production, and the rolled section on the part. It is usually produced by forcing a knurling die into the surface of a rotating part, displacing material from the original diameter. Two methods of specifying the comparative tooth spacing are currently in use - CIRCULAR PITCH and DIAMETRAL PITCH. The CIRCULAR PITCH system has been used for many years and is based on the distance between teeth (pitch) and expressed as TEETH per INCH of circumference or TPI. The DIAMETRAL PITCH system is fully explained in American Standard ANSI/ASME B94.6-1984. Unlike gearing, only four standard pitches are used (64, 96, 128, & 160) for blank diameters from 3/32" to 1". Diametral Pitch dies are designed to permit accurate tracking on standard fractional sized blanks, making blank diameter selection easier. Due to the many variables involved in any knurling operation (speeds, feeds, coolant, hardness of piece, condition of pins, etc.), determining proper blank diameters for circular pitch dies is a bit more difficult, and usually involves some amount of experimentation. The tips along with the formulas on the following pages should help, but if problems persist, just give us a call and we'll be glad to offer our advise. (also see GENERAL TERMS at left).