Facing: Facing is the operation of machining the ends of a piece of work to produce a flat surface square with the axis. This is also used to cut the work to the required length. The operation involves feeding the tool perpendicular to the axis of rotation of the work piece. A properly ground facing tool is mounted in a tool holder in the tool post. A regular turning tool may also be used for facing a large work piece. The cutting edge should be set at the same height as the centre of the work piece. The selection of hand-feed or power feed depends upon the length of the cut. The surface is finished to the size by giving usual roughing and finishing cuts. For roughing, the average value of the cross feed is from 0.3 to 0.7 mm per revolution and the depth of cut is from 2 to 5 mm. For finishing, the feed ranges from 0.1 to 0.3 mm per rev. and the depth of cut is from 0.7 to 1 mm.
Knurling: Knurling is the process of embossing a diamond shape pattern on the surface of a work piece. The purpose of knurling is to provide an effective gripping surface on a work piece, to prevent it from slipping when operated by hand. In some press fit work knurling is done to increase the diameter of a shaft. The operation is performed by a special knurling tool which consists of a set of hardened steel rollers in a holder with the teeth cut on their surface in a definite pattern. Knurls are available in coarse, medium and fine pitches.
Recessing: Recessing can also be called as grooving or necking. So the recessing tools are sometimes called necking tools. Recessing tools may be either straight or bent shank types. As the recess is usually narrow, the cutting edge is kept narrow. It is relieved by 1o to 2oon each side towards the shank. The sides are relieved to make the tool free cutting. The rake angle should be decreased or the face should be made hollow to the radius. The tool should be set exactly in centre. If tool is set below or above the centre, it will break.