Many industrial concerns have workshops of their own. For repair of worn shafts, lathe machine is excellent. Keyway slots can be machined by using a milling machine, while a shaping machine can do machining of large flat areas. A drilling machine does drilling of holes.
A skilled Maintenance Engineer should know how to use all these machines in order to make his own repairs in a safe manner. Very often he has to supervise machinists. The information below should be useful for that purpose.
The lathe machine uses a single-point-cutting tool for a variety of turning, facing, and drilling jobs. Excess metal is removed by rotating work piece over fixed cutting tool to form straight or tapered cylindrical shapes, grooves, shoulders and screw threads. It can also be used for facing flat surfaces on ends of cylindrical parts.
The work piece is clamped onto a horizontal rotating shaft by a 3-jaw or 4-jaw chuck. The latter chuck can be used to cut off-centered cylinders. The rotating horizontal spindle to which chuck is attached is usually driven at speeds that can be varied.
The cutting tool is fixed onto a tool rest and manipulated by hand. It can also be power driven on straight paths parallel or perpendicular to work axis. This is useful for screw cutting.
Internal turning known as boring results in enlargement of an already existing hole. The holes are more accurate in roundness, concentricity, and parallelism than drilled holes. A hole is bored with a single-point-cutting tool that feeds along inside of work piece.
The shaping machine is used to machine flat surfaces, grooves, shoulders, T-slots, and angular surfaces with single-point tools. The cutting tool on shaper oscillates, cutting on forward stroke, with work piece feeding automatically toward tool during each return stroke.
The drilling machine is used to cut holes in metal with a twist drill. By changing cutting tool, they can be used to do reaming, boring, counter boring, countersinking, and threading.
The milling machine uses a rotating cutting tool to cut flat surfaces, grooves, and shoulders, inclined surfaces, dovetails, and T-slots. Cutters of many shapes are changed to cut different grooves.
Metal-cutting tools are classified as single point or multiple point. The lathe and shaping machine use single point cutting tool while milling and drilling machines use multiple-point-cutting tools.