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a metalcutting machine tool whose cutting tool is used to plane flat horizontal, vertical, and inclined surfaces of rectilinear generatrices. There are two basic types of planers: standard planers and shapers.
The principal motion of planers is reciprocal in a straight line. In shapers, the cutter is attached to a head and is reciprocated; in standard planers, the workpiece is mounted on the table, and the table reciprocates. Cutting is effected during the planing stroke, which is followed by a faster, return stroke, during which the cutter or workpiece returns to its original position. The stroke speeds remain constant in all standard planers and in shapers with hydraulic drive; they vary from zero to maximum speed and back to zero in shapers with mechanical drive. The feed motion is in a direction transverse to the direction of the strokes and is accomplished at the end of each return stroke. In shapers, the feed motion is imparted to the table with the attached workpiece; in standard planers, it is imparted to the cutter attached to the head.
Small and medium-size workpieces are worked on shapers. Standard planers are used to plane relatively large workpieces, several medium-size workpieces simultaneously, and workpieces with long, narrow surfaces, primarily in single-item and small-lot production. The use of planers in large-lot and mass production is not feasible because of the nature of the return stroke. In such manufacturing, planers are replaced with milling, broaching, and grinding machines.
REFERENCESSee references under METALCUTTING MACHINE TOOL.
D. L. IUDIN