Tool Forces and Chip Formation In Orthogonal Cutting Of Loblolly Pine

Specimens of earlywood and latewood o f Pinus taeda L . were excised so that length along the grain was 3 inches and thickness was 0.1 inch. These specimens were cut orthogonally-as with a carpenter’s plane-in the three major directions. Cutting velocity was 2 inches per minute. When cutt ing was in the planing (90-O) direction, thin chips, intermediate to high moisture content, rake angles of 5 and 15O favored formation of the Franz Type II chip and accompanying good surfaces. In the O-90 direction, a knife with 70’ rake angle cut the best veneer; wood cut saturated yielded the highest proportion of continuous veneer, although saturated earlywood developed some compression tearing. When cutting was across the grain (90-90 direction), McKenzie Type I chips were formed and the best surfaces were achieved with a knife having 45Orake angle cut t ing saturated wood; earlywood was more difficult to surface smoothly than latewood. For each cutting direction, regression equations were developed to state average cutting forces (normal and parallel) in terms of rake angle, depth of cut, specific gravity, and moisture content. Tool Forces and Chip Formation in Orthogonal Cutting of Loblolly Pine The objective of the study reported in this paper was to determine chip types and tool forces typical of loblolly pine earlywood and latewood machined orthogonally. Orthogonal cutting is the machining process in which the cutting edge is perpendicular to the relative motion of tool and workpiece. The surface generated is a plane parallel to the original work surface. A carpenter’s plane cuts orthogonally, as does a bandsaw. Rotary peeling of veneer approximates orthogonal cutting. A two-number notation used by McKenzie (1961) is useful in describing the machining situation (fig. 1).