Machining with applied chip tension—Part I: Theory

Abstract

Machining with applied chip tension is the basis of a process, strip peeling, for making small batches of metal special strip products. An approximate slip-line field numerical analysis of the process, related to the matrix method, is presented which shows how pulling stress and its direction affect chip thickness and curvature and tool forces. Pulling parallel to, or within 5° of, the rake face produces straight chips but results in less reduction of chip thickness and tool forces than pulling at more than 5° to the rake face. In the latter case chips are formed curled and are subsequently plastically straightened by the pulling force. Chip failure by plastic straightening and other causes is discussed and it is recommended that the pulling direction should be between 5 and 20° from the rake face. Influences of rake angle and friction stress are also considered.