Effect of tool geometry on built-up-edge formation

Abstract

When l~ frictlonal resistance at the chip loot mterface is considerably high, the conlact layers subjected 10all sided compression may shear from the bulk of the chip_ Such separated layers are caned BUE. It consist of a part of the metal being machined \hal is heavily dcfomlcd, stagnant on the tool face and frequently adheres 10 the tool. In most of the machining operation SUE evident mosl frequently_ BUE is [\YOlo three times harder than the metal bemg machined, SIJthat it can cut a layer of metal on the work. Since It is a sort of extension of the \001, the HUE changes the tool geometry. Consequently, as 11travels together wilh the tool (is relation to work) the SUE aITe<:lsthe deformation of Ihe layer being cut, tool wear, forces sLimg on the tool and the surface fmish produced. The service life of present-day high speed and powerful machinery depends not only on the kind, quality and heat treatment of the metals of which Its component parts are made, but also on the surface quality obtained in machining the parls. The quahty ofa machined surface is charactenzed hy the accuracy of its manufacture is respect to the dimenstons >peelfied by the designer and roughness obtained in machining. Accuracy and roughness of the machined surrace are mainly influenced by the BUE, In finish machining, howcver, when a high quality surface finish is required, a I3UE IS undesirable, It was ohserved that with the mcrease or pnncipal side cutting angle ror vanous rake angle, maximum height of BUE shift from left to nght in each case of h vs lf' Figure. 11m:.~ also ohserved that the height of BUE was minimum at rake angle -r and principal side cutting angle 45". Wilh the Increase of rake angle from negalive to positive value for various principal side cutting angle, maxImum height of BUE shin hom left to right in each case. II was also ohserved that height of BUE was minimum at rake angle -2.5" to +2.5" lor pnneipal side cotting angle 45" In thiS'present study contou~ was plotted to represcnt thc interactive elTect of slde cutting angle and rakc angle on the height of RUE. By plotting rake angle vs pnncipal side cutting angle, it was observed that increase of principal sidc cutting angle had less iniloence on height of BUE at higher rake anglc. But a lower rake angle (y = -20" to +20") height of BUE decreases with Ihe increase of principal sidc cutting angle With thc inerca.<;eof rakc angle for a particular value of prlllcipal side cutting angle hClghtof BUE incrca;es.