An Analysis of the Milling Process, Part II—Down Milling

Abstract

Abstract The method of milling here described as down milling is compared with up milling on the basis of geometric characteristics such as length of tooth path, radius of curvature, thickness of the undeformed section of the chip, chip formation, character of the milled surface, power required in cutting S.A.E. 1112 steel and cast iron, and intensity of vertical and horizontal components of the cutting force obtaining for various depths of cut. Typical mechanical backlash-eliminating devices for the feeding mechanisms of milling machines to permit down-milling operations are described. Results obtained in actual application of down milling are given together with information on cutter life and production. The analytical and factual data presented permit a comparison of the advantages and disadvantages inherent in both methods of milling. It is shown that the power required at the cutter not including the feed is slightly more in down milling than in up milling. The total power supplied to the machine, however, is slightly less in down milling than in up milling. Actual intensities of horizontal and vertical components of the forces on the cutting edge are given for both methods of milling. Down milling, known for many years but not generally used in milling operations until recently, finds an ever-widening field of application.