Cutting Process in Slot Milling of AISI420 Stainless Steel Manufactured in Additive Process

Hybrid manufacturing involving additive and subtractive process in the same platform has been attracted to produce complex shaped parts with excellent surface finish and accuracy in surgical, aerospace, tool and die industries. The microstructures of metals fabricated by laser powder bed fusion are different from the wrought material. The machining of the material hardened in situ locally heat treated due to laser scanning is conducted without lubrication in the hybrid manufacturing. The paper discusses the milling process of AISI 420 martensitic stainless steel manufactured in additive process with comparing to a quenched wrought material and a quenched-tempered material. The cutting tests were conducted in slotting with a helical square end mill. The chip and the burr formations are discussed with the measured cutting forces. Then, the cutting forces are analyzed in a chip flow model, in which the three-dimensional chip flow is interpreted as a piling up of orthogonal cuttings in the planes containing cutting and chip flow velocities. The shear angle and the shear stress on the shear plane during chip formation are associated with the cutting force.