Prediction of Shearing and Ploughing Constants in Milling of Inconel 718

Abstract

The present study proposes an integrated prediction model for both shearing and ploughing constants for the peripheral milling of Inconel 718 by using a preidentified mean normal friction coefficient. An equation is presented for the identification of normal mean friction angle of oblique cutting in milling. A simplified oblique cutting model is adopted for obtaining the shear strain and shearing constants for a tool of given helix angle, radial rake angle, and honed edge radius. The shearing and ploughing constants predicted from analytical model using the Merchant’s shear angle formula and the shear flow stress from the selected Johnson–Cook material law are shown to be consistent with the experimental results. The experimentally identified normal friction angles and shearing and edge ploughing constants for the Inconel 718 milling process are demonstrated to have approximately constant values irrespective of the average chip thickness. Moreover, the predicted forces obtained in milling aged Inconel 718 alloy are in good agreement with the experimental force measurements reported in the literature. Without considering the thermal–mechanical coupling effect in the material law, the presented model is demonstrated to work well for milling of both annealed and aged Inconel 718.

Determination of force coefficient based on instantaneous forces and linear mechanistic model in ball end milling

“…The increase in edge force coefficient values could be attributed to an increase in edge length with increasing axial engagement, which results in a larger cutting-edge radius and thus a greater plowing effect. 2,3 Generalized empirical equations using the fourthorder curve fitting for cutting force coefficients are shown in equations ( 29) and (30).…”

“…The increase in edge force coefficient values could be attributed to an increase in edge length with increasing axial engagement, which results in a larger cutting-edge radius and thus a greater plowing effect. 2,3…”

“…Plowing effect is observed in the cutter that has a cutting-edge radius and negligible in cutter with a sharp edge. 2,3 For the precise prediction of cutting forces, the determination of these coefficients is essential. Koenigsberger and Sabberwal 4 showed the relationship between instantaneous forces and chip cross-section area based on the mechanistic model in slab milling and face milling using a constant function of uncut chip thickness and rake angle of the cutter.…”

Closed-form models for the cutting forces of general-helix cylindrical milling tools

“…For the empirical approach, linear graphical/regression analysis [4][5][6] or nonlinear regression analysis [5][6][7][8] of the relationship between the experimentally measured cutting force and chip thickness gives the cutting force coefficients. The semi-analytical approach combines the mechanics of orthogonal cutting and orthogonal-to-oblique transformation in determining the chip-forming force coefficients 4,[9][10][11][12][13][14][15] while the edge force coefficients are determined experimentally as in the empirical approach.…”

Forces Shapes in 3-Axis End-Milling: Classification and Characteristic Equations

“…In milling such cutting forces are not constant during the process and their shape and magnitude change significantly with cutting process parameters [7]. Different cutting force models have been proposed in the literature, and most of them relate cutting forces to the chip thickness by utilizing cutting force coefficients [8][9][10]. In peripheral milling, chip thickness can be fairly approximated by sinusoidal functions, however, this simple formulation is valid for straight teeth tools (i.e., zero helix angle) which are practically never adopted in actual operations [11].…”