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.

Keywords

• milling
• friction coefficient
• shearing constants
• ploughing constants
• Inconel 718