Abstract
The critical problems faced during the machining process of heat resistant superalloys, (HRSA), is the concentration of heat in the cutting zone and the difficulty in dissipating it. The concentrated heat in the cutting zone has a negative influence on the tool life and surface quality of the machined surface, which in turn, contributes to higher manufacturing costs. This paper investigates improved heat dissipation from the cutting zone on the tool wear through surface features on the cutting tools. Firstly, the objective was to increase the available surface area in high temperature regions of the cutting tool. Secondly, multiple surface features were fabricated for the purpose of acting as channels in the rake face to create better access for the coolant to the proximity of the cutting edge. The purpose was thereby to improve the cooling of the cutting edge itself, which exhibits the highest temperature during machining. These modified inserts were experimentally investigated in face turning of Alloy 718 with high-pressure coolant. Overall results exhibited that surface featured inserts decreased flank wear, abrasion of the flank face, cutting edge deterioration and crater wear probably due to better heat dissipation from the cutting zone.
Highlights
Alloy 718 is a nickel base alloy with high mechanical and thermal strength in combination with outstanding weldability and creep resistance property at elevated temperature
The surface features on the rake face close to the cutting edge of Gen I insert were modified based on the theoretical chip contact area to act as channels for the coolant, Gen II insert
Gen II insert showed improvement in the tool life, a reduced flank wear by 20–35%, tool-chip contact and flank wear area by 12–17% compared to Gen I insert
Summary
Alloy 718 is a nickel base alloy with high mechanical and thermal strength in combination with outstanding weldability and creep resistance property at elevated temperature This makes it a natural choice when producing components for hot sections in jet engines. To improve the heat dissipation from the cutting zone, a potential solution introduced by Pigott and Colwell in 1952 [2], was to focus the coolant jet to the cutting edge at a high-pressure. The investigations have been directed towards using textures in combination with high-pressure coolant to improve the heat transfer rate for improving tool life. This paper explains the design criteria of different generations of inserts and provides results from the investigation of the tool wear mechanism and tool-chip contact area in correlation to the improved heat dissipation of surface featured cutting tools
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