Machining damage mechanism in end milling of the GH4099 superalloy honeycomb core with ice fixation

Abstract

Superalloy honeycomb cores have the advantages of high temperature resistance, light weight, and high specific strength, and are widely used in aerospace and defense industries. However, honeycomb cores have thin-walled and porous structural characteristics, the contact state between the tool and the honeycomb wall is variable during cutting, which is prone to machining damage and will adversely affect subsequent assembly and service performance. In this paper, GH4099 superalloy honeycomb core was taken as the research object. First, through the force analysis of the honeycomb wall, the difference of honeycomb wall damage mechanism in end milling without and with ice fixation was revealed. Next, an instantaneous rotation entrance angle analytical model taking into account honeycomb structure, tool size, and cutting parameters was established to characterize the contact state between the tool and the honeycomb wall. Finally, the milling experiment of superalloy honeycomb cores with ice fixation was carried out, and the maximum deformation displacement and damage area were used to quantify the degree of machining damage. The results indicated that the closer the rotation entrance angle is to 180°, or the larger the cutting width, the worse the machining quality of the honeycomb wall. Controlling the rotation entrance angle θREA＜90° and the cutting width ae＜0.80 mm is conducive to enhancing the shearing effect of the cutting edge on the honeycomb wall, which can effectively reduce the machining damage of honeycomb wall, and provide technical guidance for the optimization of low-damage machining processes of thin-walled porous metal materials.