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In this paper, FEM is used to simulate the three stages of catastrophic shear occurrence, expansion and shear band formation when serrated chips are formed under adiabatic shear behavior in high-speed machining of hardened steel GCr15 with PCBN tool. By comparing data of simulation and experiment on chip morphology characters, it is indicated that they are in good accordance. Hereby, the author has analyzed strain and temperature distribution in adiabatic shear band, and dynamic characters of cutting force . The research results show that adiabatic shear band begins from tool tip and extends to workpiece free surface, and it is characterized by large strain and high temperature. In addition, it results from adiabatic shear behavior that cutting force waves regularly in a numerical range.

Tool wear plays an important role in cutting process research. It affects the quality of machined surface and cutting parameter to a great extent, such as cutting force, cutting temperature and cutting quiver. In order to predict tool wear in hard cutting process by using FEM method, the character of tool wear during cutting process is presented firstly, and Usui’s tool wear rate model is introduced. Then the FEM model for steady state cutting process using Abaqus is established. FEM model describes the workpiece material characteristic accurately for the process of PCBN tool cutting GCr15 by adoptiving Johnson-Cook constitutive model. Simulation results of steady cutting process offer foundation to simulate tool wear.

Tool wear plays an important part during cutting process, and wear loss has a close relationship with cutting condition, which affects machined surface mostly. In order to accomplish tool wear prediction in way of FEM, based on founding of cutting model under steady state, interrelated parameters needed for tool wear prediction, such as cutting temperature, contact pressure and raletive sliding velocity are extracted. By compiling Python subprogram and using Abaqus tool in hard cutting process PCBN tool wear is predicted, which provide foundation for optimizing cutting condition.

In the cutting process, cutting force is one of the important physical parameters, which affects the generation of cutting heat, tool life and surface precision of workpiece directly. In this paper an orthogonal design of experiment and subsequent data is analyzed using high speed finish hard cutting GCr15 whose hardness is 65HRC. Cutting speed is 200-400m/min, to study the influence of cutting parameters on cutting force, cutting force empirical model has obtained from least square method.

PCBN cutting tool’s wear in high speed precision reaches tool wear criterion will cause cutting force and cutting temperature increase clearly, chip color change or melt. Even vibration in cutting will influence dimension accuracy and surface quality of workpiece. It is very useful to establish model by FEM simulation of tool wear predicted. The influence of tool wear in cutting conditions will assurance of machining quality and efficiency, decreasing rate of product cost. PCBN cutting tool’s wear is simulated by FEM software Deform 2D, rake face wear state can be analysed by the influence of tools geometric parameters and cutting parameters tool wear.

The formation mechanisms and properties of white layers produced in precision hard part machining of GCr15 hardened steels are not clearly understood to date. Microstructure of white layers formed during machining of GCr15 hardened steel (62±2 HRC) was investigated. Hard turned surface with white layer usually consists of three layers: a white layer (untempered martensite), a transition layer (over-tempered martensite), and the bulk material. Martensite, austenite and carbide are observed in the white layer, hardness of white layer is larger than that of bulk material and transition layer, it was caused by extremely small grain size and high dislocation density. The depth of white layer is about 7-14µm with the flank wear reached 0.1mm, the optimal width of the flank wear which generated low depth of white layer is essential to perform the super-finishing process.

A 3D model is established in this paper to simulate cutting process of PCBN tool cylindrical cutting hardened steel GCr15 using ABAQUS/Explicit. The model effectively overcomes serious element distortions and cell singularity in high strain domain caused by material large deformation by adopting shear failure criteria and element deletion criteria. In this study cutting force, cutting temperature, surface residual stress field as well as side flow are forecasted of hard cutting process with chamfering tool preparation. It shows that satisfactory results could be obtained by FEM. The simulation results provide theoretical basis for studying hard cutting mechanism and selecting the best cutting condition in practical.