An investigation on cutting sound effect on power consumption and surface roughness in CBN tool-assisted hard turning

In machining activities, sound emission is one of the key factors toward the operator's health and safety. Sound generation during cutting is the outcome of the interaction between tool and work. The intensity of sound greatly influences the cutting power consumption and surface finish obtained during machining. Therefore, the current work emphasized the analysis of sound emission, power consumption, and surface roughness in hard turning of AISI 4340 steel using a CBN tool which was rarely found in the literature. Response surface methodology (RSM) and artificial neural network (ANN) techniques were utilized to formulate the model for each response. The results indicated that the maximum value of input parameters exhibited the highest level of sound due to the creation of vibration in the machine and tool. Higher sound level indicates the generation of lower power consumption but at the same instant surface roughness was leading with increment in sound level. The feed rate exhibited the utmost noteworthy consequence on surface quality with 87.71% contribution. The cutting power can be decreased by choosing the high level of cutting parameters. The RSM and ANN have a good correlation with experimental data, but the accuracy of the ANN is better than the RSM.

Diffusion mechanism in cutting Ni-based alloy containing γ′ phase (Ni3Al) with CBN tool based on MD simulation

Ni-based alloys are widely used in aerospace because of their high strength and high temperature oxidation resistance. CBN tool is suitable for precision machining of Ni-based alloy. Diffusion wear is an important wear form of CBN tool in the process of cutting Ni-based alloy. Therefore, it is of great significance to study the diffusion phenomenon in the process of cutting Ni-based alloy with CBN tool. In this paper, the cutting model of Ni-based alloy containing γ′ phase (Ni3Al) with CBN tool is established based on the molecular dynamics (MD) simulation method. The self diffusion activation energy of all kinds of atoms in the workpiece and the formation energy of several point defects in the tool are calculated, so as to study in depth the atom diffusion mechanism according to the simulation results. The results show that the atoms in the crystal boundary of the workpiece are the most easily diffused, followed by the atoms in the phase boundary, and the atoms in the lattice are the most difficult to diffuse. When the workpiece atoms diffuse into the tool, it is easier to diffuse into the tool grain boundary than to form interstitial impurity atoms or displacement impurity atoms. It is more difficult to form the substitutional impurity atom than to form the interstitial impurity atom.

High Speed Machining of Inconel 718 with High Pressure Coolant Focusing on Material Structures of CBN Tools

Recently, cubic boron nitride (CBN) cutting tools and high pressure coolant (HPC) have garnered significant attention for high performance machining of difficult-to-cut materials, such as nickel-based super alloy, Inconel 718. In this study, the cutting performance of a low-CBN-content (L-CBN) cutting tool, which is known as a suitable CBN material structure for the high-speed machining of Inconel 718, is investigated under the HPC conditions. The experimetntal results show that, although crater wear is significantly suppressed as the coolant pressure increases, the combination of high cutting speed and high pressure coolant causes severe thermal cracking on the tool rake face of the L-CBN cutting tool. Hence, we evaluate the cutting performance of high-CBN-content (H-CBN) cutting tool which has smaller coefficcient of thermal expansion, compared with the L-CBN cutting tool. A series of cutting experiments shows that changing the material structure of the CBN tool effectively suppressed thermal cracking and that the H-CBN tool is a highly promising option for the high performance machining of Inconel 718.

Evaluating CBN tool life in hardened boring operations in long overhangs

This work aims to monitor the tool wear process using optical microscopy, so that the lifespan of the tool could be verified. The tool overhang was varied until it reached a limit (the deepest hole it could machine). The results show that, when the tool overhang is within its stability range, the flank wear of the tool is accentuated when the tool overhang outreaches its stability limit.