Effect of Micro Textures on the Cutting Performance of Circular Saw Blade Under Fluid Lubrication

In this paper, linear micro textures that parallel to the sawtooth edge were fabricated on the surface of the high speed steel W6Mo5Cr4V2 circular saw blade by laser engraving. Further, cutting performance of micro textured circular saw blade (TCS) and traditional circular saw blade (CS), including sawing arc length, sawing force, sawing temperature, machined surface roughness and wear mechanism, were investigated in sawing 304 stainless steel pipes under the cutting fluid condition. Results showed that the largest sawing arc length and sawing force were occurred on the circular saw blade sawing outward from the inner wall. In addition, TCS circular saw blade exhibited better cutting performance and the mechanisms were found, on the one hand, the effective sawtooth-chip contact length was reduced due to the micro textures fabricated on the sawtooth surface, on the other hand, cutting fluid can be better penetrated into the micro textures and formed stable lubrication film in sawtooth-chip contact interface.

Numerical Research of the Plastic Strain in Hard Turning in Case of Orthogonal Cutting

This paper shows the chip forming morphology of the plastic strain in the chip root in function of the cutting data. The knowledge of strain mechanisms may advance the increase of material removal efficiency thus appoint newer fields of application. The experiments on the examined case hardened steel at 62±2 HRC were carried out at different cutting speeds and feed rates. Our experiments were completed by means of Finite Element Method (FEM) in case of orthogonal cutting. For the simulation the data of experiments done previously were used. In the course of the FEM analysis the occurrence of the adiabatic shear as well as the sawtooth chip forming mechanism were examined. The relationship between plastic strain and the change of cutting data was investigated. In the paper the change of the morphology of chip formation is compared depending on the cutting speed.

Predicting the Effects of Rake Angle, Cutting Speed and Feed Rate on Chip Morphology in Hard Turning

This paper proposes a thermo-mechanical orthogonal cutting finite element model (FEM) to investigate the variation of chip morphology from continuous chip to small and large saw-tooth chip. The corresponding experiments of hard turning AISI 52100 steel are conducted to validate the proposed FE model. Three one-factor simulation experiments are conducted to determine the evolution of chip morphology along feed rate, rake angle and cutting speed respectively. The chip morphology evolution is described by the variations of dimensional values, saw-tooth degree and chip segmental frequency. The research suggests that chip morphology transit from continuous to sawtooth chip with increasing the feed rate and cutting speed, and changing a positive rake angle to a negative rake angle. There exists a critical cutting speed at which the chip morphology transfers from continuous to saw-tooth chips. The saw-tooth chip segmental frequency decreases as the feed rate and negative rake angle value increase, but increases almost linearly with the cutting speed. The larger negative rake angle, the larger feed rate and high cutting speed dominate the sawtooth chip morphology while positive rake angle, small feed rate and low cutting speed determine continuous chip morphology.

Microcosmic Observing and Analysing of the Chips Formation from Precision Hard Cutting GCr15 Bearing Steel

The sawtooth chip from hard cutting can influence on the precision of the form and dimension, the machined surface integrity and the tool life. A study on the microcosmic dynamic fracture mechanism of hardened bearing steel carried out by the author, based on the microcosmic observing and analysing of sections of the chips from PCBN tools cutting GCr15 bearing steel. The experiments and analyses indicate that the adiabatic shear loses stabilization in the primary deformation zones due to thermal softening during cutting machining, and shear ductile fracture limitation of the chip forms. The sawtooth chip formation of GCr15 bearing steel hardened cutting results not from the periodical brittleness fracture but from periodical adiabatic shear fracture; being no clear damnification before the adiabatic shear loses stabilization, thermal softening occurs and be controlled by nucleation, growth and coalescence of microvoids in the whole shear fracture tenacity progress.

Experimental and numerical study of chip formation during straight turning of hardened AISI 4340 steel

The present paper is a contribution to the investigation of physical phenomena accompanying sawtooth chip formation in the case of hard turning. The study concerns the machining with coated carbide of tempered AISI 4340 steel with a Rockwell C hardness of 47 HRC. The main idea in this paper deals with the establishment of a direct relationship between serrated-chip morphology simultaneously with force component signals derived from acquisition at high frequency and with the width of facets detected on a workpiece machined surface. This experimental work was supported by a numerical simulation based on Abaqus/ Explicit software. Numerical results dealing with effect of temperature evolution on the chip morphology show that the beginning of the sawtooth chip initiation is due to an adiabatic shear at the tool tip with propagation pathway towards the free surface. In addition, computed results have a good corroboration with those obtained experimentally.