Study of Chip Morphology and Chip Formation Mechanism During Machining of Magnesium-Based Metal Matrix Composites

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Brian Davis ◽  
David Dabrow ◽  
Licheng Ju ◽  
Anhai Li ◽  
Chengying Xu ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Formation Mechanism ◽  
Chip Formation ◽  
Metal Matrix ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Matrix Composites ◽  
Particle Type ◽  
Chip Formation Mechanism ◽  
Cutting Speeds

Magnesium (Mg) and its alloys are among the lightest metallic structural materials, making them very attractive for use in the aerospace and automotive industries. Recently, Mg has been used in metal matrix composites (MMCs), demonstrating significant improvements in mechanical performance. However, the machinability of Mg-based MMCs is still largely elusive. In this study, Mg-based MMCs are machined using a wide range of cutting speeds in order to elucidate both the chip morphology and chip formation mechanism. Cutting speed is found to have the most significant influence on both the chip morphology and chip formation mechanism, with the propensity of discontinuous, particle-type chip formation increasing as the cutting speed increases. Saw-tooth chips are found to be the primary chip morphology at low cutting speeds (lower than 0.5 m/s), while discontinuous, particle-type chips prevail at high cutting speeds (higher than 1.0 m/s). Using in situ high-speed imaging, the formation of the saw-tooth chip morphology is found to be due to crack initiation at the free surface. However, as the cutting speed (and strain rate) increases, the formation of the discontinuous, particle-type chip morphology is found to be due to crack initiation at the tool tip. In addition, the influences of tool rake angle, particle size, and particle volume fracture are investigated and found to have little effect on the chip morphology and chip formation mechanism.

Study of Chip Morphology and Chip Formation Mechanism During Machining of Magnesium-Based Metal Matrix Composites

2017 ◽  
Author(s):  
Brian Davis ◽  
David Dabrow ◽  
Licheng Ju ◽  
Anhai Li ◽  
Chengying Xu ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Formation Mechanism ◽  
Chip Formation ◽  
Metal Matrix ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Matrix Composites ◽  
Particle Type ◽  
Chip Formation Mechanism ◽  
Cutting Speeds

Magnesium (Mg) and its alloys are among the lightest metallic structural materials, making them very attractive for use in the aerospace and automotive industries. Recently, Mg has been used in metal matrix composites (MMCs), demonstrating significant improvements in mechanical performance. However, the machinability of Mg-based MMCs is still largely elusive. In this study, Mg-based MMCs are machined using a wide range of cutting speeds in order to elucidate both the chip morphology and chip formation mechanism. Cutting speed is found to have the most significant influence on both the chip morphology and chip formation mechanism, with the propensity of discontinuous, particle-type chip formation increasing as the cutting speed increases. Saw-tooth chips are found to be the primary chip morphology at low cutting speeds (lower than 0.5 m/s), while discontinuous, particle-type chips prevail at high cutting speeds (higher than 1.0 m/s). Using in situ high speed imaging, the formation of the saw-tooth chip morphology is found to be due to crack initiation at the free surface. However, as the cutting speed (and strain rate) increases, the formation of the discontinuous, particle-type chip morphology is found to be due to crack initiation at the tool tip. In addition, the influences of tool rake angle, particle size, and particle volume fracture are investigated and found to have little effect on the chip morphology and chip formation mechanism.

Chip Morphology and Chip Formation Mechanisms During Machining of ECAE-Processed Titanium

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Brian Davis ◽  
David Dabrow ◽  
Ryan Newell ◽  
Andrew Miller ◽  
John K. Schueller ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Chip Formation ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Shear Localization ◽  
Coarse Grained ◽  
Cyclic Shear ◽  
Uniform Shear ◽  
Chip Formation Mechanism ◽  
Speed Regime

Severe plastic deformation (SPD) processing such as equal channel angular extrusion (ECAE) has been pioneered to produce ultrafine grained (UFG) metals for improved mechanical and physical properties. However, understanding the machining of SPD-processed metals is still limited. This study aims to investigate the differences in chip morphology when machining ECAE-processed UFG and coarse-grained (CG) titanium (Ti) and understand the chip formation mechanism using metallographic analysis, digital imaging correlation (DIC), and nano-indentation. The chip morphology is classified as aperiodic saw-tooth, continuous, or periodic saw-tooth, and changes with the cutting speed. The chip formation mechanism of the ECAE-processed Ti transitions from cyclic shear localization within the low cutting speed regime (such as 0.1 m/s or higher) to uniform shear localization within the moderately high cutting speed regime (such as from 0.5 to 1.0 m/s) and to cyclic shear localization (1.0 m/s). The shear band spacing increases with the cutting speed and is always lower than that of the CG counterpart. If the shear strain rate distribution contains a shift in the chip flow direction, the chip morphology appears saw-tooth, and cyclic shear localization is the chip formation mechanism. If no such shift occurs, the chip formation is considered continuous, and uniform shear localization is the chip formation mechanism. Hardness measurements show that cyclic shear localization is the chip formation mechanism when localized hardness peaks occur, whereas uniform shear localization is operative when the hardness is relatively constant.

Experimental Analysis of Ti6Al4V Orthogonal Cutting

2015 ◽  
Vol 665 ◽  
pp. 17-20 ◽  
Author(s):  
Apostolos Korlos ◽  
Orestis Friderikos ◽  
Dimitrios Sagris ◽  
Constantine David ◽  
Gabriel Mansour
Keyword(s):  
Formation Mechanism ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Chip Morphology ◽  
Serrated Chip ◽  
Wide Range ◽  
Chip Formation Mechanism ◽  
Serrated Chip Formation ◽  
Chip Geometry ◽  
Cutting Speeds

The chip formation mechanism in orthogonal cutting is a phenomenon that attracts the attention of many researchers. This paper investigates experimentally the orthogonal cutting of Ti6Al4V at different cutting conditions aiming at the understanding of the chip formation mechanism. Serrated chip formation is obtained during orthogonal cutting of Ti6Al4V in a wide range of cutting speeds. The results are analyzed in order to extract useful indices relevant to chip geometry, as the adiabatic zone angle and other dimensions that describe the serrated chip. The cutting forces and the acoustic emission are measured. Finally, by the aid of 3D Computed Tomography (CT) the chip morphology is analyzed to better understand the segmentation process.

FEM Prediction of Chip Morphology during the Machining of Particulates Reinforced Al Matrix Composites

2011 ◽  
Vol 188 ◽  
pp. 220-223 ◽  
Author(s):  
H. Guo ◽  
Dong Wang ◽  
Li Zhou
Keyword(s):  
Shear Failure ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Element Model ◽  
Matrix Composites ◽  
Segmented Chip ◽  
Sic Particulates ◽  
Al Matrix Composites ◽  
Cutting Speeds ◽  
Al Matrix

Chip morphology and segmentation play a predominant role in determining the machinability and tool wear during the machining of SiC particulates reinforced Al matrix composites. In this paper, a 2D coupled thermo-mechanical finite element model was used for simulating the segmented chip formation at different cutting conditions. The generation of segmentation is achieved by element erase and the shear failure, as well as the continuous adaptive remeshing technical. The results show that the chip is often discontinuous at lower cutting speeds, and with the increasing of the cutting speed, the chip becomes serrated. Fundamental observations from the simulations are concluded and a guideline for further research is proposed.

The Effect of Build Up Edge Formation on the Machining Characteristics in Austempered Ferritic Ductile Iron

2013 ◽  
Author(s):  
Şakir Yazman ◽  
Ahmet Akdemir ◽  
Mesut Uyaner ◽  
Barış Bakırcıoğlu
Keyword(s):  
Surface Roughness ◽  
Ductile Iron ◽  
Cutting Forces ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Salt Bath ◽  
Chip Formation Mechanism ◽  
Machining Properties ◽  
Machining Characteristics ◽  
Cutting Speeds

In this study, chip formation mechanism during the machining of austempered ferritic DI and the effect of the emerging chip morphology on such machining properties as surface roughness and cutting forces has been scrutinized. After austenitizing at 900 °C for 90 min, DI specimens were austempered in a salt bath at 380 °C for 90 min. Chip roots were produced by using a quick stop device during the machining of austempered specimens in different cutting speeds. The metallographies of these specimens were performed and chip morphologies were examined. The fact that the cutting speed increased led to a decrease in built-up edge formation. Depending on this fact, it was detected that the change in built-up edge thickness substantially affected the surface roughness and cutting forces. It was also detected that during the machining, with the effect of cutting forces and stress, spheroidal graphites were broken off in the chip and lost their sphericity and so that the chip became fragile and unstable and grafites here displayed a lubricant feature.

Research on Chip Formation Mechanism of Laser-Assisted Machining of Fused Silica Based on Variable Laser Angle

2020 ◽  
Author(s):  
Pengfei Pan ◽  
Huawei Song ◽  
Junfeng Xiao ◽  
Zuohui Yang ◽  
Guoqi Ren ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Chip Formation ◽  
Incident Angle ◽  
Chip Morphology ◽  
Fused Silica ◽  
Machining Process ◽  
Laser Assisted Machining ◽  
Chip Formation Mechanism ◽  
On Chip ◽  
Cutting Model

Abstract Laser-assisted machining (LAM) is a promising technology for improving the machinability of hard-to-cut materials. In this study, based on the finite element method (FEM), a cutting model of thermally coupled non-uniform temperature field is established. The chip formation mechanism of fused silica during the laser-assisted machining process is explored from the aspects of laser power and laser incident angle. The results show that as the laser incident angle increases, the continuity of the chip increases gradually. An annular tool holder that can adjust the angle between the laser beam and the tool was designed. And the similar chip morphology obtained by variable-angle cutting experiments verified the effectiveness of the cutting model. Moreover, fracture chips and continuous banded chips are found in both simulation and experiment, which implies that the cutting mechanism works under a hybrid mode of brittle fracture and plastic deformation in the LAM process.

scholarly journals Effect of cutting speed on chip formation and wear mechanisms of coated carbide tools when ultra-high-speed face milling titanium alloy Ti-6Al-4V

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771370 ◽  
Author(s):  
Anhai Li ◽  
Jun Zhao ◽  
Guanming Hou
Keyword(s):  
Tool Wear ◽  
Chip Formation ◽  
Wear Mechanisms ◽  
Failure Mechanisms ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Face Milling ◽  
Formation Mechanisms ◽  
Tool Wear Mechanisms ◽  
Cutting Speeds

Chip morphology and its formation mechanisms, cutting force, cutting power, specific cutting energy, tool wear, and tool wear mechanisms at different cutting speeds of 100–3000 m/min during dry face milling of Ti-6Al-4V alloy using physical vapor deposition-(Ti,Al)N-TiN-coated cemented carbide tools were investigated. The cutting speed was linked to the chip formation process and tool failure mechanisms of the coated cemented cutting tools. Results revealed that the machined chips exhibited clear saw-tooth profile and were almost segmented at high cutting speeds, and apparent degree of saw-tooth chip morphology occurred as cutting speed increased. Abrasion in the flank face, the adhered chips on the wear surface, and even melt chips were the most typical wear forms. Complex and synergistic interactions among abrasive wear, coating delamination, adhesive wear, oxidation wear, and thermal mechanical–mechanical impacts were the main wear or failure mechanisms. As the cutting speed was very high (>2000 m/min), discontinuous or fragment chips and even melt chips were produced, but few chips can be collected because the chips easily burned under the extremely high cutting temperature. Large area flaking, extreme abrasion, and serious adhesion dominated the wear patterns, and the tool wear mechanisms were the interaction of thermal wear and mechanical wear or failure under the ultra-high frequency and strong impact thermo-mechanical loads.

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