Micro-Structural Analysis of Chip Formation During Orthogonal Machining of Al/SiCp Composites

2000 ◽  
Vol 123 (3) ◽  
pp. 315-321 ◽  
Author(s):  
S. S. Joshi ◽  
N. Ramakrishnan ◽  
P. Ramakrishnan
Keyword(s):  
Free Surface ◽  
Structural Analysis ◽  
Chip Formation ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Shear Plane ◽  
Point Of View ◽  
Unique Case ◽  
Orthogonal Machining ◽  
Cutting Point

Discontinuously Reinforced Aluminum (DRA) Composites form unique case from the research in metal cutting point of view. Reinforcement in these materials acts as “macroscopic” and “isolated” discontinuities in the path of the tool. The mechanism of chip formation for such materials is yet to be evolved completely. In this paper, the mechanism of chip formation during machining of Al/SiCp composites based on the micro-structural analysis of chips and chip roots is presented. It was evident that the mechanism involves initiation of a gross fracture on the chip free surface and its propagation toward the tool nose. The extent of propagation of gross fracture depends upon the cutting speed and volume of reinforcement in composites. A model of deformation of the material along the shear plane is presented in terms of a ratio of length of flow-type deformation on the shear plane to the total length of shear plane. Influence of volume of reinforcement in composites and cutting speed on the ratio was verified experimentally.

New Development in the Theory of the Metal-Cutting Process: Part II—The Theory of Chip Formation

1961 ◽  
Vol 83 (4) ◽  
pp. 557-568 ◽  
Author(s):  
P. Albrecht
Keyword(s):  
Shear Zone ◽  
Tool Life ◽  
Chip Formation ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Shear Plane ◽  
Cutting Process ◽  
Chip Formation Mechanism ◽  
Bending Stresses ◽  
Set Up

Introduction of the concept of ploughing into the metal-cutting process lead to the abandoning of the assumption of collinearity of the resultant force on tool face and on the shear plane. With this understanding the tool face force is found to produce a bending effect causing bending stresses in the shear zone. Study of the chip formation mechanism when varying cutting speed showed that increased bending action reduces the shear angle and vice versa. A set-up for the development of an analytical model of the chip formation process based on the combined effect of shear and bending stresses in the shear zone has been given. Application of the gained insight to the design of the cutting tool for maximum tool life by controlling of the chip-tool contact was suggested. Brief introduction to the study of cyclic events in chip formation and their relation to the tool life is presented.

Microstructural Characterization of Chip Segmentation Under Different Machining Environments in Orthogonal Machining of Ti6Al4V

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Shashikant Joshi ◽  
Asim Tewari ◽  
Suhas S. Joshi
Keyword(s):  
Plastic Strain ◽  
Room Temperature ◽  
Microstructural Analysis ◽  
Cutting Speed ◽  
Microstructural Characterization ◽  
Shear Plane ◽  
Band Formation ◽  
Orthogonal Machining ◽  
Two Temperatures ◽  
Experimental Values

Segmented chips are known to form in machining of titanium alloys due to localization of heat in the shear zone, which is a function of machining environment. To investigate the correlation between machining environments and microstructural aspects of chip segmentation, orthogonal turning experiments were performed under three machining environments, viz., room, LN2, and 260 °C. Scanning electron and optical microscopy of chip roots show that the mechanism of chip segment formation changes from plastic strain and mode II fracture at room temperature, to predominant mode I fracture at LN2 and plastic strain leading to shear band formation at 260 °C. The chip segment pitch and shear plane length predicted using Deform™ matched well with the experimental values at room temperature. The microstructural analysis of chips show that higher shear localization occurs at room temperature than the other two temperatures. The depth of machining affected zone (MAZ) on work surfaces was lower at the two temperatures than that of at the room temperature at a higher cutting speed of 91.8 m/min.

scholarly journals Experiments in the Machining of Ice at Negative Rake Angles

1984 ◽  
Vol 30 (104) ◽  
pp. 77-81 ◽  
Author(s):  
D.K. Lieu ◽  
C.D. Mote
Keyword(s):  
Cutting Force ◽  
Chip Formation ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Rake Angle ◽  
Cutting Depth ◽  
Orthogonal Machining ◽  
Cutting Force Components ◽  
Force Components

AbstractThe cutting force components and the cutting moment on the cutting tool were measured during the orthogonal machining of ice with cutting tools inclined at negative rake angles. The variables included the cutting depth (< 1 mm), the cutting speed (0.01 ms−1to 1 ms−1), and the rake angles (–15° to –60°). Results of the experiments showed that the cutting force components were approximately independent of cutting speed. The resultant cutting force on the tool was in a direction approximately normal to the cutting face of the tool. The magnitude of the resultant force increased with the negative rake angle. Photographs of ice-chip formation revealed continuous and segmented chips at different cutting depths.

A New Analysis of the Forces in Orthogonal Metal Cutting

1965 ◽  
Vol 87 (4) ◽  
pp. 480-486 ◽  
Author(s):  
J. D. Cumming ◽  
S. Kobayashi ◽  
E. G. Thomsen
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Minimum Energy ◽  
Cutting Speed ◽  
Shear Plane ◽  
Force Model ◽  
Shearing Stress ◽  
Orthogonal Metal Cutting ◽  
Linear Force ◽  
Dynamic Shearing

The mechanics of orthogonal cutting have been reexamined and for the shear-plane concept of metal cutting, linear and quadratic-force models were suggested. It was shown that for steel SAE-1213, investigated under variable cutting conditions, the dynamic shearing stress remained constant and the linear-force model correlated with those experimental data which were obtained under the absence of a BUE. The angle λ formed by the shear plane and the direction of the resultant force remained constant for each test condition but varied with cutting speed. Neither the Ernst and Merchant minimum energy, nor the Lee and Shaffer solutions are in agreement with experimental observations.

Cutting Model in Machining of Al/SiCp Metal Matrix Composite

2011 ◽  
Vol 410 ◽  
pp. 291-297
Author(s):  
Sayed Mohamad Nikouei ◽  
R. Yousefi ◽  
Mohammad Ali Kouchakzadeh ◽  
M.A. Kadivar
Keyword(s):  
Chip Formation ◽  
Cutting Forces ◽  
Metal Matrix ◽  
Cutting Speed ◽  
Shear Plane ◽  
Good Method ◽  
Depth Of Cut ◽  
Machining Forces ◽  
Experimental Cutting ◽  
Cutting Model

Prediction of shear plane angle is a way for prediction of the mechanism of chip formation, machining forces and so on. In this study, Merchant and Lee-Shaffer theories are used for prediction of shear plane angles and cutting forces in machining of Al/SiCpMMC with 20% of SiC as reinforcement particles. The experimental cutting forces are compared with the calculated cutting force based on shear plane angles extracted from Merchant and Lee-Shaffer theories. The variation of these cutting forces with cutting speed, feed rate and depth of cut has been discussed. The results showed that Merchant theory may be used as a good method for prediction of chip formation in machining of Al/SiCpMMC.

Mechanics of Saw-Tooth Chip Formation in Metal Cutting

1999 ◽  
Vol 121 (2) ◽  
pp. 163-172 ◽  
Author(s):  
A. Vyas ◽  
M. C. Shaw
Keyword(s):  
Chip Formation ◽  
Hard Turning ◽  
Metal Cutting ◽  
Weight Ratio ◽  
Point Of View ◽  
Root Cause ◽  
Aerospace Applications ◽  
High Speeds ◽  
Thermal Origin ◽  
Extensive Experimental Data

The saw-tooth chip was the last of the major types to be identified. This occurred in 1954 during machining studies of titanium alloys which were then being considered for aerospace applications because of their large strength-to-weight ratio and corrosion resistance. This is a type of chip that forms when very hard brittle materials are machined at high speeds and feeds. Since this is an area of machining which will be of increasing interest in the future, particularly in hard turning, it is important that the mechanism and mechanics of this type of chip formation be better understood. At present, there are two theories concerning the basic origin of saw-tooth chips. The first to appear assumed they are of thermal origin while the second assumes they arise due to the periodic development of cracks in the original surface of the work. The thesis presented here is that the root cause for saw-tooth chip formations is cyclic cracking. This is followed by a discussion of extensive experimental data that supports this point of view.

Chip Formation in High-Speed Milling of Titanium Alloy with PCD Tools

2014 ◽  
Vol 800-801 ◽  
pp. 150-154 ◽  
Author(s):  
An Hai Li ◽  
Jun Zhao ◽  
Hong Guo Zheng ◽  
Yong Hong Lu
Keyword(s):  
Free Surface ◽  
Chip Formation ◽  
High Speed ◽  
End Milling ◽  
Cutting Speed ◽  
Sharp Decrease ◽  
Water Soluble ◽  
Cutting Fluid ◽  
High Speed Milling ◽  
Pcd Tools

This paper presents a detailed analysis of chip morphology through an experimental study of high-speed milling of Ti-6Al-4V alloy with PCD tools. Milling tests were conducted for cutting speed range from 125 m/min to 2000 m/min with water-soluble cutting fluid. The collected chips were firstly examined with a digital cameras and the free surface of the chips was analyzed by a scanning electron microscope (SEM). Geographical parameters of chip morphologies were described in saw-tooth/lamella frequency on the free surface and chip width. Experimental results show that the variation of chips in high-speed end milling of Ti-6Al-4V alloy is as follows, long and straight-shaped → spiral-shaped → curly-shaped → irregular-shaped. The free surface of chips exhibits saw-tooth lamella structures. The lamella becomes clearer and more obvious at higher cutting speeds. Within the same measurement distance, there is a sharp decrease in the lamella number within same measuring range. This should be attributed to the enhancement of the thermal mechanical coupled field applied to the chip formation processes.

An Analysis of the Mechanism of Orthogonal Cutting and Its Application to Discontinuous Chip Formation

1961 ◽  
Vol 83 (4) ◽  
pp. 545-555 ◽  
Author(s):  
Keiji Okushima ◽  
Katsundo Hitomi
Keyword(s):  
Chip Formation ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Plastic Region ◽  
Flow Region ◽  
Shear Plane ◽  
Experimental Result ◽  
Conventional Theory ◽  
Boundary Lines ◽  
Continuous Chip

Instead of the conventional theory of the mechanics of metal cutting based on a process of shear confined to a single shear plane, the concept of flow region, a fairly large transitional deformation zone which exists between the rigid region of work and the plastic region of steady chip, was developed. The mechanics of orthogonal cutting was analyzed, theoretical equations for angles of boundary lines of the flow region and for strain in chip were deduced in the case of simple continuous chip formation and confirmed in cutting tests on lead. The concept of flow region was also applied to discontinuous chip formation, and theoretical expressions for angles of boundary lines of the flow region were ascertained to be in agreement with the experimental result for carbon steel.

scholarly journals Strain Rate of Metal Deformation in the Machining Process from a Fluid Flow Perspective

2020 ◽  
Vol 10 (9) ◽  
pp. 3057
Author(s):  
Keguo Zhang ◽  
Keyi Wang ◽  
Zhanqiang Liu ◽  
Xiaodong Xu
Keyword(s):  
Fluid Flow ◽  
Strain Rate ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Shear Plane ◽  
Cutting Process ◽  
Machining Process ◽  
Rake Face ◽  
Metal Deformation

Metal cutting speeds are getting faster with the development of high-speed cutting technology, and with the increase in cutting speed, the strain rate will become larger, which makes the study of the metal cutting process more inconvenient. At the same time, with the increase in strain rate, the dislocation movement controlling the plastic deformation mechanism of metal will change from thermal activation to a damping mechanism, which makes the metal deformation behave more like a fluid. Therefore, it is necessary to explore new ways of studying machining from the perspective of fluid flow. Based on this, a fluid model of the metal cutting process is established, and a method for calculating the strain rate is proposed from the point of view of flow. The results of the simulation and measurements are compared and analyzed. The results show that the strain rate on the rake face will be affected by the friction between the chip and tool; the nearer the distance between the chip layer and tool rake face, the bigger the strain rate will be. The strain rate in the central shear plane is much larger than in other areas along the shear plane direction, and in which two ends are the biggest. It can achieve rougher, quantitative research. This shows it is feasible to study machining from the viewpoint of fluid flow, though it still needs a lot of theoretical support and experimental confirmation.

scholarly journals Fracture toughness, chip types and the mechanics of cutting wood. A review COST Action E35 2004–2008: Wood machining – micromechanics and fracture

Holzforschung ◽  
2009 ◽  
Vol 63 (2) ◽  
Author(s):  
David J. Wyeth ◽  
Giacomo Goli ◽  
Anthony G. Atkins
Keyword(s):  
Fracture Toughness ◽  
Chip Formation ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Surface Damage ◽  
Surface Separation ◽  
Wood Processing ◽  
Shear Yield ◽  
The Cost

Abstract Historical studies for predicting cutting forces in wood processing are based on the Piispanen/Ernst-Merchant theory employed in metal cutting where the offcut/chip is formed in shear. This analysis has been recently improved to include significant work of surface separation and formation (i.e., the fracture toughness of the workpiece, as well as the shear yield stress and friction). The new theory is applied here to wood cutting experiments. It is well known that chip formation and surface damage depend on grain orientation and chip thickness, but experiments reveal that chip formation alters with cutting speed as well. During the COST E35 action a series of experiments and special devices to orthogonally cut wood at high and low speed have been developed. In this paper, an overview of the cutting devices and the main results are given.

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