Mechanics of Metal Cutting for a Material of Variable Flow Stress

1963 ◽  
Vol 85 (4) ◽  
pp. 339-345 ◽  
Author(s):  
P. L. B. Oxley
Keyword(s):  
Flow Stress ◽  
Carbon Tetrachloride ◽  
Cutting Force ◽  
Shear Zone ◽  
Metal Cutting ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Variable Depth ◽  
Variable Flow ◽  
Interface Friction

A new analysis is presented in which the variable flow stress property of the work material is taken into account. It is shown that changes in the so-called angle of tool-chip interface friction can result from changes in the shear zone mechanism and, for example, the paradoxical behavior observed when cutting with carbon tetrachloride as a “lubricant” can be accounted for in this way. It is concluded that if actual predictions are to be made about the cutting process, i.e., without first making cutting tests, then the angle of tool-chip interface friction cannot be accepted as given information. The analysis is extended to cutting with a variable depth of cut, and in agreement with experiment it is predicted that, with all other cutting conditions the same, the cutting force will be less for an increasing depth of cut than for a decreasing depth of cut.

Influence of Free Surface Environment on the Shear Zone in Metal Cutting

1966 ◽  
Vol 181 (1) ◽  
pp. 687-705 ◽  
Author(s):  
P. L. Barlow
Keyword(s):  
Free Surface ◽  
Carbon Tetrachloride ◽  
Strain Hardening ◽  
Shear Zone ◽  
Chemical Reaction ◽  
Cutting Forces ◽  
Metal Cutting ◽  
The Body ◽  
Surface Barrier ◽  
Rehbinder Effect

It has previously been suggested that the reduction in cutting forces obtained by the presence of fluids such as CCl4 on the backface or free surface of the forming chip was due to diffusion of the fluid into the body of the chip in the region of the shear zone. In the present work, experiments with carbon tetrachloride tagged with carbon-14 and with carbon tetrachloride tagged with chlorine-36 were performed with the object of assessing the extent of diffusion of lubricants into the chip when present on the free surface only. The results obtained disprove former hypotheses and suggest that the reduced cutting force is due solely to chemical reaction at the surface of the chip. Confirmation of the sensitivity of the surface of the deforming shear zone to change in surface condition was obtained by removing metal from this region by an electropolishing technique during slow speed cutting. By varying the electropolishing conditions increased or decreased cutting forces could be obtained. It is proposed that the result both of chemical reaction at the surface and of surface removal is to reduce the strain-hardening rate of the metal undergoing shear by reducing the surface barrier to the flow of dislocations out of the metal. The association of the surface reaction of carbon tetrachloride with a change in the strain-hardening characteristics of the metal in the shear zone leads to a classification of the backface phenomenon as a Rehbinder effect and enables this effect to be more closely defined than was hitherto possible. Evidence is also presented which indicates that the backface effect does not contribute to the reduction in cutting forces during rakeface lubrication and is therefore unimportant in practice where flood lubrication of the cutting region invariably occurs.

scholarly journals Investigation of AlCrN-Coated Inserts on Cryogenic Turning of Ti-6Al-4V Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1338
Author(s):  
Lakshmanan Selvam ◽  
Pradeep Kumar Murugesan ◽  
Dhananchezian Mani ◽  
Yuvaraj Natarajan
Keyword(s):  
Tool Wear ◽  
Cutting Force ◽  
Physical Vapor Deposition ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Machined Surface ◽  
Coated Carbide ◽  
Cryogenic Conditions

Over the past decade, the focus of the metal cutting industry has been on the improvement of tool life for achieving higher productivity and better finish. Researchers are attempting to reduce tool failure in several ways such as modified coating characteristics of a cutting tool, conventional coolant, cryogenic coolant, and cryogenic treated insert. In this study, a single layer coating was made on cutting carbide inserts with newly determined thickness. Coating thickness, presence of coating materials, and coated insert hardness were observed. This investigation also dealt with the effect of machining parameters on the cutting force, surface finish, and tool wear when turning Ti-6Al-4V alloy without coating and Physical Vapor Deposition (PVD)-AlCrN coated carbide cutting inserts under cryogenic conditions. The experimental results showed that AlCrN-based coated tools with cryogenic conditions developed reduced tool wear and surface roughness on the machined surface, and cutting force reductions were observed when a comparison was made with the uncoated carbide insert. The best optimal parameters of a cutting speed (Vc) of 215 m/min, feed rate (f) of 0.102 mm/rev, and depth of cut (doc) of 0.5 mm are recommended for turning titanium alloy using the multi-response TOPSIS technique.

Predicting Cutting Forces for Oblique Machining Conditions

1982 ◽  
Vol 196 (1) ◽  
pp. 141-148 ◽  
Author(s):  
G C I Lin ◽  
P Mathew ◽  
P L B Oxley ◽  
A R Watson
Keyword(s):  
Thermal Properties ◽  
Flow Stress ◽  
Cutting Force ◽  
Plane Strain ◽  
Cutting Forces ◽  
Material Flow ◽  
Cutting Conditions ◽  
Orthogonal Plane ◽  
Simplifying Assumptions ◽  
Experimental Cutting

Using orthogonal (plane strain) machining theory together with certain simplifying assumptions based on experimental observations it is shown how the three components of cutting force in oblique machining can be predicted from a knowledge of the work material flow stress and thermal properties and the cutting conditions. A comparison of predicted and experimental cutting force results is given.

Force Modeling in Laser-Assisted Microgrooving Including the Effect of Machine Deflection

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Ramesh Singh ◽  
Shreyes N. Melkote
Keyword(s):  
Flow Stress ◽  
Cutting Force ◽  
Cutting Forces ◽  
Laser Power ◽  
Continuous Wave ◽  
Dimensional Accuracy ◽  
Thermal Softening ◽  
Depth Of Cut ◽  
Force Model ◽  
Cutting Force Model

Laser assisted mechanical micromachining is a process that utilizes highly localized thermal softening of the material by continuous wave laser irradiation applied simultaneously and directly in front of a miniature cutting tool in order to produce micron scale three-dimensional features in difficult-to-machine materials. The hybrid process is characterized by lower cutting forces and deflections, fewer tool failures, and potentially higher material removal rates. The desktop-sized machine used to implement this process has a finite stiffness and deflects under the influence of the cutting forces. The deflections can be of the same order of magnitude as the depth of cut in some cases, thereby having a negative effect on the dimensional accuracy of the micromachined feature. As a result, selection of the laser and cutting parameters that yield the desired reduction in cutting forces and deflection, and consequently an improvement in dimensional accuracy, requires a reliable cutting force model. This paper describes a cutting force model for the laser-assisted microgrooving process. The model accounts for the effect of elastic deflection of the machine X-Y stages on the forces and accuracy of the micromachined feature. The model combines an existing slip-line field based force model with a finite element based thermal model of laser heating and a constitutive material flow stress model to account for thermal softening. Experiments are carried out on H-13 steel (42 HRC (hardness measured on the Rockwell ‘C’ scale)) to validate the force model. The effects of process parameters, such as laser power and cutting speed, on the forces are also analyzed. The model captures the effect of thermal softening and indicates a 66% reduction in the shear flow stress at 35 W laser power. The cutting force and depth of cut prediction errors are less than 20% and 10%, respectively, for most of the cases examined.

Effects of Cutting Conditions on the Machinability of Stainless Steel Formed by Laser Cladding

2013 ◽  
Vol 797 ◽  
pp. 166-171
Author(s):  
Bing Wang ◽  
Zhan Qiang Liu ◽  
Lun Chang Su ◽  
Lin Qing Zhang
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Cutting Force ◽  
Laser Cladding ◽  
Cutting Parameters ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Corner Radius ◽  
1045 Steel

The paper investigates the effects of cutting conditions on the machinability of stainless steel coatings manufactured onto AISI 1045 steel by laser cladding technology. Two kinds of CBN (cubic boron nitride) tools with different corner radius and two different depths of cut were adopted in the experiments. Cutting force during machining, surface roughness and microhardness of machined surface were measured and analyzed. The results show that both the cutting force and surface roughness increase with the increase of depth of cut. When the other cutting parameters are identical, the surface roughness decreases with the increase of tools corner radius while the variations of different cutting force components present different tendencies. The microhardness of the machined surface and its varied gradient in the direction of depth of cut increase with the increase of tools corner radius. The experiment results will provide valuable suggestions for optimization of cutting performance for laser cladding coatings in order to obtain excellent surface quality.

A Preliminary Study on Machinability of Super Austenitic Stainless Steel

2015 ◽  
Author(s):  
Ashwin Polishetty ◽  
Mohanad Fakhri Abdulqader Alabdullah ◽  
Nihal Pillay ◽  
Guy Littlefair
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cutting Force ◽  
Metal Cutting ◽  
Metal Removal ◽  
Metallographic Analysis ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Microstructural Changes ◽  
Super Austenitic Stainless Steel

Stainless steel is the most widely used alloys of steel. The reputed variety of stainless steel having customised material properties as per the design requirements is Duplex Stainless Steel and Austenitic Stainless Steel. The Austenite Stainless Steel alloy has been developed further to be Super Austenitic Stainless Steel (SASS) by increasing the percentage of the alloying elements to form the half or more than the half of the material composition. SASS (Grade-AL-6XN) is an alloy steel containing high percentages of nickel (24%), molybdenum (6%) and chromium (21%). The chemical elements offer high degrees of corrosion resistance, toughness and stability in a large range of hostile environments like petroleum, marine and food processing industries. SASS is often used as a commercially viable substitute to high cost non-ferrous or non-metallic metals. The ability to machine steel effectively and efficiently is of utmost importance in the current competitive market. This paper is an attempt to evaluate the machinability of SASS which has been a classified material so far with very limited research conducted on it. Understanding the machinability of this alloy would assist in the effective forming of this material by metal cutting. The novelty of research associated with this is paper is reasonable taking into consideration the unknowns involved in machining SASS. The experimental design consists of conducting eight milling trials at combination of two different feed rates, 0.1 and 0.15 mm/tooth; cutting speeds, 100 and 150 m/min; Depth of Cut (DoC), 2 and 3 mm and coolant on for all the trials. The cutting tool has two inserts and therefore has two cutting edges. The trial sample is mounted on a dynamometer (type 9257B) to measure the cutting forces during the trials. The cutting force data obtained is later analyzed using DynaWare supplied by Kistler. The machined sample is subjected to surface roughness (Ra) measurement using a 3D optical surface profilometer (Alicona Infinite Focus). A comprehensive metallography process consisting of mounting, polishing and etching was conducted on a before and after machined sample in order to make a comparative analysis of the microstructural changes due to machining. The microstructural images were capture using a digital microscope. The microhardness test were conducted on a Vickers scale (Hv) using a Vickers microhardness tester. Initial bulk hardness testing conducted on the material show that the alloy is having a hardness of 83.4 HRb. This study expects an increase in hardness mostly due to work hardening may be due to phase transformation. The results obtained from the cutting trials are analyzed in order to judge the machinability of the material. Some of the criteria used for machinability evaluation are cutting force analysis, surface texture analysis, metallographic analysis and microhardness analysis. The methodology followed in each aspect of the investigation is similar to and inspired by similar research conducted on other materials. However, the novelty of this research is the investigation of various aspects of machinability and drawing comparisons between each other while attempting to justify each result obtained to the microstructural changes observed which influence the behaviour of the alloy. Due to the limited scope of the paper, machinability criteria such as chip morphology, Metal Removal Rate (MRR) and tool wear are not included in this paper. All aspects are then compared and the optimum machining parameters are justified with a scope for future investigations.

Experimental Investigations of Cutting Conditions Influence on Main Cutting Force and Surface Roughness Based on Chip Form Types in Cast Nylon Turning

2011 ◽  
Vol 110-116 ◽  
pp. 3563-3569 ◽  
Author(s):  
Bandit Suksawat
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Feed Rate ◽  
Causal Effect ◽  
Cutting Speed ◽  
High Speed Steel ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Path Coefficient ◽  
Cutting Depth

This paper aims to investigate cutting conditions influence on main cutting force and surface roughness based on considered chip form types in cast nylon turning operation with single-point high speed steel cutting tool. The 75 experiments were performed by average of three levels of cutting speed, five levels of cutting depth and five levels of feed rate. The results reveal that main cutting forces were increased by an increasing of cutting speed and cutting depth for all obtained chip form types for all chip form types. The surface roughness is affected by increasing of feed rate and reduction of cutting speed for 2.3 Snarled and 4.3 Snarled chip form types. The statistical path-coefficient analysis results are shown that the main cutting force affected by cutting speed, depth of cut and feed rate with total causal effect value of 0.5537, 0.4785 and 0.1718, respectively. The surface roughness is influenced by feed rate, cutting speed and depth of cut with 0.8400, -0.2419 and-0.0711 of total causal effect value, respectively. These results are useful to perform varying cutting conditions for high quality of workpiece in cast nylon turning by control the chip form type.

A Fractal Analysis of Cutting Force in Simulation and Experiment

2013 ◽  
Vol 589-590 ◽  
pp. 122-127 ◽  
Author(s):  
Guang Ming Zheng ◽  
Jun Zhao ◽  
Xin Yu Song ◽  
Xiang Cheng
Keyword(s):  
Fractal Dimension ◽  
Cutting Force ◽  
Fractal Analysis ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Element Model ◽  
Cutting Process ◽  
Depth Of Cut ◽  
Practical Implementation ◽  
Mechanical Coupling

A 3D finite element model (FEM) of metal cutting was constructed based on the thermal-mechanical coupling theory. The cutting process of Sialon ceramic tools turning Inconel 718 was simulated and experimented. The effect of cutting speed, feed rate and depth of cut on the cutting force was analyzed. According to the correlation characteristics between the data points, the fractal characteristics of cutting forces in the cutting process were also investigated. The results showed that the cutting speed had a great effect on the fractal dimension of cutting force. The simulation results were in good agreement with the experimental findings. It was concluded that the minimum fractal dimension of cutting force was obtained at v=230 m/min under these experiment conditions. The fractal analysis is a simple and powerful tool for quantifying the stability of cutting process. The finding of this research is valuable for future practical implementation.

scholarly journals EFFECT OF CUTTING SPEED IN THE TURNING PROCESS OF AISI 1045 STEEL ON CUTTING FORCE AND BUILT-UP EDGE (BUE) CHARACTERISTICS OF CARBIDE CUTTING TOOL

SINERGI ◽  
2020 ◽  
Vol 24 (3) ◽  
pp. 171
Author(s):  
Sobron Yamin Lubis ◽  
Sofyan Djamil ◽  
Yehezkiel Kurniawan Zebua
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Cutting Process ◽  
Depth Of Cut ◽  
Aisi 1045 Steel ◽  
1045 Steel

In the machining of metal cutting, cutting tools are the main things that must be considered. Using improper cutting parameters can cause damage to the cutting tool. The damage is Built-Up Edge (BUE). The situation is undesirable in the metal cutting process because it can interfere with machining, and the surface roughness value of the workpiece becomes higher. This study aimed to determine the effect of cutting speed on BUE that occurred and the cutting strength caused. Five cutting speed variants are used. Observation of the BUE process is done visually, whereas to determine the size of BUE using a digital microscope. If a cutting tool occurs BUE, then the cutting process is stopped, and measurements are made. This study uses variations in cutting speed consisting of cutting speed 141, 142, 148, 157, 163, and 169 m/min, and depth of cut 0.4 mm. From the results of the study were obtained that the biggest feeding force is at cutting speed 141 m/min at 347 N, and the largest cutting force value is 239 N with the dimension of BUE length: 1.56 mm, width: 1.35 mm, high: 0.56mm.

ANALYSIS OF CUTTING FORCES WHILE TURNING DIFFERENT MATERIAL

2020 ◽  
Vol 15 (4) ◽  
Author(s):  
Krishna Kumar M ◽  
Sangaravadivel P
Keyword(s):  
Cutting Force ◽  
Strain Gauge ◽  
Cutting Forces ◽  
Metal Cutting ◽  
Tool Material ◽  
Radial Force ◽  
Machining Process ◽  
Depth Of Cut ◽  
Work Piece ◽  
Feed Force

The measurement of cutting forces in metal cutting is essential to estimate the power requirements, to design the cutting tool and to analyze machining process for different work and tool material combination. Although cutting forces can be measured by different methods, the measurement of cutting forces by a suitable dynamometer is widely used in industrial practice. Mechanical and strain gauge dynamometer are most widely used for measuring forces in metal cutting. The principle of all dynamometers is based on the measurement of deflections or strain produced from the dynamometer structure from the action of cutting force. In this project, a dynamometer is used to measure cutting force, feed force and radial force by using strain gauge accelerometer while turning different material in lathe. The dynamometer is a 500kg force 3- component system. As the tool comes in contact with the work piece the various forces developed are captured and transformed into numerical form system. In this project three forces of different materials such as aluminum, mild steel, brass, copper have been noted down. The forces on these materials with variation in speed and depth of cut are studied. Graphs are drawn on how these forces vary due to variation in speed.

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