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.

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.

Tool Wear Investigation on Dry Electrostatic Cooling in Turning Titanium Alloy Ti6Al4V

2010 ◽  
Vol 97-101 ◽  
pp. 2058-2061 ◽  
Author(s):  
Hui Wang ◽  
Rong Di Han ◽  
Yang Wang
Keyword(s):  
Titanium Alloy ◽  
Tool Wear ◽  
Tool Life ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Cutting Fluid ◽  
Dry Cutting ◽  
Set Up ◽  
Titanium Alloy Ti6al4v ◽  
Emulsion Oil

The machinability of Titanium Alloy Ti6Al4V is poor, the traditional methods to machining is application of cutting fluids with the active additives which cause environmental pollution and health problems. In this paper, the dry electrostatic cooling was applied instead of cutting fluid for the aim of green cutting Ti6Al4V. The ionized device and gas supply system was set up, the effects of dry electrostatic cooling, emulsion oil and dry cutting on tool wear have been examined in turning of Ti6Al4V with carbide tools YG8, the curve between tool flank wear and cutting time was proposed, and the equation between cutting speed and tool life was set up. The results of experiments indicated that application of dry electrostatic cooling reduced the tool wear and increased the tool life. The research results show that clean production was achieved in metal cutting associated with dry electrostatic cooling.

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.

Analysis and Fabrication of a Mechanical Quick-Stop for Research on Chip Formation in Hard Turning Process

2019 ◽  
Vol 889 ◽  
pp. 87-94
Author(s):  
Nguyen Thi Quoc Dung
Keyword(s):  
Chip Formation ◽  
Hard Turning ◽  
Manufacturing Industry ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Cutting Process ◽  
Machining Process ◽  
Machining Parameters ◽  
Machining Processes ◽  
On Chip

Metal cutting is one of the most important machining processes in manufacturing industry. Thorough understanding of metal cutting process facilitates the optimization in selection of cutting tools and machining parameters. There are several methods used for studying phenomena in metal cutting process. Using a quick-top device is an efficient technique for investigation cutting process in which cutting action is stopped so suddenly that the “froze” specimen called the chip root honestly depicts what happened during cutting action. Design strategies of a quick-stop are accelerating cutting tool away from the workpiece or decelerating the workpiece remaining in engagement with the tool. Operation of a quick-stop device can be either mechanically or by explosive. Quick-stop devices can be utilized for various types of machining processes such as: turning, milling, drilling. This paper described the analysis, fabrication, and testing of a quick-stop device which is used for researching on chip formation in hard turning. This device has simple and safe operation which utilizes spring forces to retract the tool from workpiece during cutting. The results of performance at cutting speed of 283 m/min show that the separation distance is quite small, less than 0.2mm so that the deformations on the root chip are close to that while actual machining process. This indicates that the device has satisfied the requirements of an equipment for studying on chip formation.

scholarly journals Study on the Cutting Efficiency of High-Speed Band Saw Blade by Taylor Tool Life and Fractal Equations

2018 ◽  
Vol 201 ◽  
pp. 01001 ◽  
Author(s):  
Sung-Hua Wu ◽  
Ming-Shyan Huang ◽  
Cheng-En Jhou ◽  
Chin-Chung Wei
Keyword(s):  
Tool Life ◽  
Chip Formation ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Local Stress ◽  
Cutting Process ◽  
Cutting Efficiency ◽  
Improvement Rate ◽  
Sawing Process

The study proposed the chip formation steady-state model and cutting efficiency model for multi-cutters by Taylor tool life and fractal equation according to uniform chip thickness in high-speed band sawing process. Furthermore, a kind of new hook-tooth can be successfully applied on continuously uniformed chip formation in order to raise the production precision. The study developed MDOF cutting dynamics, which can be applied on multi-cutting process by Taylor tool life and fractal equations. Factors of affecting band-sawing included the cutting force, the cutting geometry, the cutting heat, the local stress-strain and the chip thickness formation uniformity. These factors had an important influence on tool wear, surface roughness, production precision and cutting efficiency in high-speed sawing process. The simulated results shown that, the wear resistance property is better at coating TiN 0.6 μm. In high-speed cutting process, the cutting improvement rate can be increased at least 13%. While the hook-tooth cutting speed achieved 120 m/min, comparing with non-coating cutting tooth, coating 0.6μm coating-layer can make the temperature decreased, obviously.

Self-Induced Vibrations in Metal Cutting

1962 ◽  
Vol 84 (4) ◽  
pp. 405-416 ◽  
Author(s):  
Paul Albrecht
Keyword(s):  
Tool Life ◽  
Chip Formation ◽  
Metal Cutting ◽  
Shear Angle ◽  
Physical Basis ◽  
Cutting Conditions ◽  
Cutting Process ◽  
Force Response ◽  
Dynamic Conditions ◽  
Cyclic Variations

Solution of the problem of dynamic stability for the machine tool-cutting process system depends primarily on the assessment of behavior of the cutting process under dynamic conditions. It has been found that under dynamic conditions, apart from force fluctuations due to variations in cutting conditions, additional force fluctuations take place as a result of cyclic variations of the shear angle in the cutting process. Difference in force response of a cutting process to the static dynamic variations of the cutting conditions has been explained by the presence of cyclic variations of shear angle under dynamic conditions. Peaks of the force wave, resulting from dynamic variation of the cutting conditions, are known to be displaced with respect to the originating wave. This displacement has been thought to be due to a time lag of the whole force response; however a sound physical basis for this point of view has not previously been found. The present investigation provides a physical basis for such observations, showing that the displacement of force peaks is caused by the skewing of the force wave by the presence of asymmetric force pulses due to cyclic variations of shear angle. The same event—the cyclic variation of the shear angle—has been recognized to be a sign of instability of the cutting process in itself, resulting in a cyclic chip formation process. Instability of the cutting process in itself has been found to depend mainly on the cutting conditions and not on the dynamic properties of the cutting system. Analytical expressions derived for the frequency and amplitude of cyclic chip formation have been found to be in a good agreement with the results of measurements of these quantities. Study of the effects of dynamic events in metal cutting upon tool life has revealed propagation of fatigue cracks on the wear land. The propagation of the cracks has been found to be in good correlation with the presence of force pulses due to the cyclic chip formation. The way in which the foregoing event affects the tool life has been reconstructed, allowing selection of those conditions which improve tool life.

Effect of Large Cross-Section Oxygen-Propane Flame Cutting on Microstructure in Heat-Affected Zone

2013 ◽  
Vol 274 ◽  
pp. 249-252
Author(s):  
Zhi Xin Wang ◽  
Yong Kui Han ◽  
Yong Qiu Chen
Keyword(s):  
Cross Section ◽  
Heat Affected Zone ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Pressure Vessels ◽  
Manufacturing Industries ◽  
Cutting Process ◽  
Pure Oxygen ◽  
Cutting Processes ◽  
34Crnimo6 Steel

Many metal-manufacturing industries include oxyfuel gas cutting among their manufacturing processes because cutting was often used in metal-cutting processes, specifically in the large castings and forgings and the fabrication of pressure vessels. The oxyfuel gas cutting process uses controlled chemical reactions to remove preheated metal by rapid oxidation in a stream of pure oxygen. Previous research has demonstrated microstructure in heat-affected zone varied depending on the gas used for the combustion as well as the cutting speed (Vc) used during the process. In this research, 34CrNiMo6 steel of 900 mm in thickness and 45 carbon steel of 450 mm in thickness were cut using an oxygen-propane flame cutting process. Then, macroscopic morphology and microstructure test were done to analyze the influence of the thickness of cutting cross-section. The results showed, in general, the width of heat-affected zone increased with the thickness of cutting cross-section. Also, it was demonstrated that heat-affected zone in the bottom and top section was wider than others.

Development of Cutting Tools With Micro-Textured Surface for High Speed Machining of Ti-6Al-4V

2021 ◽  
Author(s):  
Mitsuru Hasegawa ◽  
Tatsuya Sugihara
Keyword(s):  
Tool Life ◽  
High Speed ◽  
Metal Cutting ◽  
Failure Process ◽  
Cutting Tools ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Cutting Fluid ◽  
Textured Surface ◽  
Textured Surfaces

Abstract In cutting of Ti-6Al-4V alloy, the cutting speed is limited since a high cutting temperature leads to severe tool wear and short tool life, resulting in poor production efficiency. On the other hand, some recent literature has reported that various beneficial effects can be provided by forming micro-textures on the tool surface in the metal cutting process. In this study, in order to achieve high-performance machining of Ti-6Al-4V, we first investigated the mechanism of the tool failure process for a cemented carbide cutting tool in high-speed turning of Ti-6Al-4V. Based on the results, cutting tools with micro textured surfaces were developed under the consideration of a cutting fluid action. A series of experiments showed that the textured rake face successfully decreases the cutting temperature, resulting in a significant suppression of both crater wear and flank wear. In addition, the temperature zone where the texture tool is effective in terms of the tool life in the Ti-6Al-4V cutting was discussed.

scholarly journals Investigation into Performance of Multilayer Composite Nano-Structured Cr-CrN-(Cr0.35Ti0.40Al0.25)N Coating for Metal Cutting Tools

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 447 ◽  
Author(s):  
Sergey Grigoriev ◽  
Alexey Vereschaka ◽  
Alexander Metel ◽  
Nikolay Sitnikov ◽  
Filipp Milovich ◽  
...  
Keyword(s):  
Tool Life ◽  
Metal Cutting ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Constructional Steel ◽  
Wear Process ◽  
Layered Architecture ◽  
Process Pattern ◽  
Resistant Layer ◽  
Cutting Speeds

This paper deals with the Cr-CrN-(Cr0.35Ti0.40Al0.25)N coating. It has a three-layered architecture with a nano-structured wear-resistant layer. The studies involved the investigation into the microstructure (with the use of SEM and TEM), elemental and phase composition (XRD and SAED patterns), wear process pattern in scratch testing, crystal structure, as well as the microhardness of the coating. Cutting tests of tools with the above coating were carried out in dry turning of steel 1045 at cutting speeds of vc = 200, 250, and 300 m·min−1. The comparison included uncoated tools and tools with the commercial TiN and (Ti,Al)N coatings with the same thickness. The tool with the Cr-CrN-(Cr0.35Ti0.40Al0.25)N coating showed the longest tool life at all the cutting speeds under consideration. Meanwhile, a tool with the coating under study can be recommended for use in turning constructional steel at the cutting speed of vc = 250 m·min−1. At this cutting speed, a tool shows the combination of a rather long tool life and balanced wear process, without any threat of catastrophic wear.

Numerical Investigation of Heat Partition in the Primary Shear Zone in Metal Cutting

2005 ◽  
Author(s):  
Vasant Pednekar ◽  
Vis Madhavan ◽  
Amir H. Adibi-Sedeh
Keyword(s):  
Partition Coefficient ◽  
Strain Rate ◽  
Shear Zone ◽  
Metal Cutting ◽  
Plastic Material ◽  
Shear Plane ◽  
Analytical Models ◽  
Machined Surface ◽  
Element Analysis ◽  
Heat Partition

The fraction of heat generated in the primary shear zone that is conducted into the workpiece is a key factor in the calculation of the shear plane temperature and in calculating the cutting forces based on material flow stress. Accurate analytical, numerical, or experimental determination of this heat partition coefficient is not available to date. This study utilizes a new approach to obtain the heat partition coefficient for the primary shear zone using results for strain, strain rate, and temperature distribution obtained from a coupled thermo-mechanical finite element analysis of machining. Different approaches, using strain rate and equivalent strain, are used for calculating the total plastic power in the primary shear zone and the heat generated by plastic deformation below the plane of the machined surface. The heat carried away by the workpiece is obtained by calculating the heat flow by convection in regions where the conduction is expected to be small. We have used an elastic perfectly plastic material model and constant thermal properties to mimic the assumptions used in analytical models. The fraction of the total heat generated in the primary shear zone that is conducted into the machined workpiece is found and compared to the prediction of different analytical models. It is found that for most of the cutting conditions, the values of heat partition coefficient are closest to those provided by Weiner’s model.

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