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.

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.

On the Effects of a Built-Up Edge on Acoustic Emission in Metal Cutting

1990 ◽  
Vol 112 (2) ◽  
pp. 184-189 ◽  
Author(s):  
D. V. Hutton ◽  
Qinghuan Yu
Keyword(s):  
Acoustic Emission ◽  
Experimental Evidence ◽  
Deformation Zone ◽  
Metal Cutting ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Rake Angle ◽  
Shear Angle ◽  
Cutting Conditions ◽  
Effective Rake Angle

Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. Results for machining SAE 1018 and 4140 steels show that the built-up edge can mask the generally accepted AE-cutting speed relation when cutting tools having small rake angles are used. Under cutting conditions conducive to development of a built-up edge, it is shown that increased acoustic emission is generated as a result of increased effective rake angle and corresponding increase of shear angle in the primary deformation zone. Three distinct types of built-up edge have been observed and classified as immature, periodic, or developed, according to effect on acoustic emission.

scholarly journals FEM-Based Study of Precision Hard Turning of Stainless Steel 316L

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2522 ◽  
Author(s):  
Ahmed Elkaseer ◽  
Ali Abdelaziz ◽  
Mohammed Saber ◽  
Ahmed Nassef
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Process Parameters ◽  
Chip Formation ◽  
Feed Rate ◽  
Cutting Conditions ◽  
Cutting Process ◽  
Surface Generation ◽  
Stainless Steel 316L ◽  
Edge Radius

This study aims to investigate chip formation and surface generation during the precision turning of stainless steel 316L samples. A Finite Element Method (FEM) was used to simulate the chipping process of the stainless steel but with only a restricted number of process parameters. A set of turning tests was carried out using tungsten carbide tools under similar cutting conditions to validate the results obtained from the FEM for the chipping process and at the same time to experimentally examine the generated surface roughness. These results helped in the analysis and understanding the chip formation process and the surface generation phenomena during the cutting process, especially on micro scale. Good agreement between experiments and FEM results was found, which confirmed that the cutting process was accurately simulated by the FEM and allowed the identification of the optimum process parameters to ensure high performance. Results obtained from the simulation revealed that, an applied feed equals to 0.75 of edge radius of new cutting tool is the optimal cutting conditions for stainless steel 316L. Moreover, the experimental results demonstrated that in contrast to conventional turning processes, a nonlinear relationship was found between the feed rate and obtainable surface roughness, with a minimum surface roughness obtained when the feed rate laid between 0.75 and 1.25 times the original cutting edge radius, for new and worn tools, respectively.

scholarly journals Effects of the Controlled Shear Angle on the Metal Cutting Process

1971 ◽  
Vol 37 (441) ◽  
pp. 701-707
Author(s):  
Tateshi KISHINAMI ◽  
Toshihiko AKIYAMA ◽  
Koichi HOSHI
Keyword(s):  
Metal Cutting ◽  
Shear Angle ◽  
Cutting Process

Chip Serration Frequency - The Primary Cause of Chatter during End Milling Operation

2011 ◽  
Vol 264-265 ◽  
pp. 1174-1179
Author(s):  
Anayet Ullah Patwari ◽  
A.K.M. Nurul Amin ◽  
Waleed Fekry Faris ◽  
Marian Azhari ◽  
S. Farahain
Keyword(s):  
Machine Tool ◽  
Tool Life ◽  
Formation Process ◽  
Chip Formation ◽  
End Milling ◽  
Ti6al4v Alloy ◽  
Cutting Conditions ◽  
Natural Mode ◽  
Machining Accuracy ◽  
System Components

Chatter is an unwanted but sometimes unavoidable phenomenon in machining. The term defines the self-excited violent relative dynamic motion between the cutting tool and work-piece. Chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy, tool life, machine-tool bearings, and machine-tool life. It is also responsible for reducing output. This paper includes the findings of an experimental study on instabilities of the chip formation process during end milling of Ti6Al4V alloy at different cutting conditions with two different two holders and its influencing factors on chatter formation. The instabilities of chip formation process are expressed as primary or secondary serrated frequency. The chip formed at different cutting conditions is analyzed and its frequency was calculated. It is observed that the primary serrated frequency is more prominent in end milling of Ti6Al4V alloy and its chip serration frequency has significant interaction effect with the with the prominent natural mode frequency of the system components. The vibration signals in frequency domain (FFT) have been analyzed to identify the chatter frequencies which have been compared with the chip serration frequencies in different cutting conditions for two different tool holders. It has been fairly concluded from the experimental findings that chatter is the outcome of resonance, in between the frequency of primary or secondary serrated frequency with the „prominent natural frequency‟ modes of the system components.

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.

Application Features of the Cutting Tool, Hardened by Laser Pulsed Radiation

2016 ◽  
Vol 870 ◽  
pp. 46-51
Author(s):  
S.I. Yaresko
Keyword(s):  
Tool Life ◽  
Cutting Tool ◽  
Process Analysis ◽  
Tool Material ◽  
Cutting Conditions ◽  
Cutting Process ◽  
Irradiation Energy ◽  
High Feed ◽  
Cut Depth ◽  
Cutting Modes

The performed studies of the application features of the cutting tool, hardened by laser pulsed radiation are based on the comprehensive cutting process analysis. In this approach, the modeling results of the cutting process with hardened tool allowing to define the area of the effective use of laser treatment (LT). In particular, the increase in the tool life only for the certain values of the cut depth at the fixed irradiation energy was observed. The causes of the observed phenomena were determined based on durometric researches and studies of the microstructure in the contact zone. The measurements were performed for the cutters (steel R18) after turning structural steel 12Kh2N4A under various cutting modes. It was found that the processes of tool material softening, observed at turning with high feed values, limits the scope of cutting conditions by hardened tool. It is shown that LT leads to increased tool life, operating at the cutting conditions when the growth of tension thermodynamic in the cutting zone does not result in the development of softening processes. It is established that the area cutting modes are restricted to the values of cut depth not exceeding 1.5 mm (V=42.5 m/min, s=0.2 mm/rev) for the investigated pair of tool-workpiece (R18-12Kh2N4A). Tool life increases by more than 4 times compared to the durability of the non-irradiated tool provided the optimal combination of laser processing and hardened tool cutting modes is achieved.

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