On the Bifurcation from Continuous to Segmented Chip Formation in Metal Cutting

2000 ◽  
pp. 67-83 ◽  
Author(s):  
T. J. Burns ◽  
M. A. Davies ◽  
C. J. Evans
Keyword(s):  
Chip Formation ◽  
Metal Cutting ◽  
Segmented Chip

Development of Advanced and Free-Machining Titanium Alloys by Micrometer-Size Particle Distribution

2011 ◽  
Vol 690 ◽  
pp. 262-265 ◽  
Author(s):  
Carsten Siemers ◽  
Judith Laukart ◽  
Badya Zahra ◽  
Joachim Rösler ◽  
Zdenek Spotz ◽  
...  
Keyword(s):  
Titanium Alloys ◽  
Chip Formation ◽  
Metal Cutting ◽  
Elevated Temperatures ◽  
Earth Metal ◽  
Dependent Change ◽  
Segmented Chip ◽  
Micrometer Size ◽  
Parameter Dependent ◽  
Cutting Experiments

The chip formation process of four different titanium alloys has been studied in several cutting experiments. Alloys containing more than 50% of a-phase at room temperature and aged metastable b-alloys form segmented chips independent of the cutting conditions. Solution treated metastable b-alloys show a cutting parameter dependent change from continuous to segmented chip formation. Lanthanum has been added to all four alloys. The microstructure of these alloys consists of a titanium matrix and micrometer-size particles. The presence of grain boundary particles leads to enhanced grain stability at elevated temperatures. In addition, short chips are observed during metal cutting only in case pure metallic rare-earth metal particles are present.

scholarly journals Simulation of plastic deformation and destruction in the process of chip formation

2018 ◽  
Vol 211 ◽  
pp. 17007
Author(s):  
Tanel Tärgla ◽  
Jüri Olt ◽  
Olga Liivapuu
Keyword(s):  
Plastic Deformation ◽  
Formation Process ◽  
Chip Formation ◽  
Rheological Model ◽  
Metal Cutting ◽  
Depth Of Cut ◽  
Key Factors ◽  
Local Zone ◽  
Complex Process ◽  
Relaxing Medium

Metal cutting is a complex process in which several mechanisms are at work simultaneously. The mathematical modelling allows carrying out research into the optimization of machining conditions. This work examines the simulation of chip formation during the process of cutting. The studies demonstrated that the chip formation process, taking into account the plastic deformation and destruction of metal in the local zone, is most appropriately represented by a rheological model in the form of a series connection of elasticductile- plastic relaxing medium of Ishlinskiy (reflecting the process of primary deformation of metal from the cut off layer) and the medium of Voigt with two elastic-dissipative elements (representing the process of deformation and frictions from the convergent shaving). The attained complex rheological model served as the basis for constructing a representative dynamic model for the chip formation process. The key factors that govern the chip formation have been taken into account, such as tool vibration frequency and amplitude, depth of cut, feed rate.

scholarly journals Cutting force sensor based on digital image correlation for segmented chip formation analysis

2016 ◽  
Vol 238 ◽  
pp. 466-473 ◽  
Author(s):  
Thomas Baizeau ◽  
Sébastien Campocasso ◽  
Frédéric Rossi ◽  
Gérard Poulachon ◽  
François Hild
Keyword(s):  
Digital Image Correlation ◽  
Cutting Force ◽  
Digital Image ◽  
Chip Formation ◽  
Force Sensor ◽  
Image Correlation ◽  
Segmented Chip

The Realities of Friction in Metal Plastic Flow With Corresponding Results During Metal Cutting

2019 ◽  
Author(s):  
Wolfgang Lortz ◽  
Radu Pavel
Keyword(s):  
Internal Friction ◽  
Strain Rate ◽  
Plastic Flow ◽  
Cross Sections ◽  
Chip Formation ◽  
Metal Cutting ◽  
Material Behavior ◽  
Deformation Pattern ◽  
Low Velocity ◽  
As Stress

Abstract Metal cutting is a dynamic process with two types of friction: on the one hand, external friction between two different bodies, and on the other hand, an internal friction inside the same material, due to plastic flow. These two different types of friction lead to different chip formation processes. In the case of built-up-edge (BUE), low velocity creates low energy, resulting in a self-hardening effect with BUE. With increasing velocity, the energy will increase and will result in high temperatures with a built-up-layer (BUL). Furthermore, under special circumstances, friction will lead to a self-blockade (a self-blocking state). This situation describes the third stage in metal plastic flow — the creation of a segmental chip. In this case the internal friction takes over. One question arises: “How can we determine these two types of different friction?” For solving these phenomena new fundamental equations based on mathematics, physics and material behavior have to be developed. This paper presents newly developed equations, which deliver the theoretical distribution of yield shear stress as well as strain rate with corresponding grid deformation pattern in metal plastic flow. For an actual cut, the plastic deformation pattern remains when the process is stopped, and therefore the theoretical result can be compared with cross-sections of the relevant chip formation areas — contrary to outputs such as stress, strain rate and temperatures which are all functions of position and time. All this will be shown and discussed in the paper, and stands in good agreement with experimental results.

A Finite Element Study of Chip Formation Process in Orthogonal Machining

2011 ◽  
Vol 1 (4) ◽  
pp. 19-45 ◽  
Author(s):  
Amrita Priyadarshini ◽  
Surjya K. Pal ◽  
Arun K. Samantaray
Keyword(s):  
Finite Element ◽  
Chip Formation ◽  
Critical Role ◽  
Fe Model ◽  
Orthogonal Machining ◽  
Adiabatic Shearing ◽  
Segmented Chip ◽  
The Right ◽  
Distribution Of Stress ◽  
Continuous Chip

This paper examines the plane strain 2D Finite Element (FE) modeling of segmented, as well as continuous chip formation while machining AISI 4340 with a negative rake carbide tool. The main objective is to simulate both the continuous and segmented chips from the same FE model based on FE code ABAQUS/Explicit. Both the adiabatic and coupled temperature displacement analysis has been performed to simulate the right kind of chip formation. It is observed that adiabatic hypothesis plays a critical role in the simulation of segmented chip formation based on adiabatic shearing. The numerical results dealing with distribution of stress, strain and temperature for segmented and continuous chip formations were compared and found to vary considerably from each other. The simulation results were also compared with other published results; thus validating the developed model.

Effect of tool wear on chip formation during dry machining of Ti-6Al-4V alloy, part 1: Effect of gradual tool wear evolution

2015 ◽  
Vol 231 (9) ◽  
pp. 1559-1574 ◽  
Author(s):  
Shoujin Sun ◽  
Milan Brandt ◽  
Matthew S Dargusch
Keyword(s):  
Plastic Deformation ◽  
Tool Wear ◽  
Chip Formation ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Machined Surface ◽  
Segmented Chip ◽  
Gradual Development ◽  
Geometric Variables ◽  
On Chip

Geometric features of the segmented chip have been investigated along with the volume of material removed at a cutting speed at which tool wear is characterized by the gradual development of flank wear when cutting Ti-6Al-4V alloy. The chip geometric variables varied with an increase in the volume of material removed as the combined effect of change in tool’s geometry and increase in cutting temperature. Plastic deformation dimples were observed as periodical regions on the machined surface, a row on each undeformed surface and region on the top of the slipping surface of the segmented chip when cutting with new tool; these dimples on the undeformed surface and machined surface are elongated in the direction of chip flow. All these dimples became less with an increase in the volume of material removed and almost disappeared when the chip was removed with the worn tool at the end of its life. A model of segmented chip formation process has been proposed to satisfactorily explain the formation of the plastic deformation dimples on the undeformed surface and machined surface of the segmented chip produced with a new cutting tool and the transition of chip geometry with the evolution of tool wear.

Investigation on Chip Formation during Machining Using Finite Element Modeling

2012 ◽  
Vol 505 ◽  
pp. 31-36 ◽  
Author(s):  
Moaz H. Ali ◽  
Basim A. Khidhir ◽  
Bashir Mohamed ◽  
A.A. Oshkour
Keyword(s):  
Finite Element ◽  
Tool Wear ◽  
Finite Element Modeling ◽  
Chip Formation ◽  
Cutting Tool ◽  
Chip Morphology ◽  
Machining Process ◽  
Element Modeling ◽  
Segmented Chip ◽  
Cutting Speeds

Titanium alloys are desirable materials for aerospace industry because of their excellent combination of high specific strength, lightweight, fracture resistant characteristics, and general corrosion resistance. Therefore, the chip morphology is very important in the study of machinability of metals as well as the study of cutting tool wear. The chips are generally classified into four groups: continuous chips, chips with built-up-edges (BUE), discontinuous chips and serrated chips. . The chip morphology and segmentation play a predominant role in determining machinability and tool wear during the machining process. The mechanics of segmented chip formation during orthogonal cutting of titanium alloy Ti–6Al–4V are studied in detail with the aid of high-speed imaging of the chip formation zone. The finite element model of chip formation of Ti–6Al–4V is suggested as a discontinuous type chip at lower cutting speeds developing into a continuous, but segmented, chip at higher cutting speeds. The prediction by using finite-element modeling method and simulation process in machining while create chips formation can contribute in reducing the cost of manufacturing in terms of prolongs the cutting tool life and machining time saving.

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.

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.

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