scholarly journals Analytical modelling of cutting forces in near-orthogonal cutting of titanium alloy Ti6Al4V

2014 ◽  
Vol 229 (6) ◽  
pp. 1122-1133 ◽  
Author(s):  
Yun Chen ◽  
Huaizhong Li ◽  
Jun Wang
Keyword(s):  
Titanium Alloy ◽  
Cutting Forces ◽  
Chemical Reactivity ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Analytical Modelling ◽  
Shear Instability ◽  
Published Data ◽  
Machining Processes ◽  
Titanium Alloy Ti6al4v

Titanium and its alloys are difficult to machine due to their high chemical reactivity with tool materials and low thermal conductivity. Chip segmentation caused by the thermoplastic instability is always observed in titanium machining processes, which leads to varied cutting forces and chip thickness, etc. This paper presents an analytical modelling approach for cutting forces in near-orthogonal cutting of titanium alloy Ti6Al4V. The catastrophic shear instability in the primary shear plane is assumed as a semi-static process. An analytical approach is used to evaluate chip thicknesses and forces in the near-orthogonal cutting process. The shear flow stress of the material is modelled by using the Johnson–Cook constitutive material law where the strain hardening, strain rate sensitivity and thermal softening behaviours are coupled. The thermal equations with non-uniform heat partitions along the tool–chip interface are solved by a finite difference method. The model prediction is verified with experimental data, where a good agreement in terms of the average cutting forces and chip thickness is shown. A comparison of the predicted temperatures with published data obtained by using the finite element method is also presented.

Effect of Coolant Pressure on Machinability of Titanium Alloy Ti6Al4V

2016 ◽  
Vol 826 ◽  
pp. 82-87 ◽  
Author(s):  
Sandip Patil ◽  
Swapnil Kekade ◽  
Pravin Pawar ◽  
Swapnil Pawar ◽  
Rajkumar Singh
Keyword(s):  
Titanium Alloy ◽  
Chemical Reactivity ◽  
Cutting Temperature ◽  
Chip Thickness ◽  
Machining Process ◽  
Mechanism Analysis ◽  
Band Formation ◽  
Titanium Alloy Ti6al4v ◽  
High Pressure Coolant ◽  
Coolant System

Titanium alloy Ti6Al4V comes with several desirable and undesirable properties. Its low thermal conductivity and high chemical reactivity makes it difficult for machining producing high cutting temperature and adhesion tendency. Cutting fluids are used to remove the heat generated at the chip tool interface during the machining process. The coolant with low pressure and improper delivery is not able to break the vapor barrier created by high cutting temperature. The current research investigates the effect of using high pressure coolant system (60 Bar) on the machinability of Ti6Al4V. The machinability was measured in terms of chip breaking, chip thickness, surface finish, tool wear, etc. A detailed statistical and chip mechanism analysis was performed emphasizing the phenomenon of shear band formation, crack formation, chip thickness, chip serration frequency, etc.

Cutting Force Model for Heat Assisted Titanium Alloy Milling

2014 ◽  
Vol 887-888 ◽  
pp. 1191-1194 ◽  
Author(s):  
Chang Yi Liu
Keyword(s):  
Titanium Alloy ◽  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Shear Banding ◽  
Cutting Speed ◽  
Constitutive Law ◽  
Force Model ◽  
Machining Processes ◽  
Machine Material ◽  
The Impact

Thermal energy sources have been applied for softening the difficult-to-machine material when it is combined with conventional machining processes. Cutting forces has been reduced during the process. To investigate the plastic deformation property of workpiece materials heated by thermal sources, and its influence to the cutting forces, the analytical model of orthogonal cutting is established. The impact of cutting speed and initial temperature of the shear banding to the cutting forces are taken account of, based on adiabatic shear banding model and Johnson-Cook material constitutive law. The shear banding average shear stress failure criteria has been proposed to decide the fracture between workpiece and chip. Simulation has been carried out and compared with experimental data of laser-heat assisted titanium alloy milling, showing good agreement.

Inverse identification of modified Johnson–Cook model for cutting titanium alloy Ti6Al4V using firefly algorithm

2019 ◽  
Vol 234 (3) ◽  
pp. 584-599 ◽  
Author(s):  
Jinhua Zhou ◽  
Junxue Ren ◽  
Yong Jiang
Keyword(s):  
Titanium Alloy ◽  
Cutting Force ◽  
Firefly Algorithm ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Cutting Process ◽  
Zone Model ◽  
Serrated Chip ◽  
Titanium Alloy Ti6al4v ◽  
Cook Model

The original Johnson–Cook equation fails to describe the significant thermal softening phenomenon of flow stress in cutting process of titanium alloy Ti6Al4V. Recently, some researchers developed some modified Johnson–Cook models of Ti6Al4V by introducing some additional parameters. But effective parameter identification method is unavailable in those research works. In this work, an inverse approach is developed to determine the additional parameters. A modified Johnson–Cook model with the hyperbolic tangent function is adopted, in which four unknown parameters need to be determined. The parameter assessment is taken as an optimization process based on the unequal division parallel-sided shear zone model. Along with the measured cutting force and chip thickness, the firefly algorithm is introduced to search for the parametric optimal solution. Those four parameters are determined when the difference between the predicted and experimental effective stress at shear plane reaches its minimum. The identified constitutive model is subsequently verified by finite element simulation of orthogonal cutting process, and compared with previous different material models. With the identified modified Johnson–Cook model, the serrated chip is observed in all the simulations. A good agreement between verification experiments and simulations is achieved. An acceptable prediction accuracy with an error of 10.28% on cutting force and an error of 18.12% on chip size is achieved.

Removal Mechanism of Titanium Alloy Ti6Al4V Based on Single-Grain High Speed Grinding Test

2011 ◽  
Vol 487 ◽  
pp. 39-43 ◽  
Author(s):  
L. Tian ◽  
Yu Can Fu ◽  
W.F. Ding ◽  
Jiu Hua Xu ◽  
H.H. Su
Keyword(s):  
Titanium Alloy ◽  
High Speed ◽  
Chip Thickness ◽  
Wheel Speed ◽  
High Speed Grinding ◽  
Tc4 Alloy ◽  
Grinding Mechanism ◽  
Single Grain ◽  
On Chip ◽  
Titanium Alloy Ti6al4v

Single-grain grinding test plays an important part in studying the high speed grinding mechanism of materials. In this paper, a new method and experiment system for high speed grinding test with single CBN grain are presented. In order to study the high speed grinding mechanism of TC4 alloy, the chips and grooves were obtained under different wheel speed and corresponding maximum undeformed chip thickness. Results showed that the effects of wheel speed and chip thickness on chip formation become obvious. The chips were characterized by crack and segment band feature like the cutting segmented chips of titanium alloy Ti6Al4V.

scholarly journals Constitutive Model and Cutting Simulation of Titanium Alloy Ti6Al4V after Heat Treatment

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4145
Author(s):  
Xiaohua Qian ◽  
Xiongying Duan
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Titanium Alloy ◽  
Orthogonal Cutting ◽  
Treatment Method ◽  
Dynamic Mechanical Properties ◽  
Ti6al4v Alloy ◽  
Stress Strain ◽  
Cutting Simulation ◽  
Titanium Alloy Ti6al4v

As a typical high specific strength and corrosion-resistant alloy, titanium alloy Ti6Al4V is widely used in the aviation, ocean, biomedical, sport, and other fields. The heat treatment method is often used to improve the material mechanical properties. To investigate the dynamic mechanical properties of titanium alloy Ti6Al4V after heat treatment, dynamic compressive experiments under high temperature and high strain rate were carried out using split Hopkinson press bar (SHPB) equipment. The stress–strain curves of Ti6Al4V alloy under different temperatures and strain rates were obtained through SHPB compressive tests. The Johnson–Cook (J–C) constitutive equation was used for expressing the stress–strain relationship of titanium alloy under large deformation. In addition, the material constants of the J–C model were fitted based on the experimental data. An orthogonal cutting simulation was performed to investigate the cutting of Ti6Al4V alloy under two different numerical calculation methods based on the established J–C model using the finite element method (FEM). The simulation results confirm that the adiabatic mode is more suitable to analyze the cutting of Ti6Al4V alloy.

Virtual Five-Axis Flank Milling of Jet Engine Impellers: Part 1 — Mechanics of Five-Axis Flank Milling

2007 ◽  
Author(s):  
W. Ferry ◽  
Y. Altintas
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Friction Angle ◽  
Flank Milling ◽  
Cutting Force Prediction ◽  
Jet Engine ◽  
End Mills ◽  
Five Axis

Jet engine impeller blades are flank-milled with tapered, helical, ball-end mills on five-axis machining centers. The impellers are made from difficult-to-cut titanium or nickel alloys, and the blades must be machined within tight tolerances. As a consequence, deflections of the tool and flexible workpiece can jeopardize the precision of the impellers during milling. This work is the first of a two part paper on cutting force prediction and feed optimization for the five-axis flank milling of an impeller. In Part I, a mathematical model for predicting cutting forces is presented for five-axis machining with tapered, helical, ball-end mills with variable pitch and serrated flutes. The cutter is divided axially into a number of differential elements, each with its own feed coordinate system due to five-axis motion. At each element, the total velocity due to translation and rotation is split into horizontal and vertical feed components, which are used to calculate total chip thickness along the cutting edge. The cutting forces for each element are calculated by transforming friction angle, shear stress and shear angle from an orthogonal cutting database to the oblique cutting plane. The distributed cutting load is digitally summed to obtain the total forces acting on the cutter and blade. The model can be used for general five-axis flank milling processes, and supports a variety of cutting tools. Predicted cutting force measurements are shown to be in reasonable agreement with those collected during a roughing operation on a prototype integrally bladed rotor (IBR).

Influence of Reground Tool Sharpness on Micro-Cutting Process

2010 ◽  
Vol 37-38 ◽  
pp. 550-553
Author(s):  
Xin Li Tian ◽  
Zhao Li ◽  
Xiu Jian Tang ◽  
Fang Guo ◽  
Ai Bing Yu
Keyword(s):  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Cutting Tools ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Cutting Process ◽  
Micro Cutting ◽  
Temperature Distributions ◽  
Edge Radius ◽  
1045 Steel

Tool edge radius has obvious influences on micro-cutting process. It considers the ratio of the cutting edge radius and the uncut chip thickness as the relative tool sharpness (RST). FEM simulations of orthogonal cutting processes were studied with dynamics explicit ALE method. AISI 1045 steel was chosen for workpiece, and cemented carbide was chosen for cutting tool. Sixteen cutting edges with different RTS values were chosen for analysis. Cutting forces and temperature distributions were calculated for carbide cutting tools with these RTS values. Cutting edge with a small RTS obtains large cutting forces. Ploughing force tend to sharply increase when the RTS of the cutting edge is small. Cutting edge with a reasonable RTS reduces the heat generation and presents reasonable temperature distributions, which is beneficial to cutting life. The force and temperature distributions demonstrate that there is a reasonable RTS range for the cutting edge.

Study on Determination of Friction Model at the Tool-Chip Interface of Titanium Alloy Ti6Al4V Based on Orthogonal Cutting

2011 ◽  
Vol 117-119 ◽  
pp. 1788-1791
Author(s):  
Yue Feng Yuan ◽  
Wu Yi Chen
Keyword(s):  
Titanium Alloy ◽  
Cutting Force ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Friction Model ◽  
Carbide Tool ◽  
Orthogonal Turning ◽  
Titanium Alloy Ti6al4v

It is necessary for cutting simulation to determine the friction model at the tool-chip interface suitable for metal cutting process. Cutting force experiments in orthogonal turning titanium alloy TI6AL4V are carried out with cement carbide tool KW10. The Coulomb frictions at the tool-chip interface are calculated based on measured cutting force, and the friction model is regressed, where cutting speed and feed rate are presented.

Dynamic Simulation of the Micro-Milling Process Including Minimum Chip Thickness and Size Effect

2012 ◽  
Vol 504-506 ◽  
pp. 1269-1274 ◽  
Author(s):  
François Ducobu ◽  
Edouard Rivière-Lorphèvre ◽  
Enrico Filippi
Keyword(s):  
Size Effect ◽  
Cutting Forces ◽  
Mechanistic Model ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Milling Process ◽  
Cutting Conditions ◽  
Micro Milling ◽  
Minimum Chip Thickness ◽  
Physical Phenomena

Micro-milling with a cutting tool is a manufacturing technique that allows production of parts ranging from several millimeters to several micrometers. The technique is based on a downscaling of macroscopic milling process. Micro-milling is one of the most effective process to produce complex three-dimensional micro-parts, including sharp edges and with a good surface quality. Reducing the dimensions of the cutter and the cutting conditions requires taking into account physical phenomena that can be neglected in macro-milling. These phenomena include a size effect (nonlinear rising of specific cutting force when chip thickness decreases), the minimum chip thickness (under a given dimension, no chip can be machined) and the heterogeneity of the material (the size of the grains composing the material is significant as compared to the dimension of the chip). The aim of this paper is to introduce some phenomena, appearing in micromilling, in the mechanistic dynamic simulation software ‘dystamill’ developed for macro-milling. The software is able to simulate the cutting forces, the dynamic behavior of the tool and the workpiece and the kinematic surface finish in 2D1/2 milling operation (slotting, face milling, shoulder milling,…). It can be used to predict chatter-free cutting condition for example. The mechanistic model of the cutting forces is deduced from the local FEM simulation of orthogonal cutting. This FEM model uses the commercial software ABAQUS and is able to simulate chip formation and cutting forces in an orthogonal cutting test. This model is able to reproduce physical phenomena in macro cutting conditions (including segmented chip) as well as specific phenomena in micro cutting conditions (minimum chip thickness and size effect). The minimum chip thickness is also taken into account by the global model. The results of simulation for the machining of titanium alloy Ti6Al4V under macro and micro milling condition with the mechanistic model are presented discussed. This approach connects together local machining simulation and global models.

Gezielte Begrenzung der Spandickenschwankungen/Development of a counter element for influencing chip formation when machining titanium. Restriction of chip thickness deviations

2020 ◽  
Vol 110 (11-12) ◽  
pp. 806-810
Author(s):  
Sebastian Berger ◽  
Jannis Saelzer ◽  
Dirk Biermann
Keyword(s):  
Titanium Alloy ◽  
Surface Quality ◽  
Tool Life ◽  
Chip Formation ◽  
Chip Thickness ◽  
Vibration Damping ◽  
Suitable Choice ◽  
Periodic Excitation ◽  
Segmented Chip ◽  
Titanium Alloy Ti6al4v

Dieser Beitrag stellt die simulative Analyse zum Einfluss eines begrenzenden Elements zur Unterdrückung der Segmentspanbildung bei der Zerspanung der Titanlegierung Ti6Al4V vor. Dabei lässt sich aufzeigen, dass eine spanbildungsinduzierte periodische Anregung des Systems durch die geeignete Wahl von Geometrie und Positionierung des Elementes verhindert werden kann, wodurch sich die Werkzeugstandzeit und die Oberflächenqualität verbessern und schwingungsdämpfende Maßnahmen obsolet werden. This paper presents the simulative analysis of the influence of a counter element for the suppression of segmented chip formation during the machining of titanium alloy Ti6Al4V. It is shown that a chip formation induced periodic excitation of the system can be prevented by a suitable choice of geometry and positioning of the element, leading to increased tool life and surface quality as well as making vibration damping methods obsolete.

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