Material Characterization for Metal-Cutting Force Modeling

1989 ◽  
Vol 111 (2) ◽  
pp. 210-219 ◽  
Author(s):  
D. A. Stephensen
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Cutting Force ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Stress And Strain ◽  
Force Model ◽  
Wide Range

Widely applicable machining simulation programs require reliable cutting force estimates, which currently can be obtained only from process-dependent machinability databases. The greatest obstacle to developing a more basic, efficient approach is a lack of understanding of material yield and frictional behavior under the unique deformation and frictional conditions of cutting. This paper describes a systematic method of specifying yield stress and friction properties needed as inputs to process-independent cutting force models. Statistically designed end turning tests are used to generate cutting force and chip thickness data for a mild steel and an aluminum alloy over a wide range of cutting conditions. Empirical models are fit for the cutting force and model-independent material parameters such as the tool-chip friction coefficient and shear stress on the shear plane. Common material yield behavior assumptions are examined in light of correlations between these parameters. Results show no physically meaningful correlation between geometric shear stress and strain measures, a weak correlation between geometric stress and strain rate measures, and a strong correlation between material properties and input variables such as cutting speed and rake angle. An upper bound model is used to fit four- and five-parameter polynomial strain-rate sensitive constitutive equations to the data. Drilling torques calculated using this model and an empirical turning force model agree reasonably well with measured values for the same material combination, indicating that end turning test results can be used to estimate mean loads in a more complicated process.

A New Analysis of the Forces in Orthogonal Metal Cutting

1965 ◽  
Vol 87 (4) ◽  
pp. 480-486 ◽  
Author(s):  
J. D. Cumming ◽  
S. Kobayashi ◽  
E. G. Thomsen
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Minimum Energy ◽  
Cutting Speed ◽  
Shear Plane ◽  
Force Model ◽  
Shearing Stress ◽  
Orthogonal Metal Cutting ◽  
Linear Force ◽  
Dynamic Shearing

The mechanics of orthogonal cutting have been reexamined and for the shear-plane concept of metal cutting, linear and quadratic-force models were suggested. It was shown that for steel SAE-1213, investigated under variable cutting conditions, the dynamic shearing stress remained constant and the linear-force model correlated with those experimental data which were obtained under the absence of a BUE. The angle λ formed by the shear plane and the direction of the resultant force remained constant for each test condition but varied with cutting speed. Neither the Ernst and Merchant minimum energy, nor the Lee and Shaffer solutions are in agreement with experimental observations.

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.

Mechanistic Cutting Force Prediction Model for Plunge Milling Considering Cutter Runout

2017 ◽  
Author(s):  
Kejia Zhuang ◽  
Xiaohu Xu ◽  
Ruiqi Xiao ◽  
Dahu Zhu ◽  
Shunsheng Guo ◽  
...  
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
End Milling ◽  
Chip Thickness ◽  
Force Model ◽  
Cutter Runout ◽  
Rough Machining ◽  
Plunge Milling ◽  
Side Milling ◽  
Cutting Mechanisms

As a kind of promising process for mass material removal in rough and semi-rough machining of hard-to-machine materials, plunge milling receives wide concerns and is often considered as one of the most effective methods in metal cutting operation, especially in aircraft industry. The cutting force in plunge milling operation differs from that in side milling or end milling for the complex geometries. To clarify the force based cutting mechanisms, a systematic study on cutting force modeling is conducted in this paper based on the precise cutting geometry which considers both the real-time uncut chip thickness calculation and cutter runout. The deduced cutting force model can be used for different cutting conditions in plunge milling process. Then, series of plunge milling operations with various cutting steps are implemented to verify the proposed force model. The results indicate that the predicted values show quite good agreement with the measured cutting forces.

scholarly journals Modeling and experimental verification of the dead metal zone for cutting force prediction in micro milling

2021 ◽  
Author(s):  
Bowen Song ◽  
xiubing jing ◽  
Jian Xu ◽  
Fujun Wang ◽  
Huaizhong Li
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
Chip Thickness ◽  
Simulation Software ◽  
Separation Point ◽  
Micro Milling ◽  
Force Model ◽  
Cutting Force Prediction ◽  
Dead Metal Zone ◽  
The Dead

Abstract In micro-cutting process, ploughing phenomenon occurring due to the dead metal zone (DMZ) leads to substantial ploughing force resulting in an obvious contribution to the total cutting force. To improve accuracy of the cutting force predicted, this paper aimed to explore the DMZ geometry related to the cutting depth and tool edge radius and thereof effect on cutting force. The prominent contribution of this research is to establish a new DMZ model by employing the slip-line field theory of the plastic formation. Based on the proposed model, DMZ are divided into shearing-dominated, mixed shearing and ploughing, and pure ploughing according to the minimum uncut chip thickness (MUCT). It is firstly proposed that the inner vertex of DMZ is the separation point of shearing effect and ploughing effect during metal cutting. The shape of the DMZ is theoretically calculated by an analytical way and verified by the simulation software. Finally, a cutting force model including shear force and ploughing force is established and verified by a series of experiments. The predicted cutting forces show remarkable agreement with those measured. The result proves that the separation point model is correct and can effectively demonstrate the ploughing force to accurately predict cutting force.

Extension of Oxley’s Analysis of Machining to Use Different Material Models

2003 ◽  
Vol 125 (4) ◽  
pp. 656-666 ◽  
Author(s):  
Amir H. Adibi-Sedeh ◽  
Vis Madhavan ◽  
Behnam Bahr
Keyword(s):  
Strain Rate ◽  
Shear Zone ◽  
Shear Force ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Material Model ◽  
Shear Zones ◽  
Carbon Steels ◽  
Maximum Temperature

The aim of the present work is to extend the applicability of Oxley’s analysis of machining to a broader class of materials beyond the carbon steels used by Oxley and co-workers. The Johnson-Cook material model, history dependent power law material model and the Mechanical Threshold Stress (MTS) model are used to represent the mechanical properties of the material being machined as a function of strain, strain rate and temperature. A few changes are introduced into Oxley’s analysis to improve the consistency between the various assumptions. A new approach has been introduced to calculate the pressure variation along the alpha slip lines in the primary shear zone including the effects of both the strain gradient and the thermal gradient along the beta lines. This approach also has the added advantage of ensuring force equilibrium of the primary shear zone in a macroscopic sense. The temperature at the middle of the primary shear zone is calculated by integrating the plastic work thereby eliminating the unknown constant η. Rather than calculating the shear force from the material properties corresponding to the strain, strain rate and temperature of the material at the middle of the shear zone, the shear force is calculated in a consistent manner using the energy dissipated in the primary shear zone. The thickness of the primary and secondary shear zones, the heat partition at the primary shear zone, the temperature distribution along the tool-chip interface and the shear plane angle are all calculated using Oxley’s original approach. The only constant used to fine tune the model is the ratio of the average temperature to the maximum temperature at the tool-chip interface (ψ). The performance of the model has been studied by comparing its predictions with experimental data for 1020 and 1045 steels, for aluminum alloys 2024-T3, 6061-T6 and 6082-T6, and for copper. It is found that the model accurately reproduces the dependence of the cutting forces and chip thickness as a function of undeformed chip thickness and cutting speed and accurately estimates the temperature in the primary and secondary shear zones.

Tool Wear Mechanisms during Machining of Alloy 625

2011 ◽  
Vol 275 ◽  
pp. 204-207 ◽  
Author(s):  
Lenka Fusova ◽  
Pawel Rokicki ◽  
Zdeněk Spotz ◽  
Karel Saksl ◽  
Carsten Siemers
Keyword(s):  
Wear Mechanisms ◽  
Gas Turbines ◽  
Metal Cutting ◽  
Elevated Temperatures ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Production Costs ◽  
Chemical Compositions ◽  
Alloy 625 ◽  
Wide Range

Nickel-base superalloys like Alloy 625 are widely used in power generation applications due to their unique properties especially at elevated temperatures. During the related component manufacturing for gas turbines up to 50% of the material has to be removed by metal cutting operations like milling, turning or drilling. As a result of high strength and toughness the machinability of Alloy 625 is generally poor and only low cutting speeds can be used. High-speed cutting of Alloy 625 on the other hand gets more important in industry to reduce manufacturing times and thus production costs. The cutting speed represents one of the most important factors that have influences on the tool life. The aim of this study is the analyses of wear mechanisms occurring during machining of Alloy 625. Orthogonal cutting experiments have been performed and different process parameters have been varied in a wide range. New and worn tools have been investigated by stereo microscopy, optical microscopy and scanning electron microscopy. Energy-dispersive X-ray analyses were used for the investigation of chemical compositions of the tool's surface as well as the nature of reaction products formed during the cutting process. Wear mechanisms observed in the machining experiments included abrasion, fracture and tribochemical effects. Specific wear features appeared depending on the mechanical and thermal conditions generated in the wear zones.

scholarly journals Prediction of Nonlinear Micro-Milling Force with a Novel Minimum Uncut Chip Thickness Model

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1495
Author(s):  
Tongshun Liu ◽  
Kedong Zhang ◽  
Gang Wang ◽  
Chengdong Wang
Keyword(s):  
Cutting Force ◽  
Chip Thickness ◽  
Micro Milling ◽  
Force Model ◽  
Force Coefficient ◽  
Uncut Chip Thickness ◽  
Milling Force ◽  
Minimum Uncut Chip Thickness ◽  
Cutting Force Coefficient ◽  
Milling Force Model

The minimum uncut chip thickness (MUCT), dividing the cutting zone into the shear region and the ploughing region, has a strong nonlinear effect on the cutting force of micro-milling. Determining the MUCT value is fundamental in order to predict the micro-milling force. In this study, based on the assumption that the normal shear force and the normal ploughing force are equivalent at the MUCT point, a novel analytical MUCT model considering the comprehensive effect of shear stress, friction angle, ploughing coefficient and cutting-edge radius is constructed to determine the MUCT. Nonlinear piecewise cutting force coefficient functions with the novel MUCT as the break point are constructed to represent the distribution of the shear/ploughing force under the effect of the minimum uncut chip thickness. By integrating the cutting force coefficient function, the nonlinear micro-milling force is predicted. Theoretical analysis shows that the nonlinear cutting force coefficient function embedded with the novel MUCT is absolutely integrable, making the micro-milling force model more stable and accurate than the conventional models. Moreover, by considering different factors in the MUCT model, the proposed micro-milling force model is more flexible than the traditional models. Micro-milling experiments under different cutting conditions have verified the efficiency and improvement of the proposed micro-milling force model.

scholarly journals Influence of Chatter of VMC Arising During End Milling Operation and Cutting Conditions on Quality of Machined Surface

1970 ◽  
Vol 2 (1) ◽  
Author(s):  
A.K.M.N. Amin, M.A. Rizal, and M. Razman
Keyword(s):  
Surface Roughness ◽  
Metal Cutting ◽  
Metal Removal ◽  
End Milling ◽  
Cutting Speed ◽  
Cutting Conditions ◽  
End Mill ◽  
Machined Surface ◽  
Operating Cycle ◽  
Wide Range

Machine tool chatter is a dynamic instability of the cutting process. Chatter results in poor part surface finish, damaged cutting tool, and an irritating and unacceptable noise. Exten¬sive research has been undertaken to study the mechanisms of chatter formation. Efforts have been also made to prevent the occurrence of chatter vibration. Even though some progress have been made, fundamental studies on the mechanics of metal cutting are necessary to achieve chatter free operation of CNC machine tools to maintain their smooth operating cycle. The same is also true for Vertical Machining Centres (VMC), which operate at high cutting speeds and are capable of offering high metal removal rates. The present work deals with the effect of work materials, cutting conditions and diameter of end mill cutters on the frequency-amplitude characteristics of chatter and on machined surface roughness. Vibration data were recorded using an experimental rig consisting of KISTLER 3-component dynamometer model 9257B, amplifier, scope meters and a PC.  Three different types of vibrations were observed. The first type was a low frequency vibration, associated with the interrupted nature of end mill operation. The second type of vibration was associated with the instability of the chip formation process and the third type was due to chatter. The frequency of the last type remained practically unchanged over a wide range of cutting speed.  It was further observed that chip-tool contact processes had considerable effect on the roughness of the machined surface.Key Words: Chatter, Cutting Conditions, Stable Cutting, Surface Roughness.

Statistical Cutting Force Model for Orthogonal Cutting of Polytetrafluoroethylene (PTFE) Composites

2013 ◽  
Author(s):  
Felicia Stan ◽  
Daniel Vlad ◽  
Catalin Fetecau
Keyword(s):  
Friction Coefficient ◽  
Cutting Force ◽  
Feed Rate ◽  
Normal Force ◽  
Polynomial Regression ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Tool Geometry ◽  
Force Model

This paper presents an experimental investigation of the cutting forces response during the orthogonal cutting of polytetrafluoroethylene (PTFE) and PTFE-based composites using the Taguchi method. Cutting experiments were conducted using the L27 orthogonal array and the effects of the cutting parameters (feed rate, cutting speed and rake angle) on the cutting force were analyzed using the S/N ratio response and the analysis of variance (ANOVA). Statistical models that correlate the cutting force with process variables were developed using ANOVA and polynomial regression. The variation of the apparent friction coefficient was analyzed with respect to tool geometry and the cutting process. The results indicated that cutting and thrust forces increase with increasing feed rate, and decrease with increasing rake angles from negative to positive values and increasing cutting speed. A power law relationship between the apparent friction coefficient and the normal force exerted by the chip on the tool-rake face was identified, the former decreasing with an increasing normal force.

Sign in / Sign up

Export Citation Format

Share Document