The Effect of Prior Cutting Conditions on the Shear Mechanics of Orthogonal Machining

1998 ◽  
Vol 120 (1) ◽  
pp. 13-20 ◽  
Author(s):  
R. Stevenson ◽  
D. A. Stephenson
Keyword(s):  
Material Properties ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Rake Angle ◽  
Cnc Machining ◽  
Machining Process ◽  
Depth Of Cut ◽  
Prior History ◽  
Machining Conditions ◽  
The Difference

It has been proposed several times in the metal-cutting literature that the machining process is non-unique and that the instantaneous machining conditions depend on the prior machining conditions (e.g. depth of cut, rake angle etc.). To evaluate the validity of this concept, a series of experiments was conducted using a highly accurate CNC machining center. For these experiments, the machining conditions were changed during the course of an orthogonal cutting experiment in a repeatable manner and the measured forces compared as a function of prior history. Tests were conducted on several tempers of 1100 aluminum and commercial purity zinc to evaluate the effect of material properties on the machining response. It was found that the change in measured cutting forces which could be ascribed to prior machining history was less than 3 percent and that material properties, particularly work hardening response, had no discernible effect on the magnitude of the difference.

Manufacturability of Aircraft Winglet for Wind Tunnel Testing

2015 ◽  
Vol 830-831 ◽  
pp. 100-103
Author(s):  
L. Gopinath ◽  
S. Ravishankar
Keyword(s):  
Wind Tunnel ◽  
Metal Cutting ◽  
Tool Path ◽  
Cutting Parameters ◽  
Cnc Machining ◽  
Depth Of Cut ◽  
Manufacturing Strategy ◽  
Thin Sections ◽  
Good Surface ◽  
Good Surface Finish

The form, shape and dimensions of the scaled down winglet model become small and thin bringing complexity to manufacturing. The trailing edge tapers to a thickness varying from 0.065mm to 0.099mm along its length. The mounting portion of the winglet is provided with a close tolerance having a slot gap of 5mm and a depth of 35 mm with an angle. Additionally, wind tunnel models require good surface finish on the aerodynamic surfaces and this involves adopting a manufacturing strategy with a control over on the metal cutting parameters to be implemented on a three axes CNC machining centre. The winglet surface is divided into segments in order to handle the cutting forces on the varying aerodynamic cross section. Various metal cutting parameters such as tool path, cutter diameter, feed rate, depth of cut, spindle speed, etc., are evaluated by monitoring segments where the metal cutting is carried out [1] and flow of chips observed. Fixtures and lugs are planned effectively to accommodate the machining of the angular slot in a three axes machining centre itself. Routing of operations to handle the varying thin sections and realisation of the close tolerance slot has enabled a reliable manufacturing approach in an economical way.

Temperature Field Numerical Analysis of Machining Process Based on the Finite Element Analysis

2014 ◽  
Vol 621 ◽  
pp. 611-616 ◽  
Author(s):  
Yan Juan Hu ◽  
Yao Wang ◽  
Zhan Li Wang
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Cutting Parameters ◽  
Element Model ◽  
Machining Process ◽  
Element Analysis ◽  
Mechanical Coupling

In order to study the temperature field distribution in the process of machining, the finite element theory was used to establish the orthogonal cutting finite element model, and the key technologies were discussed simultaneously. By using ABAQUS software for cutting AISI1045 steel temperature field of numerical simulation, the conclusion about changing rule of cutting temperature field can be gotten. The results show that this method can efficiently simulate the distribution of temperature field of the workpiece, cutter and scraps, which is effected by thermo-mechanical coupling in metal work process. It provides the theory evidence for the intensive study of metal-cutting principle, optimizing cutting parameters and improving processing technic and so on.

Numerical Simulation of Metal Cutting Process Based on ANSYS/LS-DYNA

2015 ◽  
Vol 727-728 ◽  
pp. 335-338 ◽  
Author(s):  
Song Jie Yu ◽  
Di Di Wang ◽  
Xin Chen
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
Plastic Material ◽  
Orthogonal Cutting ◽  
Cutting Process ◽  
Machining Process ◽  
Linear Deformation ◽  
Deformation Problem ◽  
Non Linear ◽  
Elastic Plastic Material

Cutting process is a typical non-linear deformation problem, which involves material non-linear, geometry non-linear and the state non-linear problem. Based on the elastic-plastic material deformation theory, this theme established a strain hardening model. Build the simulation model of two-dimensional orthogonal cutting process of workpiece and tool by the finite element method (FEM), and simulate the changes of cutting force and the process of chip formation in the machining process, and analyzed the cutting force, the situation of chip deformation. The method is more efficient and effective than the traditional one, and provides a new way for metal cutting theory, research of material cutting performance and cutting tool product development.

scholarly journals Analysis of critical negative rake angle and friction characteristics in orthogonal cutting of AL1060 and T2

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987806 ◽  
Author(s):  
Yanchun Ding ◽  
Guangfeng Shi ◽  
Hua Zhang ◽  
Guoquan Shi ◽  
Dongdong Han
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Tools ◽  
Flow Characteristics ◽  
Rake Angle ◽  
Machined Surface ◽  
Friction Characteristics ◽  
Model Based ◽  
Stagnant Region ◽  
Cutting Experiments

The stagnant region often appears in front of the tool cutting edge, which is caused by mechanical inlay and excessive pressing in plastic metal cutting with large negative rake angle tools at a low speed. It results in the change of the effective negative rake angle which can affect the flow characteristics of material, the quality of machined surface and the abrasion loss of cutting tools. However, the critical negative rake angle model based on the existence of the stagnant region has not been reported yet. Therefore, in order to investigate the critical negative rake angle value considering the stagnant region, a critical negative rake angle model based on the principle of minimum required energy is established, and the correctness of the theoretical model is verified by orthogonal cutting experiments. At the same time, the influence of the critical value of the large negative rake angle tool on the machined surface quality is studied through different cutting experiments. These experimental results show that the deviations of both experimental and theoretical critical negative rake angle are less than 5% during the orthogonally cutting of the aluminium (AL1060) and copper (T2) materials by the negative rake angle tool. Meanwhile, the critical negative rake angle is related to the adhesive friction coefficient of tool–workpiece contact surface. The analysis of friction characteristics shows that the deviation values of both theoretical and experimental critical negative rake angle are proportional to the coefficient of adhesive friction and the thickness of the stagnant region. Critical negative rake angle has a significant effect on roughness and residual stress of the machined surface.

The Influence of Extreme Speeds and Rake Angles in Metal Cutting

1963 ◽  
Vol 85 (1) ◽  
pp. 49-64 ◽  
Author(s):  
W. N. Findley ◽  
R. M. Reed
Keyword(s):  
Coefficient Of Friction ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Shear Plane ◽  
Rake Angle ◽  
Lateral Extrusion ◽  
Tool Force ◽  
Steep Decrease ◽  
Peak Value ◽  
Antimony Alloy

A study is presented of the effect of wide variations in speed of cutting and rake angle on orthogonal cutting of several metals—mainly a lead-antimony alloy. It was observed that enormous decreases in tool forces occurred in the lead-antimony with increase in speed from 6 to 3800 fpm, and decrease in rake angle from +30° to −60°. Explanations for these variations are proposed. An unusual observation was that a transition as speed increased from continuous to discontinuous chips occurred at large negative rake angles. Possible causes of this behavior are discussed. Another unusual observation was that a steep rise in tool force occurred with increase in speed for rake angles of 0° and +30°. The rise to a peak value was followed by an equally steep decrease in tool forces. Other observations discussed include the appearance of side spikes on the chips, chip curl, lateral extrusion of chips, influence of normal stress occurring on the shear plane, and the apparent coefficient of friction.

Cutting Forces in Orthogonal Cutting of Unidirectional GFRP Composites

1996 ◽  
Vol 118 (3) ◽  
pp. 419-425 ◽  
Author(s):  
G. Caprino ◽  
L. Nele
Keyword(s):  
Size Effect ◽  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Rake Angle ◽  
Depth Of Cut ◽  
Vertical Force ◽  
Fibre Direction ◽  
Unit Width ◽  
Relief Angle

The results of orthogonal cutting tests carried out on unidirectional glass fiber reinforced plastic composites, using HSS tools, are presented and discussed. During the tests, performed on a milling machine at very low cutting speed to avoid thermal effects, the cutting speed was held constant and parallel to the fibre direction. Three parameters, namely the tool rake angle α, the tool relief angle γ, and the depth of cut t, were varied. According to the experimental results, the horizontal force per unit width, Fhu, undergoes a dramatic decrease, never verified for metals, with increasing α. Besides, Fhu is only negligibly affected by the relief angle, and linearly increases with t. Similarly to metals, an effect of the depth of cut on the specific energy (size effect) is found also for composites. However, the presented results indicate that the size effect can be analytically modeled in a simple way in the case of composites. The vertical force per unit width, Fvu, exhibits a marked reduction when the relief angle is increased. Fvu, is also very sensitive to the rake angle: the lower α the higher is Fvu. It is shown that this behavior probably reflects a strong influence of the rake angle on the forces developing at the flank. A linear dependence of the vertical force on the depth of cut is also demonstrated. Finally, the experimental data are utilized to obtain empirical formulae, allowing an approximate evaluation of cutting forces.

Measuring fracture toughness from machining tests

2009 ◽  
Vol 223 (12) ◽  
pp. 2861-2869 ◽  
Author(s):  
Y Patel ◽  
B R K Blackman ◽  
J G Williams
Keyword(s):  
Fracture Toughness ◽  
Aluminium Alloy ◽  
Coefficient Of Friction ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Shear Plane ◽  
Rake Angle ◽  
Sufficient Information ◽  
The Coefficient Of Friction ◽  
Adhesion Toughness

An analysis of the forces involved in orthogonal cutting or machining is presented in which yielding on a shear plane is assumed. The fracture toughness Gc is included and it is observed that Gc may be determined by measuring the cutting and transverse forces together with the chip thickness for a range of cutting depths. This latter measurement enabled the shear plane angle ϕ to be determined experimentally. A simplified version of the analysis is also given in which ϕ is predicted by a cutting force minimization scheme. Neither scheme requires any details of the friction condition to be known since the transverse force is sufficient information for any type to be included in the analysis. A friction model including a coefficient of friction and an adhesion toughness is also utilized. Data for both polymer and metal cutting are taken from the literature and Gc is determined. In some datasets the tool rake angle α is also varied and the values of Gc and the yield stress σY are found to be independent of α. The force minimization method gives a good estimate of ϕ for most polymers. For metals (aluminium alloy, steel, and brass) the method worked well. For aluminium alloy Gc was independent of α and the predicted and measured ϕ values agreed. For steel and brass this was not so. Gc was mostly independent of α except at low values where high values of Gc were observed. A constant value of the coefficient of friction was observed for each α value but values for both the coefficient of friction and the adhesion toughness varied significantly with increasing rake angle.

The Monitoring System for Stability of CNC Machining Based on cDAQ and LabVIEW

2014 ◽  
Vol 1039 ◽  
pp. 177-182
Author(s):  
Man Meng ◽  
Wen Jun Zhang ◽  
Peng Chong Wang ◽  
Denis Niedenzu ◽  
Ying Zhong Tian
Keyword(s):  
Monitoring System ◽  
Online Monitoring ◽  
Cnc Machining ◽  
Machining Process ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Online Monitoring System ◽  
Main Factors ◽  
The Stability

In recent years, researching the stability of the CNC machining process is a hotpot in CNC industry. Based on cDAQ and labVIEW, online monitoring system is presented, meanwhile, both software structure and hardware structure are introduced in detail. Researches show that vibration and pressure are the main factors for the quality of the flatness. By studying the relative vibration between the spindle and the platform in the Z axis direction, as well as the shifty pressure that tool works on the flatness of the workpiece, four experiments are designed in this paper under different technological conditions including free moving, Axial Depth of cut, speed and feed speed, which verify the reliability of the online monitoring system.

An Experimental and Computational Study of Temperature and Strain Fields in Metal Cutting

2001 ◽  
Author(s):  
Alan T. Zehnder ◽  
Yogesh K. Potdar ◽  
Xiaomin Deng ◽  
Chandrakant Shet
Keyword(s):  
Spatial Resolution ◽  
Metal Cutting ◽  
Computational Study ◽  
Orthogonal Cutting ◽  
Critical Role ◽  
Rake Angle ◽  
General Purpose ◽  
Temperature Fields ◽  
Ir Detectors ◽  
Strain Fields

Abstract Metal cutting is a thermo-mechanically coupled process in which plasticity induced heating and friction play a critical role. In this paper, we outline a methodology that combines high resolution experiments with numerical simulations. The simulations were performed with a general purpose finite element code. With this code we evaluate the effects of chip-tool interface friction and rake angle on temperature and cutting force and show that results for residual stresses in the workpiece are consistent with experimental data. We hypothesize that by closely coupling simulations to fine scale spatial and temporal experimental measurements of temperature and strain fields, questions related to choice of parameters in FE simulations can be resolved. We have designed and conducted orthogonal cutting experiments to measure temperatures, using IR detectors, with a spatial resolution of 27 × 27 μm and time scale of 200 ns. Experimentally obtained temperature fields are compared with FE results. We also obtain deformation fields with a spatial resolution of 50 × 50 μm.

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