Effect of coefficient of friction at the sliding zone of chip-tool interface on chip curl diameter and secondary shear zone thickness during tapping process

Inconel 718 is gaining its importance in the aerospace and power plant industries because of its high strength to weight ratio. The lack of understanding of the tool chip interface for Inconel 718 restricts the prediction of the apparent coefficient of friction and thus the cutting forces, thereby the machining efficiency. In the present study an analytical model has been developed accounting the actual variation of stresses over the rake face. The model focuses on the variation of shear stresses in the sticking region and has been considered to be increasing exponentially with distance from tool tip. The primary shear zone is assumed to be a thin layer with constant thickness and has been modelled using Johnson Cook material model. The shear stresses at the entry and exit of the primary shear zone has been calculated using iterative techniques proposed in the literature. The secondary shear zone has been analyzed dividing the contact length into two distinct regions and each region has been dealt separately. The ratio of real area of contact to the apparent area of contact has been given consideration and dealt with at macroscopic level. Experimental values have been extracted from previous studies on Inconel 718. The predictions of the analytical model was found to be in good agreement with experimental results. The experimental apparent coefficient of friction was obtained as 0.5119 against 0.4733 from the developed model at a velocity of 70 mm/min, depth of cut of 1mm, nose radius of 0.8mm and with negative rake angle (−6°) with CNMG0812 tool. The predicted and the experimental friction coefficient showed a variation of 7.07% – 10% and thus can serve as reliable model for Inconel 718.

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On the hydrodynamic characteristics of the secondary shear zone in metal machining with sticking-sliding friction using the boundary layer theory

Wear ◽

10.1016/0043-1648(87)90221-3 ◽

1987 ◽

Vol 115 (3) ◽

pp. 349-359 ◽

Cited By ~ 4

Author(s):

R.M. El-Zahry

Keyword(s):

Boundary Layer ◽

Shear Zone ◽

Sliding Friction ◽

Boundary Layer Theory ◽

Hydrodynamic Characteristics ◽

Metal Machining ◽

Secondary Shear Zone

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Insights into Machining of a β Titanium Biomedical Alloy from Chip Microstructures

Metals ◽

10.3390/met8090710 ◽

2018 ◽

Vol 8 (9) ◽

pp. 710 ◽

Cited By ~ 2

Author(s):

Damon Kent ◽

Rizwan Rahman Rashid ◽

Michael Bermingham ◽

Hooyar Attar ◽

Shoujin Sun ◽

...

Keyword(s):

Shear Band ◽

Shear Zone ◽

Biomechanical Properties ◽

Temperature Fields ◽

Large Strains ◽

Shear Direction ◽

Grain Sizes ◽

Β Phase ◽

Secondary Shear Zone ◽

Cutting Speeds

New metastable β titanium alloys are receiving increasing attention due to their excellent biomechanical properties and machinability is critical to their uptake. In this study, machining chip microstructure has been investigated to gain an understanding of strain and temperature fields during cutting. For higher cutting speeds, ≥60 m/min, the chips have segmented morphologies characterised by a serrated appearance. High levels of strain in the primary shear zone promote formation of expanded shear band regions between segments which exhibit intensive refinement of the β phase down to grain sizes below 100 nm. The presence of both α and β phases across the expanded shear band suggests that temperatures during cutting are in the range of 400–600 °C. For the secondary shear zone, very large strains at the cutting interface result in heavily refined and approximately equiaxed nanocrystalline β grains with sizes around 20–50 nm, while further from the interface the β grains become highly elongated in the shear direction. An absence of the α phase in the region immediately adjacent to the cutting interface indicates recrystallization during cutting and temperatures in excess of the 720 °C β transus temperature.

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Effect of Minimum Quantity Lubrication to Prediction of Cutting Temperature Distribution in Turning Material AISI-1045

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.902.97 ◽

2020 ◽

Vol 902 ◽

pp. 97-102

Author(s):

Tran Trong Quyet ◽

Pham Tuan Nghia ◽

Nguyen Thanh Toan ◽

Tran Duc Trong ◽

Luong Hong Sam ◽

...

Keyword(s):

Temperature Distribution ◽

Shear Zone ◽

Orthogonal Cutting ◽

Cutting Temperature ◽

Chip Thickness ◽

Minimum Quantity Lubrication ◽

Minimum Quantity ◽

The Difference ◽

Secondary Shear Zone ◽

Cutting Model

This paper presents a prediction of cutting temperature in turning process, using a continuous cutting model of Johnson-Cook (J-C). An method to predict the temperature distribution in orthogonal cutting is based on the constituent model of various material and the mechanics of their cutting process. In this method, the average temperature at the primary shear zone (PSZ) and the secondary shear zone (SSZ) were determined for various materials, based on a constitutive model and a chip-formation model using measurements of cutting force and chip thicknes. The J-C model constants were taken from Hopkinson pressure bar tests. Cutting conditions, cutting forces and chip thickness were used to predict shear stress. Experimental cutting heat results with the same cutting parameters using the minimum lubrication method (MQL) were recorded through the Testo-871 thermal camera. The thermal distribution results between the two methods has a difference in value, as well as distribution. From the difference, we have analyzed some of the causes, finding the effect of the minimum quantity lubrication parameters on the difference.

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Primary Chip Formation During an Extremely High Speed Micromachining Process

Manufacturing Engineering and Materials Handling Engineering ◽

10.1115/imece2004-59248 ◽

2004 ◽

Author(s):

M. J. Jackson ◽

C. H. Hamme ◽

L. J. Hyde ◽

G. M. Robinson ◽

H. Sein ◽

...

Keyword(s):

Shear Zone ◽

Chip Formation ◽

High Speed ◽

Cutting Tools ◽

Machining Processes ◽

Orthogonal Machining ◽

Shear Process ◽

Order Of Magnitude ◽

Cutting Zone ◽

Secondary Shear Zone

The advent of nanotechnology has created a demand for precision-machined substrates so that ‘bottom-up’ nanomanufacturing processes can be used to produce functional products at the nanoscale. However, machining processes must be scaled down by an order of magnitude that requires very stable desktop machine tools to produce precision-machined substrates using cutting tools that are rotated at speeds in excess of one million revolutions per minute. Therefore, the mechanics of chip formation at this scale are critical when one considers the effect of chip formation on the generation of surface roughness on the substrate. The tight curl of a machined chip in orthogonal machining appears to be part of the primary shear process. It is also known that transient tight curl occurs before a secondary shear zone develops ahead of the removal of the chip from the cutting zone. However, continuum models predict that curled chips incorporate stresses due to the establishment of a secondary shear zone. A model is presented in terms of the heterogeneous aspects of continuous chip formation, which shows very good agreement with experimental data.

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Analysis of adhered contacts and boundary conditions of the secondary shear zone

Wear ◽

10.1016/j.wear.2015.01.016 ◽

2015 ◽

Vol 330-331 ◽

pp. 608-617 ◽

Cited By ~ 7

Author(s):

S. Bahi ◽

G. List ◽

G. Sutter

Keyword(s):

Boundary Conditions ◽

Shear Zone ◽

Secondary Shear Zone

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Predictive Analytical and Thermal Modeling of Orthogonal Cutting Process—Part I: Predictions of Tool Forces, Stresses, and Temperature Distributions

Journal of Manufacturing Science and Engineering ◽

10.1115/1.2162590 ◽

2005 ◽

Vol 128 (2) ◽

pp. 435-444 ◽

Cited By ~ 66

Author(s):

Yiğit Karpat ◽

Tuğrul Özel

Keyword(s):

Shear Zone ◽

Thermal Modeling ◽

Orthogonal Cutting ◽

Cutting Process ◽

Field Analysis ◽

Normal Stress Distribution ◽

Modeling Approach ◽

Temperature Distributions ◽

Secondary Shear Zone ◽

1045 Steel

In this paper, a predictive thermal and analytical modeling approach for orthogonal cutting process is introduced to conveniently calculate forces, stress, and temperature distributions. The modeling approach is based on the work material constitutive model, which depends on strain, strain rate, and temperature. In thermal modeling, oblique moving band heat source theory is utilized and analytically combined with modified Oxley’s parallel shear zone theory. Normal stress distribution on the tool rake face is modeled as nonuniform with a power-law relationship. Hence, nonuniform heat intensity at the tool-chip interface is obtained from the predicted stress distributions utilizing slip line field analysis of the modified secondary shear zone. Heat sources from shearing in the primary zone and friction at the tool-chip interface are combined, heat partition ratios are determined for temperature equilibrium to obtain temperature distributions depending on cutting conditions. Model validation is performed by comparing some experimental results with the predictions for machining of AISI 1045 steel, AL 6082-T6, and AL 6061-T6 aluminum. Close agreements with the experiments are observed. A set of detailed, analytically computed stress and temperature distributions is presented.

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Identification of Material Constitutive Laws for Machining—Part II: Generation of the Constitutive Data and Validation of the Constitutive Law

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4002455 ◽

2010 ◽

Vol 132 (5) ◽

Cited By ~ 16

Author(s):

Bin Shi ◽

Helmi Attia ◽

Nejah Tounsi

Keyword(s):

Shear Zone ◽

High Speed ◽

Split Hopkinson Pressure Bar ◽

Orthogonal Cutting ◽

Material Behavior ◽

Constitutive Law ◽

Primary Zone ◽

Wide Range ◽

Static Conditions ◽

Secondary Shear Zone

This paper presents an integral methodology to obtain a wide range of constitutive data required for the identification of the constitutive equation used in simulating cutting processes. This methodology is based on combining the distributed primary zone deformation (DPZD) model developed in Part I (Shi et al., 2010, ASME J. Manuf. Sci. Eng., 132, p. 051008.) of this study with quasi-static indentation (QSI) tests, orthogonal cutting tests at room temperature (RT) and high temperature. The QSI tests are used to capture the material properties in the quasi-static conditions, which solve the unstable solutions for the coefficients of the constitutive law. The RT cutting tests are designed to fulfill the assumptions embedded in the developed DPZD model in order to provide the distributed constitutive data encountered in the primary shear zone. To capture the material behavior in the secondary shear zone, the orthogonal cutting tests with a laser preheating system are designed to raise the temperature in the primary zone to the level encountered in the secondary zone. As an application of the generated constitutive data, the Johnson–Cook model is identified for Inconel 718. This constitutive law is further validated using high speed split Hopkinson pressure bar tests and orthogonal cutting tests combined with finite element simulations. In comparison with the previous approaches reported in the open literature, the developed DPZD model and methodology significantly improve the accuracy of the simulation results.

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Experimental-Analytical Method for Temperature Determination in the Cutting Zone during Orthogonal Turning of GRADE 2 Titanium Alloy

Materials ◽

10.3390/ma14154328 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4328

Author(s):

Łukasz Ślusarczyk

Keyword(s):

Titanium Alloy ◽

Shear Zone ◽

Analytical Method ◽

Cutting Forces ◽

Experimental Tests ◽

Forming Process ◽

Orthogonal Turning ◽

Cutting Zone ◽

Secondary Shear Zone ◽

Oxley’S Theory

The paper presents an experimental-analytical method for determination of temperature in the cutting zone during the orthogonal turning of GRADE 2 titanium alloy. A cutting insert with a complex rake geometry was used in the experiments. The experimental part of the method involved orthogonal turning tests during which the cutting forces and the chip forming process were recorded for two different insert rake faces. The analytical part used a relationship between the cutting forces and the temperature in the Primary Shear Zone (PSZ) and the Secondary Shear Zone (SSZ), which are described by the Johnson-Cook (J-C) constitutive model and the chip forming model according to the Oxley’s theory. The temperature in the PSZ and SSZ was determined by finding the minimum difference between the shear flow stress determined in the J-C model and the Oxley’s model. Finally, using the described method, the relationship between the temperature in the PSZ and SSZ and the rake face geometry was determined. In addition, the temperature in the cutting zone was measured during the experimental tests with the use of a thermovision camera. The temperature distribution results determined experimentally with a thermovision camera were compared with the results obtained with the described method.

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