Theoretical Analysis of Serrated Chip Formation Based on Ideal Models in High Speed Cutting

2010 ◽  
Vol 154-155 ◽  
pp. 239-245
Author(s):  
Chong Yang Gao ◽  
Bin Fang ◽  
Yuan Tong Gu
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
Engineering Application ◽  
Chip Thickness ◽  
Chip Morphology ◽  
Formation Model ◽  
Serrated Chip ◽  
Serrated Chip Formation ◽  
Serrated Chips ◽  
The Ideal

In this paper, two ideal formation models of serrated chips, the symmetric formation model and the unilateral right-angle formation model, have been established for the first time. Based on the ideal models and related adiabatic shear theory of serrated chip formation, the theoretical relationship among average tooth pitch, average tooth height and chip thickness are obtained. Further, the theoretical relation of the passivation coefficient of chip’s sawtooth and the chip thickness compression ratio is deduced as well. The comparison between these theoretical prediction curves and experimental data shows good agreement, which well validates the robustness of the ideal chip formation models and the correctness of the theoretical deducing analysis. The proposed ideal models may have provided a simple but effective theoretical basis for succeeding research on serrated chip morphology. Finally, the influences of most principal cutting factors on serrated chip formation are discussed on the basis of a series of finite element simulation results for practical advices of controlling serrated chips in engineering application.

Research on Adiabatic Shear during Serrated Chip Formation of High Speed Turning of Hardened Steel

2010 ◽  
Vol 139-141 ◽  
pp. 743-747
Author(s):  
Chun Zheng Duan ◽  
Hai Yang Yu ◽  
Min Jie Wang ◽  
Bing Yan ◽  
Yu Jun Cai
Keyword(s):  
Chip Formation ◽  
Cutting Forces ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Rake Angle ◽  
Adiabatic Shear ◽  
Cutting Condition ◽  
Serrated Chip ◽  
Serrated Chip Formation

The development of chip morphology, critical cutting condition of adiabatic shear during serrated chip formation and cutting forces were observed and measured by high speed turning experiment for 30CrNi3MoV hardened steel. Results show that the cutting speed and rake angle are leading factors to influence chip morphology and cutting forces. With the increase of cutting speed, the continuous band chip transforms into serrated chip at a certain critical value. As the rake angle is changed from positive to negative, the critical cutting speed of adiabatic shear significantly decreases, the cutting forces abruptly reduces when the serrated chip forms. The results from predicting critical cutting speed using the critical cutting condition criterion of adiabatic shear in metal cutting process show that the leading reason of serrated chip formation is that the adiabatic shear fracture repeatedly occurs in the primary shear zone.

Investigation of Chip Morphology in High-Speed Milling of Nickel-Based Superalloy GH706

2014 ◽  
Vol 800-801 ◽  
pp. 113-118
Author(s):  
Sheng Lei Xiao ◽  
Xian Li Liu ◽  
Yu Wang ◽  
Kai Li
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Adiabatic Shear ◽  
Shear Instability ◽  
Serrated Chip ◽  
High Speed Milling ◽  
Nickel Based Superalloy ◽  
Serrated Chip Formation

This paper analyzed the serrated chip formation process and mechanism in high-speed milling of nickel-based superalloy GH706. Firstly, analyzed two theories of serrated chip formation: cyclical fracture theory and adiabatic shear theory. Secondly, used the simulation of chip formation in high-speed milling of GH706 process, and concluded that the two major theories have achieved dialectical unity when machining for such difficult machining materials. Finally experiments for serrated chip, when cutting speed exceeded 200/min, serrated chips became more obvious. Research has shown that for nickel-based superalloy, adiabatic shear instability of the unstable thermoplastic in the first deformation zoon become the leader of formation of serrated chip, followed as the speed increases, fracture aggravate the degree of serrated chip.

Prediction of Chip Morphology and Formation in High Speed Milling of Hardened Steels

2015 ◽  
Vol 1120-1121 ◽  
pp. 1145-1152
Author(s):  
Jun Zhong Pang ◽  
Xiao Bin Huang ◽  
Dou Dou Chang ◽  
Jie Pan
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
Shear Banding ◽  
Chip Morphology ◽  
Material Model ◽  
Adiabatic Shear ◽  
Serrated Chip ◽  
Adiabatic Shear Banding ◽  
Serrated Chip Formation ◽  
Material Constitutive Equation

A P20 steel are machined in the milling speed range of 200 to 942m/min. The morphology and formation of the chips are investigated at various speeds. The serrated chips with adiabatic shear band are observed at a high milling speed. The transition from continuous to serrated chip formation is favored by the increase in work material hardness and milling speed. The study assumes that the chip segmentation is only induced by adiabatic shear banding, without material failure in the primary shear zone. Based on adiabatic shear theory, using the JC and the power material constitutive equation, the modified material model which takes into a strain softening is developed for prediction of the serrated chip formation. Experimental measurements are compared with the simulation results.

Experimental and FEM Study of Serrated Chip Formation in High Speed Turning Processes

2011 ◽  
Vol 264-265 ◽  
pp. 1021-1026
Author(s):  
U. Umer ◽  
Li Jing Xie ◽  
Syed Jawid Askari ◽  
S.N. Danish ◽  
S.I. Butt
Keyword(s):  
Chip Formation ◽  
Cutting Forces ◽  
High Speed ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Serrated Chip ◽  
High Speed Turning ◽  
Serrated Chip Formation

The finite element method (FEM) has been used to model high speed turning processes with orthogonal cutting conditions. In most of the situations, continuous chip formation is used to analyze the turning process due to its stability and allowing many conditions to simplify the process. However with the increasing applications of high speed turning, serrated chip formation is becoming a more common phenomenon in metal cutting. Serrated chips usually occur in machining of difficult to cut materials at or above a threshold speed. An updated Lagrangian formulation has been used in this study which works with element deletion technique based on a failure criterion. The Johnson Cook strain-hardening thermal-softening material model is used to model serrated chip formation. In addition high speed turning experiments were conducted on AISI H13 tubes using PCBN to analyze serrated chip phenomenon. The chips were analyzed after surface treatment using scanning electron microscope. It has been found that the length of cuts in the chip increases with the cutting speed and the chip changes from serrated to discontinuous. Different process variables like cutting forces, chip morphology, stress, strain and temperature distributions are predicted at different process parameters using FEM. The results show cyclic variation in the cutting forces at high cutting speeds due to varying chip load.

Analytical Predictive Modeling of Serrated Chip Formation in High Speed Machining of 7075-T6 Aluminum Alloy

2004 ◽  
Author(s):  
Ning Fang ◽  
Juhchin Yang ◽  
Nan Liu
Keyword(s):  
Aluminum Alloy ◽  
Chip Formation ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Tool Geometry ◽  
High Speed Machining ◽  
Serrated Chip ◽  
Serrated Chip Formation

High speed machining has received increasingly broad applications in various industries, especially in the aircraft and aerospace industry, where a large number of structural frames are machined. Based on Manyindo and Oxley’s descriptive model of serrated chip formation, this paper proposes a new mathematical model for high speed machining of 7075-T6 aluminum alloy. The new model integrates Johnson-Cook’s material model with Oxley’s machining theory and is validated by using the published experimental data. A good agreement between the predicted and experimental degree of chip segmentation is reached. The effects of cutting conditions and tool geometry on the serrated chip geometry, the cutting forces, and the shear-plane angles are quantitatively investigated. The analysis shows that a large undeformed chip thickness, a negative tool rake angle, and a high cutting speed strengthen the degree of chip segmentation in high speed machining.

Finite Element Investigation of the Influence of Thermophysical Parameters on Segmented Chip Formation during High Speed Cutting

2011 ◽  
Vol 130-134 ◽  
pp. 2817-2821
Author(s):  
You Xi Lin ◽  
Cong Ming Yan
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
Specific Heat ◽  
Chip Formation ◽  
High Speed ◽  
Element Model ◽  
Serrated Chip ◽  
High Speed Cutting ◽  
Thermophysical Parameters ◽  
Serrated Chip Formation

A 2D fully thermal mechanical coupled finite element model is applied to study the influence of material parameters on serrate chip formation during high speed cutting process. The serrated chip formation during high speed machining was predicted. Of interests are the effects of thermal conductivity, specific heat and density. Results showed significant influence of these thermophysical parameters on the serrated chip phenomena, especially in the case of the density. Increasing thermal conductivity specific heat and density lead to a decreasing degree of segmentation. The influence of the thermal conductivity on the cutting force and the specific heat on maximum temperatures in the shear band is also discussed.

Characteristics of serrated chip formation in high-speed machining of metallic materials

2016 ◽  
Vol 86 (5-8) ◽  
pp. 1201-1206 ◽  
Author(s):  
Qibiao Yang ◽  
Yin Wu ◽  
Dun Liu ◽  
Lie Chen ◽  
Deyuan Lou ◽  
...  
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
High Speed Machining ◽  
Metallic Materials ◽  
Serrated Chip ◽  
Serrated Chip Formation
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