Evaluation of Chip Morphology in Hard Turning Using Constitutive Models and Material Property Data

2006 ◽  
Vol 129 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Gérard Poulachon ◽  
Alphonse L. Moisan ◽  
I. S. Jawahir
Keyword(s):  
Flow Stress ◽  
Chip Formation ◽  
Hard Turning ◽  
Constitutive Relations ◽  
Cutting Temperature ◽  
Mechanical Tests ◽  
Bearing Steel ◽  
Material Behavior ◽  
Shear Instability ◽  
Instability Criterion

Modeling of machining operations requires the use of constitutive relations which could represent as close as possible the material behavior in the primary and secondary zones. The knowledge of these behavior laws involves the use of different types of sophisticated mechanical tests which should provide with sufficient accuracy the material behavior for the relevant conditions of machining. In this paper, first, the flow stress of 100Cr6 (AISI 52100) bearing steel in its HV730 hardness state has been identified in order to assess the machinability in case of hard turning. With this, the dependence of the flow stress on strain, strain rate and temperature, which poses significant difficulty, is presented. Second, the material machinability is evaluated with a shear instability criterion, enabling the prediction of chip formation with or without the shear localization. Quick-stop tests have been carried out on the bearing steel treated at different hardness values showing the chip formation variation. Micro-hardness tests performed on these quick-stop test samples show the effects of cutting temperature. A greater understanding of applied machinability is gained through this precise study of work material physical properties and behavior.

Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples

2012 ◽  
Author(s):  
Linwen Li ◽  
Bin Li ◽  
Xiaochun Li ◽  
Kornel F. Ehmann
Keyword(s):  
Thin Film ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Chip Formation ◽  
Hard Turning ◽  
Cutting Temperature ◽  
Temperature Distributions ◽  
Field Distributions ◽  
Thin Film Thermocouples ◽  
Cutting Zone

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions are measured by thin film thermocouples (TFTCs) embedded into Polycrystalline Cubic Boron Nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. Using these measurements, steady and dynamic phenomena during hard turning as well as the chip morphology and formation process were analyzed based on the cutting temperature distributions in the insert. The relationship between the cutting temperature-field distributions in the PCBN insert and the segmented chip formation is analyzed using temperature-distribution mapping. It is shown that the temperature-distribution in the cutting zone depends on the shearing band distribution in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.

PCBN Tool Wear Mechanism in Hard Turning Hardened Bearing Steel

2006 ◽  
Vol 315-316 ◽  
pp. 334-338 ◽  
Author(s):  
S.J. Dai ◽  
Dong Hui Wen ◽  
Ju Long Yuan
Keyword(s):  
Wear Mechanism ◽  
Hard Turning ◽  
Cutting Temperature ◽  
Tool Material ◽  
Bearing Steel ◽  
Workpiece Material ◽  
Pcbn Tool ◽  
Wear Pattern ◽  
Tool Wear Mechanism ◽  
Cutting Zone

The wear pattern and mechanism during continuous hard turning GCr15 hardened bearing steel with BZN8200 PCBN cutting tool was studied. Experimental results showed that the main wear pattern is crater wear in rake face and mechanical wear in flank face, the main wear mechanism is made-up with adhesive, oxidization and diffusive wear. The adhesive wear is generated by melt workpiece material flows with binder material of PCBN tool during initial cutting, oxidative wear is derived by cutting temperature and pressure of cutting zone when the flank wear increase after initial cutting, diffusive wear phenomenon is the absolute mechanism with the diffusive effect between workpiece and tool material in final cutting time.

Cutting temperature and tool wear of hard turning hardened bearing steel

2002 ◽  
Vol 129 (1-3) ◽  
pp. 200-206 ◽  
Author(s):  
X.L Liu ◽  
D.H Wen ◽  
Z.J Li ◽  
L Xiao ◽  
F.G Yan
Keyword(s):  
Tool Wear ◽  
Hard Turning ◽  
Cutting Temperature ◽  
Bearing Steel

Research Status of Subsequent Machining of Laser Cladding Layers

2020 ◽  
Vol 15 ◽  
Author(s):  
Lei Li ◽  
Yujun Cai ◽  
Guohe Li ◽  
Meng Liu
Keyword(s):  
Tool Wear ◽  
Surface Quality ◽  
Laser Cladding ◽  
Wear Surface ◽  
Chip Formation ◽  
Cutting Temperature ◽  
Dimensional Accuracy ◽  
Cutting Parameters ◽  
Cladding Layer ◽  
Cladding Layers

Background: As an important method of remanufacturing, laser cladding can be used to obtain the parts with specific shapes by stacking materials layer by layer. The formation mechanism of laser cladding determines the “Staircase effect”, which makes the surface quality can hardly meet the dimensional accuracy of the parts. Therefore, the subsequent machining must be performed to improve the dimensional accuracy and surface quality of cladding parts. Methods: In this paper, chip formation, cutting force, cutting temperature, tool wear, surface quality, and optimization of cutting parameters in the subsequent cutting of laser cladding layer are analyzed. Scholars have expounded and studied these five aspects but the cutting mechanism of laser cladding need further research. Results: The characteristics of cladding layer are similar to that of difficult to machine materials, and the change of parameters has a significant impact on the cutting performance. Conclusion: The research status of subsequent machining of cladding layers is summarized, mainly from the aspects of chip formation, cutting force, cutting temperature, tool wear, surface quality, and cutting parameters optimization. Besides, the existing problems and further developments of subsequent machining of cladding layers are pointed out. The efforts are helpful to promote the development and application of laser cladding remanufacturing technology.

A Comparative Study on Hydraulic Bulge Testing and Analysis Methods

2008 ◽  
Author(s):  
Eren Billur ◽  
Muammer Koc¸
Keyword(s):  
Flow Stress ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Material Behavior ◽  
Biaxial Stress ◽  
Dome Height ◽  
Bulge Test ◽  
Analysis Methods ◽  
Bulge Testing ◽  
Hydraulic Bulge

Hydraulic bulge testing is a material characterization method used as an alternative to tensile testing with the premise of accurately representing the material behavior to higher strain levels (∼70% as appeared to ∼30% in tensile test) in a biaxial stress mode. However, there are some major assumptions (such as continuous hemispherical bulge shape, thinnest point at apex) in hydraulic bulge analyses that lead to uncertainties in the resulting flow stress curves. In this paper, the effect of these assumptions on the accuracy and reliability of flow stress curves is investigated. The goal of this study is to determine the most accurate method for analyzing the data obtained from the bulge testing when continuous and in-line thickness measurement techniques are not available. Specifically, in this study the stress-strain relationships of two different materials (SS201 and Al5754) are obtained based on hydraulic bulge test data using various analysis methods for bulge radius and thickness predictions (e.g., Hill’s, Chakrabarty’s, Panknin’s theories, etc.). The flow stress curves are calculated using pressure and dome height measurements and compared to the actual 3-D strain measurement from a stereo optical and non-contact measurement system ARAMIS. In addition, the flow stress curves obtained from stepwise experiments are compared with the ones from above methods. Our findings indicate that Enikeev’s approach for thickness prediction and Panknin’s approach for bulge radius calculation result in the best agreement with both stepwise experiment results and 3D optical measurement results.

Determining Deformation Behavior of AISI 9310 Steel Varying Temperature and Strain Rate for Aerospace Applications

2021 ◽  
Author(s):  
Adanma Akoma ◽  
Kevin Sala ◽  
Chase Sheeley ◽  
Lesley D. Frame
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Test Sample ◽  
Material Behavior ◽  
Image Correlation ◽  
Sample Length ◽  
Stress Behavior ◽  
Flow Stress Behavior ◽  
The Impact

Abstract Determination of flow stress behavior of materials is a critical aspect of understanding and predicting behavior of materials during manufacturing and use. However, accurately capturing the flow stress behavior of a material at different strain rates and temperatures can be challenging. Non-uniform deformation and thermal gradients within the test sample make it difficult to match test results directly to constitutive equations that describe the material behavior. In this study, we have tested AISI 9310 steel using a Gleeble 3500 physical simulator and Digital Image Correlation system to capture transient mechanical properties at elevated temperatures (300°C – 600°C) while controlling strain rate (0.01 s-1 to 0.1 s-1). The data presented here illustrate the benefit of capturing non-uniform plastic strain of the test specimens along the sample length, and we characterize the differences between different test modes and the impact of the resulting data that describe the flow stress behavior.

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