Analytical modeling of work hardening of duplex steel alloys in milling process

2021 ◽  
Author(s):  
yousef mohammadi ◽  
Hossein Amirabadi
Keyword(s):  
Analytical Model ◽  
Work Hardening ◽  
Experimental Tests ◽  
Material Model ◽  
Milling Process ◽  
Temperature Fields ◽  
Machined Surface ◽  
Strain And Strain Rate ◽  
Subsurface Layers ◽  
Sever Plastic Deformation

Abstract Sever plastic deformation in cutting operations such as milling, might change mechanical properties of the machined surface. This study presents an analytical model to calculate work hardening of the upper layers of the workpiece in the milling process of 2205 duplex stainless steel. In this regards, the stresses in the cutting regions are calculated to find the stress and temperature fields in the workpiece. Then the strain and strain rate values are calculated for each point of the surface and subsurface layers using the determined stress field. Finally, Johnson-Cook material model is used to calculate flow stress and work hardening. Experimental results of the different machining conditions has been used to validating the proposed model, however comparisons of subsurface microhardness obtained by analytical model with experimental tests shown that the model properly predicts the amount of work hardening.

scholarly journals A Unique Model to Estimate Geometric Deviations in Drilling and Milling Due to Two Uncertainty Sources

2021 ◽  
Vol 11 (5) ◽  
pp. 1996
Author(s):  
Wilma Polini ◽  
Andrea Corrado
Keyword(s):  
Machine Tool ◽  
Information And Communication Technologies ◽  
Simulation Models ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Milling Process ◽  
Machined Surface ◽  
Uncertainty Sources ◽  
Geometric Deviations ◽  
Form Deviation

Industry 4.0 involves the use of information and communication technologies to transform industry by intelligent networking machines and processes. The availability of big data sets from manufacturing and inspection allow for developing new and more accurate simulation models. This involves the development of new machining simulation models to consider the geometrical deviations of the workpiece due to the machine tool, the part datum surfaces and the fixturing equipment. This work presents a model that kinematically correlates the locator uncertainty, the form deviation on the part datum surface in contact with the locators and the volumetric uncertainty of the machine tool, with the geometric deviations of a surface due to a drilling or milling process. An analytical model was developed in a Matlab® file to simulate the surface geometrical deviations from nominal during drilling or milling. It is new as regards the state of the art because it takes into account two sources of uncertainty. This numerical approach allows for avoiding experimental tests, with a resultant saving of time, energy and material. It was applied to drilling, face milling and contouring processes. It was proved that machine tool volumetric uncertainty influences the form deviation of the machined surface, while the locator configuration and the datum form deviation affect the orientation of the machined surface, as should be in reality. The proposed model allows us to take into account geometrical deviations of the part datum surfaces of 0.001 mm, location deviations in the locators of ± 0.03 mm and machine tool positional and rotational uncertainties of 0.01 mm and σd=0.01∗π180 mm, respectively.

scholarly journals Fabrication and characterization of resistive double square loop arrays for ultra-wide bandwidth microwave absorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ji-Young Jeong ◽  
Je-Ryung Lee ◽  
Hyeonjin Park ◽  
Joonkyo Jung ◽  
Doo-Sun Choi ◽  
...  
Keyword(s):  
Sheet Resistance ◽  
Manufacturing Process ◽  
End Milling ◽  
Milling Process ◽  
Wide Bandwidth ◽  
Machined Surface ◽  
Array Pattern ◽  
Micro End Milling ◽  
Array Structures ◽  
Printing Processes

AbstractMicrowave absorbers using conductive ink are generally fabricated by printing an array pattern on a substrate to generate electromagnetic fields. However, screen printing processes are difficult to vary the sheet resistance values for different regions of the pattern on the same layer, because the printing process deposits materials at the same height over the entire surface of substrate. In this study, a promising manufacturing process was suggested for engraved resistive double square loop arrays with ultra-wide bandwidth microwave. The developed manufacturing process consists of a micro-end-milling, inking, and planing processes. A 144-number of double square loop array was precisely machined on a polymethyl methacrylate workpiece with the micro-end-milling process. After engraving array structures, the machined surface was completely covered with the developed conductive carbon ink with a sheet resistance of 15 Ω/sq. It was cured at room temperature. Excluding the ink that filled the machined double square loop array, overflowed ink was removed with the planing process to achieve full filled and isolated resistive array patterns. The fabricated microwave absorber showed a small radar cross-section with reflectance less than − 10 dB in the frequency band range of 8.0–14.6 GHz.

Basic Experimental and Numerical Investigations on Chip Pressing

2013 ◽  
Vol 554-557 ◽  
pp. 630-637 ◽  
Author(s):  
Martin Grüner ◽  
Marion Merklein
Keyword(s):  
Numerical Simulation ◽  
Aluminium Alloys ◽  
Testing Machine ◽  
Material Model ◽  
Extrusion Process ◽  
Milling Process ◽  
Numerical Investigations ◽  
Compression Direction ◽  
Universal Testing ◽  
The Stability

Aluminium alloys show a great potential for lightweight constructions due to their high strength and low density but the production of this material is very energy consuming. Also the recycling of aluminium alloys, e.g. chips from the milling process, shows different challenges. Beside contamination by cooling lubricant and oxidation of the surface of the chips the melting and rolling process for new semi finish products needs a high amount of energy. TEKKAYA shows a new approach for recycling of aluminium alloy chips by an extrusion process at elevated temperatures producing different kinds of profiles. A new idea is the production of components directly out of chips using severe plastic deformation for joining of the chips similar to the accumulative roll bonding process in sheet metal forming. In a first approach aluminium alloy chips out of a milling process were uniaxial compressed with different loads inside an axisymmetric tool installed in a universal testing machine. The compressed chip disks subsequently were tested with two experiments to gain information on their stability. First experiment is a disk compression test with the disk standing on its cylindrical surface, giving information on the stability perpendicular to the compression direction. Second experiment is a stacked disk compression test with three disks to investigate the stability parallel to compression direction. During all three tests force and displacement values are recorded by the universal testing machine. These data are also processed to calculate or identify input parameters for the numerical investigations. For numerical simulation ABAQUS in conjunction with the Drucker-Prager-Cap material model, which is often used for sintering processes, seems to be a good choice. By numerical simulation of the experiments and comparison with the experiments input parameters for the material model can be identified showing good accordance. This material model will be used in future numerical investigations of an extrusion process to identify tool geometries leading to high strains inside the material and by this to an increased stability of the parts.

Study on Machining Mechanism of Glass Using Discrete Element Method

2014 ◽  
Vol 577 ◽  
pp. 108-111 ◽  
Author(s):  
Ying Qiu ◽  
Mei Lin Gu ◽  
Feng Guang Zhang ◽  
Zhi Wei
Keyword(s):  
Discrete Element Method ◽  
Element Model ◽  
Discrete Element ◽  
Rake Angle ◽  
Milling Process ◽  
Micro Milling ◽  
Discrete Element Model ◽  
Machined Surface ◽  
Damage Depth ◽  
Element Method

The discrete element method (DEM) is applied to glass micromachining in this study. By three standard tests the discrete element model is established to match the main mechanical properties of glass. Then, indentating, cutting, micro milling process are simulated. Results show that the vertical damage depth is prevented from reaching the final machined surface in cutting process. Tool rake angle is the most remarkable factor influencing on the chip deformation and cutting force. The final machined surface is determined by the minimum cutting thickness per edge. Different cutting thickness, cutter shape and spindle speed largely effect on the mechanism of glass.

Experimental investigation of the influence of cutting parameters on surface quality and on the special characteristics of micro-milled surfaces of hardened steels

2021 ◽  
pp. 095440622110130
Author(s):  
Barnabás Zoltán Balázs ◽  
Márton Takács
Keyword(s):  
Surface Quality ◽  
Surface Profile ◽  
Cutting Parameters ◽  
Relevant Information ◽  
Milling Process ◽  
Micro Milling ◽  
Machined Surface ◽  
Analysis Of Dynamics ◽  
Five Axis ◽  
Coated Carbide

Micro-milling is one of the most essential technologies to produce micro components, but due to the size effect, it has many special characteristics and challenges. The process can be characterised by strong vibrations, relatively large run-out and tool deformation, which directly affects the quality of the machined surface. This paper deals with a detailed investigation of the influence of cutting parameters on surface roughness and on the special characteristics of micro-milled surfaces. Several systematic series of experiments were carried out and analysed in detail. A five-axis micromachining centre and a two fluted, coated carbide micro-milling tool with a diameter of 500 µm were used for the tests. The experiments were conducted on AISI H13 hot-work tool steel and Böhler M303 martensitic corrosion resistance steel with a hardness of 50 HRC in order to gain relevant information of machining characteristics of potential materials of micro-injection moulding tools. The effect of the cutting parameters on the surface quality and on the ratio of Rz/ Ra was investigated in a comprehensive cutting parameter range. ANOVA was used for the statistical evaluation. A novel method is presented, which allows a detailed analysis of the surface profile and repetitions, and identify the frequencies that create the characteristic profile of the surface. The procedure establishes a connection between the frequencies obtained during the analysis of dynamics (forces, vibrations) of the micro-milling process and the characterising repetitions and frequencies of the surface.

scholarly journals Surface Integrity Investigation to Determine Rough Milling Effects for Assessment of Machining Allowance for Subsequent Finish Milling of Alloy 718

2021 ◽  
Vol 5 (2) ◽  
pp. 48
Author(s):  
Jonas Holmberg ◽  
Anders Wretland ◽  
Johan Berglund ◽  
Tomas Beno ◽  
Anton Milesic Karlsson
Keyword(s):  
Surface Integrity ◽  
Milling Process ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Milling Operations ◽  
Milling Operation ◽  
Machining Allowance ◽  
Rough Milling

The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm.

scholarly journals Machining-Induced Work Hardening Behavior of Inconel 718 Considering Edge Geometries

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 397
Author(s):  
Bin Zhou ◽  
Weiwei Zhang ◽  
Zhongmei Gao ◽  
Guoqiang Luo
Keyword(s):  
Grain Size ◽  
Work Hardening ◽  
Inconel 718 ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Machined Surface ◽  
Work Hardening Behavior ◽  
Hardening Behavior ◽  
Significant Difference ◽  
Optimization Of Cutting Parameters

As a representative type of superalloy, Inconel 718 is widely employed in aerospace, marine and nuclear industries. The significant work hardening behavior of Inconel 718 can improve the service performance of components; nevertheless, it cause extreme difficulty in machining. This paper aims to investigate the influence of chamfered edge parameters on work hardening in orthogonal cutting of Inconel 718 based on a novel hybrid method, which integrates Coupled Eulerian-Lagrangian (CEL) method and grain-size-based functions considering the influence of grain size on microhardness. Orthogonal cutting experiments and nanoindentation tests are conducted to validate the effectiveness of the proposed method. The predicted results are highly consistent with the experimental results. The depth of work hardening layer increases with increasing chamfer angle and chamfer width, also with increasing feed rate (the uncut chip thickness). However, the maximum microhardness on the machined surface does not exhibit a significant difference. The proposed method can provide theoretical guidance for the optimization of cutting parameters and improvement of the work hardening.

scholarly journals A Modified Analytical Heat Source Model for Numerical Simulation of Temperature Field in Friction Stir Welding

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Xiangqian Liu ◽  
Yan Yu ◽  
Shengli Yang ◽  
Huijie Liu
Keyword(s):  
Heat Flux ◽  
Friction Stir Welding ◽  
Analytical Model ◽  
Heat Generation ◽  
Tilt Angle ◽  
Temperature Fields ◽  
Analytical Models ◽  
Maximum Temperature ◽  
Thermal Cycles ◽  
Friction Stir

In the conventional analytical model used for heat generation in friction stir welding (FSW), the heat generated at the pin/workpiece interface is assumed to distribute uniformly in the pin volume, and the heat flux is applied as volume heat. Besides, the tilt angle of the tool is assumed to be zero for simplicity. These assumptions bring about simulating deviation to some extent. To better understand the physical nature of heat generation, a modified analytical model, in which the nonuniform volumetric heat flux and the tilt angle of the tool were considered, was developed. Two analytical models are then implemented in the FEM software to analyze the temperature fields in the plunge and traverse stage during FSW of AA6005A-T6 aluminum hollow extrusions. The temperature distributions including the maximum temperature and heating rate between the two models are different. The thermal cycles in different zones further revealed that the peak temperature and temperature gradient are very different in the high-temperature region. Comparison shows that the modified analytical model is accurate enough for predicting the thermal cycles and peak temperatures, and the corresponding simulating precision is higher than that of the conventional analytical model.

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