Modeling the Material Microstructure Effects on the Surface Generation Process in Microendmilling of Dual-Phase Materials

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
A. M. Abdelrahman Elkaseer ◽  
S. S. Dimov ◽  
K. B. Popov ◽  
M. Negm ◽  
R. Minev
Keyword(s):  
Chip Thickness ◽  
Machining Process ◽  
Surface Generation ◽  
Dual Phase ◽  
Generation Process ◽  
Phase Boundaries ◽  
Material Microstructure ◽  
Workpiece Material ◽  
Multiphase Materials ◽  
Proposed Model

The anisotropic behavior of the material microstructure when processing multiphase materials at microscale becomes an important factor that has to be considered throughout the machining process. This is especially the case when chip-loads and machined features are comparable in size to the cutting edge radius of the tool, and also similar in scale to the grain sizes of the phases present within the material microstructure. Therefore, there is a real need for reliable models, which can be used to simulate the surface generation process during microendmilling of multiphase materials.This paper presents a model to simulate the surface generation process during microendmilling of multiphase materials. The proposed model considers the effects of the following factors: the geometry of the cutting tool, the feed rate, and the workpiece material microstructure. Especially, variations of the minimum chip thickness at phase boundaries are considered by feeding maps of the material microstructure into the model. Thus, the model takes into account these variations that alter the machining mechanism from a proper cutting to ploughing and vice versa, and are the main cause of microburr formation. By applying the proposed model, it is possible to estimate more accurately the resulting roughness because the microburr formation dominates the surface generation process during microendmilling of multiphase materials. The proposed model was experimentally validated by machining two different samples of dual-phase steel under a range of chip-loads. The roughness of the resulting surfaces was measured and compared to the predictions of the proposed model under the same cutting conditions. The results show that the proposed model accurately predicts the roughness of the machined surfaces by taking into account the effects of material multiphase microstructure. Also, the developed model successfully elucidates the mechanism of microburr formation at the phase boundaries, and quantitatively describes its contributions to the resulting surface roughness after microendmilling.

On the Modeling and Analysis of Machining Performance in Micro-Endmilling, Part I: Surface Generation

2004 ◽  
Vol 126 (4) ◽  
pp. 685-694 ◽  
Author(s):  
Michael P. Vogler ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Surface Roughness ◽  
Ductile Iron ◽  
Single Phase ◽  
Chip Thickness ◽  
Thickness Effect ◽  
Surface Generation ◽  
Generation Model ◽  
Generation Process ◽  
Machining Performance ◽  
Minimum Chip Thickness

This paper examines the surface generation process in the micro-endmilling of both single-phase and multiphase workpiece materials. We used 508 μm dia endmills with edge radii of 2 and 5 μm to machine slots in ferrite, pearlite, and two ductile iron materials at feed rates ranging from 0.25 to 3.0 μm/flute. A surface generation model to predict the surface roughness for the slot floor centerline is then developed based on the minimum chip thickness concept. The minimum chip thickness values were found through finite element simulations for the ferrite and pearlite materials. The model is shown to accurately predict the surface roughness for single-phase materials, viz., ferrite and pearlite. Two phenomena were found to combine to generate an optimal feed rate for the surface generation of single-phase materials: (i) the geometric effect of the tool and process geometry and (ii) the minimum chip thickness effect. The surface roughness measurements for the ductile iron workpieces indicate that the micromilling surface generation process for multiphase workpiece materials is also affected by the interrupted chip-formation process as the cutting edge moves between phases resulting in burrs at the phase boundaries and the associated increases in surface roughness.

Model-Based Analysis of the Surface Generation in Microendmilling—Part I: Model Development

2006 ◽  
Vol 129 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Xinyu Liu ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Stochastic Model ◽  
Surface Topography ◽  
Deterministic Model ◽  
Elastic Recovery ◽  
Chip Thickness ◽  
Surface Generation ◽  
Generation Model ◽  
Generation Process ◽  
Floor Surface ◽  
Tool Edge

This paper presents the development of models that describe the surface-generation process for microendmilling. The surface-generation models for the sidewall and floor surfaces consist of deterministic and stochastic models. In the sidewall surface-generation model, the deterministic model characterizes the surface topography generated from the relative motion between the major cutting edge and the workpiece material. The model includes the effects of the process kinematics, dynamics, tool edge serration, and process faults (e.g., tool tip runout). The stochastic model predicts the increased surface roughness generated from ploughing due to the significant tool edge radius effect. In the floor surface-generation model, the deterministic model characterizes the three-dimensional surface topography over the entire floor surface and considers the effects of the minimum chip thickness, the elastic recovery, and the transverse vibration. The variation of the ploughing amount across the swept arc of the cutter due to the varying chip load conditions is considered in the stochastic model.

Modelling of Ultra-Precision Turning Processes in Consideration of Unbalances

2011 ◽  
Vol 223 ◽  
pp. 839-848 ◽  
Author(s):  
Christina Brandt ◽  
Jenny Niebsch ◽  
Jost Vehmeyer
Keyword(s):  
Surface Quality ◽  
High Surface ◽  
Machining Process ◽  
Surface Generation ◽  
Generation Process ◽  
Optical Components ◽  
Diamond Machining ◽  
Precision Turning ◽  
Ultra Precision ◽  
Machine Interaction

In order to manufacture optical components or mechanical parts with high surface roughness requirements, diamond machining is used. To achieve the desired surface quality, the understanding of the surface generation process and its influencing parameters is important. Here, the crucial parameter is the residual unbalance of the main spindle. As the residual un-balance affects the process and vice versa, the investigation of the process-machine interaction is necessary. In this paper we present a model describing this interaction between dynamical unbalances that occur during the machining process and the engine-shaft structure at the example of an ultra-precision turning lathe. This model allows the determination of the achievable surface quality of a workpiece for a given balancing state. On the other hand we will present a mathematical method to solve the corresponding inverse problem of computing the necessary residual balancing state and balancing weights for a given desired or given measured surface quality.

Hierarchical Concept-Driven Language Model

2021 ◽  
Vol 15 (6) ◽  
pp. 1-22
Author(s):  
Yashen Wang ◽  
Huanhuan Zhang ◽  
Zhirun Liu ◽  
Qiang Zhou
Keyword(s):  
Language Model ◽  
Generation Process ◽  
Data Generation ◽  
Modeling Framework ◽  
Long Distance ◽  
Short Text ◽  
Proposed Model ◽  
Scalable Inference ◽  
End To End ◽  
Hidden Layer

For guiding natural language generation, many semantic-driven methods have been proposed. While clearly improving the performance of the end-to-end training task, these existing semantic-driven methods still have clear limitations: for example, (i) they only utilize shallow semantic signals (e.g., from topic models) with only a single stochastic hidden layer in their data generation process, which suffer easily from noise (especially adapted for short-text etc.) and lack of interpretation; (ii) they ignore the sentence order and document context, as they treat each document as a bag of sentences, and fail to capture the long-distance dependencies and global semantic meaning of a document. To overcome these problems, we propose a novel semantic-driven language modeling framework, which is a method to learn a Hierarchical Language Model and a Recurrent Conceptualization-enhanced Gamma Belief Network, simultaneously. For scalable inference, we develop the auto-encoding Variational Recurrent Inference, allowing efficient end-to-end training and simultaneously capturing global semantics from a text corpus. Especially, this article introduces concept information derived from high-quality lexical knowledge graph Probase, which leverages strong interpretability and anti-nose capability for the proposed model. Moreover, the proposed model captures not only intra-sentence word dependencies, but also temporal transitions between sentences and inter-sentence concept dependence. Experiments conducted on several NLP tasks validate the superiority of the proposed approach, which could effectively infer meaningful hierarchical concept structure of document and hierarchical multi-scale structures of sequences, even compared with latest state-of-the-art Transformer-based models.

scholarly journals Effect of Cutting Parameters and Tool Geometry on the Performance Analysis of One-Shot Drilling Process of AA2024-T3

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 854
Author(s):  
Muhammad Aamir ◽  
Khaled Giasin ◽  
Majid Tolouei-Rad ◽  
Israr Ud Din ◽  
Muhammad Imran Hanif ◽  
...  
Keyword(s):  
Feed Rate ◽  
Surface Defects ◽  
Thrust Force ◽  
Cutting Tools ◽  
Chip Thickness ◽  
Cutting Parameters ◽  
Spindle Speed ◽  
Machining Process ◽  
Tool Geometry ◽  
Drilling Process

Drilling is an important machining process in various manufacturing industries. High-quality holes are possible with the proper selection of tools and cutting parameters. This study investigates the effect of spindle speed, feed rate, and drill diameter on the generated thrust force, the formation of chips, post-machining tool condition, and hole quality. The hole surface defects and the top and bottom edge conditions were also investigated using scan electron microscopy. The drilling tests were carried out on AA2024-T3 alloy under a dry drilling environment using 6 and 10 mm uncoated carbide tools. Analysis of Variance was employed to further evaluate the influence of the input parameters on the analysed outputs. The results show that the thrust force was highly influenced by feed rate and drill size. The high spindle speed resulted in higher surface roughness, while the increase in the feed rate produced more burrs around the edges of the holes. Additionally, the burrs formed at the exit side of holes were larger than those formed at the entry side. The high drill size resulted in greater chip thickness and an increased built-up edge on the cutting tools.

Identification of Process Damping Coefficient Based on Material Constitutive Property

2014 ◽  
Author(s):  
Xiaoliang Jin
Keyword(s):  
Energy Dissipation ◽  
Flank Wear ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Machining Process ◽  
Damping Coefficient ◽  
Chatter Stability ◽  
Workpiece Material ◽  
Process Damping ◽  
Constitutive Property

The contact between the tool flank wear land and wavy surface of workpiece causes energy dissipation which influences the tool vibration and chatter stability during a dynamic machining process. The process damping coefficient is affected by cutting conditions and constitutive property of workpiece material. This paper presents a finite element model of dynamic orthogonal cutting process with tool round edge and flank wear land. The process damping coefficient is identified based on the energy dissipation principle. The simulated results are experimentally validated.

Data Ownership and Secure Medical Data Transmission using Optimal Multiple Key-Based Homomorphic Encryption with Hyperledger Blockchain

2021 ◽  
Author(s):  
Naresh Sammeta ◽  
Latha Parthiban
Keyword(s):  
Data Transmission ◽  
Homomorphic Encryption ◽  
Medical Data ◽  
Healthcare Sector ◽  
Transmission Model ◽  
Generation Process ◽  
Suggested Model ◽  
Blockchain Technology ◽  
Proposed Model ◽  
Data Ownership

Recent healthcare systems are defined as highly complex and expensive. But it can be decreased with enhanced electronic health records (EHR) management, using blockchain technology. The healthcare sector in today’s world needs to address two major issues, namely data ownership and data security. Therefore, blockchain technology is employed to access and distribute the EHRs. With this motivation, this paper presents novel data ownership and secure medical data transmission model using optimal multiple key-based homomorphic encryption (MHE) with Hyperledger blockchain (OMHE-HBC). The presented OMHE-HBC model enables the patients to access their own data, provide permission to hospital authorities, revoke permission from hospital authorities, and permit emergency contacts. The proposed model involves the MHE technique to securely transmit the data to the cloud and prevent unauthorized access to it. Besides, the optimal key generation process in the MHE technique takes place using a hosted cuckoo optimization (HCO) algorithm. In addition, the proposed model enables sharing of EHRs by the use of multi-channel HBC, which makes use of one blockchain to save patient visits and another one for the medical institutions in recoding links that point to EHRs stored in external systems. A complete set of experiments were carried out in order to validate the performance of the suggested model, and the results were analyzed under many aspects. A comprehensive comparison of results analysis reveals that the suggested model outperforms the other techniques.

Modeling Payne effect on basis of linearization of a visco-hyperelastic model

2021 ◽  
Author(s):  
Safia BOUZIDI ◽  
Hocine BECHIR
Keyword(s):  
Characteristic Property ◽  
Nonlinear Viscoelasticity ◽  
Loss Modulus ◽  
Dynamic Strain ◽  
Material Microstructure ◽  
Payne Effect ◽  
Proposed Model ◽  
Storage And Loss Moduli ◽  
Hyperelastic Model ◽  
Complex Young’S Modulus

Abstract The present work concerns the modeling of the Payne effect in nonlinear viscoelasticity. This effect is a characteristic property of filled elastomers. Indeed, under cyclic loading of increasing amplitude, a decrease is shown in the storage modulus and a peak in the loss modulus. In this study, the Payne effect is assumed to arise from a change of the material microstructure, i.e., the thixotropy. The so-called intrinsic time or shift time was inferred from solving a differential equation that represents the evolution of a material's microstructure. Then, the physical time is replaced by the shift time in the framework of a recent fractional visco-hyperelastic model, which was linearized in the neighborhood of a static pre-deformation. As a result, we have investigated the effects of static pre-deformation, frequency, and magnitude of dynamic strain on storage and loss moduli in the steady state. Thereafter, the same set of parameters identified from the complex Young's modulus was used to predict the stress in the pre-deformed configuration. Finally, it is demonstrated that the proposed model is reasonably accurate in predicting Payne effect.

OPTIMISING CUTTING PARAMETERS FOR HOT TURNING ON EN31 MATERIAL

2021 ◽  
Vol 5 (10) ◽  
Author(s):  
Prof. Hemant k. Baitule ◽  
Satish Rahangdale ◽  
Vaibhav Kamane ◽  
Saurabh Yende
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Machining Process ◽  
Depth Of Cut ◽  
Multiple Time ◽  
Turning Process ◽  
Workpiece Material ◽  
Hot Turning

In any type of machining process the surface roughness plays an important role. In these the product is judge on the basis of their (surface roughness) surface finish. In machining process there are four main cutting parameter i.e. cutting speed, feed rate, depth of cut, spindle speed. For obtaining good surface finish, we can use the hot turning process. In hot turning process we heat the workpiece material and perform turning process multiple time and obtain the reading. The taguchi method is design to perform an experiment and L18 experiment were performed. The result is analyzed by using the analysis of variance (ANOVA) method. The result Obtain by this method may be useful for many other researchers.

Automatic tool selection for milling operations Part 1: Cutting data generation

2000 ◽  
Vol 214 (4) ◽  
pp. 271-282 ◽  
Author(s):  
I D Carpenter ◽  
P G Maropoulos
Keyword(s):  
Tool Life ◽  
Chip Thickness ◽  
Minimum Cost ◽  
Optimization Criterion ◽  
Cnc Machining ◽  
Data Generation ◽  
Tool Selection ◽  
Workpiece Material ◽  
Milling Operations ◽  
Wide Range

The selection of tools and cutting data is a central activity in process planning and is often liable to an element of subjectivity. It is further complicated by the wide range of choice presented by the various operation types and the huge portfolio of cutters and inserts available from many different tool manufacturers. This paper describes a procedure to select consistently and efficiently tools for rough and finish milling operations performed on a computer numerical controlled (CNC) machining centre. A wide range of milling operations is considered, including faces, square shoulders, slots, T-slots, pockets, holes and profiles. An initial set of feasible tools is generated that satisfy the constraints of the tool type, the operation geometry, the insert geometry and carbide grade, the workpiece material and the machine tool capacity. Each tool consists of a holder and one or more indexable carbide inserts. Aggressive cutting data are generated for each feasible tool using a rapid search procedure in the permissible depth/width/feed space for good chip control. The cutting data are further refined by a set of technological constraints, which include tool life, surface finish, machine power and available spindle speeds and feeds. The overall cutting data optimization criterion is selected by the user from minimum cost, maximum production rate or predefined tool life. A new optimization criterion, called ‘harshness’, allows the user to influence the chip thickness that is achieved for any given cutter. Any feasible tools that fail to satisfy all the constraints and optimization criteria are discarded.

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