Developing Complete Prediction Capability for Thermal Damages in Finish Machining of a Hardened Steel

Author(s):  
Jing Shi ◽  
C. Richard Liu

The material thermal damages in hard turning can be classified as re-tempering and re-quenching, and the capability of predicting both damages is critical to obtaining optimal machining parameters for best part service performance. In this study, thermal damages were represented by material hardness change, and models for re-quenching and re-tempering were constructed through heat treatment experiments. The model for re-tempering describes hardness change based on material thermal history, while the re-quenching model defines material hardness as a function of material quenching temperature. In the meantime, a valid finite element (FE) model was adopted to calculate the material temperature histories in 3D hard turning. The obtained thermal histories were fed into the damage models, and thus the distributions of thermal damages beneath machined surfaces could be predicted.

Author(s):  
Serafino Caruso ◽  
Stano Imbrogno

AbstractGrain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,…) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation…) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterized by large plastic deformation.


Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3030
Author(s):  
Łukasz Smakosz ◽  
Ireneusz Kreja ◽  
Zbigniew Pozorski

Edgewise compression response of a composite structural insulated panel (CSIP) with magnesium oxide board facings was investigated. The discussed CSIP is a novel multifunctional sandwich panel introduced to the housing industry as a part of the wall, floor, and roof assemblies. The study aims to propose a computational tool for reliable prediction of failure modes of CSIPs subjected to concentric and eccentric axial loads. An advanced numerical model was proposed that includes geometrical and material nonlinearity as well as incorporates the material bimodularity effect to achieve accurate and versatile failure mode prediction capability. Laboratory tests on small-scale CSIP samples of three different slenderness ratios and full-scale panels loaded with three different eccentricity values were carried out, and the test data were compared with numerical results for validation. The finite element (FE) model successfully captured CSIP’s inelastic response in uniaxial compression and when flexural action was introduced by eccentric loads or buckling and predicted all failure modes correctly. The comprehensive validation showed that the proposed approach could be considered a robust and versatile aid in CSIP design.


Author(s):  
Vahid Pourmostaghimi ◽  
Mohammad Zadshakoyan

Determination of optimum cutting parameters is one of the most essential tasks in process planning of metal parts. However, to achieve the optimal machining performance, the cutting parameters have to be regulated in real time. Therefore, utilizing an intelligent-based control system, which can adjust the machining parameters in accordance with optimal criteria, is inevitable. This article presents an intelligent adaptive control with optimization methodology to optimize material removal rate and machining cost subjected to surface quality constraint in finish turning of hardened AISI D2 considering the real condition of the cutting tool. Wavelet packet transform of cutting tool vibration signals is applied to estimate tool wear. Artificial intelligence techniques (artificial neural networks, genetic programming and particle swarm optimization) are used for modeling of surface roughness and tool wear and optimization of machining process during hard turning. Confirmatory experiments indicated that the efficiency of the proposed adaptive control with optimization methodology is 25.6% higher compared to the traditional computer numerical control turning systems.


2011 ◽  
Vol 223 ◽  
pp. 473-482 ◽  
Author(s):  
Sergio Delijaicov ◽  
Carlos Eddy Valdez Salazar ◽  
Éd Claudio Bordinassi ◽  
Linilsson Rodrigues Padovese

This work studies the influence of machining parameters, such as cutting speed and forces, feed rate, cutting depth, and tool flank wear, on the generation of surface residual stresses in DIN 100Cr6 steel conical bearing rings submitted to a hard turning process. A complete factorial planning was used to perform the tests and projected measurement. Cutting forces were measured by a piezoelectric dynamometer and residual stresses were determined by the hole-drilling method using strain gage. Results showed that after 2000 m of tool machining, phase transformations had been observed on sample surfaces, with white layer formation, and deeper, a dark layer whose thickness varied depending on the severity level of turning and the tool wear (in machined distance). Increase in tool wear generated minor values of compressive residual stresses and the surface roughness presented almost the same values in all experiments, except when the bigger parameters were used.


2014 ◽  
Vol 97 ◽  
pp. 338-345 ◽  
Author(s):  
Varaprasad.Bh ◽  
Srinivasa Rao.Ch ◽  
P.V. Vinay

2019 ◽  
Vol 18 (04) ◽  
pp. 625-655 ◽  
Author(s):  
Asutosh Panda ◽  
Sudhansu Ranjan Das ◽  
Debabrata Dhupal

The present study addresses the machinability investigation in finish dry hard turning of high strength low alloy steel with coated ceramic tool by considering cutting speed, feed and depth of cut as machining parameters. The technological parameters like surface roughness, flank wear, chip morphology and economical feasibility have been considered to investigate the machinability performances. Twenty seven set of trials according to full factorial design of experiments are performed and analysis of variance, multiple regression method, Taguchi method, desirability function approach and finally Gilbert’s approach are subsequently applied for parametric influence study, mathematical modeling, multi-response optimization, tool life estimation and economic analysis. Results indicated that feed and cutting speed are the most significant controlled as well as dominant factors for hard turning operation if the minimization of the machined surface roughness and tool flank wear is considered. Abrasions, adhesion followed by plastic deformation have been observed to be the principal wear mechanism for tool life estimation and observed tool life for coated ceramic insert is 47[Formula: see text]min under optimum cutting conditions. The total machining cost per part is ensued to be lower ($0.29 only) as a consequence of higher tool life, reduction in downtime and enhancement in savings, which finds economical benefits in hard turning. The current work demonstrates the substitution of conventional, expensive and slow cylindrical grinding process, and proposes the most expensive CBN tool alternative using coated ceramic tools in hard turning process considering techno-economical and ecological aspects.


2017 ◽  
Vol 80 (1) ◽  
Author(s):  
Amrifan Saladin Mohruni ◽  
Muhammad Yanis ◽  
Edwin Kurniawan

Hard turning is an alternative to traditional grinding in the manufacturing industry for hardened ferrous alloy material above 45 HRC. Hard turning has advantages such as lower equipment cost, shorter setup time, fewer process steps, greater part geometry flexibility and elimination of cutting fluid. In this study, the effect of cutting speed and feed rate on surface roughness in hard turning was experimentally investigated. AISI D2 steel workpiece (62 HRC) was machined with Cubic Boron Nitride (CBN) insert under dry machining. A 2k-factorial design with 4 centre points as an initial design of experiment (DOE) and a central composite design (CCD) as augmented design were used in developing the empirical mathematical models. They were employed for analysing the significant machining parameters. The results show that the surface roughness value decreased (smoother) with increasing cutting speed. In contrary, surface roughness value increased significantly when the feed rate increased. Optimum cutting speed and feed rate condition in this experiment was 105 m/min and 0.10 mm/rev respectively with surface roughness value was 0.267 µm. Further investigation revealed that the second order model is a valid surface roughness model, while the linear model cannot be used as a predicted model due to its lack of fit significance.


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