https://escholarship.org/content/qt4h56k1ch/qt4h56k1ch.pdf

Advanced monitoring of machining operations

Titanium and nickel alloys represent a significant metal portion of the aircraft structural and engine components. When these critical structural components in aerospace industry are manufactured with the objective to reach high reliability levels, surface integrity is one of the most relevant parameters used for evaluating the quality of finish machined surfaces. The residual stresses and surface alteration (white etch layer and depth of work hardening) induced by machining of titanium alloys and nickel-based alloys are very critical due to safety and sustainability concerns. This review paper provides an overview of machining induced surface integrity in titanium and nickel alloys. There are many different types of surface integrity problems reported in literature, and among these, residual stresses, white layer and work hardening layers, as well as microstructural alterations can be studied in order to improve surface qualities of end products. Many parameters affect the surface quality of workpieces, and cutting speed, feed rate, depth of cut, tool geometry and preparation, tool wear, and workpiece properties are among the most important ones worth to investigate. Experimental and empirical studies as well as analytical and Finite Element modeling based approaches are offered in order to better understand machining induced surface integrity. In the current state-of-the-art however, a comprehensive and systematic modeling approach based on the process physics and applicable to the industrial processes is still missing. It is concluded that further modeling studies are needed to create predictive physics-based models that is in good agreement with reliable experiments, while explaining the effects of many parameters, for machining of titanium alloys and nickel-based alloys.

Machining induced surface integrity in titanium and nickel alloys: A review

An overview of the machinability of aeroengine alloys

Achieving sustainability in manufacturing requires a holistic view spanning not just the product, and the manufacturing processes involved in its fabrication, but also the entire supply chain, including the manufacturing systems across multiple product life-cycles. This requires improved models, metrics for sustainability evaluation, and optimization techniques at the product, process, and system levels. This paper presents an overview of recent trends and new concepts in the development of sustainable products, processes and systems. In particular, recent trends in developing improved sustainability scoring methods for products and processes, and predictive models and optimization techniques for sustainable manufacturing processes, focusing on dry, near-dry and cryogenic machining as examples, are presented.

Sustainable manufacturing: Modeling and optimization challenges at the product, process and system levels

Surface integrity in material removal processes: Recent advances

Understanding the frictional contact behavior between fixture elements and the workpiece helps improve the Fixturing layout leading to better dimensional accuracy and geometric integrity of machined parts. It also affects the machining process dynamics and stability. The tangential (friction) force on the workpiece/fixture contact surface plays an important role in fixture design as it can be utilized to reduce the number of fixture components, thereby exposing more of the workpiece features to machining operations and providing a damping mechanism to dissipate input energy from machining forces out of the workpiece/fixture system. Therefore, proper modeling of the workpiece/fixture contact requires the modeling of friction conditions. The nonlinearity of the problem arises, both from the variation of the extent of contact surfaces, interrupted nature of the cutting forces and the effect of friction. The workpiece/fixture frictional contact is modeled using the finite element method. This paper presents the results of an experimental investigation of the characteristics of workpiece/fixture contact and its implementation in a numerical simulation of face milling.

Experimental Investigation of Workpiece/Fixture Contact and Its Implementation in Numerical Simulation of Machining Processes

Heavy metal stress, including from chromium, has detrimental effects on crop growth and yields worldwide. Plant growth-promoting rhizobacteria (PGPR) have demonstrated great efficiency in mitigating these adverse effects. The present study investigated the potential of the PGPR strain Azospirillum brasilense EMCC1454 as a useful bio-inoculant for boosting the growth, performance and chromium stress tolerance of chickpea (Cicer arietinum L.) plants exposed to varying levels of chromium stress (0, 130 and 260 µM K2Cr2O7). The results revealed that A. brasilense EMCC1454 could tolerate chromium stress up to 260 µM and exhibited various plant growth-promoting (PGP) activities, including nitrogen fixation, phosphate solubilization, and generation of siderophore, trehalose, exopolysaccharide, ACC deaminase, indole acetic acid, and hydrolytic enzymes. Chromium stress doses induced the formation of PGP substances and antioxidants in A. brasilense EMCC1454. In addition, plant growth experiments showed that chromium stress significantly inhibited the growth, minerals acquisition, leaf relative water content, biosynthesis of photosynthetic pigments, gas exchange traits, and levels of phenolics and flavonoids of chickpea plants. Contrarily, it increased the concentrations of proline, glycine betaine, soluble sugars, proteins, oxidative stress markers, and enzymatic (CAT, APX, SOD, and POD) and non-enzymatic (ascorbic acid and glutathione) antioxidants in plants. On the other hand, A. brasilense EMCC1454 application alleviated oxidative stress markers and significantly boosted the growth traits, gas exchange characteristics, nutrient acquisition, osmolyte formation, and enzymatic and non-enzymatic antioxidants in chromium-stressed plants. Moreover, this bacterial inoculation upregulated the expression of genes related to stress tolerance (CAT, SOD, APX, CHS, DREB2A, CHI, and PAL). Overall, the current study demonstrated the effectiveness of A. brasilense EMCC1454 in enhancing plant growth and mitigating chromium toxicity impacts on chickpea plants grown under chromium stress circumstances by modulating the antioxidant machinery, photosynthesis, osmolyte production, and stress-related gene expression.

/pdf/metal-resistant-pgpr-strain-azospirillum-brasilense-emcc1454-2c3rxg42.pdf

Metal-Resistant PGPR Strain Azospirillum brasilense EMCC1454 Enhances Growth and Chromium Stress Tolerance of Chickpea (Cicer arietinum L.) by Modulating Redox Potential, Osmolytes, Antioxidants, and Stress-Related Gene Expression

An intelligent machining controller is developed for cutting-force regulation of the peripheral milling process. This controller combines parameter adaptive control algorithms(s) with heuristic logic, which monitors the performance of the control algorithms. The development of knowledge and rule bases for intelligent control is discussed, and the resulting improvements in control performance are demonstrated using real-time experiments. >

https://ieeexplore.ieee.org/iel2/716/5019/00194749.pdf

Intelligent control for computer integrated manufacturing

Due to its exceptional electrical and thermal conductivity, pure copper is frequently employed in industry as the base metal for thermal management and electromagnetic applications. The growing need for complicated and efficient motor designs has recently accelerated the development of copper additive manufacturing (AM). The present work aims to improve the power density of the copper laser powder bed fusion (Cu-LPBF) coil by increasing the slot-filling factor (SFF) and the electrical conductivity. Firstly, the dimensional limitation of Cu-LPBF fabricated parts was identified. Sample contouring and adjusting beam offset associated with optimum scan track morphology upgraded the minimum feature spacing to 80 μm. Accordingly, the printed winding’s slot-filling factor increased to 79% for square wire and 63% for round wire. A maximum electrical conductivity of 87% (IACS) was achieved by heat treatment (HT). The electrical impedance of full-size Cu-LPBF coils, newly reported in this study, was measured and compared with solid wire. It can reflect the performance of Cu-LPBF coils (power factor) in high-frequency applications. Furthermore, surface quality benefited from either sample contouring and HT, where the side surface roughness was lowered by 45% and an additional reduction of 25% after HT.

https://www.mdpi.com/1996-1944/16/13/4694/pdf?version=1688020083

On the Fabrication of High-Performance Additively Manufactured Copper Winding Using Laser Powder Bed Fusion

This study investigates the feasibility of fabricating defect-free functionally graded bimaterials (FGMs) with enhanced wear resistance via incorporation of vanadium carbide (VC) into H13 tool steel. Three distinct composite powders containing 1, 3, and 5wt.%VC were prepared through ball-milling and subjected to laser powder bed fusion (LPBF) process to print different composites on top of monolithic H13 in a wide range of process parameters. Almost fully-dense parts were achieved (maximum of 99.8, 99.8, and 99.5% for 1, 3 and 5wt.%VC composite systems, respectively); however, the increase in VC content narrowed down the processability window range from 60 J/mm3 for 1, and 3wt.%VC systems to 30 J/mm3 for 5wt.%VC system. The mechanical properties of optimum samples were characterized through microhardness, nanohardness, and wear tests. The incorporation of VC significantly improved the mechanical properties, 17-40% in microhardness, 10-40% in nanohardness, and 20-53% in wear resistance. The underlying reasons behind such an improvement were correlated to the dissolution of VC during the heating stage of the LPBF process and the formation of (V+C)-supersaturated solid solution in large extents as a result of extremely high cooling rates. This study introduces LPBF-processed FGMs as promising candidates for applications in which wear resistance is paramount.

Mohamed Elbestawi

Papers

Experimental Investigation of Workpiece/Fixture Contact and Its Implementation in Numerical Simulation of Machining Processes

Metal-Resistant PGPR Strain Azospirillum brasilense EMCC1454 Enhances Growth and Chromium Stress Tolerance of Chickpea (Cicer arietinum L.) by Modulating Redox Potential, Osmolytes, Antioxidants, and Stress-Related Gene Expression

Intelligent control for computer integrated manufacturing

On the Fabrication of High-Performance Additively Manufactured Copper Winding Using Laser Powder Bed Fusion

Laser Powder Bed Fusion of Functionally Graded Bi-Materials: Role of VC on Functionalizing AISI H13 Tool Steel