Environmental friendly cutting fluids and cooling techniques in machining: a review

Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented.

https://iopscience.iop.org/article/10.1088/0963-0252/21/4/043001/pdf

Atmospheric-pressure plasma sources for biomedical applications

The generalization of the Local Density Approximation (LDA) method for the systems with strong Coulomb correlations is presented which gives a correct description of the Mott insulators. The LDA+U method is based on the model hamiltonian approach and allows to take into account the non-sphericity of the Coulomb and exchange interactions. parameters. Orbital-dependent LDA+U potential gives correct orbital polarization and corresponding Jahn-Teller distortion. To calculate the spectra of the strongly correlated systems the impurity Anderson model should be solved with a many-electron trial wave function. All parameters of the many-electron hamiltonian are taken from LDA+U calculations. The method was applied to NiO and has shown good agreement with experimental photoemission spectra and with the oxygen Kα X-ray emission spectrum.

http://absimage.aps.org/image/MAR06/MWS_MAR06-2005-007233.pdf

First-principles calculations of electronic structure and spectra of strongly correlated systems: the LDA+U method

Study on microstructure, mechanical properties and machinability of efficiently additive manufactured AISI 316L stainless steel by high-power direct laser deposition

Aluminum Metal Matrix Composites (MMCs) sought over other conventional materials in the field of aerospace, automotive and marine applications owing to their excellent improved properties. These materials are of much interest to the researchers from few decades. These composites initially replaced Cast Iron and Bronze alloys but owing to their poor wear and seizure resistance, they were subjected to many experiments and the wear behavior of these composites were explored to a maximum extent and were reported by number of research scholars for the past 25 years. In this paper an attempt has been made to consolidate some of the aspects of mechanical and wear behavior of Al-MMCs and the prediction of the Mechanical and Tribological properties of Aluminum MMCs.

/pdf/mechanical-and-tribological-behavior-of-particulate-4x05huiioi.pdf

Mechanical and Tribological Behavior of Particulate Reinforced Aluminum Metal Matrix Composites – a review

The effects of tool geometry on residual stress distribution in the machined surface and subsurface of Al 7050-T751 were experimentally investigated. In the experiments, the residual stresses were measured by using X-ray diffraction technique in combination with electro-polishing technique. The results showed that the subsurface residual stresses generated in the end-milling cutting processes were compressive; and the nose radius, rake/relief angle and diameter of the solid end mill had a significant effect on residual stresses profiles. The dynamometer Kistler 9257A was used to measure the milling force, which was helpful to explain the phenomenon of machining induced residual stress.

Experimental investigation of the effect of tool geometry on residual stresses in high speed milling 7050-T7451 aluminium alloy

Influence on Powders and Process Parameters on Bonding Shear Strength in Laser Cladding

In order to reduce misalignment, enhance tight tolerance, and improve machining efficiency, a novel double cone integrated tool was developed and experimentally investigated during one-shot drilling of aluminum and aluminum alloy stacks in this paper. This special tool geometry can finish drilling, reaming, and countersinking processes at the same time. Its machining properties were comparatively evaluated with a standard twist drill (reference drill) by means of a series of experiments. Experimental results highlighted the influence of tool geometry on cutting force and vibration signals for drilling, reaming, and countersinking processes, respectively. The results indicated that the double cone integrated drill can induce a little larger thrust force than a reference drill due to its longer cutting edge. In addition, the chip morphologies generated by different processes and cutting variations also have been comparatively analyzed. The double cone drill under a larger feed rate was prone to produce smaller chips. Furthermore, the double cone drill can achieve smaller burrs, better surface integrity, and lighter tool wear compared with reference drill. The information obtained from this study can provide a better understanding of the one-shot drilling process and guidance for achieving higher efficiency and better hole quality.

Experimental investigation on the performance of novel double cone integrated tool in one-shot drilling of metal stacks

As an important energy conversion mechanism, centrifugal compressors play an important role in the national economy. The blade is one of the most critical components of the compressor. Damaged blades contain extremely high added value for remanufacturing. Thus, remanufacturing research on damaged and retired impeller/blade is getting more and more attention. Laser additive and milling subtractive composite remanufacturing technology is an effective means to achieve metal parts remanufacturing. In this paper, an advanced methodology for the remanufacturing of complex geometry and expensive components via reverse engineering, free-form surface modeling, laser additive repaired and machining is presented. The approach involves the integration of 3D non-contact digitization to obtain the point cloud data of damaged parts, adaptive free-form surface reconstruction to get the digital model of damage location, and laser additive manufacturing process containing slicing and path planning and subsequent multi-axis milling operation. The methodology has been successfully implemented on thin-curved centrifugal compressor blades. The results have shown that the composite remanufacturing method is an effective solution to realize the remanufacturing of damaged blades, and can be applied to the remanufacturing of other complicated parts.

https://www.mdpi.com/2504-4494/2/4/73/pdf

Research on Laser Additive and Milling Subtractive Composite Remanufacturing Process of Compressor Blade

For studying the influence of a bilateral slid rolling process (BSRP) on the surface integrity of a thin-walled aluminum alloy structure, and revealing the generation mechanism of residual stresses, a self-designed BSRP appliance was used to conduct rolling experiments. With the aid of a surface optical profiler, an X-ray stress analyzer, and a scanning electron microscope (SEM), the differences in surface integrity before and after BSRP were explored. The internal changing mechanism of physical as well as mechanical properties was probed. The results show that surface roughness (Ra) is reduced by 23.7%, microhardness is increased by 21.6%, and the depth of the hardening layer is about 100 μm. Serious plastic deformation was observed within the subsurface of the rolled region. The residual stress distributions along the depth of the rolling surface and milling surface were tested respectively. Residual stresses with deep and high amplitudes were generated via the BSRP. Based on the analysis of the microstructure, the generation mechanism of the residual stresses was probed. The residual stress of the rolling area consisted of two sections: microscopic stresses caused by local plastic deformation and macroscopic stresses caused by overall non-uniform deformation.

Jie Sun

Papers

Experimental investigation of the effect of tool geometry on residual stresses in high speed milling 7050-T7451 aluminium alloy

Influence on Powders and Process Parameters on Bonding Shear Strength in Laser Cladding

Experimental investigation on the performance of novel double cone integrated tool in one-shot drilling of metal stacks

Research on Laser Additive and Milling Subtractive Composite Remanufacturing Process of Compressor Blade

Study on the Surface Integrity of a Thin-Walled Aluminum Alloy Structure after a Bilateral Slid Rolling Process