Conventional Milling Process Research Articles

The structure and properties of 2024 aluminum composites reinforced with TiO2 nanoparticles

The ultrafine-grained 2024 aluminum alloy (A2024) and A2024 matrix composites containing titanium oxide (TiO2, ~50nm in size) are fabricated by conventional mechanical milling and hot-press process. With the aid of the optimum fabrication process, the TiO2 particles are well dispersed in the A2024 matrix. Owing to the characteristics of the TiO2 particles, the interface structure is found to be clean and clear without any micropores and contaminations. Without the strengthening by precipitates, the hardness, elastic modulus and yield stress are effectively increased with the increasing volume content of TiO2 particles up to 10vol%. The strengthening effects by introducing TiO2 particles are evaluated by the thermally induced dislocation effect and the Orowan strengthening effect. The composite in the present study has great potential for application as structural materials.

마이크로 밀링과 X-선 리소그래피 공정을 이용한 다층 마이크로 구조물 제작 공정 개발

Conventional machining technologies such as a milling process have limitations in accuracy to fabricate microstructures. Deep X-ray lithography using the synchrotron radiation is a promising micromachining process with an excellent accuracy, whereas there are difficulties in the fabrication of multi-layered structures. Therefore, it is mainly used for fabricating simple monolayered microstructures with a high aspect ratio. In this study, a novel technology for fabricating multi-layered microstructures is proposed by combining two processes. In advance, an X-ray resist material is cut and machined into various shapes and heights by the micro milling process. Subsequent X-ray irradiation process facilitates the fabrication of multi-layered microstructures. The proposed technology can overcome the limitation of the pattern accuracy in conventional milling process and the difficulty of the multi-layered machining in x-ray process. The usefulness of the proposed technology is demonstrated in this study by applying the technique in the realization of various multi-layered microstructures.

Prediction of cutting and feed forces for conventional milling process using adaptive neuro fuzzy inference system (ANFIS)

<p>Due to the extensive use of highly automated machine tools in the industry, the manufacturing requires reliable models for the prediction of output performance of machining processes. The prediction of cutting forces plays an important role in the manufacturing industry. The focus of this paper is to develop a reliable method to predict cutting forces (force in X-direction and force in Z-direction) for milling process during conventional machining of mild steel. This paper implements an adoptive Neuro-fuzzy interface system (ANFIS) to actualize an efficient model for prediction of cutting forces during conventional milling. A set of three input machining parameters like speed, feed and depth of cut, which has a major impact on the cutting forces was chosen as input to represent the machining condition. Our result confirms that ANFIS model with Gaussian member function is a better predictive tool for prediction of milling forces with minimum average test error.</p>

Effect of cutting speed on tool life in ultrasonic-assisted milling process

Machining processes are inherently involved with tool wear, which is an influential factor in cutting forces, surface roughness, and machining costs. In conventional machining of some materials, there are some limitations regarding rapid wear of tool and large machining forces. As a result, new machining techniques have been developed in recent years, among which is the ultrasonic-assisted machining. This machining method is a combination of ultrasonic vibrations with conventional machining process. The goal of this article is to compare the tool life in ultrasonic-assisted milling and conventional milling processes. In experimental tests, one-dimensional ultrasonic vibrations have been applied on workpiece in the feed direction of tool. By varying spindle speed, the width of flank wear land of cutting tool has been obtained in ultrasonic-assisted milling and conventional milling processes, and the results are compared with each other. Due to tool rotation, the direction of workpiece vibrations with respect to edge of cutting tool varies in time. Consequently, there is the possibility of improper and uncontrolled contacts between tool and workpiece. In order to examine this issue, the relative speed of workpiece in normal direction of tool flank surface has been obtained analytically, and the results have been used in explaining the experimental observations. The experimental results have shown that in spindle speeds of n = 500, 1000, and 2000 r/min, tool life in ultrasonic-assisted milling process is less than in conventional milling process; however, for spindle speed of n = 3150 r/min, due to change in tool wear mechanism and decrease of relative speed of workpiece in normal direction of tool flank surface, tool life in ultrasonic-assisted milling process becomes larger than that in conventional milling process.

高圧巨大ひずみ加工による粉末固化と高性能材料の創製

In this review paper, high-pressure torsion (HPT) is introduced as a processing tool for powder consolidation. It is shown that not only HPT can refine the grain size to the submicrometer and/or nanometer range in bulk metallic materials but also can achieve consolidation of metallic and ceramic powders including mechanical alloying, synthesis of intermetallics, allotropic phase transformation and fabrication of metal-matrix composites. Supersaturation of Fe in ultrafined grained Al is achieved in the Al - Fe system where Fe solubility in Al is as little as 0.052 mass%. Allotropic phase transformation of Ti and Zr occurs from α phase to ω phase during operation of HPT because of high pressure in comparison with the conventional ball milling process. Nanograined NiAl and TiAl intermetallics form by HPT processing including successive annealing at temperatures as low as ～0.35Tm where Tm is the melting temperature of the intermetallics. Fabrication of composites is feasible with nano ceramic particles dispersed in the metal matrix. Finally, applications of HPT to ceramics such as Al2O3 and ZrO2 demonstrate that it is possible to introduce plastic strain into their powders and thus to make their consolidation at reduced temperatures.

Electrochemical performance of surfactant-processed LiFePO4 as a cathode material for lithium-ion rechargeable batteries

This study focuses on the effect of addition of surfactant as a dispersing agent during vibratory ball milling of LiFePO4 (LFP) precursor materials on the electrochemical performance of solid-state reaction synthesized LFP for lithium-ion battery cathode material. LFP particles formed after calcinations of ball milled LFP precursors (Li2CO3, FeC2O4, and NH4H2PO4) showed better size uniformity, morphology control, and reduced particle size when anionic surfactant (Avanel S-150) was used. The specific surface area of LFP particles increased by approximately twofold on addition of surfactant during milling. These particles showed significantly enhanced cyclic performance during charge/discharge due to a reduced polarization of electrode material. Electrodes fabricated from LFP particles by conventional milling process showed a 22 % decrease in capacity after 50 cycles, whereas the performance of electrode prepared by surfactant processed LFP showed only 3 % loss in capacity. The LFP particles were characterized using XRD, FE-SEM, particle size distribution, density measurement, and BET-specific surface area measurement. Electrochemical impedance spectra and galvanostatic charge/discharge test were performed for the electrochemical performance using coin-type cell.

Evaluation of the physico-chemical properties of an amorphous magnesium silicate synthesized by an ultrasound-assisted precipitation

Natural talc is a very interesting filler for plastic and rubber materials and paints because it improves their properties by delivering mechanical reinforcement and barrier effects. Good dispersion in a polymer matrix requires fine particles, of nanometric size that are easy to disperse. However, at the moment the main drawback in the use of natural talc is that, with a conventional milling process, nanometric particle sizes are difficult and expensive to obtain. The objective of this study is to develop a process of magnesium silicate synthesis made by precipitation. This step is the first in the manufacturing process of synthetic talc.This study examines the influence of different process parameters on product properties (the way the reactants are added, the reactants themselves, molalities and ultrasound). The synthesized product is highly agglomerated, whatever process parameters are used, but the use of some specific parameters could result in a reduction in the size of the agglomerates. The addition of reactants by a mixing system with ultrasound during the synthesis could be the best method to synthesize the smallest particles. Moreover initial reactant molalities influence the nucleation rate and thus the agglomeration phenomenon. But initial reactant molalities also have an effect on solid purity. Amorphous silica can co-precipitate with magnesium silicate in some molality ranges.

Finite Element Analysis of Ultrasonic Vibration Assisted Milling of Ti-6Al-4V

Finite element analysis models of both ultrasonic vibration assisted and conventional milling of Ti-6Al-4V were developed. In ultrasonic vibration assisted milling model, high frequency vibration (frequency, f=20kHz; amplitude, a=50 um) is superimposed on the movement of the cutting tool. Comparative analyses of temperature distribution, cutting forces, cutting stress were carried out for both ultrasonic vibration assisted and conventional milling processes. Overall reduction in milling forces and temperatures for ultrasonic vibration assisted milling in comparison to conventional milling is obtained.

Preparation of high saturation magnetic MgFe2O4 nanoparticles by microwave-assisted ball milling

In this present paper, well-ordered magnesium ferrite nanoparticles with high saturation magnetization were directly synthesized at low temperature with microwave‐assisted ball milling. The as-milled products were characterized by X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results showed that the mean size and the saturation magnetization of the magnesium ferrite nanoparticles are about 30nm and 43.40emu/g, respectively. Compared with conventional milling process, the microwave‐assisted ball milling is a simple and environment‐friendly approach and which could be considered as a promising ball milling approach for the synthesis of high performance ferrite nanoparticles in the future.

Investigation of the effect of cutting speed and vibration amplitude on cutting forces in ultrasonic-assisted milling

In this article, critical cutting speed in ultrasonic-assisted milling has been calculated and tool–workpiece separation zones have been determined analytically. In order to investigate the ultrasonic-assisted milling process, a special experimental setup has been designed and established that applies one dimensional vibration to the workpiece. Cutting forces in conventional milling and ultrasonic-assisted milling processes have been measured experimentally and the effect of cutting speed and workpiece vibration amplitude on cutting forces have been investigated. As cutting speed increases, the degree of tool–workpiece engagement in one tool revolution increases; as a result, the effect of ultrasonic vibration on milling process decreases and cutting forces in ultrasonic-assisted milling and conventional milling processes become closer to each other. An increase in vibration amplitude increases the reduction rate of cutting forces in the ultrasonic-assisted milling process compared with conventional milling process.

A Time Domain Simulation Approach for Micro Milling Processes

Prediction of Process Machine Interactions (PMI) can be achieved using models for conventional milling processes in the time and frequency domain. However, instabilities such as regenerative chatter can also be observed in micro milling processes using filigree cemented carbide end mills. The dominant chatter frequencies are basically related to the end mills eigenfrequencies. Nevertheless, the dynamic characteristics of the machine tool structure and the work piece must not be neglected. In this paper a comprehensive time domain process model is presented. The machine tool dynamics are considered as non-coupled oscillators based on measured frequency response functions at the tool holder. The end mill is modeled as rotating Euler-Bernoulli beam with variable boundary conditions at the tool clamping. At first, the parameter identification for a geometric cutting force model is described. It contains the cutting edge radius as a time-depended parameter. Thereafter, the modeling and parameter identification of the structural parts are presented. A stability criterion is defined with special regard to the tool deflection at the TCP. Finally, simulation results at different stable and unstable operating points for full immersion cutting are discussed in detail and compared to experimental tests.

Melt emulsification—Is there a chance to produce particles without additives?

Melt emulsification is a well known process. Milk is thus homogenized for over 100 years. In the melt emulsification process, the future disperse phase is melted and dispersed into droplets, the size of which is controlled by an emulsification process. After emulsification, the droplets are cooled down and solid particles of spherical shape are formed. In order to realize melt emulsification processes, we developed the new SHM (Simultaneous Homogenizing and Mixing) nozzle, which enables us to mix separate phases directly into the droplet forming zone of homogenization nozzles. This molten milk fat globule can be homogenized at elevated fat content (up to 42 vol% instead of max. 17 vol%) and elevated temperatures (up to 150 °C instead of max. 70 °C) without loosing product quality as for conventional homogenization processes. In addition, more than 80% of the energy costs can be saved and additional mixing units can be spared. This is realized by a controlled and quick dilution and cooling down of molten fat globules directly after their disruption in the nozzle itself. SHM-technology also allows for the dispersing of molten waxes. Instant cooling down after adjusting particle sizes also allows us to work without emulsifiers or other additives as absolutely required in conventional melt emulsification processes where molten droplets will coalesce upon their collisions in the homogenization nozzle. SHM-melt emulsification is thus an alternative to conventional milling processes, which are often limited by the stickiness of these products.

A new method of synthesizing ultrafine vanadium carbide by dielectric barrier discharge plasma assisted milling

A new high efficiency method of synthesis of ultrafine vanadium carbide (VC) at a low carburization temperature has been developed. Firstly, a mixture of V 2O 5 and graphite powders is milled using dielectric barrier discharge plasma assisted milling (denoted as DBDP milling) for 4 h, and then the milled powders are carburized at 1200 °C, causing the V 2O 5 to react completely with graphite to form ultrafine VC. The formation temperature of VC is much lower than that needed in the conventional milling and heating process. This is because of the greatly enhanced reaction between V 2O 5 and graphite arising from the unique lump-like morphology and large number of clean surface contacts and greater surface area induced by DBDP milling.

Microwave pretreatment: A clean and dry method for palm oil production

The present study shows that microwave pretreatment coupled with solvent extraction is a clean and dry process for the production of crude palm oil (CPO). The results indicate that palm fruits microwave heated for 3 min achieved oil yield comparable to the conventional and commercial palm oil milling process with an average of 20%. Fatty acid composition (FAC) of the CPO produced shows an increment in lauric acid (C12:0) as the duration of microwave exposure increases. Due to the absence of wet-heat treatment or sterilization process, the resultant palm oil also exhibits desirable and very low free fatty acid (FFA) (0.26%) and moisture content (0.05%). The current approach has also provided surprisingly high vitamin E and carotenes content. The highest concentration of vitamin E (2345 ppm) and carotene content (1585 ppm) was recorded for palm fruits subjected to microwave for 2 min. It shows that under the investigated conditions in the present study, the quality of CPO produced using microwave treatment coupled with hexane extraction possesses superior qualities compared to the conventional palm oil milling process.

Modeling and Experimental Analysis the Effect of Minimum Chip Thickness on Cutting Temperature in Micro-End-Milling Process

In this paper, the effect of minimum chip thickness on cutting temperature in micro-end- milling of aluminum alloy Al2024-T6 using a tungsten-carbide cutter are investigated and analyzed. The three-dimensional coupled thermal-mechanical finite element model is adopted to determine the effects of varying depth of cut on cutting temperature considering size effects. The simulation results show that the cutting temperature in micro-end-milling is lower than those occurring in conventional milling processes. When the depth of cut is approximately 40% of the cutting edge radius, there is no chip formation. The maximum temperature occurs at the contact region between micro cutting edge and workpiece, which shows an obvious size effect. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high precision infrared camera. The influence of various cutting depths on cutting temperature has been verified in experiments. The experimental measurements results are in a good agreement with the simulation results.

Supported metal NPs on magnesium using SCFs for hydrogen storage: Interface and interphase characterization

Mixing catalyst NPs with magnesium was proved to be an efficient way to improve the sorption kinetics of hydrogen. Recently, as an alternative to conventional ball milling process, we have reported the interest of using the supercritical fluid chemical deposition process to deposit catalyst metal NPs on the surface of Mg crystals in order to improve significantly the material cyclability for hydrogen storage. Through a detailed characterization of the obtained composite nanostructured materials (SEM, XPS, HRTEM), we demonstrate hereafter the creation of a chemical link, through the formation of metallic interphases between the supported metal catalyst NPs and the magnesium particles, explaining potentially the improvements previously reported. Additionally, this work opens new routes towards the development of more complex materials, with a possible control of the interface between the supported NPs and their support, opening interesting perspectives, for instance in the field of catalysis.

Development of Advanced Ceramics by Powder Composite Process

A powder composite process was applied to develop several kinds of advanced ceramics. TiO2 nanoparticles and Si3N4 particles were mixed using a powder composite process to disperse TiN nanoparticles in Si3N4 ceramics, which are expected to be used as novel materials for next-generation hybrid ceramic bearings. TEM observations showed that the TiO2 nanoparticles were directly bonded to submicron Si3N4 particles. Si3N4 ceramics with uniformly-dispersed TiN nanoparticles were fabricated using the composite particles. The amount of damage caused by the Si3N4 ceramics with TiN nanoparticles to the mating metals in a ball-on-disk test was comparable to the damage caused by Si3N4 ceramics without TiN particles. Nanocomposite particles of Al2O3-doped ZnO prepared by a powder composite process were also used for fabricating ZnO ceramics. TEM observations revealed the uniform presence of Al2O3 nanoparticles on ZnO particles. A sintering body fabricated using the composite powder prepared by this powder composite process had more uniform and finer microstructures than that fabricated using a powder mixture prepared by conventional wet mixing. The ZnO ceramics prepared by the powder composite process exhibited higher electrical conductivity than those prepared by the conventional wet ball milling process. CNT-dispersed Al2O3 ceramics were fabricated using a powder mixture of CNT and fine Al2O3 powder prepared by the powder composite process. It was shown that CNTs were uniformly dispersed in the developed CNT-dispersed Al2O3 ceramics, and that they had high electrical conductivity and strength.

Fabrication of ZnO ceramics using ZnO/Al2O3 nanocomposite particles prepared by mechanical treatment

Nanocomposite particles of Al2O3-doped ZnO prepared by mechanical treatment were used for fabricating ZnO ceramics. TEM observations revealed that Al2O3 nanoparticles uniformly existed on a ZnO particle. The sintering body fabricated using the composite powder prepared by this mechanical treatment process had more uniform and finer microstructures than that fabricated using the powder mixture prepared by conventional wet mixing. The ZnO ceramics prepared by the mechanical treatment exhibited higher electrical conductivity than those prepared by the conventional wet ball milling process.

Synthesis and mechanical properties of diimide‐hydrogenated natural rubber vulcanizates

AbstractHydrogenated natural rubber (HNR), providing an ethylene–propylene alternating copolymer, was prepared by the chemical modification of natural rubber latex (NRL) using diimide generated from hydrazine (N2H4) and hydrogen peroxide (H2O2), with copper sulfate (CuSO4) as catalyst. 1H‐NMR analysis indicated that 48% hydrogenation was performed with a mole ratio of N2H4/double bonds = 4 and H2O2/N2H4 = 1.5 at 50°C for 7 h. The obtained HNR was subjected to a sulfur cure by using a conventional milling process. The cure characteristics, mechanical properties before and after heat aging, and abrasion and ozone resistances of HNR vulcanizate were examined and compared with those of natural rubber (NR), ethylene propylene diene terpolymer (EPDM) and 50 : 50 NR/EPDM vulcanizates. The results indicated that the cure rate of 48% HNR showed no significant change when compare to both NR and 50 : 50 NR/EPDM blends, and offered a better processing advantage over EPDM. The mechanical properties and abrasion resistance of a 48% HNR vulcanizate were comparable to those of a NR vulcanizate. Additionally, its heat and ozone resistances were better than those of NR vulcanizate, due to a reduction in the amount of double bonds in the backbone chain. Thus, hydrogenation of NR can lead to a type of rubber that has improved heat and ozone resistances while still maintaining its good mechanical properties. Consequently, it improves the properties of NR for a wide range of applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Improved NC path validation and manipulation with augmented reality methods

Five-axis milling offers many advantages over the conventional three-axis milling process. However, because of the potentially complex motions, it is difficult for the machine tool operator to anticipate the actual movement based on the NC program. In this paper a software system for the NC path validation and manipulation during the milling process is introduced. This system is meant to expand the information given to the machine tool operator by enriching the view with data of a concurrently running milling simulation. The simulation is synchronized with the real-world machine tool movement by detecting the position of a marker that is mounted on the head stock. With this combination of real-world view and computer-generated data, which is called Augmented Reality, the machine tool operator is able to detect critical situations—like collisions between tool holder and workpiece or excessive forces—and may adjust the NC program accordingly.