Milling Parameters Research Articles

Parameters Optimization of Multipass Milling Process by an Effective Modified Particle Swarm Optimization Algorithm

The selection of the optimal metal milling parameters greatly impacts final product quality and production efficiency in modern manufacturing systems. The profit rate is also sensitive to the selected parameters. This research focuses on determining the optimal parameters of a multipass milling process using an improved particle swarm optimization (PSO) method. The objective is to minimize the production time. The proper number of passes, the optimal cut speed, and feed rate are considered as the parameters (the decision variables in the model) which are needed to be optimized. Furthermore, the permissive arbor strength, arbor deflection, and motor power are the constraints of the model. The penalty function method is used as the constraints handling technique to address the constraints efficiently in the proposed method. A case is adopted and solved to evaluate the performance of the proposed method. The experimental part is analyzed and compared with advanced methods. Experimental results show that the proposed method is very effective for parameters optimization of a multipass milling process and outperforms other methods.

A guide to direct mechanocatalysis.

Direct mechanocatalysis (DM) describes solvent-free catalytic reactions that are initiated by mechanical forces in mechanochemical reactors such as ball mills. The distinctive feature of DM is that the milling materials, e.g. the milling balls themselves are the catalyst of the reaction. In this article we follow the historical evolution of this novel concept and give a guide to this emerging, powerful synthesis tool. Within this perspective we seek to highlight the impact of the relevant milling parameters, the nature of the catalyst and potential additives, the scope of reactions that are currently accessible by this method, and the thus far raised hypotheses on the underlying mechanisms of direct mechanochemical transformations.

Mechanochemical, Water‐Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst

AbstractAsymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo‐ and heterocyclic ketones. The scale‐up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h−1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.

Optimization of Formulation and Operating Parameters for Ginkgo biloba Extract Nanosuspension by Wet Ball Milling Using a Box–Behnken Design

In the present work, the formulation of nanosuspension of Ginkgo biloba extract (GBE) and the operating parameters of wet ball milling (WBM) was optimized using the Box–Behnken design (BBD) method. The key formulation factors evaluated were GBE concentration, milling speed, milling time, and sodium dodecyl sulfate (SDS) concentration. A quadratic model with the correlation coefficient ( R 2 ) value of 0.9276 was established based on the experimental data, implying that this model is significant; meanwhile, the analysis of variance (ANOVA) showed that the SDS concentration was the most significant factor on particle size, followed by GBE concentration, milling speed, and milling time was the slighter significant factor. The GBE nanosuspension with the particles size of 171.2 nm was prepared under the optimized conditions of GBE concentration (7.459 g/L) in combination with milling time (1.492 h), milling speed (9.253 m/s), and SDS concentration (0.846 g/L). The freeze-dried nanosuspension exhibited spherical particle morphology with uniform size by scanning electron microscopy. In addition, the melting behavior of the raw material and milled GBE was analyzed by differential scanning calorimetry and it was found that the melting point decreased due to the decrease of particle size. Furthermore, the dissolution rates of the optimized GBE showed better dissolution properties than the unprocessed GBE. The results show that it is feasible to prepare GBE nanosuspension on a commercial scale by WBM to increase the bioavailability of GBE.

Prediction of Structural and Magnetic Properties of Nanocrystalline Mechanically Alloyed Fe-Ni Powders Using Multi-Gene Genetic Programming Approach

In this paper, a theoretical model based on multi-gene genetic programming (MGGP) approach has been applied to predict the structural and magnetic properties in nanocrystalline Fe–Ni powders prepared by mechanical alloying (MA) using a planetary ball mill. The MGGP model was used to correlate the input parameters (milling speed, chemical composition, and milling time), to output parameters (crystallite size and coercivity) of nanocrystalline Fe–Ni powders. The model obtained was tested with additional data to demonstrate its performance and prediction ability. The MGGP model is a robust and efficient method to find an accurate mathematical relationship between input and output data. A sensitivity analysis study was applied to determine the most influential milling parameters on the crystallite size and coercivity.

Optimization of milling parameters considering high efficiency and low carbon based on gravity search algorithm

According to the characteristics of NC milling, an approach for optimization of milling parameters considering high efficiency and low carbon based on gravity search algorithm is proposed. Taking the carbon emission and processing time as the objectives, the cutting rate, feed per tooth, and cutting width as the optimization variables. A multi-objective optimization model of NC milling parameters is established. An non-dominated sorting gravity search algorithm (NSGSA) is used to solve the multi-objective model, and the position update backoff operation is introduced. Finally, taking NC machining process as an example, the multi-objective optimization results and the single objective optimization results are compared respectively, the actual data show that when the optimization objective is high efficiency and low carbon, the processing time and carbon emissions are 173 and 192 respectively. The comparison results show that the combination of processing parameters obtained by multi-objective optimization is the best, the optimal parameter combination obtained by NSGSA algorithm is verified by grey correlation analysis, and the grey correlation degree of the optimal solution set is 0.81, which is the largest in all solution sets. This approach can help the decision-makers flexibly select the corresponding milling parameters, and provide decision-makers with flexible selection decisions suitable for various scenarios.

ОПРЕДЕЛЕНИЕ КОНСТРУКТИВНЫХ ПАРАМЕТРОВ СТУПЕНЧАТОЙ ДИСКОВОЙ МЕЛЬНИЦЫ

The calculation of the design parameters of a disc mill equipped with a feeder made in the form of a conical hopper is given. For shredders of the disintegrator type, it is very important to ensure the uniformity of loading of the crushed material of the working zone of active impact on particles. In addition, the most important factor is the throughput capacity of all sections of the grinding plant. The throughput should be determined by the design and technological parameters of the working chamber of the mill. Its overload can lead to a blockage of the working chamber, and insufficient throughput will negatively affect the intensity and effectiveness of the impact on the particles of the material. For example, insufficient concentration of particles in the secondary zone of the grinding chamber leads to a decrease in the efficiency of mutual abrasion. The article attempts to determine the design and technological parameters in the loading and accelerating parts of the disk mill. At the same time, it is necessary to coordinate the throughput of the disk spreader and the volumetric flow rate of the material particles flowing from the hopper. In this case, it is advisable to take into account that as a result of a rather high rotational speed and the size of the initial particles, with the wrong height of the radial blade of the spreader, material particles can roll over the radial blades, which leads to a delay of the material in the zone of the spreading disc. Therefore, it is necessary to determine the calculation formulas for finding the required height of the radial blade of the spreading disc, depending on the size of the initial particles. The formula demonstrates that the height of the separating blade depends on the particle size, the speed of rotation of the disks and the distance to the point of meeting of the particle with the radial blade.

ОПРЕДЕЛЕНИЕ КОНСТРУКТИВНЫХ ПАРАМЕТРОВ СТУПЕНЧАТОЙ ДИСКОВОЙ МЕЛЬНИЦЫ

The calculation of the design parameters of a disc mill equipped with a feeder made in the form of a conical hopper is given. For shredders of the disintegrator type, it is very important to ensure the uniformity of loading of the crushed material of the working zone of active impact on particles. In addition, the most important factor is the throughput capacity of all sections of the grinding plant. The throughput should be determined by the design and technological parameters of the working chamber of the mill. Its overload can lead to a blockage of the working chamber, and insufficient throughput will negatively affect the intensity and effectiveness of the impact on the particles of the material. For example, insufficient concentration of particles in the secondary zone of the grinding chamber leads to a decrease in the efficiency of mutual abrasion. The article attempts to determine the design and technological parameters in the loading and accelerating parts of the disk mill. At the same time, it is necessary to coordinate the throughput of the disk spreader and the volumetric flow rate of the material particles flowing from the hopper. In this case, it is advisable to take into account that as a result of a rather high rotational speed and the size of the initial particles, with the wrong height of the radial blade of the spreader, material particles can roll over the radial blades, which leads to a delay of the material in the zone of the spreading disc. Therefore, it is necessary to determine the calculation formulas for finding the required height of the radial blade of the spreading disc, depending on the size of the initial particles. The formula demonstrates that the height of the separating blade depends on the particle size, the speed of rotation of the disks and the distance to the point of meeting of the particle with the radial blade.

Influence of Powder Milling and Annealing Parameters on the Formation of Cubic Li7La3Zr2O12 Compound.

Li-ion batteries are widely used as energy storage devices due to their excellent electrochemical performance. The cubic Li7La3Zr2O12 (c-LLZO) compound is regarded as a promising candidate as a solid-state electrolyte for lithium-ion batteries due to its high bulk Li-ion conductivity, excellent thermal performance, and chemical stability. The standard manufacturing procedure involves the high-temperature and lengthy annealing of powders. However, the formation of the tetragonal modification of LLZO and other undesired side phases results in the deterioration of electrochemical properties. The mechanical milling of precursor powders can enhance the powders’ reactivity and can result in an easier formation of c-LLZO. The aim of this work was to study the influence of selected milling and annealing parameters on c-LLZO compound formation. The starting powders of La(OH)3, Li2CO3, and ZrO2 were subjected to milling in various ball mills, under different milling conditions. The powders were then annealed at various temperatures for different lengths of times. These studies showed that the phase transformation processes of the powders were not very sensitive to the milling parameters. On the other hand, the final phase composition and microstructure strongly depended on heat treatment conditions. Low temperature annealing (750 °C) for 3 h produced 90% of c-LLZO in the powder structure.

Feed Direction-Dependent Milling Dynamics of an Asymmetric Flexible Machining System

Abstract Asymmetric flexible machining system has been widely used in numerical control machining. In traditional milling dynamics model, the cutter feed direction is usually defined as parallel to its vibration DOF, while the nonparallel condition and its induced milling dynamics response are not deeply considered. This paper presents a general dynamics modeling method for asymmetric flexible machining systems. First, to the best of the author’s knowledge, a new dimension named feed direction is proposed, which is used to establish the generalized coupling relationship between the vibration displacement and the regenerative milling force, thus improve the applicability of the milling dynamics model and reduce the experimental workload compared with the traditional modeling. Second, through the theoretical and experimental research, it is shown that the asymmetric flexible machining system has a significant feed direction-dependent characteristics, and implied the existence of high performance machining region with higher stability and lower surface location error (SLE) by contrast with the symmetric milling system and the traditional models. Finally, by controlling the feed direction angle, the milling parameters in roughing and finishing operations are optimized, and the machining efficiency has been greatly improved on the premise of stable cutting and machining accuracy.

Use of enameling wastewater in the wet milling process for ‘monoporosa’ tile composition

Water is becoming scarce for ceramic processing, even in certain regions of Brazil. In the wet milling process, the ceramic slips are formed by 30 wt% water to achieve the adequate density and viscosity for an efficient milling. Wastewater from other ceramic processes, as enameling, could be used for milling. The aim of this work was the study of the milling process of a ceramic tile composition using wastewater without treatment in place of clean water. The raw materials forming the ‘monoporosa’ composition and the wastewater were characterized (XRF, particle size) as well as the monoporosa composition (STD) (XRD, residue at #325 ASTM sieve, flow time viscosity, density). The milling parameters were mill rotation (15 or 19 rpm), mill loading capacity (70 or 100%) and type of water (wastewater or clean water) used as the factors (and levels) in a full factorial design, totaling 8 experiments (level factor = 2³). The tests were carried out in a mill of 148 L capacity, with a load of 87 kg of raw materials and addition of 34 L of wastewater (1.05 g/L) or clean water (1.0 g/L density). The density, viscosity, and residue at the 4, 6, 8 and 10th hour of milling were determined. As a result, the use of wastewater increases the density of the liquid medium and thus increases the milling residue, as evidenced in the 10th milling hour. At the end of the work, it was possible to reduce the total milling time in a 12,000 L industrial mill by 2 h (25%), without changing the characteristics of the slip, even using wastewater as liquid medium. • Wastewater from enameling was used in industrial milling process of ‘monoporosa’. • Mill rotation, loading capacity and wastewater were the main factors of the design. • The milling residue and slip viscosity were determined along milling time. • At the end of milling, the rotation was the most significant factor for milling. • A reduction of 25% of milling time (2 h) was possible even using wastewater.

The Influence of Relative Humidity and Storage Conditions on the Physico-chemical Properties of Inhalation Grade Fine Lactose.

Dry powder inhalers (DPIs) are favorable devices for the delivery of dry formulations to the lungs; still, they largely fail to deliver higher doses of active pharmaceutical ingredient (API) to the lower airways. Addition of fine particles of excipient (fines) to the blend of API and carrier was shown to improve aerosolization performance. Lactose monohydrate is ubiquitous excipient used for this purpose. Lactose exists in a thermodynamically stable crystalline form; however, processes like milling, sieving, or even mixing may induce alteration of crystalline structure and introduce amorphous domains, which could further affect the physico-chemical properties of the material. Therefore, the aim of this work is a detailed characterization of two commercially available types of inhalation grade fine lactose powders (Inhalac 400 and Inhalac 500) prepared using different air-jet milling parameters, with a focus on impact of storage conditions on material properties. We found that the different milling parameters resulted in variable particle size distribution (PSD), and thus surface areas, variable initial amorphous content, cohesivity, flowability, and moisture sorption of materials. In addition, exposure of fine powders to higher humidity reduced the amorphous content present in the materials, but also affected agglomeration tendency and dispersion behavior of both powders. We believe the obtained findings to be important for the aerosolization performance of carrier-based DPIs containing fines and thus need to be duly considered during formulation development.

Tribological properties and damage behavior of brown rice based on milling process

Head rice grain has a high edible quality, while rice milling process produces lots of broken rice, mainly due to pressure and friction work. In this work, based on the structural properties of brown rice, a developed friction tester was used to analyze the tribological behavior of brown rice. Test results show that rice starch granules have a loose, polyhedral structure, which produce cracks easily and increases the abrasion of brown rice. Three kinds of brown rice show different fracture behaviors. Different friction behaviors appear with rice and milling iron kind, main rice wear mechanisms include fatigue damage, plastic deformation, adhesive wear and abrasive wear. It shows that the study provides a method to understand rice milling mechanism and has a positive influence on selection of materials and parameters for rice milling.

On short glass fiber reinforced thermoplastics with high fiber orientation and the influence of surface roughness on mechanical parameters

Injection molding is a common process for manufacturing thermoplastic polymers. Preconnected to fabrication, mechanically loaded parts are examined in structural simulation. A crucial prerequisite for a valid structural simulation for any material is the underlying material data. To determine this data, different phenomena must be considered such as influences of load type, strain rate, environmental conditions and in case of fiber reinforced materials the fiber orientation (FO) in the considered area. Because of rheological effects, injection molded parts often possess a non-homogeneous FO distribution. This makes it challenging to create testing plates for specimen extraction with a well-defined FO over thickness and width in the considered area. In this paper, a novel testing part is introduced with an unidirectionally oriented testable area. It shows a FO degree of more than 0.75, which has been validated with μ-CT measurement and two thermoplastic materials: polyamide and polybutylene terephthalate, both reinforced with 30 weight percent of short glass fibers. In order to resolve influences of the already addressed FO distribution in injection molded parts, tensile test specimens need to be extracted out of specially designed plates via milling and cannot be injection molded directly. Experiments were carried out to study possible effects of preparation on the mechanical properties of specimens with both materials and two milling parameter sets. The first milling parameter set creates reproducible surface roughnesses, whereas the second parameter set shows a correlation between FO and roughness value: when milling perpendicularly to the main FO lower roughnesses are reached than milling in fiber direction. Uncertainties of the normalized rupture strain from orthogonally extracted specimens seem to be larger than the values from those extracted in fiber direction.

Parametric optimization of cutting parameters for micro-machining of titanium Grade-12 alloy using statistical techniques

The main aim of this research work is to examine the impact of machining parameters on the tool wear, machining forces and surface quality in micro-machining of light weight titanium Gr-12 alloy using statistical technique. The Taguchi method has been efficiently used here to associate input variables and output response relationship and also to evaluate the parametric effects by ANOVA analysis. The test results using a linear regression model were correlated. The output results indicated that the depth of cut and speed of cutting have substantial effects on machining force, surface quality and tool wear. The obtained results have been confirmed through confirmation tests with less than 6% error value. It proves that the projected statistical approach is reliable, and is an optimization and typical model for prediction of micro milling parameters for titanium Gr-12 alloy.

Highly enhancing electromagnetic properties in Fe-Si/MnO-SiO2 soft magnetic composites by improving coating uniformity

Fe-Si/MnO-SiO2 soft magnetic composites (SMCs) are prepared by sintering ball milled Fe-Si/MnO2 core–shell structured composites. The correlation between the coating uniformity and electromagnetic properties have been investigated via adjusting ball milling parameters in detail. The results indicate that uniform MnO2 coating can be transformed into MnO-SiO2 composite coatings with high insulation due to the high temperature reaction between MnO2 and Si. Agate ball is more effective than stainless steel ball to improve the uniformity of MnO2 coating as well as the electromagnetic properties such as significantly higher resistivity, lower core loss and better frequency stability of permeability. Moreover, increasing the ball milling time from 4 h to 24 h can obviously improve the coating uniformity and thus result in the remarkable increase of the resistivity from 2.4 mΩ·cm to 356.9 mΩ·cm. And the core loss and dynamic loss decrease rapidly while the Ms shows a slight decline. When the ball milling time reaches 24 h, the Fe-Si SMCs exhibits superior magnetic properties such as high Ms (181.0 emu/g), very low core loss (361.5 kW/m3 at 100 kHz) and good frequency stability of permeability (65) from 50 Hz to 1000 kHz.

Analyzing the Effects of Milling and Sintering Parameters on Crystalline Phase Evolution and Mechanical Properties of Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 Amorphous Ribbons

Analyzing the Effects of Milling and Sintering Parameters on Crystalline Phase Evolution and Mechanical Properties of Al86Ni8Y6 and Al86Ni6Y4.5Co2La1.5 Amorphous Ribbons

The mechanochemical Friedel‐Crafts polymerization as a solvent‐free cross‐linking approach toward microporous polymers

AbstractHerein we report the mechanochemical Friedel‐Crafts alkylation of 1,3,5‐triphenylbenzene (TPB) with two organochloride cross‐linking agents, dichloromethane (DCM) and chloroform (CHCl3), respectively. During a thorough milling parameter evaluation, the DCM‐linked polymers were found to be flexible and extremely sensitive toward parameter changes, which even enables the synthesis of a polymer with a SSABET of 1670 m2/g, on par with the solution‐based reference. Contrary, CHCl3‐linked polymers are exhibiting a rigid structure, with a high porosity that is widely unaffected by parameter changes. As a result, a polymer with a SSABET of 1280 m2/g could be generated in as little as 30 minutes, outperforming the reported literature analogue in terms of synthesis time and SSABET. To underline the environmental benefits of our fast and solvent‐free synthesis approach, the green metrics are discussed, revealing an enhancement of the mass intensity, mass productivity and the E‐factor, as well as of synthesis time and the work‐up in comparison to the classical synthesis. Therefore, the mechanochemical polymerization is presented as a versatile tool, enabling the generation of highly porous polymers within short reaction times, with a minimal use of chlorinated cross‐linker and with the possibility of a post polymerization modification.

Effect of Ball Mill Parameters’ Variation on the Particles of a Mechanical Activation-Assisted Leaching: A Hydrometallurgical Mechanics

Effect of Ball Mill Parameters’ Variation on the Particles of a Mechanical Activation-Assisted Leaching: A Hydrometallurgical Mechanics

Machinability of Scots pine during peripheral milling with helical cutters

Scots pine (Pinus sylvestris L.) is a fast-growing wood that has been widely manufactured into various furnishing products. To improve the machinability of Scots pine, the cutting force and surface roughness during peripheral milling with helical cutters was assessed via an orthogonal experimental design. Experimental results revealed that the resultant cutting force is positively related to the depth of cut, but negatively correlated with inclination angle of cutting edge and cutting speed. However, surface roughness first declines and then increases with increasing inclination angle, and it also shows an increasing trend with the increasing depth of cut and decreasing cutting speed. Furthermore, the depth of cut significantly contributes to the resultant force and surface roughness, while both the cutting speed and inclination angle have insignificant impacts on the resultant force and surface roughness. Finally, the optimized milling parameters were determined as 62° inclination angle of cutting edge, 45 m/min cutting speed, and 0.2 mm depth of cut, and these parameters are proposed for the quality finishing of Scots pine machining.