Optimization Of Grinding Parameters Research Articles

Multi-objective titanium alloy belt grinding parameters optimization oriented to resources allocation and environment

Belt grinding is a widely adopted method in processing titanium alloy materials. However, its unique grinding mechanism will greatly affect grinding efficiency. Meanwhile, in order to finish processing task, adopting the method of replacing belts frequently will further make processing time, cost, and energy consumption rise, as well as the pollution during the whole processing. Considering the problems above, first, establish a multi-objective optimization model, which takes spindle rotary speed, feed speed of workpiece, grinding depth, and axial feed as the variables and takes processing time, SEC (specific energy consumption), cost, and environmental impact as objective optimization functions. Secondly, multi-objective particle swarm optimization algorithm is applied to solve resources allocation objectives for Pareto optimal solutions. Then, analytic hierarchy process is applied to analyze the degree of environmental impact of each solution among Pareto optimal solutions and finalize the best optimization solution of belt grinding. Finally, an experiment case is performed to verify the effectiveness of the optimization model. The result shows that, compared with experience-guided parameters, the optimized grinding parameters make processing efficiency improve by 17.3% and SEC declines by 13.2% cost decline by 17.0%. The proposed optimization method of grinding parameters is effective and can be applied to engineering practice. Meanwhile, it can provide a reference to the selection of grinding processing parameters.

ЗАСТОСУВАННЯ ЕВОЛЮЦІЙНИХ МЕТОДІВ ОПТИМІЗАЦІЇ ДЛЯ ВИБОРУ РЕЖИМІВ ШЛІФУВАННЯ

Defining optimal grinding regimes with the use of traditional methods of mathematical programming and numerical analysis usually turns out to be not effective enough, therefore, solving this problem on the basis of evolutionary methods of optimization is presented in this paper. Depending on the features of technological process, there may be several optimality criteria, so the problem transforms into multi-objective optimization.Premature convergence of the algorithm, as well as general low level of fitness among the obtained results and significant fluctuations of the average values of fitness for the sequence of generations can obstruct proper definition of the processing parameters. Analysis of studies and publications related to grinding process optimization revealed the problem of configuration of the fundamental evolutionary operators, which remains relevant for the conditions of the applied problem.In order to prevent premature convergence of the algorithm, it is important to provide gradual concentration of the problem solutions set in the direction of the global extremum area. In that case, genetic algorithm parameters should be cus-tomized to provide improvement of the average fitness of population based on the obtained results and simultaneous search of new solutions in the feasible region. Values of the weighting factors of the complex optimality criterion are defined on the basis of configuration of the area of perspective solutions. Results of the technological process of grinding optimization using pre-sented evolutionary algorithm, classical genetic algorithm, and also such evolutionary methods as ant colony optimization method, particle swarm optimization method and scatter search method reveal an advantage of the suggested approach in convergence rate with stable reliability for all the considered algorithms.Thus, taking into account features of the optimal grinding parameters search using evolutionary methods, in this paper recommendations are presented concerning an algorithm for the stated problem resolving and preventing from complications typical for this way of solving.

Optimization of Grinding Parameters for the Workpiece Surface and Material Removal Rate in the Belt Grinding Process for Polishing and Deburring of 45 Steel

Surface roughness and the material removal rate (MRR) are two important indicators during the grinding process. The former determines the surface quality while the latter reflects the grinding efficiency directly. In this paper, the two indicators are taken into consideration simultaneously and differently by converting them into a comprehensive goal with using weighting objective method. A prediction model was established for each comprehensive goal with each different combination of surface roughness and MRR weighting coefficient. The optimal value of abrasive size, contact force, belt linear speed, and feed speed were obtained under different grinding situations by using a central composite design (CCD) combined with response surface analysis. The experimental results showed that the comprehensive goal can be used effectively as an indicator to control the grinding performance and improve the optimization process.

Investigation of parametric control method and model in abrasive belt grinding of nickel-based superalloy blade

Abrasive belt grinding is gradually recognized as an effective machining technology for blade. However, the complex contact characteristics of this technology make the grinding quality of blade unable to be precisely controlled. In order to solve this problem, a parametric control method for precision abrasive belt grinding of blade was proposed, and a multi-parameter test platform for state parameters (grinding force, vibration, and temperature) was established. The grinding experiments of nickel-based superalloy samples were carried out, and the prediction model of state parameters based on back propagation neural network was constituted. The prediction accuracy of the model was 93.58%. On this basis, the grinding experiments of nickel-based superalloy blade were conducted. The influence of state parameters on the evaluation parameters (material removal, profile accuracy, surface quality) was analyzed and the optimal grinding parameters were determined. The experimental results showed that the machining quality of new-type aeroengine blades can be effectively improved by this parametric control method and model.

Experimental investigation on high-shear and low-pressure grinding process for Inconel718 superalloy

In this work, we reported a novel grinding method with high tangential grinding force and low normal grinding force using specially developed grinding tools. The tools were made of flexible composites based on the principle of liquid body armor and the shear thickening mechanism of non-Newtonian fluid. During grinding, abrasive particles are capable of generating a “hydro-cluster effects” under reverse tangential load, which lead to the decreased normal grinding force and the increased tangential grinding force. Hence, workpiece materials are removed under “high-shear and low-pressure” grinding mode. A serial of grinding experiments were carried out on Inconel718. The results showed that the novel grinding tool had an excellent grinding performance on Inconel718 workpieces. The value of surface roughness decreased from Ra 473.7 nm to Ra 153.0 nm under the optimal grinding parameters, i.e., wheel speed of 1 m/s, workpiece speed of 2000 mm/min, and grinding depth of cut of 180 μm. The surface defects of the Inconel718 workpiece were gradually removed. Meanwhile, the uniformed grinding textures were generated. The surface of the grinding tool had residual wear debris, and there was a little loss of grains after 240 grinding cycles.

Effect of grinding parameters on microstructure evolution of TC21 titanium alloy with bimodal starting microstructure

Abstract This study aims to investigate the deformation behavior of two-phase titanium alloy Ti–6Al–3Mo–2Zr–2Sn–2Nb–1Cr (TC21) during grind hardening (GH) process. According to dynamic material modeling (DMM) combine Kumar’s instability criterion, the processing maps were constructed to discuss processing properties of material. Results suggest that the ideal processing region is in the temperature of 880 °C, strain rate range 10−3-0.03s−1. The evolution mechanism of α phase was revealed using TEM microstructural analysis under different grinding conditions. It is interesting that, some secondary-precipitated α phase with approximate orientation usually combine to form lamellar α colonies, while some ones with different orientations split to short rod-like or globular structure particularly at higher grinding depth. The optimum grinding parameters for TC21 is at grinding depth range 60–90 μm, wheel speed of 20 m s−1 followed by aging treatment. Most of all, the GH technology has a significantly advantage than heat treatment for exhibiting higher micro-hardness and lower friction coefficient.

The optimization of accuracy and efficiency for multistage precision grinding process with an improved particle swarm optimization algorithm

For metal rolling, the quality of final rolled productions (for instance, metal sheets and metal foils) is affected by steel roll’s cylindricity. In roll grinding process, grinding parameters, which typically involve multiple substages, determine the steel roll’s quality and the grinding efficiency. In this article, a modified particle swarm optimization was presented to dispose of roll grinding multi-objective optimization. The minimization of steel roll’s cylindrical error and maximization of grinding efficiency were optimization objectives. To build the correlation between grinding parameters and cylindrical error, the response surface model of cylindrical error was regressed from the operation data of machine tool. The improved particle swarm optimization was employed to the roll grinding parameter optimization, and the optimal compromise solutions between grinding efficiency and cylindrical error were obtained. Based on the optimal compromise solutions, engineers or computer were capable to determine the corresponding most efficient roll grinding parameters according to the requirement of the final cylindrical error specification. To validate the efficacy of the improved particle swarm optimization, the validation experiment was carried out on the practical roll grinding operation. The error between the calculated optimized cylindrical error and experimental cylindrical error is less than 7.73%.

Thermal damage control for dry grinding of MgO/CeO2 glass ceramic

MgO/CeO2 glass ceramic is a key solid catalyst and accelerant produced by raw mixing, prilling and pressure sintering. Grinding, as a high-efficiency machining method was used to obtain MgO/CeO2 glass ceramic components with accurate size to meet the size requirements of design. However, thermal damage occurring on the ground surface may change the properties of the components and affect their performance in subsequent applications. In this work, a grinding thermal model was established and validated by experiments. On the basis of this thermal model, the grinding temperature can be controlled to < 100 °C by selecting optimal grinding parameters and thus prevent grinding burn. The mechanism of potential chemical reactions on the grinding surface was further studied by analysing the transient temperature jump at a grain wear flat area and comparing the change in element mass fraction before and after grinding. The performance of a normal resin bond diamond wheel and a resin bond wheel with Ni–P alloy coating on the diamond grains was compared. Results showed that the latter intensified the redox reaction because of the catalytic actions of Ni and P, and the mass fraction of each elements on the workpiece surface shows obvious uneven distribution due to the surface spalling of Ni–P alloy. All these results indicated that key issues are the optimal setup of process parameters to control the grinding zone temperature and the selection of a proper grinding wheel to avoid catalytic elements such as Ni and P.

Stability analysis for SiC grinding based upon harmonic wavelet and Lipschitz exponent

In order to effectively identify the stability degree of grinding and obtain better surface integrity of machined workpiece in grinding application, in this paper, a quantitative assessment approach based on harmonic wavelet and Lipschitz exponent is proposed, using silicon carbide as an example. To begin with, the Lipschitz exponent is defined and calculated by harmonic wavelet modulus maxima (HWMM) and linear regression algorithm, respectively. Then the Kurtosis based on Lipschitz exponent (KLE) is defined as a quantitative indicator. In grinding experiment, the acceleration signals and grinding force signals of the X/Y directions are selected, and experimental parameters including wheel speed, workpiece speed and grinding depth are employed to investigate the grinding stability in grinding stage. Experimental results show that the grinding stability is relatively worse at low wheel speed, low-high workpiece speed and large grinding depth in terms of KLE index, which may provide a new guidance to explore optimized grinding parameters and thus obtain good surface integrity in engineering applications.

Optimization of grinding efficiency considering surface integrity of bearing raceway

In order to improve the grinding efficiency of bearing raceways, a multi-objective optimization method that considers the surface integrity constraints of the bearing raceway is proposed. Appropriate design points are selected through an orthogonal test, and a response surface model of the grinding parameters along with the response output is established on the basis of the test results. Explicit expressions for the grinding force and roughness are formulated, and the constraints necessary to meet the quality requirements are obtained. The genetic algorithm NSGA-II is applied to the multi-objective optimization of grinding time and material removal rate, and the Pareto set is solved. The results of the study show that using optimized grinding parameters can reduce the grinding time and material removal rate, and can also help broaden the available knowledge base on high-speed and high-efficiency grinding technology.

Modeling and optimization of machining parameters during grinding of flat glass using response surface methodology and probabilistic uncertainty analysis based on Monte Carlo simulation

In this paper, the performance of diamond grinding wheels was investigated. The industrial diamond crystals with a size of 140/170 mesh were utilized. The microstructure of the grinding tool was observed using a Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis Device (EDX). The experiments were designed using Box–Behnken method and optimum grinding parameters for glass were analytically determined. Experimental studies were carried out on a surface grinding machine in a flat glass factory. Grinding characteristics were examined with respect to surface roughness. The effects of grinding parameter on output responses were studied using analysis of variance (ANOVA). Probabilistic uncertainty analysis depends on Monte Carlo simulation was applied. Moreover, after the experiments using the optimized cutting parameters, the microstructure of the grinding wheels was analyzed. From results, the established model and optimization method could be employed for predicting surface roughness and this work is reliable and suitable for solving the problems encountered in machining operations. The lifetime of Cu-based grinding discs can be increased by adding Zn and Fe to the matrix material.

Multi-Objective Optimization for Grinding Parameters of 20CrMnTiH Gear with Ceramic Microcrystalline Corundum.

(1) The alloy material 20CrMnTiH is widely used in gear manufacturing, but difficult to process, and its quantity (efficiency) and quality (surface quality) are generally negative correlation indicators. As a difficult but realistic problem, it is of important practical significance to explore how to efficiently grind high-precision low-carbon alloy gear workpieces. (2) Firstly, the pixel method was applied to analyze the grinding principles and explore the grinding parameters—the grinding wheel speed and grinding wheel frame moving speed—as well as the feed rate, which impacts the grinding indicators. Secondly, based on the ceramic microcrystalline corundum grinding wheel and the 20CrMnTiH gear workpiece, controlled experiments with 28 groups of grinding parameters were conducted. Moreover, the impact curves of the grinding parameters on the grinding indicators—the grinding efficiency, grinding wheel life, and surface roughness—were obtained by the multiple linear regression method. Finally, the multi-objective optimization method was used to comprehensively optimize the grinding process. (3) Compared with the traditional grinding process, under optimized grinding parameters, the 20CrMnTiH gear workpieces have a lower surface roughness and a longer grinding wheel life, and require a shorter time to achieve grinding accuracy. (4) The grinding experiments showed that the grinding parameters are linearly related to the grinding indicators. The optimization results show that the precision, efficiency, and economy of the 20CrMnTiH gear grinding process have been improved via the comprehensive optimization of the grinding parameters.

A study on material removal mechanism of ultramicro-grinding (UMG) considering tool parallel run-out and deflection

Micro-grinding is capable of machining complex structures in a wide variety of hard and brittle materials when compared to other micro-machining processes. In recent years, more attentions have been paid to micro-grinding field, but not much even little has been paid to ultramicro-grinding (UMG). What usually be called UMG is a kind of micro-grinding process, during which grinding tool is extremely small, usually less than 50 μm. In this scale, tool parallel run-out and tool deflection have a big effect on grinding results. In view of the abovementioned facts, the exact prediction of grinding force in UMG is still not fully developed, especially when considering tool parallel run-out and tool deflection. In order to better explain the grinding process and the material removal mechanism in UMG, this paper proposes an analytical grinding force prediction model considering the related cutting parameters, tool parallel run-out, tool deflection, size effect, and the exact trochoidal trajectory of single grain. In this prediction model, final undeformed chip thickness is computed by considering tool parallel run-out and tool deflection, then forces are calculated based on the final undeformed chip thickness. In order to study the special characteristics of UMG, a series of UMG single-factor experiments have been conducted, and the parameters of tool parallel run-out and tool deflection were measured during the experiment. The proposed grinding force model is validated through UMG orthogonal experiment with grinding tool about 40 μm diameter, and the workpiece is single-crystal silicon. During the experiment, the total indicated run-out (TIR) and grinding forces in both x and y directions are measured and analyzed, and the relationship between grinding forces and cutting parameters, between TIR value and cutting parameters, and between grinding forces and TIR value are investigated. Relative to the general cutting condition, a sliding situation (cutting depth is extremely low) is found and analyzed. Based on the experiment results, an empirical formula for cutting parameters and TIR is obtained. To verify the model, comparisons among experimental result, the proposed model and the previous three force models are made, and the final comparison result shows that the proposed model agrees better with the experimental results than other three previous models, only a few mismatched points (E > 10%) are found, and the biggest error for Fx is 18.12% and for Fy is 20.91%, indicating the effectiveness and accuracy of the proposed model. The proposed grinding force model is not only expected to be meaningful to optimize grinding parameters but also anticipated to be powerful to provide the basis for the more accurate grinding force prediction.

Optimization of Grinding Parameters for Minimum Grinding Time When Grinding Tablet Punches by CBN Wheel on CNC Milling Machine

Cutting regime parameters play an important role in determining the efficiency of the grinding process and the quality of the ground parts. In this study, the influences of the cutting parameters, including the cutting depth (ae), the feed rate (Fe) and the wheel speed (RPM) on the grinding time when grinding tablet shape punches by a cubic boron nitride (CBN) wheel on a CNC (Computerized Numerical Control) milling machine are investigated. The Taguchi technique based on orthogonal array and analysis of variance (ANOVA) was then applied to design the number of experiments and evaluate the influence of cutting depth, feed rate and wheel speed on the grinding time. The results show that among the three cutting parameters, the most influential parameter on the grinding time is the cutting depth. The second influential parameter on the grinding time is the feed rate. The least influential parameter on grinding time is the wheel speed. In addition, the optimal condition of cutting parameters obtained for grinding tablet shape punches by cubic boron nitride wheels on a CNC milling machine are a cutting depth of 0.03 mm, wheel speed of 5000 rpm and feed rate of 3500 mm/min. This optimum cutting parameters ensure the least grinding time.

OPTIMIZATION OF CYLINDRICAL GRINDING PROCESS PARAMETERS OF SS316L AUSTENTIC STAINLESS STEEL BY TAGUCHI METHOD

The main objective of this study is to optimize the cylindrical grinding parameters that can be utilized to predict optimal grinding parameters to achieve minimum surface roughness of a material. A SS 317L Austentic steel round rod of 80 mm x 168 mm was considered for cylindrical grinding in this study. Cutting speed, depth of cut and feed rate were chosen as input variables while Surface roughness (Ra) selected as output response. An L9 orthogonal array was selected for this study and S/N ratios were analyzed to study the surface roughness characteristics. Nine experiments were conducted in the surface grinding machine with different values of input parameters obtained from the orthogonal array. The surface roughness values were optimized in the optimization software (Minitab version 17) and the optimal solution was obtained for minimum response. Minimum surface roughness is achieved with 100 rpm cutting speed, 0.03 mm depth of cut and 1 mm/s feed rate. The confirmation experiments were conducted for the optimal solution obtained from Taguchi experiment and the results are verified.

Influence of surface integrity on fatigue behavior of Inconel 718 and Ti6Al4V workpieces with CBN electroplated wheel

High-speed grinding with cubic boron nitride (CBN) electroplated wheels has been widely used in the aviation manufacturing field, such as the machining of nickel-based and titanium alloys. The requirement of dimensional precision and consistency of parts can be met effectively because of the high feasibility and grinding performance of CBN electroplated wheels. Meanwhile, surface integrity has a direct and significant effect on the fatigue behavior of workpieces. Therefore, the influence of surface integrity machined by CBN electroplated wheels on fatigue behavior of Inconel 718 and Ti6Al4V specimens is investigated. Based on the experimental results of surface roughness, microhardening rate, and residual stress measured, low-cycle fatigue tests were carried out to analyze the influence mechanisms of surface integrity on low-cycle fatigue life. Under the given experimental conditions, it can be obtained that surface roughness has predominant and negative effects on the number of cycles to failure (Nf) of Inconel 718 specimens when surface roughness is higher than Ra 0.4 μm. However, when surface roughness is less than Ra 0.3 μm, surface microhardening rate has predominant and positive effects on Nf. Compared with polished specimens, Nf of ground specimens can be increased by 47.5% utilizing the optimized parameters and conditions. As for Ti6Al4V specimens, both surface roughness and microhardening rate have negative effects on Nf. Micro-recast layer and molten drops have been observed on machined surface of Ti6Al4V specimens, which have significant and negative effects on the fatigue behavior of workpieces. At the same time, Nf of ground specimens with CBN electroplated wheels is less than that of milled specimens even utilizing the optimized grinding parameters. From all the comparison results, it can be achieved that the influence mechanisms of surface integrity on fatigue behavior of Inconel 718 and Ti6Al4V specimens with CBN electroplated wheels are different due to the material properties.

Influence of surface topography evolution of grinding wheel on the optimal material removal rate in grinding process of cemented carbide

Most of the reported studies on the optimization of grinding parameters do not consider the evolution of the surface topography of grinding wheels, and the established empirical models will no longer apply when the surface conditions of the grinding wheel changes. In this paper, an integrated model based on the surface topography of grinding wheel is established. The grinding process of cemented carbide is simulated using the established model, and the simulation results are analyzed to obtain the surface roughness model and the specific grinding energy model based on the undeformed chip thickness distribution. Subsequently, the grinding constraint models are defined according to the two grinding constraints—surface roughness and specific grinding energy. Through inversion analysis, the maximum material removal rate of the given grinding wheel surface conditions satisfying the defined grinding constraints are obtained, and the influence rules of the grinding wheel surface conditions on the maximum material removal rate are analyzed. Then the grinding wheel surface conditions are adjusted by changing the radial dressed height of the grinding wheel and the arrangement distance of the grains in wheel circumferential direction to improve the maximum material removal rate of the grinding wheel. Finally, the optimization results are verified through grinding tests of cemented carbide.

Application of NSGA-II for optimisation of cylindrical plunge grinding process parameters

Cylindrical grinding (finishing) operation is widely used for obtaining accurate surface finish on components in automobile sectors. Present industries are facing a challenge of producing high quality components with low power consumption and low manufacturing cost due to increased competition. In this paper, optimum process parameters values are obtained for dressing depth of cut, dressing cross feed rate and grinding feed rate of cylindrical plunge grinding operation. Experiments were performed as per L9 orthogonal array with replica on computer numerical control angular head grinding machine. Mathematical model has been developed using response surface methodology for determining grinding responses. The results of RSM are further used to obtain Pareto front optimal solutions using NSGA-II approach. A novel method is developed to obtain grinding ratio. The established results are helpful to decide optimal grinding parameters.

Application of NSGA-II for optimisation of cylindrical plunge grinding process parameters

Cylindrical grinding (finishing) operation is widely used for obtaining accurate surface finish on components in automobile sectors. Present industries are facing a challenge of producing high quality components with low power consumption and low manufacturing cost due to increased competition. In this paper, optimum process parameters values are obtained for dressing depth of cut, dressing cross feed rate and grinding feed rate of cylindrical plunge grinding operation. Experiments were performed as per L9 orthogonal array with replica on computer numerical control angular head grinding machine. Mathematical model has been developed using response surface methodology for determining grinding responses. The results of RSM are further used to obtain Pareto front optimal solutions using NSGA-II approach. A novel method is developed to obtain grinding ratio. The established results are helpful to decide optimal grinding parameters.

Utilization of grinding aids in oil shale milling

ABSTRACTGrinding aids (GAs) effectively reduce the energy requirements of the grinding process and improve grinding productivity. Two GAs (sodium silicate and triethanolamine (TEA)) were selected and their mechanisms of action were explored. The effect of the different grinding parameters on oil shale grinding efficiency was determined. The adsorption characteristics of the GAs were investigated using scanning electron microscopy (SEM), pulp viscosity, surface potential, and Fourier transform infra-red spectroscopy (FTIR). The results indicate that compared to grinding without GAs, the addition of sodium silicate and triethanolamine (TEA), increases the yield of −0.075 mm particles by −2.97% and 14.05%, respectively. The optimal grinding parameters were determined for a pulp concentration 40%, a steel ball weight ratio of Φ32 mm: Φ25 mm: Φ22 mm: Φ18 mm (50:24:17:9), and a grinding time of 20 min. The flotation test results indicate that compared to sodium silicate, TEA is the more suitable GA. The addition of sodium silicate reduced the sharp edges of the particles, increased the pulp viscosity and reduced the surface potential. It was not conducive to pulp dispersion. Conversely, TEA reduced the pulp viscosity and increased the surface potential, which enhanced the repulsive force between the particles, increasing the particle spacing, and the dispersion of the pulp. Sodium silicate and TEA both formed hydrogen bonds or chemical bonds on the surface of the mineral particles, strengthened the steric-hinderance effect, and enhanced the repulsive force between the particles.