Grinding Performance Research Articles

Building a model of the compression grinding mechanism in a tumbling mill based on data visualization

The object of the study reported here is the grinding process in a tumbling mill where the mechanism of destruction by crushing is implemented, which is caused by the mechanism of compression loading. The compressive interaction in the active zone of the lower end of the granular loading chamber of the rotating drum at the transition of the shear layer to the solid zone was taken into account. The task to determine the parameters of the compressive action was solved, which was caused by the difficulties of modeling and the complexity of the hardware analysis of the behavior of the internal loading of the mill. A mathematical model was built based on data visualization for the compression grinding mechanism. The power of compressive forces was taken as an analog of grinding performance. The initial characteristic of compression was considered to be the mean speed of movement in the central averaged normal cross-section of the shear layer. The influence on the performance of the mass fraction of the shear layer and the reversibility of loading was taken into account. The effect of rotation speed on productivity was evaluated by experimental modeling at a chamber filling degree of 0.45 and a relative size of grinding bodies of 0.0104. The maximum value of energy and grinding productivity was established at a relative speed of rotation ψω=0.6–0.65. The maximum value of the share of the shear layer loading was found at ψω=0.4–0.45. The results have made it possible to establish a rational speed during crushing by compression, ψω=0.55–0.65. This value was smaller in comparison with impact crushing, ψω=0.75–0.9. The observed effect is explained by the detected activation for the shear loading layer during slow rotation, in contrast to the fast rotation for the drop zone. The model built makes it possible to predict rational technological parameters of the process of medium and fine grinding in a tumbling mill by compression.

Design and analysis of a novel flexible variable stiffness damping mechanism for grinding electric spindle

The purpose of this research is to design a flexible variable stiffness damping mechanism to solve the load impact problem in the grinding process of permanent magnet electric spindle. Firstly, combined with the structure and usage scene of the grinding permanent magnet electric spindle, according to the design principles and technical indicators, a novel flexible variable stiffness vibration damping joint is proposed. Then the stiffness and energy storage model of the flexible variable stiffness damping mechanism is established, and the stiffness and energy storage characteristics of the mechanism are analyzed. The strength and dynamic characteristics of the flexible variable stiffness mechanism are analyzed by Ansys and Adams, respectively. Finally, an experimental platform for the comprehensive performance verification of the flexible variable stiffness damping mechanism is built to verify the dynamic characteristics and damping effect of the mechanism. The research results show that the designed flexible variable stiffness structure has better vibration damping effect and can improve the grinding performance of the permanent magnet electric spindle.

Analysis of the material removal and heat transfer during internal cooling grinding of GH4169

Nickel-based superalloys exhibit exceptional characteristics and have extensive applications in marine, energy, chemical, and various other fields. Nevertheless, nickel-based superalloys tend to produce substantial heat while being ground. The air barrier effect makes it difficult to spray coolant onto the grinding surface, resulting in poor cooling that leads to surface quality deterioration. This paper proposes a pressurized internal cooling grinding wheel with a removable abrasive ring to investigate the effects of flow channel structure and abrasive ring mounting position on grinding performance. A model was constructed to assess the flow and temperature fields of the grinding arc area, utilizing flow-solid heat transfer. The simulation results indicated that the cooling effect was more effective when the flow channel structure was a 2 mm diameter arc and the runner outlet was placed in the gap area. Additional trials were carried out on the grinding of GH4169 superalloys using pressurized internal cooling wheels to assess and evaluate the impact of flow channel structure and runner outlet position on grinding temperature, surface roughness, and surface topography. The findings indicate that the grinding wheel, characterized by its arc-shaped flow channel structure and runner outlet position within the gap area, exhibits superior grinding performance, resulting in reduced grinding temperature and enhanced surface quality.

Atomization mechanism and machinability evaluation with electrically charged nanolubricant grinding of GH4169

Nanofluid minimum quantity lubrication (NMQL), which offers excellent economic and environmental benefits, has the greatest potential to replace traditional metal grinding with fluids. However, insufficient infiltration performance, poor atomization properties, and inferior controllability are found in pneumatic atomization minimum quantity lubrication (MQL), hindering the improvement of grinding performance. Electrostatic atomization MQL (EMQL) is expected to address the coexistence of grindability and sustainability through electrical charge empowerment. Nevertheless, studies addressing the effects and mechanisms of electrically charged nanolubricants in the grinding of nickel-based superalloys remain scarce. In this study, the atomization characteristics of EMQL are experimentally investigated, and results show that the droplet volume average diameter and diameter Rosin–Rammler distribution span of EMQL decreased by 7.1 % and 40.3 %, respectively, in comparison with those of MQL. Then, a series of grinding experiments on GH4169 with different cooling conditions are conducted. Results show that compared with those for MQL grinding, the coefficients of friction for EMQL and NMQL grinding decreased by 9.35 % and 15.62 %, the specific grinding energies decreased by 16.71 % and 29.06 %, and the values of surface roughness Sa decreased by 3.04 % and 14.33 %, respectively. The optimal combination of atomization method and medium for grinding GH4169 is EMQL and nanolubricant. Sa showed a 16.12 % decrease for the surface machined via the optimal combination compared with the surface machined via flooding. Last, to support the interpretation of the grinding outcomes, the antifriction mechanisms of electrically charged nanolubricants are analyzed in combination with the wetting, infiltration, and film-formation capabilities of droplets. The findings of this work are expected to provide experimental references for the surface integrity improvement of the nickel-based superalloy grinding process.

An Experimental Investigation of the Effects of Dressing and Grinding Parameters on Sustainable Grinding of Inconel 738 Used for Automated Manufacturing

The significant effect of the dressing process on the surface of the grinding wheel (GW) and the need to provide an optimal dressing condition are the requirements of reduction machining time and energy consumption in the sustainable grinding process. In this study, for the first time, the results of changes in the parameters of the dressing process and changes in the topography of the grinding surface on the surface roughness of the Inconel 738 have been presented using single-edge and four-edge diamond dressers. The use of minimum quantity lubrication (MQL) and wet condition are other variables in this study to reduce the consumption of cutting fluid and prevent its destructive effects on the environment. The results indicate that the MQL technique increases the grinding performance of Inconel 738 by reducing ground workpiece surface roughness and decreasing the coolant–lubricant consumption comparing to the conventional wet grinding process. Additionally, it has been found from the experimental results that applying a single-edge dresser generates finer topography on the grinding wheel and, consequently, has a better surface finish in the grinding process compared to the multipoint diamond dressing tool with the same dressing and grinding parameters. In other words, increasing the dressing feed rate during dressing of the grinding wheel using a multipoint dresser makes a finer wheel surface topography and as a result decreases the surface roughness of the ground workpiece compared to a single-edge dresser. With multipoint diamond tools, the grinding performance during the life of the dressing tool also tends to remain more consistent, which is a definite advantage in automated production. Therefore, application of a multipoint dresser leads to a reduction in dressing time and increased production capability.

Effects of ultrasonic vibrations on brazing mechanism and evaluating grinding performance of CBN tools

Effects of ultrasonic vibrations on brazing mechanism and evaluating grinding performance of CBN tools

A review on minimum quantity lubrication (MQL) assisted machining processes using mono and hybrid nanofluids

PurposeBecause many cutting fluids contain hazardous chemical constituents, industries and researchers are looking for alternative methods to reduce the consumption of cutting fluids in machining operations due to growing awareness of ecological and health issues, government strict environmental regulations and economic pressures. Therefore, the purpose of this study is to raise awareness of the minimum quantity lubrication (MQL) technique as a potential substitute for environmental restricted wet (flooded) machining situations.Design/methodology/approachThe methodology adopted for conducting a review in this study includes four sections: establishment of MQL technique and review of MQL machining performance comparison with dry and wet (flooded) environments; analysis of the past literature to examine MQL turning performance under mono nanofluids (M-NF); MQL turning performance evaluation under hybrid nanofluids (H-NF); and MQL milling, drilling and grinding performance assessment under M-NF and H-NF.FindingsFrom the extensive review, it has been found that MQL results in lower cutting zone temperature, reduction in cutting forces, enhanced tool life and better machined surface quality compared to dry and wet cutting conditions. Also, MQL under H-NF discloses notably improved tribo-performance due to the synergistic effect caused by the physical encapsulation of spherical nanoparticles between the nanosheets of lamellar structured nanoparticles when compared with M-NF. The findings of this study recommend that MQL with nanofluids can replace dry and flood lubrication conditions for superior machining performance.Practical implicationsMachining under the MQL regime provides a dry, clean, healthy and pollution-free working area, thereby resulting the machining of materials green and environmentally friendly.Originality/valueThis paper describes the suitability of MQL for different machining operations using M-NF and H-NF.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2023-0131/

Fabrication of PCD face grinding wheel with positive rake angle by femtosecond laser and its performance evaluation in cemented carbide grinding

Super-hard abrasive grinding is considered to be the main approach to realize precision and ultra-precision machining of difficult-to-machine materials such as cemented carbide, engineering ceramics, titanium alloys and superalloy materials encountered. However, heavy grinding force, high grinding temperature and poor surface integrity are prone to be encountered in conventional negative rake angle grinding of difficult-to-machine materials. In response to these problems, a novel concept of positive rake angle grinding is first proposed and an abrasive grain regularly arranged binder-less polycrystalline diamond face grinding wheel with positive rake angle has been designed and fabricated by femtosecond laser ablation. To evaluate the grinding performance of the face grinding wheel with positive rake angle, grinding experiments of YG8 cemented carbide are conducted and compared with the traditional electroplated diamond grinding tool with equivalent abrasive grain dimension and distribution. The results show that compared with the conventional negative rake angle grinding, the normal and tangential forces in positive rake angle face grinding are reduced by 30.3 % ∼ 36.4 % and 21.1 % ∼ 29.3 %, respectively, and the ratio of normal to tangential force is reduced by 12.6 % ∼ 20.3 %. The surface roughness and average depth of subsurface metamorphic layer are also significantly smaller. The laser fabricated polycrystalline diamond face grinding wheel also has better wear resistance in the grinding of cemented carbide. Therefore, it can be concluded that better ground surface quality is obtained by the novel grinding wheel with positive rake angle. The innovative grinding method can fill the research gap on the grinding mechanism of positive rake angle grinding and further enrich the grinding theory of difficult-to-machine materials.

The efficiency of grinding aids in the production of a bio-filling material in a stirred media mill

In recent years, the importance of recycling in reducing environmental pollution and protecting natural resources has increased daily. Eggshells are among the agro-based wastes from food processing in industries and households, causing adverse environmental impacts on our environment. In the dry grinding experiments conducted in the study, the effects of five dosages of ten grinding aids from five groups on the product were investigated, and it was planned to reduce the adverse impacts of waste on the environment by using it efficiently. Furthermore, the combinations of chemicals yielding the best results in each group in terms of particle size were also tested under the same conditions. The present research investigated the influence of grinding aid type and amount in various groups on product size (d10, d50, and d80), energy consumption (kWh/t), and grinding media coating (g/m2). The current research is promising in preventing the depletion of natural resources and transforming waste into valuable and usable products. Moreover, the utilized grinding aids considerably enhanced the grinding performance. In all experiments with grinding aids, better results concerning product size, energy consumption, and grinding media coating with the product were achieved in comparison with the tests without grinding aids.

Prediction and optimization of tower mill grinding power consumption based on GA-BP neural network

Grinding is commonly responsible for the liberation of valuable minerals from host rocks but can entail high costs in terms of energy and medium consumption, but a tower mill is a unique power-saving grinding machine over traditional mills. In a tower mill, many operating parameters affect the grinding performance, such as the amount of slurry with a known solid concentration, screw mixer speed, medium filling rate, material-ball ratio, and medium properties. Thus, 25 groups of grinding tests were conducted to establish the relationship between the grinding power consumption and operating parameters. The prediction model was established based on the backpropagation “BP” neural network, further optimized by the genetic algorithm GA to ensure the accuracy of the model, and verified. The test results show that the relative error of the predicted and actual values of the backpropagation “BP” neural network prediction model within 3% was reduced to within 2% by conducting the generic algorithm backpropagation “GA-BP” neural network. The optimum grinding power consumption of 41.069 kWh/t was obtained at the predicted operating parameters of 66.49% grinding concentration, 301.86 r/min screw speed, 20.47% medium filling rate, 96.61% medium ratio, and 0.1394 material-ball ratio. The verifying laboratory test at the optimum conditions, produced a grinding power consumption of 41.85 kWh/t with a relative error of 1.87%, showing the feasibility of using the genetic algorithm and BP neural network to optimize the grinding power consumption of the tower mill.

Evaluating the performance of electrical discharge face grinding on super alloy monel 400

Conventional machining of super alloy Monel 400 is difficult due to its high strength, low heat conductivity, and gummy nature. In this work, the performance of the electrical discharge diamond face grinding (EDDFG) while processing supper alloy Monel 400 is assessed using the super abrasive diamond-coated grinding wheels of three different grit numbers. Preliminary experiments highlighted the superior performance of the EDDFG as compared to that of electrical discharge machining (EDM) and electrical discharge face grinding (EDFG); in terms of material removal rate (MRR), average surface roughness (Ra), and microscopic images of surfaces using scanning electron microscope (SEM). This work aimed to assess the influence of the diamond grit number (DG n ) of the grinding wheel along with other process parameters, viz. grinding wheel speed (GWS), peak current (I p ), and pulse-on-time (T on ) on Ra and MRR. The analysis of variance (ANOVA) confirmed that DG n and GWS significantly affect the response variables. Finally, the multi-objective genetic algorithm (GA) optimization approach was used to determine the optimal parametric settings of the EDDFG process.

Study on grinding performance during ultrasonic vibration-assisted grinding ultra-high strength steels

Study on grinding performance during ultrasonic vibration-assisted grinding ultra-high strength steels

Influence of wire electrical discharge conditioning on the grinding performance of metal-bonded diamond grinding tools

Wire Electrical Discharge Conditioning (WEDC) is an efficient non-conventional method for conditioning metal, resin, and hybrid bonded super-abrasive grinding tools. Since the diamond and CBN grains are not affected directly by the WEDC and only the electrically conductive bond material is eroded by the process, high grain protrusions are achievable. Therefore, unlike the common mechanical conditioning methods using WEDC, the microtopography of the grinding tool can be influenced by the process parameters, directly affecting the grinding efficiency. However, the selection of WEDC process parameters is influenced by the specifications of the grinding tool, particularly the grain size and concentration. This study aims to investigate the effects of WEDC parameters and strategies on the microtopography and material removal rate of metal-bonded grinding tools, considering different grain sizes and concentrations. Additionally, the correlation between the microtopography of grinding tools conditioned by the WEDC process and their grinding efficiency was investigated by analyzing tool wear, grinding forces, and surface roughness of tungsten carbide workpieces. The results indicate that the material removal rate of the WEDC process decreases as the grain size and concentration of metal-bonded diamond grinding tools increase. Furthermore, it was observed that employing high spark energy parameters reduces the grain protrusion of grinding wheels with small grain sizes. However, the utilization of high-energy sparks is necessary to create larger spark gaps and achieve a higher material removal rate.

Investigation of the usage of waste materials and By-Products as grinding aids in calcite grinding

Along with the increasing importance of water worldwide, it is thought that developments in fine grinding processes performed by dry grinding and using grinding aids are too essential to be ignored. Indeed, grinding chemicals in the form of pure or commercial mixtures are intensively used in mineral processing plants in dry grinding systems to micronized sizes, e.g., dry grinding of calcite to micronized sizes. This study investigated the usage of olive pomace oil (OPO) and olive waste water (OWW), waste/by-products of the olive oil industry, as grinding aids in the dry grinding of calcite to micronized sizes using a laboratory-scale stirred ball mill and compared them with pure and commercial grinding aids. The test results were evaluated in terms of product fineness, powder flowability, color factor, surface adsorption characteristics, and agglomeration behavior. The study revealed that using any of the grinding aids tested improved the grinding process in comparison with the no aid condition. It was understood from the experiments and analyses that using OPO and OWW as grinding aids positively affected grinding performance. Particularly, the particle size analyses showed that the product fineness obtained in dry grinding tests was close to that obtained with commercial and pure grinding aids. Considering all the investigated grinding aids (except for OWW), powder flowability increased with the increasing concentration of the grinding aid. Remarkably, the OWW results demonstrated that the increase in dosage was not beneficial in terms of the ffp index. However, the enhancement of particle size was obvious. When evaluated in terms of product quality, four types of grinding aids increased total color differences with respect to feeding material and no aid test. Furthermore, the Fourier transform infrared spectroscopy (FTIR) conducted to determine the interaction between particle surfaces and grinding aids indicated that the grinding aids used in this study were adsorbed on the calcite surfaces by their non-polar, polar functional group and hydroxyl group. The analysis, in which the agglomeration phenomenon was examined with SEM (scanning electron microscopy) images, revealed that using grinding aids reduced the formation of agglomerates in comparison with the no grinding aid condition.

The Grinding Parameter Optimization under the Carbon Benefit Objective

Grinding is a high carbon emission process in processing technology. To improve the energy efficiency of the grinding process and reduce the carbon emissions and costs of the grinding process, the concept of carbon efficiency is proposed. The study takes the maximisation of carbon benefit in the grinding process as the optimization objective. The linear speed of the grinding wheel, the feed speed of the workpiece and the radial feed speed of the grinding wheel are taken as the optimization variables. Considering the grinding performance of the grinding wheel, taking the performance of the machine tool and the machining requirements of the workpiece as constraints, a multi-objective optimization model of the grinding process is established. The model is optimized by a genetic algorithm, and the effectiveness of this method is verified by a case.

Application of machine learning techniques in environmentally benign surface grinding of Inconel 625

This work explores the grinding performance of Inconel 625 by comparing tangential forces and surface roughness under dry, wet, and minimum quantity lubrication (MQL) environments. Response surface methodology (RSM) and machine learning (ML) techniques establish correlations between inputs and outputs. RSM shows the quadratic regression model effectively captures experimental variability. Four ML models, namely: multilayer perceptron, KNN, and SVM with two kernels, were implemented to predict outcomes, among which KNN appeared as a better-suited model. Lower tangential forces and better ground surface quality support the suitability of MQL grinding compared with dry and wet grinding. Micro-graph investigations of the ground surfaces and chip morphology findings also upkeep the emergence of MQL grinding as a sustainable alternative for Inconel 625 grinding.

Energy-Efficient Advanced Ultrafine Grinding of Particles Using Stirred Mills—A Review

The present literature review explores the energy-efficient ultrafine grinding of particles using stirred mills. The review provides an overview of the different techniques for size reduction and the impact of energy requirements on the choice of stirred mills. It also discusses the factors, including the design, operating parameters, and feed material properties, influencing the grinding performance. The review concludes that stirred mills have significant potential for achieving the energy-efficient ultrafine grinding of particles. Stirred mills have unique designs and operations, which provide higher grinding efficiency, lower energy consumption, and reduced media consumption compared to traditional tumbling mills. The review highlights the advantages of stirred mills over conventional grinding methods and their potential to revolutionise industrial processes while lowering the environmental impacts.

Exploring the effects of a new lifter design and ball mill speed on grinding performance and particle behaviour: A comparative analysis

Ball mills are the leading grinding equipment in the mineral processing industry. Balls are the primary component in the grinding of materials. Lifters lift these balls to the shoulder position before cataracts them to the toe position. Almost all classical theories do not consider the lifter's geometry in calculating the energy consumption of ball mills and focus only on the fill level of the charge, the lifter dimensions, their number, and the mill's rotational speed. To improve the ball mill's performance, a new shape of the lifters was proposed in the present research work. Simulation through the EDEM software and the discrete element method (DEM) was used to predict the particle behaviour and conduct a comparative study on the influence of the lifter geometry and ball mill rotational speed on torque, power draw, and kinetic energy. The validation of our results is evaluated by a confrontation of the experimental tests of discontinuous grinding with a 573 x 160 cm of Bian. The results show that using helical lifters has a more significant effect on the grinding efficiency, the torque, and the power draw of the ball mill. They decrease the wear rate of liners and lifters when mill speeds are extremely high (90%, 100%).

Tribological Mechanism of Graphene and Ionic Liquid Mixed Fluid on Grinding Interface under Nanofluid Minimum Quantity Lubrication

Graphene has superhigh thermal conductivity up to 5000 W/(m·K), extremely thin thickness, superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength, making it possess great potential in minimum quantity lubrication (MQL) grinding. Meanwhile, ionic liquids (ILs) have higher thermal conductivity and better thermal stability than vegetable oils, which are frequently used as MQL grinding fluids. And ILs have extremely low vapor pressure, thereby avoiding film boiling in grinding. These excellent properties make ILs also have immense potential in MQL grinding. However, the grinding performance of graphene and ionic liquid mixed fluid under nanofluid minimum quantity lubrication (NMQL), and its tribological mechanism on abrasive grain/workpiece grinding interface, are still unclear. This research firstly evaluates the grinding performance of graphene and ionic liquid mixed nanofluids (graphene/IL nanofluids) under NMQL experimentally. The evaluation shows that graphene/IL nanofluids can further strengthen both the cooling and lubricating performances compared with MQL grinding using ILs only. The specific grinding energy and grinding force ratio can be reduced by over 40% at grinding depth of 10 μm. Workpiece machined surface roughness can be decreased by over 10%, and grinding temperature can be lowered over 50 ℃ at grinding depth of 30 μm. Aiming at the unclear tribological mechanism of graphene/IL nanofluids, molecular dynamics simulations for abrasive grain/workpiece grinding interface are performed to explore the formation mechanism of physical adsorption film. The simulations show that the grinding interface is in a boundary lubrication state. IL molecules absorb in groove-like fractures on grain wear flat face to form boundary lubrication film, and graphene nanosheets can enter into the grinding interface to further decrease the contact area between abrasive grain and workpiece. Compared with MQL grinding, the average tangential grinding force of graphene/IL nanofluids can decrease up to 10.8%. The interlayer shear effect and low interlayer shear strength of graphene nanosheets are the principal causes of enhanced lubricating performance on the grinding interface. EDS and XPS analyses are further carried out to explore the formation mechanism of chemical reaction film. The analyses show that IL base fluid happens chemical reactions with workpiece material, producing FeF2, CrF3, and BN. The fresh machined surface of workpiece is oxidized by air, producing NiO, Cr2O3 and Fe2O3. The chemical reaction film is constituted by fluorides, nitrides and oxides together. The combined action of physical adsorption film and chemical reaction film make graphene/IL nanofluids obtain excellent grinding performance.

Building a model of the impact grinding mechanism in a tumbling mill based on data visualization

A mathematical model was built based on data visualization for the impact grinding mechanism in a tumbling mill, which is mainly implemented during coarse grinding. The determination of impulse interaction parameters is problematic due to the difficulty of modeling and the complexity of hardware analysis of the behavior of intramill loading. Conceptually, it was envisaged to identify the relative dynamic parameters of the impact action as components of the model, which are criteria for the similarity of the loading movement and the grinding process. Impact power was taken as an analog of grinding performance. The initial characteristic of the impact was considered to be the averaged vertical component of the speed of loading movement in the flight zone at the boundary of contact with the shear layer. The formalization of the model revealed the effect on the performance of the mass fraction of the flight zone and the reversibility of loading. The method of numerical modeling was applied, based on experimental visualization of the behavior of granular loading in the cross section of a rotating chamber. The influence of the rotation speed on the performance at a chamber filling degree of 0.45 and a relative particle size of a milling load of 0.0104 was estimated by experimental simulation. The maximum productivity value was found at the relative speed of rotation ψω=1–1.05. A rational condition for impact grinding at ψω=0.75–0.9 has been established. The test proved the effectiveness of using visualization to evaluate dynamic loading interaction analogs. Verification of modeling results was implemented by comparison with the data of the technical standard. The use of similarity criteria unifies approaches to modeling different mechanisms of destruction. The model built makes it possible to predict the rational parameters of the grinding processes by impact, crushing, and abrasion