Grinding Operations Research Articles

REGULARITIES OF VIBRATION FINISHING AND GRINDING PROCESSING AND DIRECTIONS OF IMPROVEMENT OF ITS INTENSITY AND QUALITY

The data on the labor intensity of manufacturing engineering products and the share of finishing and grinding operations in the total labor costs of their manufacture are presented. The list and the degree of mastering the technological operations of finishing and grinding processing, performed in the conditions of machine-building industries during the last years are given. The grounds are given for highlighting the method of vibration processing as the most promising for ensuring complete mechanization of the process of finishing and cleaning, as well as achieving high technological characteristics of the surface roughness of parts. An assessment was made of the influence of modes, the trajectory of the movement of the reservoir and the grain size of the granules of the abrasive medium on metal removal. It is indicated that the intensity and quality of vibration treatment is estimated quantitatively by the weight removal of metal and qualitatively by the roughness of the processed surface. It is indicated that the determining factor in this case is the speed of the oscillating movement of granules and parts, the difference of which represents the speed of vibration processing, depending on the speed of the oscillating movement of the medium. It is noted that in order to increase the productivity of the process, it is necessary to increase the speed of the medium by increasing the frequency and amplitude of the reservoir oscillations. The layer-by-layer transmission of a force impulse from the bottom of the reservoir to the bulk medium is considered. The physical meaning of increasing productivity by increasing the amplitude of the reservoir oscillations is indicated. The conditions for obtaining metal removal are indicated, which provide increased efforts for the interaction of granules with parts at high micro-cutting speeds. Experimental studies are described to determine the influence of the amplitude and frequency of oscillations on the results of vibration finishing and grinding. Graphic dependences of metal removal were obtained for various ratios of the sample weight to the weight of the medium granule. The dependence of metal removal on the ellipticity coefficient and the amplitude of the reservoir oscillations was obtained in a similar way. It is noted that the vertical component of the amplitude during in-plane oscillations of the reservoir is the determining factor of the complex influence of the parameters of the ellipse coefficient of the trajectory of the reservoir and its amplitude of oscillations. It has been established that when using a coarse-grained abrasive, the penetration of grains into the metal of the part occurs to a greater depth and larger metal chips are removed with a large metal removal. With a small grain size of the abrasive, small chips are removed with a small metal removal and a decrease in the height of micro-roughness.

Feasibility of granite processing waste as a fill material in geotechnical applications

India is the third largest granite producer worldwide, and an increasing trend in its export has been seen year by year. Granite is generally sold in dimensional and finished form. Large quarried granite blocks are processed to get a finished dimensional granite in processing industries. Processing comprises sawing, grinding and polishing operations. In processing operations, about 30 to 35 per cent of the mass of large granite blocks is left as fine Granite Processing Waste (GPW) in the form of slurry. Dumping of GPW is of major concern for the processing industries; it is often unscientifically dumped. Disposal of GPW in an unscientific manner causes adverse effects on humans and the environment. Delightful results are obtained in previous studies addressing its use in concrete, mortar building blocks and stabilization of expansive soils. GPW has the potential to serve as a fill material in geotechnical applications. However, a comprehensive characterization of GPW addressing its use as a fill material is significantly lacking. The current study intends to characterize GPW in light of its application as a non-conventional fill material in place of natural materials. Based on geotechnical and geoenvironmental tests carried out on GPW involving grain size analysis, Atterberg limits, hydraulic conductivity, swelling potential, compaction characteristics, surface morphology, chemical composition, elemental and mineralogical composition, pH and organic content analysis, it can be inferred that GPW is comparable to conventional fill materials.

An analysis on CNC machined surface roughness between AA7475 and AA7475/fly ash composite

The present investigation is the influence of limited reinforcement of fly ash (5 wt%) effects on surface roughness. In this regard, the fly Ash reinforced aluminium alloy (AA7475) composite was prepared and machined and measured the surface roughness to compared to aluminium alloy (AA7475). The sample size is 32 (16 for each tool) with 95% CI pre-test power 80% was used. The surface grinding operation is used to remove surface abnormalities. These pieces are machined in specific contour milling and are performed with different tools. Machined specimens are tested using a profilometer for calculating surface roughness and it was performed according to ASTM D3039 standards. The findings suggested that the plain aluminium alloy (AA7475) had a surface roughness of 0.51 mm and the composite aluminium alloy (AA7475) reinforced with 5 wt% fly ash had a surface roughness of 0.38 mm. The statistical value analysis yielded a significance value of 0.034 (p>0.05), indicating that there was substantial variation across the groups. In this research investigation, it was found that the surface roughness of a composite made of a 5 wt% fly ash augmented aluminium alloy (AA7475) was 32.27% lower than that of a plain aluminium alloy.

New Calculation Methodology of the Operations Number of Cold Rolling Rolls Fine Grinding

This article considers the methods of calculating the number of operations for the fine grinding of cold rolling rolls which allows one to ensure the least labor-intensive processing of the part. Based on the analysis of the patterns in the operation of single abrasive grains, the dependence of the productivity of the fine-grinding process on the grain size of the wheel, the grinding allowance, the grinding mode, the size of the workpiece, and the wheel, is proposed. To analyze the productivity of the finishing grinding processes, a productivity indicator, independent of the size of the wheel and the workpiece, is analyzed, and the impact on the productivity indicator of the number of finishing grinding operations, as well as the following sequence of their optimization, is established. To simplify the calculation of the optimal number of operations, graphs and a nomogram are constructed. According to the proposed methodology, the calculation of the number of finishing operations of cold rolling rolls of various sizes was carried out. Experimental verification of the proposed theoretical dependencies and methods for calculating the optimal number of grinding operations was also carried out.

Effect of Situated Learning on Students’ Psycho-Productive Skills in Machine Woodworking in Technical Colleges in Rivers State

This research aims to examine the effect of situated learning on students’ psycho-productive skills in machine woodworking in technical colleges in Rivers State. Two research questions were posed to conduct the study, while two null hypotheses were formulated for the study. The population comprised all 160 National Technical Certificate (NTC) II woodwork students of two Government Technical Colleges. The instrument had a 0.76 Reliability Index using the KR-20 formula. The study found that situated learning is superior to the demonstration method in imparting psycho-productive skills in drilling operations in machine woodworking. The study also found that the group taught grinding operations with situated learning in machine woodworking performed better than the group taught grinding operations with the demonstration method. Based on the findings of the study, the following recommendations were made: Situated learning should be adopted by curriculum developers and instructors as one of the participatory methods of machine woodworking teaching and learning in technical colleges in Rivers State.

Analysis of Efficient and Fast Prediction Method for the Kinematics Solution of the Steel Bar Grinding Robot

Aiming at the robotization of the grinding process in the steel bar finishing process, the steel bar grinding robot can achieve the goal of fast, efficient, and accurate online grinding operation, a multi-layer forward propagating deep neural network (DNN) method is proposed to efficiently predict the kinematic solution of grinding robot. The process and kinematics model of the grinding robot are introduced. Based on the proposed method, simulations of the end position and orientation, and joint angle of the grinding robot are given. Three different methods, including SGD + tanh, Nadam + tanh, Nadam + ELU, are used to test the DNN calculation process results show that the method combining Nadam with ELU function has the fastest solution speed and higher accuracy can be obtained with the increase in iteration times. Finally, the Nadam optimizer is used to optimize the calculation results of the example. The optimization results show that this method accelerates the convergence rate of trajectory prediction error and improves the accuracy of trajectory prediction. Thus, the proposed method in this paper is an effective method to predict the kinematic solution when the grinding robot works online.

Sensor and actuator integrated tooling systems

The advances in electronics, sensors, actuators, smart materials, computers, and communication technologies led to new and improved mechatronics-based smart tooling systems. This paper reviews the sensors and actuators used in tooling systems. The sensor principles to measure force, displacement, and temperature are explained. Actuators based on piezo, magnetorheological fluid, shape memory alloy, and magnetostrictive principles are discussed. Wireless and wire-based power supply and signal transmission techniques to stationary and rotating tools are described. The integration of sensors, actuators, power supply, and microcontrollers to various tooling systems used in boring, milling, turning, and grinding operations are presented along with their process monitoring and control applications in the industry. It is shown that the sensor-actuator tooling systems improve the accuracy, robustness, and productivity of machining which adds intelligence to the machine tools. The current challenges include widening the operating bandwidth of tooling systems, wireless power and high-speed data transmission, miniaturization of actuators and sensors, and onboard processing using embedded micro-controllers.

Method of digital automatic design of grinding operations carried out on CNC cylindrical grinding machines

Based on the literature review, the problem is formulated, which consists in the absence of detailed recommendations for the design of grinding operations for CNC cylindrical grinding machines. This paper provides a solution to the problem described above using the developed method, which includes: the formation of initial data, the formation of grinding cycles, and the calculated determination of cycle parameters.

EXPERIMENTAL RESEARCH AND DEVELOPMENT OF A METHOD FOR CALCULATING THE PARAMETERS OF BOREHOLE HYDROMONITOR DISINTEGRATION OF RICH IRON ORE IN PLACE

Purpose. Study and development of a rational methodology for calculating the parameters of the process of downhole hydrodisintegration of martite ore massifs by pressure rotating water jets. Methods. Mine experimental-methodical and experimental-experimental works on: stage-by-stage study of the engineering and geological situation of ore deposits and selection of experimental sites; development of technological schemes for the hydrodisintegration of the ore in place and the creation of appropriate experimental equipment; selection of means for providing hydro-extracting operations; the choice of methods for monitoring and measuring the parameters of the hydrodisintegration process; generalization and analysis of the results of experiments and development of recommendations for the creation of technology and equipment, taking into account the achieved indicators. Results. A technique for calculating the parameters of hydrodisintegration of rich martite ores martite ore in places has been developed based on the study of the features of the formation of rotating compact water jets by borehole hydromonitors. Scientific novelty. Relationships between the structural and morphological characteristics and jointing of martite ores (porosity, the ratio of the grain composition of the ore, the ultimate uniaxial compression strength of ore and lumpiness) and the parameters of the hydromonitoring effect (water pressure, the initial diameter of the jet and the speed of its movement along the exposure of the face), which make it possible to determine rational technological parameters of hydrodisintegration products. Practical implication. Borehole hydromonitor disintegration of martite ores in place is a combined ore preparation process, including enrichment grinding operations and classification of destruction products according to their granulometric composition during their erosion. At the same time, there is a selective opening of ore-forming minerals that improve the quality of the ore by 0.5–1.5% compared to natural, a decrease in the mass fraction of silica from 2.0–1.2 to 0.5–0.3%, which ensures the production of iron ore raw materials of the highest quality – superconcentrates with an iron content of 69.0–69.5%. Control of the granulometric composition of hydrodisintegration products is achieved by adjusting the initial water pressure at the outlet of the jet nozzle, the speed of the jet along the face exposure and the orientation of the jet relative to the elements of occurrence and texture of the ores.

Evaluation of gold ore properties and their impact on grinding operations

Purpose. The purpose of this paper is to evaluate the efficiency of grinding operations in terms of how mechanical properties (e.g., strength properties and ore texture) affect the Bond Work Index. Methods. The specimens have been collected in the Eastern Desert of Egypt, namely Abu Marwat, Hamash and Al Sadd. As a result, strength parameters such as compressive strength, cohesiveness and hardness have been assessed. Ore texture, mineral content and bonds between tiny fabric units have been examined using X-Ray Diffraction (XRD) and thin section. Findings. This research shows that as the strength properties of the rock increase, the Bond Working Index also increases. Moreover, the results indicate that the level of cohesion of ore minerals with the surrounding tailings, on the one hand, and the variance in the tailing content, on the other hand, play a significant role in the processing operation, given the discrepancy in the Bond Work Index for the six Abu Marawat gold ores of 18.8%. Originality. This research attempts to develop a methodology for assessing the efficiency of grinding operations as a function of rock strength properties and ore texture in relation to the Bond Work Index. Practical implications. Ore texture is one of the most important factors influencing the grinding process. Since grinding consumes a considerable amount of energy, the economic evaluation is based on increasing the grinding efficiency. According to previous research, the petrographic, which varies from sample to another, has an impact on the mechanical properties as well as the grinding operations.

Analysis of Operating Conditions for Vibration of a Self-Propelled Monorail Branch Chipper

Aimed at the problems of difficult treatment, unreasonable utilization and serious waste of fruit tree residue, combined with the terrain and planting characteristics of hilly orchards, a self-propelled monorail branch chipper was developed. It can realize long distances and large ranges of crushing operations and debris tiling in the garden. Because the monorail branch chipper adopts the half-empty suspension support method, the moving operations and discontinuous cutting of branches can lead to vibration failures or hazards. In response to this problem, modal analysis of a track system with different numbers of nodes by ANSYS software showed that an increase in the number of track sections decreases the natural frequency of each order under the condition of rigid fixation of the support rods, and weakness of vibration is especially seen in sections 1–4, but after a certain amount, the vibrational change tends to level off. The number of lateral rods should be increased for distal short rail branches of less than four sections to reduce operational and operational vibration. The vibration level test results of field multi-condition and multi-point grinding operations showed that the static vibration amplitude of the crusher is basically the same as that of the mobile state. The vibration amplitude of the chipper is significantly increased when in the states from no-load to grinding operation, and the maximum vibration occurs in the left and right direction of the transverse rail, which provides a theoretical basis and optimization direction for further optimization of the single-track branch chipper operational stability problem.

Design and Development of a Petrol-Powered Hammer Mill Machine

A conventional hammer mill is a device consisting of a rotating head with free- swinging hammers, which reduce rock, grains or similarly hard objects to a predetermined size through a perforated screen. Hammer mills can be used for grinding laterite sand in its not-so-fine form into a finer/smaller form for sand production for the building/housing sector. This project is focused on the design, development, and testing of a hammer mill that has a small scale production capability for usage by small and medium scale (SME’s). The grinding process is achieved by the use of a hammer in beating the material fed into fine particles; the fineness aimed depends on the detachable screen with aperture sizes ranging from 87µm to 2 mm. The conceptual design was based on the principle of design by analysis. The methodology adopted was to examine the most critical defects of conventional hammer mills and provide solutions. The major components of the new hammer mill are Inlet tray, Throat, Magnetic chamber, Rotor, Crushing chamber, Hammer mill body, Hammers/Beaters, Screen, Bearings, Discharge, Table or stand, Mechanical drive, Pulleys, The simple aim of this paper is to develop a hammer mill machine that will enhance the efficient grinding operation of laterite rock into a sandy profile to be used in the construction/housing sector. This paper presents the design of an efficient hammer mill machine that was developed with locally sourced materials with ease of maintenance amongst other advantages. The machine is driven by an electric motor of 7.5kW at a speed of 1440rpm and with the appropriate pulley ratio, the machine operated at a speed of 4320RPM with an operating rate of 250kg/hour. Several fabrication techniques such as welding, machining, etc. are adopted for the fabrication of the machine. Dry rocky laterite sample was tested with the machine for operational effectiveness and the result shows that the machine has a grinding capacity of 250kg/hr and grinding efficiency 0f 98.2%. The fabricated laterite grinding machine performed well with high sieving efficiency, reliability, durability with an estimated cost of 965,000.00 Nigerian Naira.
 The study was carried out in Akure, Ondo State, Nigeria. A performance evaluation was carried out on the machine and the grinding efficiency of 94.4% was achieved.

RETRACTED ARTICLE: Minimization of Surface Roughness and Residual Stress in Grinding Operations of Inconel 718

The residual stress and surface roughness enhancement of ground surfaces can decrease the lifetime of workpiece by reducing its fatigue life. It is critical to accurately predict and minimize the residual stress and surface toughness of ground surfaces in order to enhance efficiency of part production using grinding operations. A virtual machining system is developed in the research work to minimize the surface integrity and residual stress during grinding operations of Inconel 718. The cutting temperature during grinding operations is calculated using the Inconel alloy Johnson–Cook law models. Then, using the finite element method, residual stress during the grinding operation is estimated. Utilizing the established virtual machining method, the surface roughness is predicted in the study. Using the Taguchi optimization approach, the grinding parameters of depth of cut and feed velocity are optimized in order to reduce surface roughness as well as residual stress throughout grinding operations on Inconel 718 superalloy. To confirm the effectiveness of the developed technique in the study, simulation and experimentation are conducted. As a result, the quality as well as reliability of the ground surfaces can be enhanced by using the developed virtual machining system in the study to minimize the surface roughness and residual stress of produced parts using grinding operations.

Finding optimum cutting conditions for augmented grindability of Ti-6Al-4V

ABSTRACT This study is dedicated toward subtractive manufacturing of difficult to process material, Ti-6Al-4 V through an extensively employed precision abrasive machining operation, grinding. Ti-6Al-4 V is the most extensively used material, which needs grinding during its finishing in many cases. However, grinding of the material is challenging due to the characteristics like high chemical reactivity at higher temperature, high hot-hardness, low elastic modulus, and low thermal conductivity. Due to elevated reactivity at raised up temperature, titanium tends to adhere to the abrasive wheel during grinding thus leading to ineffective cutting performance. Its low thermal conductivity intensifies thermal damage to the bonded abrasives forming glazed grits. The present experimental study deals with finding optimum cutting conditions for enhancing grindability of the alloy that involves optimizing the grinding infeed values for different conventional wheels. The optimized dressing infeed is used in the subsequent grinding operation where enhancement of grinding condition is investigated under the application of cutting fluids. The major considerations of the study are identifying coolants and delivery techniques, which follow sustainable developments, and suitable conventional abrasive grinding wheels.

Influence of grinding on rail surface and profile - A review

Consistent running of rolling stock on the rails causes fatigue to accumulate and leads to various defects on both the rails and the wheels. Rail grinding operations are used to remove these surface defects, resulting in an increase in the lifespan of the rails and avoiding premature replacement of rails, which is an enormous cost to the exchequer. Various grinding parameters influence the quality of grinding and the resultant surface quality of rails. In this paper, we will be reviewing the various parameters that impact the grinding quality, rail profile, and quality of the surface finish post-grinding.

Investigating the Effect of Grinding Time on High-Speed Grinding of Rails by a Passive Grinding Test Machine.

High-speed rail grinding is a unique passive grinding maintenance strategy that differs from conventional grinding techniques. Its grinding behavior is dependent on the relative motion between the grinding wheel and rail; hence, it possesses great speed and efficiency. In this study, the effects of the duration of grinding time and the increase in the number of grinding passes on the grinding of high-speed rails were investigated using passive grinding tests with a single grinding time of 10 s and 30 s and grinding passes of once, twice, and three times, respectively. The results show that when the total grinding time was the same, the rail removal, grinding ratio of grinding wheels, rail grinding effect, grinding force, and grinding temperature were better in three passes of 10 s grinding than in one pass of 30 s grinding, indicating that the short-time and multi-pass grinding scheme is not only conducive to improving the grinding efficiency and grinding quality in the high-speed rail grinding but can also extend the service life of the grinding wheels. Moreover, when the single grinding times were 10 s and 30 s, respectively, the grinding removal, grinding efficiency, grinding marks depth, and surface roughness of rail increased with the number of grinding passes, implying that the desired rail grinding objective can be achieved by extending the grinding time via the multi-pass grinding strategy. The results and theoretical analysis of this study will contribute to re-conceptualizing the practical operation of high-speed rail grinding and provide references for the development of the grinding process and grinding technology.

Application of a Cryogenic Cooling System on the Grinding Operation of Polyether Ether Ketone Biomaterial (PEEK)

Application of a Cryogenic Cooling System on the Grinding Operation of Polyether Ether Ketone Biomaterial (PEEK)

Texturing Methods of Abrasive Grinding Wheels: A Systematic Review.

Creating textures on abrasive wheels is a strategy that allows a significant improvement in grinding operations. The reduction of the internal stresses in the workpiece and the temperature during the grinding operation generates an increase in the dimensional accuracy of the workpiece and a longer tool life. Textured abrasive wheels can be produced in many different ways. Depending on the processing method, the dimensional accuracy of the tool and its applicability is changed. Some methods can produce tools with three-dimensional grooves; there are also methods that are employed for the re-texturing of grooves after the grooved zone wears out. In the literature, the benefits of textured grinding wheels over traditional wheels have been extensively discussed. However, information on the particularities of texturing methods is still lacking. To clarify the advantages, limitations, and main advances regarding each of the groove production methods, the authors of this article carried out a systematic review. The objective of this work is to establish the factors that are affected by groove production methods and the technological advances in this area. The benefits and drawbacks of various grooving techniques are then reviewed, and potential study areas are indicated.

Material removal and surface damage in high-speed grinding of enamel

Although high-speed grinding of the enamel surface is often required in restorative dentistry, the knowledge of grinding mechanics, material removal, and fracture damage mechanism related to this process is still relatively limited; therefore, it is important to perform relevant scientific and theoretical research. As per the occlusal surface and the buccal/lingual surface of the teeth, the experimental scheme of high-speed grinding of the enamel surface using a diamond grinding bur was designed, and the grinding force, force ratio, grinding temperature, chips, surface morphology, surface damage, and other important characteristics were tested and analyzed. Furthermore, the grinding geometry model, grinding mechanics, material fracture, and removal mechanism associated with the high-speed grinding of an enamel surface were considered. The results show that the grinding force, friction coefficient, grinding temperature, and surface damage achieved through buccal/lingual surface grinding are considerably greater, and the grinding quality is worse than that obtained via occlusal surface grinding under the same grinding conditions. With the increase in the feed rate, grinding force, friction coefficient, grinding temperature, and surface damage obviously increase, and the surface quality decreases. The embrittlement effect and the ironing mechanism are present during the process of high-speed grinding of enamel. Regardless of the feed rate, the three types of material fracture modes of the buccal/lingual surface are more serious than those of the occlusal surface (making it more likely to produce unstable large chips or tearing chips); moreover, the brittle fracture and damage of the final machined surface are more obvious. The cutting mechanics and cutting mechanism identified in this study will provide scientific guidance for dental grinding operations.

Dry Permanent Magnetic Separator: Present Status and Future Prospects

Dry permanent magnetic separators have been widely used in the mineral and coal processing industries due to their simple operation and high separation efficiency. These tools not only discard some amount of bulk gangue from the raw ore, thereby reducing the volume of the grinding operation and cutting energy consumption, but also do not require water in the sorting process, thereby expanding their applicability to arid and cold areas. With the depletion of global iron ore resources, a dry, low-cost processing or pre-sorting prior to the wet separation has received the attention of industrial practitioners as a potential alternative. The performance of dry magnetic separators plays a critical role in dry processing This paper reviews the dry magnetic separators available in the literature and describes their operating principles, separation performance, and applications. A detailed comparison of different separators is also conducted to evaluate the differences in their sorting performance and mechanisms and to provide a reference for the optimization of dry magnetic separators.