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Decreasing cutting force is always crucial in cutting processes. One method to achieve this is by minimizing tool wear, for which rotary cutting is a highly effective technique. The use of a cylindrical tool offers the additional benefit of easy tool fabrication, which is especially advantageous for a microtool capable of machining micropins. However, there have been no reported studies on rotary cutting using a cylindrical microtool. It should be noted that if a microtool is fabricated by electrical discharge machining, it is expected to engage in cylindrical grinding as well. This suggests that both rotary cutting and cylindrical grinding can be carried out simultaneously; however, there have also been no reported studies on simultaneous cutting and grinding. Therefore, the present study investigated whether this machining method can perform micropin machining, if it actually involves both cutting and grinding actions, and whether the combination of these actions enhances material removal capability. In turning and grinding experiments, where only one of the tool and workpiece was rotated, both actions were observed. Furthermore, it was confirmed that micropin machining can be performed by rotating both the tool and workpiece, resulting in a decrease in machining force to approximately one-quarter to one-half compared to that of turning. This indicates that simultaneous cutting and grinding was carried out, and the overlap of their actions enhanced material removal capability. In addition, the relationship between the machining conditions and machining force was investigated. At a small depth of cut, a tool with smaller surface roughness exhibited lower machining force than a tool with larger roughness, and the opposite was true at a large depth of cut. Finally, an ultrasmall-diameter micropin with a diameter less than 3 μm was successfully machined using conditions capable of reducing machining force. • Micropin machining was performed using a cylindrical microtool fabricated by EDM. • Simultaneous cutting and grinding can be carrid out with tool rotation. • Machining force was significantly reduced by overlapping cutting and grinding. • The tool surface roughness determined the dominance between cutting and grinding. • A micropin with a diameter less than 3 μm was successfully machined. [ABSTRACT FROM AUTHOR]

GH4169 superalloy is an outstanding material used in aerospace, and precision grinding is widely applied to machine GH4169 superalloy, where the grinding force plays essential role on the ground surface quality and the achieved surface topography. In this paper, the material removal mechanism under different machining parameters is analyzed in cylindrical grinding of GH4169 superalloy. The interaction process between abrasive grain and workpiece material is investigated to establish the simulation model of material removed based on the kinematics. The random wheel topography is constructed statistically using the probability density function that characterizes the distribution of the grains. The simulated grinding force and surface topography are in good agreement with the experimental results. Specifically, the errors of the tangential and normal grinding force are 5.33% and 6.33% and the errors of the roughness Sa and Sz are 5.51% and 7.40%, respectively. Based on the simulation model and calculation results, the machining parameters are optimized for cylindrical grinding of GH4169 (vs = 45 m/s, f = 150 mm/min, ap = 3 μm, vw = 0.262 m/s) to improve the achieved surface quality. [ABSTRACT FROM AUTHOR]

Due to its exceptional mechanical properties, 18CrNiMo7-6 alloy steel is one of the preferred materials for producing critical components, such as high-speed heavy-duty gearboxes. To study the relationship between cylindrical grinding parameters (e.g., workpiece speed, wheel speed, and grinding depth) and responses (i.e., grinding force, temperature, and surface residual stress), dimensional analysis and finite element simulation of cylindrical grinding were performed in this paper. A mathematical model for predicting the grinding force and residual stress of cylindrical grinding was proposed, and numerical and experimental verifications of cylindrical 18CrNiMo7-6 alloy steel were carried out. The numerical verification results showed that the maximum relative errors of the model for predicting the grinding force and residual stress were 7.9% and 11.2%, respectively. The experimental results revealed that the maximum absolute errors were 1.31 N and 33.7 MPa, respectively. To consider the simplification between finite element simulation and experiments, a modified model was proposed, with the errors of 5.4% and 8.6% for grinding force and residual stress, respectively. The results of this study indicate that the proposed model can guide practical grinding operations and help optimize machining parameters, improve production efficiency, and achieve high-quality machining results. [ABSTRACT FROM AUTHOR]

The performance of a grinding wheel is greatly determined by its structure which in turn is influenced by the characteristics of the bonding material. Vitrified bonds were used in 50% of the wheels, which are mixtures of clay, feldspar and fusible materials. Vitrified wheels were fired at temperatures >1270°C. The main aim of this work is to focus on the feasibility of a low melting bonding material that would render the wheels a better or comparatively closer performance level than that of the conventional wheels, thereby attempting to reduce fuel and time consumption. Suitable low melting bonds were chosen based on the results of fusibility tests and chemical analysis, and their properties such as density, sound index (SI) and Young's modulus (YM) were evaluated. Performance characteristics were investigated through a cylindrical grinding test and compared along with the standard wheel. Attempts have been made to reduce the size of bonds to improve their properties, and the results obtained were promising. [ABSTRACT FROM AUTHOR]

Cylindrical grinding is a conventional method used in the manufacturing industry to produce high-precision cylindrical parts. Surface roughness and hardness in cylindrical grinding are influenced by a combination of factors including wheel selection, speed, feed rate, and coolant application. Careful consideration of these factors can help to optimize grinding performance and achieve the desired surface finish and hardness. In this work, grinding process parameters (table feed, depth of cut, work speed) are optimized for minimum surface roughness and hardness during dry grinding of AISI D3 steels. Three levels of process parameters were identified and generated the experimental trials using a Design of Experiments software, Minitab 18. L27 Orthogonal Array was used to generate the trails. Experiments were conducted for the generated trails and responses were noted. From the optimization of surface roughness, it was found that, working speed is the most significant term compared to other two. Similarly, from the optimization of hardness, it was observed that feed rate has less influence on hardness of grind surface. Confirmation experiments are carried out to further validate the results. [ABSTRACT FROM AUTHOR]

The acoustic emission (AE) technique is an effective method for monitoring grinding wheels, and numerous studies have been published on applying an AE to monitor grinding wheels. However, there are few studies on the effect of the location of the AE sensor in stably acquiring the AE signals generated during deterioration in cylindrical grinding wheels. In this study, we propose a stable method for detecting the deterioration of a cubic boron nitride (cBN) grinding wheel during cylindrical grinding using AE. We compared the AE signals acquired during grinding from an AE sensor located on the hydrostatic bearing, which supports the grinding wheel shaft, with those from the tailstock spindle. Although positioning the AE sensor on the hydrostatic bearing was found to reduce the AE signal intensity, the AE signal variations were smaller at the same grinding position, and the effect of the grinding position was less than that for the tailstock spindle. Moreover, positioning an AE sensor on the hydrostatic bearing is considered to provide the characteristics of AE signals specifically focused on the changes in cBN on the grinding wheel surface allowing the surface roughness of the workpiece to be estimated during grinding. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main disadvantage caused by the traditional heat sources is due to the lack of adaptability to the change of process parameters, resulting in a larger calculation error in the calculation of grinding temperature. For this, an epitrochoid heat flux distribution (EHFD) model for cylindrical grinding considering the influence of process parameters is established. In doing so, the grinding trajectory of two adjacent grains that can vary adaptively with the process parameters is employed to determine the equation of epitrochoid heat flux curve, and the grinding temperature is further obtained by the moving heat source theory. After the validation of the grinding temperature experiment and comparisons with the traditional heat sources, the superiority of the proposed method is reflected in grinding trajectory, undeformed chip thickness, heat source shape, and grinding temperature at the varied process parameters. The change in process parameters can make the epitrochoid heat flux distribution exhibit the widely used triangular heat source characteristic at its leading edge, causing the newly proposed heat source to have a better temperature prediction ability than other heat source models. [ABSTRACT FROM AUTHOR]

Grinding is mostly utilized as finishing process in production. Thus, it is required to maintain performance of grinding wheel for preventing grinding failures such as grinding burn, loading, chatter marks, and so on. Although regular dress-interval for grinding wheel is adopted in practice, if degradation of grinding performance can be detected in process, not only the best dress interval can be determined, but also no-failure grinding can be realized. Therefore, in this study, super abrasive wheel with new disk design is made smart by means of attaching sensors on disk of wheel to monitor load of grinding wheel. Also, in order to realize in-process grinding control, tool-work-velocity-control-system which is consist of microcomputer and original electro board has been developed. This system can control grain depth of cut by means of controlling relative velocity between grinding tool and workpiece. Utilizing the smart super abrasive wheel and the tool-work-velocity-control-system, cylindrical grinding experiment is executed. As the result, the combination of those developed items shows availability that they can provide continue of grinding process without any failure even if sharpness of grinding tool is degraded.

The acoustic emission (AE) technique is an effective method for monitoring grinding wheels, and numerous studies have been published on applying an AE to monitor grinding wheels. However, there are few studies on the effect of the location of the AE sensor in stably acquiring the AE signals generated during deterioration in cylindrical grinding wheels. In this study, we propose a stable method for detecting the deterioration of a cubic boron nitride (cBN) grinding wheel during cylindrical grinding using AE. We compared the AE signals acquired during grinding from an AE sensor located on the hydrostatic bearing, which supports the grinding wheel shaft, with those from the tailstock spindle. Although positioning the AE sensor on the hydrostatic bearing was found to reduce the AE signal intensity, the AE signal variations were smaller at the same grinding position, and the effect of the grinding position was less than that for the tailstock spindle. Moreover, positioning an AE sensor on the hydrostatic bearing is considered to provide the characteristics of AE signals specifically focused on the changes in cBN on the grinding wheel surface allowing the surface roughness of the workpiece to be estimated during grinding.

To improve the ability of the machine tool to identify chatter during the grinding process, a chatter recognition method is proposed based on the BP (back propagation) neural network model. By extracting the relevant feature values of the high-frequency acoustic emission signals and vibration signals in the processing process, multi-feature signal samples library about flutter are obtained. The multi-feature signal sample library is used to learn and train the BP neural network to establish recognition model. The model realizes on-line monitoring and accurate identification of whether chattering occurring during machine tool processing. The experimental results show that the flutter recognition based on the BP neural network model verifies that the measured test results are consistent with the actual flutter and network recognition results. Therefore, this method can effectively identify the flutter phenomenon in the processing process and play the role of online intelligent monitoring.

This paper attempts to develop a machining error diagnosis method for classifying the error sources on the external/internal contour surfaces which are fabricated using a two-axis cylindrical grinding machine. A derivation of the contour profile to grinding wheel motion trajectory and also the grinding wheel motion trajectory to the contour profile equations has been performed. Due to the contours having a sinusoidal polynomial polar curve instead of a rose curve, the grinding wheel motion trajectory equation is then used to generate the NC code for the machining. The grinding wheel motion trajectory equation is needed for the synthesis of the profile error caused by the motion error as well as the variation of the grinding wheel diameter. The two-axis motion equation is obtained by transforming the non-circular contour equation through the coordinates of the grinding wheel and workpiece. The influence of different machining parameters such as grinding wheel outer diameter error, grinding wheel feed rate, and workpiece rotation speed on the external/internal contour profile is being studied and analyzed. The diagnosis method is based on the least square method to assemble the components of the profile error due to each individual error sources. The actual machining with probe system is used to verify the diagnosis result. [ABSTRACT FROM AUTHOR]

Cutting force is a vital parameter that affects product quality. Proper control of the cutting force helps optimize the production process as it improves productivity and product quality. This paper assesses the influence of machining parameters, such as alloy steel hardness and workpiece diameters, to cutting forces when external cylindrical grinding by experimental methods. The cutting force was measured using a workpiece shaft-mounted sensor with a balanced bridge-type resistor sensor. Steel for testing: 40Cr, 9CrSi, 65Mn, and W18Cr4V, which were heat-treated at three different hardness levels: 40, 50, and 60 HRC. The Taguchi method's experimental results show that the main parameters affecting cutting forces are: Feed rate of the grinding wheel Sd, cutting depth t, and hardness of workpiece material on the HRC scale. Since then, we built a mathematical model of the normal cutting force function Fn and tangent cutting force function Ft according to Sd, t, and HRC of 9CrSi steel then tested again with three steel types: 40Cr, 65Mn, and W18Cr4V for quite similar results. The cutting force is controlled through cutting parameters suitable for different hardness and workpiece material based on this model.

Cylindrical grinding operation is an important metal cutting process used as a finish process to achieve the surface quality and dimensional stability of the products. In this context, experimental work and statistical analysis in researches contribute to improve product quality of manufactured parts. Tempered steels are widely used for automotive components and manufacturing applications. The objective of this study is to analyze the surface roughness (Ra) values of cryogenically (cryo) treated and tempered steels in cylindrical grinding operation. According to the grinding experiments created by the Taguchi method, grinding wheels (Al2O3 and SiC), heat treated steel samples (HT, CT24, and CT36) and depth of cut (50, 100, and 150 μ m) were selected to determine the optimum surface roughness values of these steels. The results showed that significant improvements in Ra values of cryo-treated and tempered steels were observed. The lowest Ra values were obtained in cryo-treated sample (CT36) with SiC grinding wheel and depth of cut (50 μ m). [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cutting force is a vital parameter that affects product quality. Proper control of the cutting force helps optimize the production process as it improves productivity and product quality. This paper assesses the influence of machining parameters, such as alloy steel hardness and workpiece diameters, to cutting forces when external cylindrical grinding by experimental methods. The cutting force was measured using a workpiece shaft-mounted sensor with a balanced bridge-type resistor sensor. Steel for testing: 40Cr, 9CrSi, 65Mn, and W18Cr4V, which were heat-treated at three different hardness levels: 40, 50, and 60 HRC. The Taguchi method's experimental results show that the main parameters affecting cutting forces are: Feed rate of the grinding wheel Sd, cutting depth t, and hardness of workpiece material on the HRC scale. Since then, we built a mathematical model of the normal cutting force function Fn and tangent cutting force function Ft according to Sd, t, and HRC of 9CrSi steel then tested again with three steel types: 40Cr, 65Mn, and W18Cr4V for quite similar results. The cutting force is controlled through cutting parameters suitable for different hardness and workpiece material based on this model. [ABSTRACT FROM AUTHOR]

The high temperatures involved in the grinding process require an efficient lubri-refrigeration method. Currently, the conventional method (flood) is the most used in industries. However, this method comes up against environmental damage and the health of operators, due to high amounts of fluid injected into the cutting region. Therefore, the use of the minimum quantity lubricant (MQL) technique with a wheel cleaning jet (WCJ) proves to be a viable alternative. This work makes a comparative analysis of the MQL + WCJ system with a conventional method. In this sense, the experiments grinding the AISI 4340 steel with an aluminum oxide wheel. The lubrication and cooling of the process were done by the conventional method, pure MQL, and diluted MQL (oil-water 1:1, 1:3, 1:5) with and without cleaning (WCJ). The output parameters evaluated were surface roughness (Ra), roundness error, G-ratio, tangential cutting force, specific energy, microstructure, and cost. The surface roughness shows an increase of only 18%, with the use of the MQL technique diluted 1:5 + WCJ compared to the conventional method. Also, the implementation of the MQL technique is cheaper than the conventional method. The results show that the addition of water in MQL favors grinding, and the efficiency of MQL increases when associated with WCJ for all parameters. [ABSTRACT FROM AUTHOR]

The grinding process consists of an essential stage of manufacture that is justified by the process' ability to guarantee precise dimensions and provide an excellent surface finish. In the present study, two grinding wheels of cubic boron nitride (CBN) abrasive grains with different friability (GL and GS) were used to perform the cylindrical grinding of the austempered ductile iron (ADI). This work compared the individual performance of each wheel, with CBN GL being of low friability and CBN GS of high. During machining with three feed rates (0.5, 1.0, and 1.5 mm/min), the conventional lubri-refrigeration method was used. In the workpieces analyzed, the tests of surface roughness, roundness deviation, specific energy, G-ratio, acoustic emission, cost analysis, microhardness, confocal microscopy, and optical microscopy were applied. The tests showed that, in almost all the output parameters, the best results obtained were using the CBN GL wheel with less friability. However, in the analysis of acoustic emission and specific energy, the results presented that the GS wheel obtained the best results; as it is a more friable tool, the efforts applied during the grinding of the GS wheel are less. Also, the microstructure analyses showed that both wheels were able to carry out the process without causing changes in the workpieces' mechanical properties. The cost analysis of the inputs showed that the increase in the feed rate produces the lowest cost. [ABSTRACT FROM AUTHOR]

The industrial market demands productivity and highest quality. Abrasion machining is a crucial point for achieving both requirements. In view of this importance, in this work, a comparative analysis is made between two wheels with different friability (low and high) in the cylindrical grinding of SAE 4340 steel and ductile iron SAE D-7003 with three feed rates (0.25, 0, 50, and 1.00 mm/min) under conventional cooling and lubrication conditions. The output parameters were average surface roughness (Ra), roundness error, wheel wear, specific energy, microhardness, and cost analysis. In a complementary way, qualitative analyzes of the surface were performed through optical microscopy, scanning electron microscopy (SEM), and confocal microscopy. It is observed that the greater ductility of the iron causes 18% rougher surfaces and less tool wear. Note that the specific energy is reduced by at least 10% with more friable wheels. On average, roundness errors are 30% lower for SAE 4340 steel, with no microstructural changes for both materials. Finally, the implementation costs for the different grinding wheels decrease with an increase in the rate of advance. [ABSTRACT FROM AUTHOR]

The coating process of high-performance films, such as electrodes for lithium-ion batteries, requires high-precision transfer of settling slurries and high-viscosity liquids. This is because transfer characteristics, such as low pulsation and quantitative transfer, have a significant impact on product performance. A single eccentric screw pump is used in this coating process. One component of this pump is a complex-shaped rotor. This rotor must have high precision and high wear and chemical resistance. To meet these requirements, we applied alumina ceramics, which have excellent material properties, to the constituent materials of the rotor. However, for rotors with hypocycloid-curved surfaces, the development of a highly accurate and highly efficient alumina ceramic grinding technology is required. For this purpose, a free-form grinding technique using small-diameter ball-end electroplated diamond grinding wheels is indispensable. In the present study, we carried out machining experiments on inclined and cylindrical surfaces as a basic study. As a result, by increasing the grinding speed with a high-speed spindle, we achieved the precision, quality, and efficiency required for rotor grinding. [ABSTRACT FROM AUTHOR]

The grinding process is a finishing operation that guarantees the surface of the workpieces with geometric and dimensional precision. This machining requires significant efforts to remove material, which can cause excessive wheel wear and even distortions on the workpiece surface. Also, the productivity and efficiency of this process are directly affected by the properties of the workpiece, wheel friability, and feed rate. In this context, it is essential to find the best machining conditions. Thus, this article makes a comparative analysis between the cylindrical grinding of SAE D-7003 ductile iron (DI) and SAE D-7003 austempered ductile iron (ADI), with two wheels of cubic boron nitride (CBN), one with low and the other with high friability, using feed rate of 0.50, 1.00, and 1.50 mm/min. The lubri-refrigeration of the process was done by the conventional method. The output parameters evaluated were surface roughness (Ra), roundness error, diametral wheel wear, tangential cutting force, microhardness, and micrograph. The tool with less friable grains reduces the surface roughness by 18%, 21%, and 29% compared with the tool with more friable grains for grinding of the DI with the feed rate of 0.50, 1.00, and 1.50 mm/min, respectively. In the ADI, the surface roughness is reduced by 27%, 26%, and 29% with a feed rate of 0.50, 1.00, and 1.50 mm/min, respectively. The results show that the low friability tool performs better in most parameters. [ABSTRACT FROM AUTHOR]

Cylindrical surface grinding can create defined textural patterns on a component with high quantity. This paper presents an experimental investigation of the frictional behaviours of ground cylindrical microstructural surfaces under a well lubrication condition. It shows that the coefficient of friction (COF) of microstructural surface is influenced by different workload and rotation speed. The results reveal that conventional surface roughness parameters do not present the influence of surface microstructure on friction performance well. However, the paper presents an interesting discovery that the friction behaviour of microstructural surfaces created by grinding could be controlled by combining dressing and grinding conditions. Such a discovery provides a logic way to reduce surface friction for energy efficiency applications. A few functional relationships have been established to illustrate the influence of microstructural features on friction. It was found that the ground microstructural surface could improve friction performance up to 20% compared to the smoother surfaces without defined surface textural patterns.

This paper presents the results of an experimental investigation as to the effects of grinding parameters on roundness error and surface roughness in cylindrical grinding. Many variables including the wheel materials, wheel loading and dressing, workpiece metallurgy, work drive mechanisms, work holding methods, coolant types, feeds and speeds, machine stiffness and age, surface conditions, centre conditions, floor vibrations all influence the quality of ground parts. However, the composite sum of these grinding parameters creates static and dynamic forces. It is obvious that the roundness error and surface roughness are created by many parameters, but in this study, only the effects of the depth of cut, work speed and feed rate which create the grinding forces in cylindrical grinding are investigated. The grinding experiments were planned according to the principles of orthogonal arrays (OAs), developed by Taguchi, and were performed so as to understand the effects of these parameters on roundness error and surface roughness. The experimental data was analysed by using statistical tools: the percent contribution from an analysis of variance (ANOVA) and the correlation between machining parameters with roundness error ( R ) and also surface roughness ( Ra ). Roundness was found to be the most related with the cutting speed, grinding force and depth of cut, while surface roughness is related to feed rate and work speed. [ABSTRACT FROM AUTHOR]

Vitrified grinding wheels are used in various end applications. They are easy to dress and have better mechanical properties. In general, grinding wheels are used till the stub portion. After usage, this stub portion is discarded as waste. Grains in this portion are fresh. Recovering and reusing the grain in the stub portion are both economically and environmentally beneficial. This work deals with the recovery and reuse of abrasive grains from vitrified brown alumina grinding wheel rejects. Grains are recovered using mechanical crushing processes. The recovered grains are used for production of resinoid cylindrical grinding wheel of 350 mm outer diameter. Performance of this grinding wheel was compared with standard grinding wheel of brown alumina grain in a CNC cylindrical grinding machine. The experiment was conducted by varying three feed rates (0.25, 0.5, and 1 mm/min). The trial wheel exhibits lower wheel wear and higher grinding ratio in all feed rates, without any loss in material removal rate. The difference in performance of the grinding wheel is correlated to the difference in toughness of the grains. It is shown that grains from vitrified rejects of brown alumina can be recovered and advantageously used in resinoid applications. This helps in reusing the otherwise wasted abrasive, thereby reducing pollution to the environment. [ABSTRACT FROM AUTHOR]

Advanced ceramics have been extensively used in industry applications due to their properties of high resistance to wear and hardness. However, there is still a high added cost related to the workpiece finish, which is usually performed by the grinding process, the only economically viable process that produces surfaces of high quality and geometric precision. Companies have been looking for optimization in the grinding process, for example in the reduction of the cutting fluid used, in this case also in order to meet the world environmental preservation requirements, without compromising the quality of the finished part. In this context, the present research sought to exploit the technique of minimum quantity of lubrication (MQL) in the external cylindrical plunge grinding of ceramics with diamond grinding wheels. Two methods of cooling-lubrication were used: the conventional and MQL, with three different feed rates (Vf1, Vf2, and Vf3) for each condition. A conventional nozzle and a proper nozzle for MQL with uniform output jet were used. Variables were analyzed as the surface roughness, roundness deviation, scanning electron microscopy (SEM), G ratio, and output acoustic emission. The results showed that the conventional cooling-lubrication gives the best results for the output variables analyzed, comparing with the MQL. However, the MQL still presented satisfactory results that may be sufficient in several cases. Considering the economic, health, and environmental benefits presented by this technique, MQL comes as a strong tendency for ceramic grinding processes. [ABSTRACT FROM AUTHOR]

Minimum Quantity Lubrication is an alternative technique to conventional techniques that are related to environmental sustainability and economic benefits. This technique promotes the substantial reduction of the amount of coolant employed in machining processes, representing a mitigation of risks to people's health that are involved with the process. On the other hand, it has been reported in the literature that some problems of using the Minimum Quantity Lubrication technique can impair the grinding efficiency. One of these problems is associated with wheel clogging phenomenon, which is caused by inefficient chip removal from the cutting zone as well as from mixture of metal dust and oil accumulated on the wheel surface during grinding. If chips lodge inside the pores of the grinding wheel as machining progresses, they will adversely affect dimensional and geometric quality of final product. Also, this will require more frequent dressing. A solution for this problem can be an effective cleaning system of the abrasive wheel during grinding with the traditional Minimum Quantity Lubrication technique Assisted with Wheel Cleaning Jet. In this context and aiming to explore the various potential health, environmental and economic benefits that have been widely reported in the literature about the use of Minimum Quantity Lubrication technique in grinding, this study presents an application of the Minimum Quantity Lubrication technique at flow rates (30, 60 and 120 mL/h) and assisted with wheel cleaning jet (Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet) in plunge grinding of a hardened steel with an aluminum oxide wheel. Experiments were also carried out with traditional Minimum Quantity Lubrication (without wheel cleaning) and with the conventional coolant techniques for comparison. The output variables were geometrical errors (surface roughness and roundness) of the workpiece, diametric wheel wear, acoustic emission, vibration and tangential cutting force. Results showed that Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet (with wheel cleaning jet) not only outperformed the traditional Minimum Quantity Lubrication technique in all the parameters analyzed, but in some cases it proved to be compatible with the conventional coolant technique under the conditions investigated. Also, most of values of the output parameters tested decreased with increase in flow rate. [ABSTRACT FROM AUTHOR]

In this paper, a study on multi-objective optimization of the cylindrical grinding process is presented. The experimental material used in this study is X12M steel. The two output parameters of the grinding process considered in this study are surface roughness and material removal rate (MRR). The cutting mode parameters including cutting speed, feed rate, and cutting depth have been selected as input parameters of the experimental process. Experimental matrix by Taguchi method has been used to design a matrix with 27 experiments. Analysis of experimental results by Pareto chart has determined the effect of input parameters on output parameters. The Data Envelopment Analysis-based Ranking (DEAR) method has been applied to determine the values of input parameters to simultaneously ensure the two criteria of minimum surface roughness and maximum MRR. Finally, the development direction for further studies has also been recommended in this study.

This paper synthesizes the design of an infeed cylindrical grinding system into a total system composed of the grinding mechanism and the grinding machine characteristics. The causalities between the grinding parameters and the machine structures are discussed, and the infeed grinding processes are analyzed as outputs that represent responses to the inputs. These relationships are integrated into a block diagram with closed-loop feedback. A novel model exhibiting practical parameters such as grinding speed, infeed rate and MRR (Material Removal Rate) is proposed. The analysis of the grinding system derived a critical factor, the “grinding time contact,” which governs the transient behaviors of process parameters such as forces and machine deflection. The process parameters during the infeed cycle including spark-out grinding were investigated, and the formulas required for the cycle design are presented. Furthermore, to improve accuracy and productivity, the features of the cycle design are described and procedures for controlling size error and roundness are discussed. Finally, the model was verified with infeed grinding tests applied to both the chuck-type cylindrical and centerless grinding methods.

In cylindrical grinding, the size accuracy of a workpiece decreases due to the thermal deformation of the ground workpiece. To improve the size accuracy, it is necessary to consider the thermal deformation of the workpiece during grinding process. In this study, we have developed an intelligent grinding system that can consider the thermal deformation of the workpiece. In this system, the thermal deformation of the workpiece during grinding process is simulated by measuring tangential grinding force. The net stock removal, that is the stock removal measured after the workpiece has been cooled, is estimated by adding the measured stock removal and the simulated thermal deformation of the workpiece. To achieve the grinding process with high accuracy, the grinding wheel is retracted when the net stock removal is reached to the grinding allowance. Using this intelligent grinding system, grinding experiments were carried out. In these experiments, the size error was reduced less than 0.3μm in radius even though the thermal deformation was more than 2μm in radius. With grinding experiments, it was confirmed that the developed grinding system could improve the size accuracy successfully.

The direct measurement of grinding temperature is always difficult due to coolant cover and very size of work and wheel interaction zone. At the same time, high heat generation in grinding often leads to grinding burns thereby affecting surface integrity; in this context, theoretical evaluation of temperature could facilitate early detection of the grinding burns. This paper therefore presents an analytical model to evaluate grinding temperature and correlates it with the occurrence of grinding burns in terms of BNA. In general, the analytical approach involves evaluating real contact length, grinding forces and finally grinding zone temperature for the plunge cylindrical grinding. The maximum rise in grinding temperature at the surface was calculated, for the wet grinding process by considering the total heat flux entering into the grinding system. Model validation experiments have been performed to measure BNA and identify parametric conditions that produce grinding burns. The model estimate of grinding zone temperature of 631 °C is in good agreement (92%) with other research works. Further, when the calculated grinding temperature reaches beyond 631 °C, the grinding burns are observed on the work surface with a BNA value of the order of 100 mp for the micro alloyed steel. The minimum thermal damage in terms of BNA is observed at higher levels of wheel speed and spark-out time and lower levels of depth of cut. [ABSTRACT FROM AUTHOR]

The extensive tribological use of nodular cast iron in ground transport industry, e.g., trains and automobiles, has brought growing scientific interest. The various applications of this material are due to the versatility of mechanical properties without adding alloy elements, making possible to achieve good results varying just the heat treatment. Due to its high fluidity, workpieces made of this material can be produced with final dimensions and shapes very close to the designed ones, making necessary just the use of finishing machining operations to get the final dimensions, more specifically those concerning the grinding process. To optimize cost production, machining processes became the focus of scientists and engineers. The grinding wheel can determine the success of an operation as its properties influence productivity and workpiece quality decisively. This work analyzes the grinding process of the ductile iron GGG-70 (average hardness of 270 HB) using two types of vitrified bonded CBN grinding wheels, which have as their only distinction the marked difference in friability of the abrasive grains. The performance of each grinding wheel will be analyzed taking into account the output parameters values obtained from surface roughness, average power, diametric wear of the grinding wheel, microstructure of the ground surfaces, and microhardness measures from the ground surface to the center of the workpiece. It was observed that the less friable wheel produced, regarding the average surface roughness, values of 0.27, 0.30, and 0.36 μm for the feed rates of 0.5, 1.0, and 1.5 mm/min, respectively, and, regarding the diametric wheel wear, produced values of 2.52, 2.99, and 4.01 μm for the same feed rates, respectively. On the other hand, when using the more friable wheel, average surface roughness values of 0.33, 0.44, and 0.64 μm and diametric wheel wear values of 3.21, 4.22, and 7.24 μm were obtained. In this way, the less friable wheel showed better results for all the conditions. Considering the feed rate order of 0.5, 1.0, and 1.5 mm/min, the improvement in surface roughness was about 18.18, 31.82, and 43.75%, respectively, and the reduction of the wheel wear was about 21.50, 29.15, and 44.61%. [ABSTRACT FROM AUTHOR]

In this study, the distribution of temperature and energy under the process parameter conditions and thermal physical parameters are investigated using a physics-based model via the finite element modeling (FEM) simulation and experimental validation during cylindrical grinding. A cylindrical grinding model is modeled to simulate the chip removal behavior in the grinding process and to measure the workpiece and chip temperatures by refining the temperature field. Workpiece speed affects the energy partition into chip more obviously than other grinding parameters. Reasonable selection of grinding parameters greatly reduces the energy partition into the workpiece from 80% to 50-30% or even lower. This study offers a comprehensive understanding of heating mechanisms during grinding and thus is very beneficial for process optimization. [ABSTRACT FROM AUTHOR]

MQL technique is considered as a cleaner machining compared to the conventional coolant delivery one, thereby ensuring environmental sustainability and economic benefits. However, one of problems commonly reported when using the MQL technique is the wheel clogging phenomenon as a result of the inefficient chip removal from the cutting zone, then the chips lodge inside the pores of the grinding wheel, adversely affecting the quality and the finishing of the final product. In this context, this study was carried out to evaluate the performance of the minimum quantity lubrication coolant technique assisted with a wheel cleaning jet (MQL + WCJ) in plunge grinding of hardened steel. This cooling-lubrication technique was tested using the following flow rates: 30, 60, and 120 ml/h. Comparative tests were also carried out with the conventional coolant technique, as well as with the traditional MQL technique (without the wheel cleaning jet). The output variables used to assess the efficiency of the MQL + WCJ technique are roughness, roundness, workpiece microhardness, grinding wheel wear, and power consumption. The results showed that the machining with the MQL + WCJ technique outperformed the traditional MQL technique in all the output parameters investigated. Also, the efficiency of the MQL + WCJ technique increased with flow rate, thereby being an alternative coolant delivery technique in grinding due to cleaner environment, more sustainable and lower consumption of fluid compared to conventional coolant one. No thermal damages and cracks on the machined surface and sub-surfaces were observed after grinding AISI 4340 steel, irrespective of the technique. [ABSTRACT FROM AUTHOR]

Surface integrity has attracted the attention of researchers for improving the functional performance of engineering products. Improvement in surface finish, one of the important parameters in surface integrity, has been attempted by researchers through different processes. Grinding has been widely used for final machining of components requiring smooth surfaces coupled with precise tolerances. Proper selection of grinding wheel material and grade with grinding parameters can result in an improved surface finish and improved surface characteristics. The present work reports the study of the effect of grinding parameters on surface finish of EN8 steel. Experiments were performed on surface grinding and cylindrical grinding for optimization of grinding process parameters for improved surface finish. Grinding wheel speed, depth of cut, table feed, grinding wheel material and table travel speed for surface grinding operation, and work speed for cylindrical grinding operation were taken as the input parameters with four types of grinding wheels (Al2O3 of grades K and L, and white alumina of grades J and K). The surface roughness was taken as an output parameter for experimentation. The grinding wheel material and grade have been observed to be the most significant variables for both cylindrical grinding and surface grinding. Surface roughness in the case of surface grinding is better compared to that of cylindrical grinding, which can be attributed to vibrations produced in the cylindrical grinding attachment. Surface roughness (Ra) values of 0.757 µm in cylindrical grinding and 0.66 µm in surface grinding have been achieved.

The high specific energy expended in grinding leads to large heat generation in contact zone of grinding wheel and workpiece, which is the great challenge in the grinding. Aiming to reduce the grinding forces and temperature, employing structured wheels has lately become a subject of special interest. Creation of spiral form structures on the surface of grinding wheels is one of the structuring methods showing great advantages in grinding in terms of grinding force and temperature reduction. However, transfer of the spiral form of the wheel surface to the workpiece surface is a problem with this method. This paper focuses on grinding of twist free surfaces by structured grinding wheels. The kinematics of grinding by the structured wheels was analyzed and simulated with the help of MATLAB. It was found that the ratio of the grinding wheel rotational speed to the workpiece rotational speed plays the key role in grinding of twist free surfaces. The experimental results proved that using the kinematic simulation, the appropriate grinding parameters could be derived to grind a twist free surface. [ABSTRACT FROM AUTHOR]

Usage of ultrasound is prevalent in a wide range of industrial applications; it is employed in aiding the removal of hard-to-machine materials. In such cases, special care needs to be taken in designing an ultrasonic horn, as the geometrical make-up of this part that strongly influences the ultrasonic power output, frequency, and amplitude transferred to the area of effect. This article proposes a novel solution to the excitation of rotating interfaces: the excitation of the workpiece in cylindrical grinding. The approach focuses on the excitation of stationary centres, holding the workpiece, rather than the workpiece itself. The modelling and development procedures for a high-power actuator as well as experimental verifications to the validity and effectiveness of the approach are provided. [ABSTRACT FROM AUTHOR]