Workpiece Rotational Speed Research Articles

Optimization of Machining Parameters of SiC Single Crystal Cut by Diamond Wire Saw

For the process of optimizing the process parameters in the process of cutting the hard and brittle materials such as single-crystal SiC by diamond wire saw, the process parameters such as wire saw speed, workpiece feed speed and workpiece rotation speed are the design variables, and the sawing force and surface roughness are the processing targets by orthogonal experimental design. The grey system theory is introduced to optimize the multi-objective cutting process. According to the experimental data, the grey correlation resolution coefficient is determined. The significant relationship between the processing parameters and the target characteristics is analyzed. The optimal combination of process parameters under multi-target conditions is obtained, namely the workpiece feed rate is 0.025mm/min, the wire saw speed is 1.6m/s, and the workpiece rotating speed is 16r/min.

A Comprehensive Review on Wire Electrical Discharge Based Hybrid Turning (WEDHT)

Conventional machining of electrically conductive high hardness materials poses challenging issues in machine tool industry. This gave rise to the development of hybrid non – conventional machining processes. Wire electrical discharge hybrid turning (WEDHT) is a novel hybrid process for both macro and micro level cylindrical components of complicated shape and size. WEDHT combines wire electrical discharge machining (WEDM) and turning operation as single operation. The WEDHT process is influenced by the many input parameters like discharge voltage, discharge current, pulse-on time, pulse-off time, spark gap and non-electrical parameters such as type of dielectrics, flushing pressure, workpiece rotational speed, wire feed etc. Hence the selection of best parameter levels in WEDHT is a complex and challenging decision without complete process understanding. This review article focused on detailed study of parametric effects on material removal rate, surface finish, roundness, recast layer and crater formation are carried out. Finally, the future directions of WEDT hybrid process is highlighted.

Infrared Thermography for Elastic Abrasive Cutting Process Monitoring

This paper presents the features of infrared thermography (IRT) for contactless study of elastic abrasive cutting process of rotating workpieces. IRT monitoring specifics along with the experimental procedures and techniques for data analysis are discussed. IRT measurement results of the influence of workpiece rotational speed, during the processing of various materials, on heat release and heat distribution at the workpiece surface, on the cut-off wheel, the cut piece and the cutting time period are presented. The operational methodology and the results obtained can be used for optimizing the abrasive cutting of rotating workpieces.

Optimal the Process Variables of Internal Grinding for Shrink Fit Tool Holder

The goal of this study was to investigate the optimal variables settings in internal grinding for shrink fit tool holder. The effects of the main grinding variables on finishing responses were comprehensively investigated based on Taguchi method. The main process variables such as abrasive grain size (AGS), grinding wheel speed (GWS), feed rate for rough (FRR), depth for rough (DR), feed rate for finishing (FRF), depth for finishing (DF), dressing speed (DS), and workpiece rotational speed (WRS) were chosen to determine their effects on grinding performances related to roundness and surface roughness in the internal grinding of the shrink fit tool holder. The experimental response values were transferred to signal-to-noise (S/N) ratios, and then the significant process variables associated with the grinding performance were examined by analysis of variance (ANOVA). In addition, the optimal combination levels of the grinding variables were also obtained from the response graphs of S/N ratios to improve the surface quality of internal grinding. The experimental results show that the significant grinding variable affecting the roundness was FRF. In addition, the significant variables with regard to surface roughness were AGS, GWS, FRR, DR, DF, and DS. The optimal grinding variable settings were achieved. Consequently, the finishing characteristics of internal grinding could be enhanced to meet the requirements of modern manufacturing applications.

Cylindrical plunge grinding of twist free surfaces by structured wheels

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.

Neural network modelling of Abbott-Firestone roughness parameters in honing processes

In present study, three roughness parameters defined in the Abbott-Firestone or bearing area curve, Rk, Rpk and Rvk, were modelled for rough honing processes by means of artificial neural networks (ANN). Input variables were grain size and density of abrasive, pressure of abrasive stones on the workpiece's surface, tangential or rotation speed of the workpiece and linear speed of the honing head. Two strategies were considered, either use of one network for modelling the three parameters at the same time or use of three networks, one for each parameter. Overall best neural network consists of three networks, one for each roughness parameter, with one hidden layer having 25, nine and five neurons for Rk, Rpk and Rvk respectively. However, use of one network for the three roughness parameters would allow addressing an indirect model. In this case, best solution corresponds to two hidden layers having 26 and 11 neurons.

Defect Reduction in the CO<sub>2</sub> Laser Cutting of Glassware Rim

Defects in glassware are unacceptable in terms of product strength and aesthetics. The unsmooth cut rim of glassware can often be found in the laser trimming of excessive part after blow molding process. Such defect is basically not safe to use and has to be rejected from the production, thereby inevitably increasing the manufacturing cost and time. Hence, this research aims to reduce the defect in glassware rim induced by the laser cutting process. A wine glass was used as a workpiece sample in this study. Laser power, laser cutting time and workpiece rotational speed were tested and optimized to reduce the defects by using the response surface methodology. The optimum condition for the laser cutting of wine glass was found to be 225-W laser power, 2.4-s cutting duration and 335-rpm rotational speed.

Dissimilar Study on Friction Welding of AA 2025 Tube Plate to Copper Tube Using an External Tool

In this project the feasibility of friction welding in tube to tube plate using an external tool (FWTPET) of commercial Copper and Aluminum 2025 tube plate is investigated using an clearance fit method and the process parameters have been prioritized using Taguchi’s L27 orthogonal array. Than experiment is conducted and take results are compressive strength and hardness testing, Radiography test, Scanning Electron Microscopy and Energy Dispersive Spectroscopy testing. Aluminum 2025 are widely used in aerospace, automotive, marine, defense, construction etc. Friction welding is preferred for joining these materials as it is a solid state forge welding process and problems related with welding of aluminum tube plate and copper tube can be subdued through this process. This welding process is a solid state welding procedure that uses a non-consumable rotating tool that is permitted to rub against the work piece hence generating frictional heat. When the weld constraints such as tool rotation speed, welding time, axial load are optimum the friction between the work piece and the tool generates enough heat to create a plastic deformation layer at the weld interface. The process doesn’t involve any melting process and whole process occurs in solid state through plastic deformation and mass flow among the work pieces. The experimental investigation of FWTPET is done by varying the friction welding parameters such as work piece rotation speed, depth and projection. The work piece is rotated at the speeds 285 rpm, 480 rpm and 750rpm, projection 0 mm,1 mm,2 mm and depth are0.5 mm,1 mm,1.5 mm.The experiment is done in a general purpose vertical milling machine. To hold the work piece a fixture is designed. A tool is also designed. This work confirms that a high quality tube to tube plate joint can be achieved using FWTPET process.

Grooves into cylindrical shapes by wire electrochemical machining

Electrochemical machining (ECM) process has unique capabilities to offer a better alternative and sometimes is considered the only available option to cut or create intricate profiles into hard materials. ECM is a mirror-shaped-process; i.e., the shape developed into the workpiece is a mirror image to the tool profile. This study presents an application of using copper wire as a tool to create peripheral grooves. This method saves time and cost of profiling the cathode as a mirror image of the predetermined workpiece shape. This article discusses the influences of input parameters—wire feed rate, wire diameter, and workpiece rotational speed—on the responses, frontal gap, metal removal rate, specific power consumption, and groove geometry, using response surface methodology (RSM). Mathematical models were developed for the aforementioned responses, and their adequacies were checked using analysis of variance (ANOVA). The process could be optimized to create predetermined groove with a specific width; for example, the optimum values of feed rate, wire diameter, and workpiece speed are 0.07 mm/min, 2.3 mm, and 450 rpm, respectively, to maximize the MRR and minimize the specific power consumption in order to create a groove of 9.4 mm in width.

Analytical solution for nonlinear oscillation of workpiece in turning process

Chatter phenomenon is one of the essential problems in metal machining processes. It causes cutting tool wear and increase of production costs. Chatter vibration is an unstable self-excited vibration that the regenerative chatter is its most common type. In this paper, regenerative chatter in turning process is investigated. A three-dimensional nonlinear dynamic model of the turning process including both structural and cutting force nonlinearities and gyroscopic effects is presented. The workpiece is modeled as a rotating clamped–free beam which is excited by cutting forces. Using the method of multiple-scales, analytical approximate response of the system is obtained. To validate the model its responses are compared with the experimental results. Using this model the influences of tool longitudinal position, workpiece diameter, depth of cut, and rotational speed of workpiece on the stability results are studied. Using these results, turning velocity intervals for stable and unstable cuts are determined.

Study of Magnetic Abrasive Finishing for AISI321 Stainless Steel

In recent years, magnetic abrasive finishing (MAF) has become a reliable unconventional technology among researchers in industries due to need for the surface roughness reduction in metals. In this study, experiments based on influential parameters in the MAF process including rotational speed, working gap, and abrasive particle size were designed and conducted in the full factorial method in order to achieve the optimum parameters in finishing of steel AISI 321. A combination of silicon carbide (SiC), iron (Fe), and oil (SAE40) was utilized as magnetic abrasive tool. Prior to the experiments, the surface of the workpiece was abraded to the lowest value of roughness in order to obtain accurate results through the procedure. In general, the results indicate that the parameters of working gap, rotational speed, and abrasive particle size influence the surface roughness from the most to the least, respectively. Indeed, the minimum surface roughness is obtained through working gap of 1 mm, workpiece rotational speed of 500 rpm, and abrasive particle size of 100 mesh, with 50% improvement compared with initial surface roughness. Finally, the more involved parameters deviate from optimum values, the worse results are obtained compared with optimum acquired consequences.

Nano-finishing of cylindrical hard steel tubes using rotational abrasive flow finishing (R-AFF) process

Abrasive flow finishing (AFF) process is used to deburr, polish and radius surfaces and edges by flowing a semisolid viscoelastic abrasive medium over the surface to be finished. The AFF process is used in the industries especially in the case of finishing complex internal and external shapes. However, the AFF process is a time-consuming process due to its low finishing rate. Efforts are made by different researchers to improve its finishing rate. Rotational abrasive flow finishing (R-AFF) process is one of such processes where in complete workpiece tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators to improve the finishing rate. In the present study, experiments are conducted on hard steel (AISI 4340) cylindrical tubes at different extrusion pressures, workpiece rotational speed, number of cycles and medium compositions for finding optimum conditions of the same for higher change in out of roundness (ΔOOR) and material removal (MR). In this study, soft styrene-butadiene- and silicone polymer-blended medium is used for finishing. Initially, these hard tubes are ground using internal grinding process. Because of grinding process, the workpiece possesses OOR of about 2.75 μm. Later, these workpieces are finished using R-AFF process and OOR improves to 1.69 μm (i.e. ≈39 % improvement). Overall, the results of R-AFF are encouraging and the experiments have shown that R-AFF has a very promising future for the industries in terms of better finishing.

A Predictive Modeling Based on Regression and Artificial Neural Network Analysis of Laser Transformation Hardening for Cylindrical Steel Workpieces

Laser surface hardening is a very promising hardening process for ferrous alloys where transformations occur during cooling after laser heating in the solid state. The characteristics of the hardened surface depend on the physicochemical properties of the material as well as the heating system parameters. To exploit the benefits presented by the laser hardening process, it is necessary to develop an integrated strategy to control the process parameters in order to produce desired hardened surface attributes without being forced to use the traditional and fastidious trial and error procedures. This study presents a comprehensive modelling approach for predicting the hardened surface physical and geometrical attributes. The laser surface transformation hardening of cylindrical AISI 4340 steel workpieces is modeled using the conventional regression equation method as well as artificial neural network method. The process parameters included in the study are laser power, beam scanning speed, and the workpiece rotational speed. The upper and the lower limits for each parameter are chosen considering the start of the transformation hardening and the maximum hardened zone without surface melting. The resulting models are able to predict the depths representing the maximum hardness zone, the hardness drop zone, and the overheated zone without martensite transformation. Because of its ability to model highly nonlinear problems, the ANN based model presents the best modelling results and can predict the hardness profile with good accuracy.

Ultrasonic Surface Strengthening of Train Axle Material 30CrMoA

As hardness of the work-surface working in the train axle has a direct relationship to train axle's life-time, a surface strengthening technology is necessary to strengthen the hardness of the work-surface. In this study, ultrasonic surface strengthening (USS) method was proposed, and its fundamental characteristics were investigated experimentally. Concretely, the influence of many principal parameters, namely workpiece rotational speed n, feed rate f and extrusion amonut P of the tool, on the train axle with material 30CrMoA were investigated. The experiment results show that (1) surface roughness decreases significantly after USS, and lowest surface roughness can be obtained under the condition of rotational speed n=610 r/min, feed rate f=0.2mm/r and extrusion amount P=130μm; (3) hardness after USS bigger than that of before USS up to 24%, under the condition of rotational speed n=610 r/min, feed rate f=0.2mm/r and extrusion amount P=180μm; (4) the residual stress value can be adjusted after USS, the value of residual stress in the work-surface can reach -950Mpa after USS and the depth of the residual compressive stress layer can reach nearly 2mm. This study confirmes that the unltrasonic strengthening technology is a highly effective processing method for improving the surface quality of train axle.

Experimental investigation of external surface finishing of AISI 440C stainless steel cylinders using the magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced machining processes implementing the material removal in micro dimensions using the magnetic field force and magnetic abrasive particles (MAPs). In this process, the machining forces are low, the surface defects such as micro-cracks are so small and a desirable smooth surface is obtained. In this paper, the effects of parameters such as working gap, workpiece rotational speed, and the material removal mechanism (injecting the abrasive slurry of SiC and Al2O3, and diamond paste) on the surface roughness has been experimentally investigated in the MAF process on the external surface of the AISI 440C stainless steel cylinders. To do the experiments, a setup was designed and manufactured, and the experiments have been implemented according to the design of experiments (DOE) and the full factorial method. The experimental data were analyzed using the analysis of variance (ANOVA). The experimental data analysis showed that the working gap and the workpiece rotational speed have a significant effect on improving the surface roughness. The obtained surface roughness under the conditions of experimental working gap of 2 mm, the workpiece rotational speed of 355 rpm, using the Al2O3 and SiC abrasive slurry injection, and diamond paste has improved as 20, 30, and 50 %, respectively. The images of scanning electron microscopy (SEM) taken from the workpiece surface texture before and after the process confirm the obtained results.

A grinding force model for ultrasonic assisted internal grinding (UAIG) of SiC ceramics

As grinding force plays an influential role in work-surface finish in grinding process, a model is necessary for optimizing input variables to achieve high product quality and productivity. However, to the best of our knowledge, there are few reports on modeling grinding force in ultrasonic assisted internal grinding (UAIG). In this study, a theoretical model is presented to predict the grinding force in UAIG of SiC ceramics. This model stems from undeformed chip length resulting from the relative motion between the grinding wheel and the workpiece. After analyzing the cutting action of an active individual grain, normal and tangential force models for the UAIG of SiC ceramics are developed. Using the developed model, the influence of many principal input variables, namely the workpiece rotational speed nw, the wheel infeed rate Vc, the wheel rotational speed ng, the UV amplitude Au, and the oscillation frequency fo, on grinding force is predicted. Comparing the predicted forces with the experimental ones, it is shown that the predicted forces agree reasonably well with the experimental ones. The obtained results show that (1) the grinding forces are reduced in the UAIG compared to conventional internal grinding, which is attributed to the formation of the longer undeformed chip length in the UAIG; (2) the influence of ng, nw, and Vc on grinding force are much pronounced, whereas that of Au and fo are not very noticeable; and (3) the force reduction of UV can be enhanced either by decreasing ng, nw, and Vc or increasing Au and fo.

Optimization of Surface Roughness during Nd:YAG Laser Micro-Turning Process of Alumina

Laser micro-turning process is one of the newly developed laser material processing technologies to generate micro-turned groove or surface on cylindrical workpiece. In the present paper, an attempt has been made to investigate the laser micro-turning operation on cylindrical shaped aluminium oxide (Al 2 O 3 ) ceramic to study the influence of different laser micro-turning process parameters namely, laser average power, pulse frequency, workpiece rotational speed, assist air pressure and Y feed rate using response surface methodology (RSM) experimental plan. The mathematical model for surface roughness (Ra) has been developed and the adequacy of the model has been tested through analysis of variance (ANOVA) results. Average power and pulse frequency are the most significant process parameters. Optimal parametric combination for minimum value of surface roughness has been achieved as 5.23μm at parametric setting of average power of 9.04 W, pulse frequency of 4108.18 Hz, workpiece rotational speed of 451.16 rpm, air pressure of 1.44 kgf/cm 2 and Y feed rate of 0.37 mm/s. Confirmation experimental results show a good agreement between RSM based optimal and experimental value of response criterion.

Influence of machining parameters on part geometrical error in abrasive waterjet offset-mode turning

Geometrical error in abrasive waterjet turned parts is an important challenge toward the commercialization of abrasive waterjet turning process. A systematic study has not been done yet to investigate the effects of process parameters on geometrical error in abrasive waterjet offset-mode turning. In this article, a comprehensive study has been performed to investigate the influence of several machining parameters on the geometrical error (part diameter percent error) in turning AA2011-T4 aluminum alloy round bars. Water pressure, cutting head traverse speed, workpiece rotational speed, abrasive mass flow rate and depth of cut were considered as the main machining parameters in a five-level statistical experimental design. Based on central composite rotatable design, a total of 52 experiments were carried out. The main effects of the parameters and interactions among them were analyzed based on the analysis of variance technique, and the response contours for the part geometrical error were obtained using a quadratic regression model (i.e. response surface methodology). The model predictions were found to be in good agreement with experimental data. Furthermore, among the significant parameters, water pressure, depth of cut and traverse speed are the most influential parameters, with percent contribution of almost 25% each. Abrasive mass flow rate is the least influential parameter with a percent contribution of 4%.

Numerical and experimental studies on grind-hardening cylindrical surface

This study focused on the rules and effects of grind hardening a cylindrical surface. A compound heat transfer model of grinding, appropriate for cylindrical surfaces, was established to study the grinding mechanism, and the temperature distribution of grind-hardening cylindrical surfaces was analysed. Experiments were conducted to validate the theoretical model and study the effect of different materials, grinding depths, workpiece rotational speeds and wheel characteristics on grind hardening. The results indicated that the transition layer and strengthened layer of steel 41Cr4 were thicker than those of steel C45E4 and that there were more explicit boundaries between the steel 41Cr4’s matrix, transition layer and strengthened layer. The surface hardness and thickness of the hardened layer were affected primarily by grinding depth. The greatest surface hardness and hardened layer thickness were obtained at a grinding depth of 0.4 mm and a workpiece rotational speed of 0.2 m/min with grinding wheel model PA46L8V for both steel 41Cr4 and C45E4.

Surface Waviness in Abrasive Waterjet Offset-Mode Turning

In this paper, surface waviness quality in abrasive waterjet offset-mode turning has been studied regarding variations of some process parameters. Influence of five main operational parameters such as water pressure, cutting head traverse speed, abrasive mass flow rate, workpiece rotational speed and depth of cut on surface waviness of turned parts have been investigated using statistical approach. Second order regression model presented for surface waviness. The model accuracy was verified by comparing with experimental data. It found that abrasive mass flow rate, cutting head traverse speed and DOC are the most influential parameters while water pressure and workpiece rotational speed show lesser effectiveness.