Workpiece Speed Research Articles

Sawing characteristics of diamond wire cutting sapphire crystal based on tool life cycle

Diamond wire saw cutting technology has been widely used in the slicing of sapphire crystal. The ultra-high hardness of sapphire makes the sawing characteristics of diamond saw wire constantly change. At present, there is a lack of in-depth understanding about the influence of sawing characteristics on the quality of sapphire as-sawn wafer, which leads to the unreasonable matching between the process parameters and the sawing characteristics of the saw wire, and reduces the as-sawn wafer quality and the saw wire life. In this paper, the slicing sapphire crystal experiment was carried out with constant process parameters and the variation of saw wire bow angle, nominal diameter and saw kerf loss, surface morphology and surface roughness of the as-sawn wafer during the whole life cycle of the saw wire from initial cutting to breakage was studied. The evolution mechanism of wear and sawing characteristics in the whole life cycle of saw wire was explored, and a reasonable processing scheme which can match the sawing characteristics was put forward. The research results show that in the whole life cycle of the saw wire, the abrasives emerge from the plating layer in turn, then the cutting edge are blunted, and finally the abrasives are greatly flattened and a small amount of falling off. Saw wire has experienced initial wear, stable wear and sever wear, and the proportion of three stages in the whole life cycle is about 0.3: 0.6: 0.1. Compared with the initial stage of wear and the late stage of rapid wear, the saw wire has higher sawing characteristics and better as-sawn wafer quality in the middle stable wear period. The sawing characteristics of new saw wire is relatively weak at the beginning of cutting, so the feed speed of workpiece should be increased gradually from low to high; When most of the abrasives finish sharpening edge, a relatively stable and high feed speed can be adopted; When the abrasives are obviously flattened or fall off, the feed speed should be decreased to accommodate the significantly reduced. cutting performance of diamond saw wire.

Modeling of external cylindrical grinding process using T1 tool steel

The selection of the optimal external cylindrical grinding conditions importantly contributes to increase of productivity and quality of the products. The external cylindrical grinding is a method of finishing machine elements surface with an indeterminate blade shape. External cylindrical grinding can process surfaces that require high gloss and precision, although it can also be used to remove large surplus stock. Therefore, multi objective optimization for the external cylindrical grinding process is a problem with high complexity. In this study, an experimental study was performed to improve the productivity and quality of grinding process. By using the experimental date, the surface roughness, cutting force, and vibrations were modeled. To achieve the minimum value of surface roughness and maximum value of material removal rate, the optimal values of external cylindrical grinding conditions were determined by using the combination of Genetic Algorithms (GAs) and weighting method. The optimum values of surface roughness and material removal rate are 0.510 μm and 5.906 mm2/s, respectively. The obtained optimal values of cutting parameters were a feed rate of 0.3 mm/rev, a workpiece speed of 188.1 rpm, a cutting depth of 0.015 mm, and a workpiece Rockwell hardness of 54.78 HRC. The optimal values of cutting parameters, and workpiece hardness were successfully verified by comparing of experimental and predicted results. The approach method of this study can be applied in industrial machining to improve the productivity and quality of the products in external cylindrical grinding process of the T1 tool steel

A user-friendly finite element model for radial mode abrasive waterjet turning

This paper aims to develop a finite element (FE) model precisely simulating the multi-particle impact in the radial mode abrasive waterjet turning (AWJT). An explicit dynamic analysis was carried out to predict the crater profile resulting from the impact of the abrasive particles along a limited segment of the jet pass over the workpiece surface. The effect of both momentum transfer loss and abrasive load ratio was taken into consideration while calculating the impact velocity of the abrasive particles. To build a user-friendly model, the scripting feature of ABAQUS was involved to automatically perform all the repetitive modeling procedures. The presented FE model considers four variable turning parameters tested at five levels each, including impact velocity, abrasive mass flow rate, traverse rate, and workpiece speed. The obtained crater profile from the simulation process was utilized to calculate the depth of cut (DOC) at different parameter combinations. A comparison between the numerical and experimental results shows a good agreement with an average absolute relative error of 9.74%.

Analytical approach-based optimization of the actively driven rotary turning for environmental and economic metrics considering energy footprint of materials

The current work has been performed an effective optimization to decrease the total energy consumption (Etotal) and total machining time (Ttotal) with the constraint of the average roughness for the actively driven rotary turning (ADRT) of the material labeled SKD11. The optimizing factors are the tool rotational speed (vt), depth of cut (a), feed rate (f), and workpiece speed (vw). The analytical approach was used to construct the models of the Etotal and Ttotal. The weightage principal component analysis (WPCA) was applied in conjunction with the non-dominated sorting particle swarm optimization (NSPSO) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to determine the weight values of machining responses and select the best optimal solution. The scientific findings revealed that the optimal values of the vt, a, f, and vw were 78 m/min, 0.21 mm, 0.44 mm/rev., and 98 m/min, respectively. The reductions in the Etotal and Ttotal were 16.99% and 17.78%, respectively. Moreover, the proposed models of the Etotal and Ttotal were significant and could be used to predict technical performances with acceptable accuracy. The optimization technique comprising the analytical method, NSPSO, WPCA, and TOPSIS was named as a powerful approach to obtain optimal outcomes.

Multi-response optimization of the actively driven rotary turning for energy efficiency, carbon emissions, and machining quality

Boosting energy efficiency and machining quality are prominent solutions to achieve sustainable production for turning operations. In this work, a machining condition-based optimization has been performed to decrease the total specific energy (SEC), carbon emission (CE), and average roughness (AR) of the actively driven rotary turning (ADRT) process. The processing factors are the tool rotational speed (Tv), depth of cut (a), feed rate (fr), and workpiece speed (Wv). The turning experiments of the mold material labeled SKD11 have been conducted on a CNC lathe. The regression method is employed to develop comprehensive models of the total specific energy, carbon emissions, and average roughness. The entropy approach is then applied to drive out the weight value of each ADRT response. Finally, the non-dominated sorting particle swarm optimization (NSPSO) is utilized to determine the optimal parameters. The findings indicated that the optimal values of the Tv, a, fr, and Wv are 77 m/min, 0.32 mm, 0.25 mm/rev., and 128 m/min, respectively. The SEC, AR, and CE are decreased by 18.07%, 10.46%, and 5.02%, respectively, as compared to the initial approach. Moreover, the developed active rotary turning operation can be considered as an effective technical solution to boost the machining efficiency of hardened steels.

WITHDRAWN: Experimental investigation and optimization of surface grinding on EN31AM steel using Taguchi and ANN

Grinding is the machining processes; it is used to enhance the dimensional accuracy and surface quality of workpiece. The surface grinding process is affected by the different process parameters such as grinding wheel speed, material removal rate (MRR), number of passes, grinding wheel grain size, work piece speed, material hardness and depth of cut respectively. The feed and speed are the important factors because by increasing these factors will directly impacts on surface roughness (SR). Even though, the SR is reduced by improving the MRR. Surface grinding is the major process in metals cutting applications; it is widely used in finishing operations of cutting machining processes. SR and MRR are the significant output responses in the manufacturing relating to quality and quantity. In this article, an experimental investigation of surface grinding of EN31AM steel is studied to minimize the SR and maximize MRR for the optimization of grinding process parameters. In addition, artificial neural network (ANN) and Taguchi also employed for optimizing the input process parameters such as depth of cut, feed, and speed.

An analysis of frictional coefficient and surface roughness in surface grinding of SKD 11 tool steel using Minimum Quantity Lubrication (MQL) and dry techniques

This study was intended to investigate the effect of the cooling method (CM), workpiece speed (Vf), and depth of cut (doc) on frictional coefficient (FC) and surface roughness (SR) in the surface grinding of SKD 11 tool steel. CM consists of minimum quantity lubrication (MQL) and dry techniques. Power function was applied to model both FC and SR. Based on the analysis of the model, CM and VF significantly affected both responses, while doc influenced only FC. SEM photographs of the ground surfaces were also presented to compare the surface quality between MQL grinding and dry grinding.

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

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

Analysis on affecting factors of magnetorheological finishing

A magnetorheological finishing experimental device was designed and fabricated to explore influencing factors during polishing process. The device consists of the subsystems of mechanical transmission, workpiece clamp, magnetorheological fluid circulation and magnetic excitation. Magnetorheological fluids of different carbonyl iron volume ratio were prepared to research the effects with different workpiece speeds, polishing wheel speeds during magnetorheological finishing. The material of the workpiece is K9 glass. Experiment results show that the material removal rate increases with the workpiece speed and the speed of the polishing wheel. The increasing of volume ratio of carbonyl iron can also increase the material removal rate when the volume ratio is low, but the removal rate decreases when the volume ratio of the carbonyl iron powder reaches high value.

Multi-objective parameter optimisation to improve machining performance on deep drilling process

Cutting parameters and factors should be selected wisely to increase the quality of a product. Therefore, the optimisation of the deep drilling process was investigated by utilising the Taguchi method on three materials by three different tools. The influences of cutting speed and workpiece temperature are investigated on machining power, surface roughness and tool wear. The results revealed that the application of preheating could provide lower power consumption and a relatively good finished surface. In continuation, analysis of variance demonstrated that all factors are effective, but the workpiece material and speed are the most influential parameters on surface roughness and power consumption, respectively. Workpiece material influenced about 72.24% on machining performance, and its effect was more than tool material (3.64%). For machining power, the effect of speed (55.41%) was higher than others. The preheating and lower speeds reduced tool wear of titanium coated and cobalt coated drills.

A combination method for multi-criteria decision making problem in turning process

This paper presents a multi-criteria decision making (MCDM) for a turning process. An experimental process was performed according to the sequence of a matrix using the Taguchi method with nine experiments. The parameters including workpiece speed, feed rate, depth of cut, and nose radius were selected as the input variables. At each experiment, three cutting force components that were measured in the three directions X, Y, and Z, were Fx, Fy, and Fz, respectively. The value of Material Removal Rate (MRR) was also calculated at each experiment. The main purpose of this study is determination of an experiment in total performed experiments simultaneously ensuring the minimum Fx, Fy, and Fz and the maximum MRR. The Entropy method was applied to determine the weights for parameters Fx, Fx, Fx, and MRR. Eight MCDM methods were applied for multi-criteria decision making, this has not been performed in any studies. The implementation steps of each method were also presented in this paper. Seven ones of these eight methods determined the best experiment in total nine performed experiments. A new multi-criteria decision-making method as well as orientation for the further works were also proposed in this study.

Geometric Theorems and Application of the DOF Analysis of the Workpiece Based on the Constraint Normal Line

Aiming at the problem of judging the degree of freedom (DOF) of the workpiece in the fixture by experience, it is difficult to adapt to the analysis of the DOF of some singular workpieces. The workpiece and the fixture are used as rigid bodies, and the workpiece is allowed to move in the plane or space under the constraints of the fixture positioning point, and a set of geometric theorems for judging the DOF and overconstraint of the workpiece can be derived according to the difference in the position of the instantaneous center of the workpiece speed. The judgment of the DOF and overconstraint of the workpiece is abstracted into rules with universal meaning, which effectively overcomes the limitations of existing methods. The research results show that (1) the DOF and overconstraint of the workpiece in the fixture depend entirely on the number of positioning normal lines of the workpiece and their geometric relationship; (2) the necessary and sufficient condition for limiting the DOF of rotation of the workpiece around a certain axis is that the workpiece has a pair of parallel normal lines in the vertical plane of the axis. Using geometric theorems to judge the DOF of the workpiece is more rigorous, simple, and intuitive, which is convenient for computer‐aided judgment and the reasonable layout of the positioning points of the workpiece, which can effectively avoid the misjudgment of the DOF and unnecessary overpositioning when the complex workpiece is combined and positioned on different surfaces. Several examples are used to verify the accuracy of the method and correct unreasonable positioning schemes.

Mathematical modeling and process parameters optimization of ultrasonic assisted electrochemical magnetic abrasive machining

A new machining technique called ultrasonic assisted electrochemical magnetic abrasive machining integrates ultrasonic vibrations, electrochemical machining and magnetic abrasive finishing is used to machine and finish biomaterials more efficiently as compared to single process. This investigation highlights a novel technique for machining of hard materials in order to improve machining efficiency with hybrid process. Experimental design of Taguchi L27 and TOPSIS methods are implemented to find the optimum parameters of process. The objective is to maximize MRR and PISF and minimize PCMH simultaneously. This research investigates the interaction between input parameters (rotational speed of work piece, machining time, working gap, ultrasonic frequency time and voltage) and their effect on output characteristics of process like MRR, PCMH and PISF. The recommended settings of parameters for UEMAM process is found to be rotational speed = 600 rpm, machining time = 5 minutes, working gap = 3 mm, frequency time = 4 sec and voltage = 3 V from TOPSIS and rotational speed = 600 rpm, machining time = 15 minutes, working gap = 3 mm, frequency time = 6 sec and voltage = 4.5 V from Taguchi optimization plot. A comparison of experimental results and theoretical results have been done to validate the proposed mathematical model. The calculation results of the model showed that the maximum value of error is not more than 7.351 while comparing with experimental results, which suggests that the mathematical model is reasonable.

Implicit Subspace Iteration to Improve the Stability Analysis in Grinding Processes

An alternative method is devised for calculating dynamic stability maps in cylindrical and centerless infeed grinding processes. The method is based on the application of the Floquet theorem by repeated time integrations. Without the need of building the transition matrix, this is the most efficient calculation in terms of computation effort compared to previously presented time-domain stability analysis methods (semi-discretization or time-domain simulations). In the analyzed cases, subspace iteration has been up to 130 times faster. One of the advantages of these time-domain methods to the detriment of frequency domain ones is that they can analyze the stability of regenerative chatter with the application of variable workpiece speed, a well-known technique to avoid chatter vibrations in grinding processes so the optimal combination of amplitude and frequency can be selected. Subspace iteration methods also deal with this analysis, providing an efficient solution between 27 and 47 times faster than the abovementioned methods. Validation of this method has been carried out by comparing its accuracy with previous published methods such as semi-discretization, frequency and time-domain simulations, obtaining good correlation in the results of the dynamic stability maps and the instability reduction ratio maps due to the application of variable speed.

Precision grinding process for gyro motor shaft of dynamic pressure air bearing

There are some problems of low accuracy, low efficiency and high cost in the precision machining for gyro motor shaft of dynamic pressure air bearing with high hardness and high brittleness, for the above questions, the research of high precision grinding technology is carried out. Firstly, the diamond grinding wheel is designed by studying the influence of different parameters on workpiece shape, surface quality and specific grinding energy, etc. Secondly, through the orthogonal test, the optimum process parameters affecting the surface roughness, roundness and cylindricity of motor shaft are determined. Finally, the grinding experiments of 20 motor shafts are completed by using the optimal parameters. The results showed that the qualified motor shaft with roundness 0.09μm, cylinder 0.32μm and roughness(Ra) 0.037μm is obtained when the workpiece speed is 308r/min, feed rate is 0.003m/min and grinding depth is 1μm.

Optimization study on magnetorheological fluid components and process parameters of cluster magnetorheological finishing with dynamic magnetic field for sapphire substrates

Sapphire is used as the base material of high-brightness LED devices, high-speed and high-frequency wireless communication devices, and solar photovoltaic conversion chips. Its surface quality determines the performance of the device. Magnetorheological (MR) finishing can avoid scratches and surface/subsurface damage caused by uneven abrasive particles due to the viscoelasticity of the polishing pad. When MR polishing was used to polish sapphire substrates, the adaptability of the MR fluid components and the rationality of polishing process was the key to quickly obtain high-quality workpiece surface. In this study, sapphire substrates were polished using cluster MR finishing with dynamic magnetic fields formed by multiple synchronous rotation magnetic poles. The components of the MR fluid were optimized by single-factor experiments, and the polishing process parameters were optimized through orthogonal experiment. The results showed that an ultra-smooth surface of Ra 0.27 nm could be obtained when sapphire substrate was polished 8 h by using the optimized MR fluid, which contained 120 nm silica sol with a mass fraction of 8 wt% and W3 carbonyl iron powders with a mass fraction of 16 wt%, also with the optimized process parameters as the machining gap, the workpiece speed, the magnetic pole speed and the rotation speed of the polishing disc were 1 mm, 350 r min−1, 45 r min−1 and 40 r min−1, respectively.

Precision electrochemical machining of tungsten micro-rods using wire electrochemical turning method

The novel wire electrochemical turning (WECT) method has been proposed to machine tungsten with neutral electrolyte and bipolar pulse current in the authors’ previous research. The influence of tool wear caused by the bipolar pulse current, which is needed to remove the oxide layer generated on tungsten surface when using a neutral electrolyte, was eliminated by the WECT method because the wire tool electrode was kept being wound during the machining process. In this paper, the influences of the most important process parameters, such as the kind of electrolyte, wire material, wire diameter, rotation speed of the workpiece rod, and frequency of the pulse voltage, were studied to understand the fundamental aspects of the WECT method and improve the machining efficiency of tungsten micro-rods. The experimental results showed that the NaCl electrolyte and the NaNO3 electrolyte had higher machining efficiency and better machining accuracy, respectively. The machining accuracy was improved with the SUS304 stainless steel wire used as tool electrode than the brass wire tool electrode. It was also found that the machining efficiency and accuracy were improved with decreasing the wire diameter and increasing the rotation speed of workpiece because the influence of stray current flowing through the side and end surface of machined micro-rod was reduced. The machinable length of micro-rod peaked at an optimum feed speed of the workpiece, and the optimum speed increased with increasing the frequency of pulse voltage. As a result, a minimum rod diameter of 11 μm was fabricated with a high aspect ratio of 36. Compared with the previous method using a platinum film as tool electrode, the aspect ratio was increased significantly because the influence of tool wear was eliminated.

Effect of Grinding Parameters on the Hardness Penetration Depth of the Steel GCr15 in Internal Grind Hardening Process

This paper discusses the effects of the depth of cut (ap ), the workpiece speed (vw ) and the grinding wheel speed (vs ) on the structure and hardness of the grind hardening layer on the steel GCr15. It was found that the completely hardened zone of the internal grind-hardened layer on the steel GCr15 mainly contains needle-shaped martensite and a very low amount of carbides and retained austenite. The grinding parameters have no significant effect on the martensite microstructure and hardness of the high-hardness zone in the internal grind-hardening process. An increase of the depth of cut and the grinding wheel speed or a decrease of the workpiece speed, leads to a thicker grind-hardening layer. From the viewpoint of increasing the hardness penetration depth, a larger the depth of cut and the grinding wheel speed and a smaller the workpiece speed should be selected, under the internal grind-hardening experimental conditions.

Multi-objective optimization using the genetic algorithms for external cylindrical grinding process of 9CrSi alloy

In this study, by performing the experimental research, the surface roughness, cutting force and vibration were modeled. The Genetic Algorithms (GAs) were applied to determine the optimal values of external cylindrical grinding conditions to achieve the minimum value of surface roughness and the maximum value of the material removal rate. The optimum values of surface roughness and material removal rate are 0.490 [Formula: see text]m and 3.974 mm2/s, respectively, that were obtained at a feed rate of 0.3 m/min, at a workpiece speed of 164.82 rpm, at a cutting depth of 0.015 mm, and a workpiece Rockwell hardness of 56.32 HRC. The optimal values were successfully verified by experimental results with very promising results.

Mekanisme Aus Pahat Putar pada Pemesinan Magnesium AZ31

Magnesium alloy is one of the most popular light material which was used in biomedical. Magnesium alloy is very light, resistant to corrosion and good biocompatible. However, magnesium alloy is flammable, so it is effortless to burn. This research investigated the wear mechanism at the edge rotary cutting tool. The cutting tool used in this experiment is carbide insert with a diameter of 16 mm. Pressured cooling air was used to reduce wear progression. The cutting parameters selected were workpiece speed at 80, 120 and 180 m/min, feed rate at 0.10, 0.15 and 0.20 mm/rev., tool speed at 25, 50 and 75 mm/min, and constant depth of cut at 0.3 mm. Tool wear and wear mechanism of the cutting tool were measured by using a microscope with particular magnification. Maximum wear on the carbide cutting tool was 0.449 mm, which was achieved at the end of tool life. Dominant wear mechanism occurred at the cutting tool was abrasive wear. Some scratches were observed at the edge of the tool as a result of hard particles. Another wear type that occurred was crater wear at the top area of the insert. The wear on the cutting tool was due to the excessive heat generated during the machining process, which was due to friction between the cutting tool and workpiece material.