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One of the industrial parts that requires very high manufacturing accuracy is industrial molds and especially cutting molds. In these molds, the clearance of the dies is equal to 0.1 of the thickness of the sheet, so the accuracy of making these molds is very important. Today, the wirecut process is widely used in making these molds. In the process, due to the lack of contact between the tool and the work piece, there is no mechanical tension and the produced parts have high precision. Nevertheless, in order to achieve the high precision required in the production of cutting molds, various methods are used. In this research, using the response surface method, the dimensional accuracy value has been investigated based on three parameters of wire speed, wire tension and generator power for Mo40 steel workpiece. Based on this method, at first, the importance of each parameter on dimensional accuracy was determined by analysis of variance. Then, by deriving the equation according to the conducted tests, the optimal value of dimensional accuracy was extracted based on the mentioned parameters. The results showed that for tension values of 1.3485 kg, wire speed of 10 cm/s and power of 46.7677%, the accuracy value reaches its maximum value. Finally, these values were experimentally tested and a 0.2 % error was recorded. Therefore, by using the method of the response procedure, the amount of dimensional accuracy can be predict and optimize in the wirecut process of industrial steel molds. [ABSTRACT FROM AUTHOR]

Diamond wire sawing (DWS) is often used to cut and slice crystalline silicon. The machining accuracy of DWS is a key performance of wire sawing. However, due to the inconsistent deformation of diamond wire relative to the workpiece in different sawing directions, the machining accuracy is different. In this paper, the machining accuracy of DWS in rip sawing and cross sawing was compared. Sawing tests were designed for rip sawing and cross sawing in different feed directions. The length of sawing kerf was used for the evaluation of machining accuracy. It was found that the machining accuracy of diamond wire pushing the workpiece (rip +) is obviously better than that of pulling the workpiece (rip −) in rip sawing as the wire stiffness of rip + is higher. The machining accuracy of cross sawing in different feed directions is related not only to wire stiffness, but also related to the wire torsion produced by lateral feed force in cross sawing. Therefore, the order of machining accuracy 1X + > 4Y − > 2Y + > 3X − shows that the cross sawing accuracy does not show an obvious law relative to rip sawing. A diamond wire electrical discharge sawing (DWEDS) was proposed in rip sawing and cross sawing to compare the machining accuracy of DWS. It was found that the machining accuracy of DWEDS is higher than that of DWS. No significant differences were found in machining accuracy between rip sawing and cross sawing in DWEDS. Finally, the characteristics of cutting force in time–frequency domain were analyzed. [ABSTRACT FROM AUTHOR]

Incurrent times wire arc additive manufacturing is becoming popular and alternate to conventional machining because of its eco-friendly as wastages. Wire arc additive manufacturing (WAAM) develops the parts by depositing wire material one layer above other because it is based on old technology i.e., welding. It even has ability to generate complex parts. As WAAM requires post processing to obtain the better surface and accuracy of dimensions. To study about the post processing of WAAM specimen, in this work Wire cut EDM is used, which can machine complicated shapes with high accuracy for any conducting material without taking into account the hardness of the material. Selection of input parameters is the key for better material removal and surface finish in Wire EDM.In this study Pulse on time, Wire tension, Servo Voltage withthree levelswereconsidered as input parameter and Material removal, Surface roughness are considered as output responses. Response surface Methodology is used for designing the experiment. It is observed that wire tension plays vital role in material removal and surface finish, pulse on time is important in material removal but not in surface finish. Servo voltage predominant for surface roughness but less influenced on material removal rate. [ABSTRACT FROM AUTHOR]

Pressing molds are widely used in the industry due to the high speed of parts production. Due to the very low clearance between the mandrel and the matrix and having complex shapes, the production of these molds is very expensive and costly. The hardness of the mold and subsequently their fatigue life should be high. One of the processes that has the ability to create surfaces with high dimensional accuracy and complex shapes is the wirecut process. In this research, in order to improve the performance and increase the life of cutting dies, the hardness of Mo40 steel is optimized. For this purpose, based on the method of the response procedure, the design of the experiment has been designed for the three parameters of wire feed speed, wire tension and generator power. Next, the obtained data are clustered and then fuzzy rules with three inputs (wire speed, tension and power) and output (hardness) are extracted. The obtained rules were entered in the toolbox of fuzzy inference systems of MATLAB software. Based on the defined fuzzy inference system, it is possible to predict the hardness based on the parameters of wire speed, wire tension and generator power. In the next phase, based on this system and within the range of available variables, the optimal value of hardness and corresponding variables were extracted. In the final phase, these values were experimentally tested and their agreement with the obtained value was observed. [ABSTRACT FROM AUTHOR]

We propose a system dynamic approach for improving the stability of wire electrical discharge machining (WEDM). The approach includes wire spool inertia isolation and a damped sandwich mechanism, which increase the fundamental frequency and damping coefficient of the system, respectively. Thus, the wire tension stability is also improved. We establish a dynamic model to simulate the dynamic behavior of the wire transport system. Then the wire tension stability is optimized through tuning the damping material parameters of the damped sandwich mechanism. The mechanism was mounted on a commercial WEDM machine to show the benefits in terms of wire tension and machining precision. Results show that the maximum overshoot of wire tension was reduced by 51% and the steady-state wire tension variation was improved from 176 to 48 gf. When cutting 10-cm-thick SKD11 tool steel, the deviation from a straight line was reduced by 45%. [ABSTRACT FROM AUTHOR]

The STAR experiment at RHIC is planning to upgrade the Time Projection Chamber which lies at the heart of the detector. We have designed an instrument to measure the tension of the wires in the multi-wire proportional chambers (MWPCs) which will be used in the TPC upgrade. The wire tension measurement system causes the wires to vibrate and then it measures the fundamental frequency of the oscillation via a laser based optical platform. The platform can scan the entire wire plane, automatically, in a single run and obtain the wire tension on each wire with high precision. In this paper, the details about the measurement method and the system setup will be described. In addition, the test results for a prototype MWPC to be used in the STAR-iTPC upgrade will be presented.

The STAR experiment at RHIC is planning to upgrade the Time Projection Chamber which lies at the heart of the detector. We have designed an instrument to measure the tension of the wires in the multi-wire proportional chambers (MWPCs) which will be used in the TPC upgrade. The wire tension measurement system causes the wires to vibrate and then it measures the fundamental frequency of the oscillation via a laser based optical platform. The platform can scan the entire wire plane, automatically, in a single run and obtain the wire tension on each wire with high precision. In this paper, the details about the measurement method and the system setup will be described. In addition, the test results for a prototype MWPC to be used in the STAR-iTPC upgrade will be presented.

Summary: Background: Tensile strength develops on wires during distraction osteogenesis (DO) using the Ilizarov system. The increase of tensile strength can lead to bending of the wires. The purpose of this study was to investigate the development and progression of wire bending during tibial lengthening using the Ilizarov system. We also identified factors that contribute to wire bending. Methods: Seventy-two segments of 36 skeletally immature achondroplasia patients (mean age, 8.5 years; range, 5.1–14.4 years) with bilateral tibial lengthening with the Ilizarov system were included in this study. The wire bending was defined as cases with loss of linearity of the wire during DO. The average distance of proximal and distal wires to the adjacent ring throughout the entire DO was measured to determine the progression of wire bending. In addition, age, height, weight, initial tibial length, gain of length, amount of correction of angular deformity, distraction index, external fixation index, and healing index were investigated to identify potential contributors to wire bending. Wire-related complications, including wire breakage, were also assessed. Results: Wire bending increased in the distraction phase (p ​

The endless diamond wire is a special application of diamond wire cutting. The loss of wire machining accuracy will cause the fluctuate and unflat surface, which will cause drum shape error with large dimension in the middle of silicon ingot and small dimension on the head and tail of silicon ingot. In this paper, based on the phenomenon of drum shape error processed by a single wire, the factors affecting the machining accuracy, including the stiffness of wire web, tension, and fluctuation of wire were studied. The reason for the influence of machining accuracy during the endless diamond wire sawing process was mainly determined by the position of diamond wire. In view of the wire-lag effect of diamond wire, the definition and evaluation method of the stiffness of the endless diamond wire web were proposed. It was found that the formation of wire bow, especially the lateral wire bow induced by the lateral force, was the main reason causing the machining accuracy. In view of the evaluation of machining accuracy, the flatness evaluation method could be used instead of the current method of extreme deviation analysis, which could provide more comprehensive evaluation of the sawing accuracy. [ABSTRACT FROM AUTHOR]

In order to meet the processing requirements of precise cylindrical parts on hard and difficult-to-machine materials, this paper introduces wire electrical discharge grinding (WEDG) using thin plate wire guide for cylindrical parts machining. The spindle system and the wire transport system to realize this processing method was added to a low speed wire electrical discharge machining (LS-WEDM) machine tool. In order to realize the online measurement of the machining accuracy of the cylindrical parts, an online measurement system of two-degree-of-freedom based on laser displacement sensor was built. The reasons for the incomplete removal of the machined surface were analyzed. Through the application of a new tool setting strategy and reasonable selection of processing parameters, the phenomenon of incomplete processing can be avoided. The experimental research on the effects of part rotational speed, wire feed rate, wire running speed and wire tension on roundness, surface roughness Sa, and surface morphology were carried out. Finally, example of the cylindrical parts is given to verify the machining accuracy. [ABSTRACT FROM AUTHOR]

Surface roughness and kerf width are the two challenging quality characteristics in wire cut electric discharge machining (WEDM) of Ti-6Al-4V to improve accuracy in machining. In this study, effect of wire displacement on the kerf width and surface roughness is studied in WEDM of Ti-6Al-4V. Mechanistic models are developed for kerf width and surface roughness using amplitude and frequency of wire vibration in X and Y directions. Amplitude and frequency of wire displacement in X and Y directions are directly measured using an accelerometer at different working conditions. The estimated kerf width and surface roughness are compared with the experimental results and the average error between them is found to be 3.7 and 4.2% respectively. The results showed that the current and wire tension have significant effect on the wire displacement. The kerf width and surface roughness are effected more by the applied current and the metal removal rate is effected by current and pulse on time. A working condition with 3.3 A of current, 15 N of wire tension, 14.4 µs of pulse on time and 41.5 µs of pulse off time is found to be an optimum working condition. [ABSTRACT FROM AUTHOR]

WEDM is used in machining conductive materials where it is required to obtained complicated and intricate shapes with high accuracy. Various applications are in the field of automobile, medical industries, aerospace etc. WEDM is an economical machining option with short product development cycle. Surface roughness, kerf width, Material removal rate, Recast layer hardness and surface microhardness in WEDM are most important responses. In this paper, effect of varied Wire tension on SR, KW, MRR, RCL hardness and surface microhardness on AISI 304 have been investigated. Pulse on time, pulse off time, current and dielectric fluid are taken as fixed parameter. Results show that Wire tension influences the SR, MRR and Surface microhardness and has no effect on kerf width in case of Stainless steel 304. [ABSTRACT FROM AUTHOR]

Wire cut electrical discharge machining was identified as a good alternative to conventional machining for machining super alloys that possess low machinability. In the present work, effect of wire tension along with current, pulse on time, and pulse off time on the performance characteristics such as spark gap, surface roughness, amplitude of wire vibration, and cutting rate were studied in wire cut electrical discharge machining of Inconel 718 metal. Experiments were conducted at five levels of the process parameters as per orthogonal array of L25 and their results were collected. These experimental results were analyzed and the interaction effect of wire tension along with current, pulse on time, and pulse off time on performance characteristics was studied using analysis of variance. Response models were developed for the four responses in terms of process parameters and the accuracy of such models was tested. In addition to the above studies, effect of the wire displacement on the kerf size, cutting rate was studied. Spark energy was also estimated for all the experiments and its effect on the performance characteristics was studied. The response models developed in this study were able to predict the experimental results i.e. amplitude of wire vibration, surface roughness, cutting rate, and spark gap with an accuracy of R 2 values of 1.0, 0.96, 0.88, and 0.99, respectively. Interaction effect of current and wire tension was found to have the most significant effect on the amplitude of cutter vibration and surface roughness. [ABSTRACT FROM AUTHOR]

Abstract We present a novel electrical technique to measure the tension of wires in multi-wire drift chambers. We create alternating electric fields by biasing adjacent wires on both sides of a test wire with a superposition of positive and negative DC voltages on an AC signal (V AC ± V DC). The resulting oscillations of the wire will display a resonance at its natural frequency, and the corresponding change of the capacitance will lead to a measurable current. This scheme is scalable to multiple wires and therefore enables us to precisely measure the tension of a large number of wires in a short time. This technique can also be applied at cryogenic temperatures making it an attractive solution for future large time-projection chambers such as the DUNE detector. We present the concept, an example implementation and its performance in a real-world scenario and discuss the limitations of the sensitivity of the system in terms of voltage and wire length. [ABSTRACT FROM AUTHOR]

The objective of the present work is to use a suitable method that can optimize the process parameters like pulse on time (TON), pulse off time (TOFF), wire feed rate (WF), wire tension (WT) and servo voltage (SV) to attain the maximum value of MRR and minimum value of surface roughness during the production of a fine pitch spur gear made of copper. The spur gear has a pressure angle of 20⁰ and pitch circle diameter of 70 mm. The wire has a diameter of 0.25 mm and is made of brass. Experiments were conducted according to Taguchi’s orthogonal array concept with five factors and two levels. Thus, Taguchi quality loss design technique is used to optimize the output responses carried out from the experiments. Another optimization technique i.e. desirability with grey Taguchi technique has been used to optimize the process parameters. Both the optimized results are compared to find out the best combination of MRR and surface roughness. A confirmation test was carried out to identify the significant improvement in the machining performance in case of Taguchi quality loss. Finally, it was concluded that desirability with grey Taguchi technique produced a better result than the Taguchi quality loss technique in case of MRR and Taguchi quality loss gives a better result in case of surface roughness. The quality of the wire after the cutting operation has been presented in the scanning electron microscopy (SEM) figure.

Electric discharge machining has been established as an effective alternative process to conventional material removal processes for machining reinforced metal matrix composites. Wire cut electric discharge machining holes were produced in a metal matrix composite (10 vol% of SiC in Al6061), which were then investigated to determine the machinability of the material using this process. It was observed that the input factors such as the size of reinforced particles, wire tension and pulse-on time significantly affect diameter error, circularity and surface roughness. Pulse-on time, the interaction between pulse-on time and wire tension contribute to the maximum diameter error. The wire tension is the most significant factor to circularity, which is followed by the interaction between pulse-on time. In particular, wire tension with low and high tensions results in poor circularity. It has been found that there are more surface defects encountered when particle sizes are smaller, and circularity is improved when particles are in a medium size. In addition, the surface defect is reduced as the particles increase the melting resistance of the surface. The higher pulse-on time leads to higher heat and more time to degrade the surface. Therefore, low pulse-on time and wire tension gave better surface finish. [ABSTRACT FROM AUTHOR]

Wire electrical discharge machining is a non-traditional cutting process for machining of hard and high strength materials. This study analyzed the effects of the main input parameters of wire electrical discharge machining of ASP30 steel (high alloyed Powder metallurgical [PM] high speed steel) as the workpiece on the material removal rate and surface roughness. The input parameters included spraying pressure and electric conductivity coefficient of the dielectric fluid, linear velocity of the wire and wire tension. The machined surface quality was evaluated using SEM pictures. Results indicated that increasing the spraying pressure of dielectric fluid leads to a higher material removal rate and surface roughness and that increasing the wire tension, linear velocity of wire, and electric conductivity of the dielectric fluid decreases the material removal rate and surface roughness. [ABSTRACT FROM AUTHOR]

This paper presents a mechatronic system approach to the improvement of part straightness accuracy in rough cutting of wire electrical discharge machining (wire EDM). The mechatronic system design integrated an active wire feed apparatus and a microcontroller-based wire tension control system into a novel wire transport system for providing a smooth wire transport and a constant wire tension value. The active wire feed apparatus was first devised to reduce the inertial effect of the wire spool on the wire transport system. Then, a proportional-integral-derivative (PID) controller was used to implement real-time wire tension control of the wire transport system. Compared to a typical wire transport system, steady-state error of wire tension control can be reduced by half using the newly developed system. Through pulse train analysis, the proportion of normal sparks to total sparks defined as normal spark ratio can be used to monitor spark gap condition as well as to be an indication of evaluating machining speed and part straightness accuracy. Experimental results show that part straightness accuracy can be significantly improved from 13 to 4 μm by the newly developed wire transport system along with optimum machining settings. [ABSTRACT FROM AUTHOR]

This paper investigated the wire tension change in high-speed wire electrical discharge machining (HSWEDM). The symmetry of the wire-winding mechanism and the resistance to the wire electrode on the upper and lower guide frames were considered the main causes of a non-even wire tension. Combined with the simulation model and the redesigned wire-winding mechanism, the adjusting wheel and the protection block were used to control the symmetry of the wire-winding mechanism and the resistance to the wire electrode on the upper guide frame. The wire tension was found to be capable of remaining stable in the machining process. The redesigned wire-winding mechanism can improve cutting stability and efficiency in large thickness cutting processes as well as the consistency of workpiece dimension in multi-cutting processes. [ABSTRACT FROM AUTHOR]