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Calculation the cutting force in machining processes is of great importance. In this paper, undeformed chip thickness in one-dimensional ultrasonic vibration assisted milling is calculated and then, a model for determining the cutting force in this process is presented. Analytical relations show that in ultrasonic assisted milling (UAM), the maximum cutting force is greater than in conventional milling (CM), but the average cutting force is decreased. To verify the proposed relations, with the aid of a particular experimental setup, one-dimensional vibration in feed direction is applied to workpiece and cutting force in CM and UAM is measured experimentally. Greater maximum cutting force in UAM and decrease of average cutting force in UAM compared to CM is observed experimentally as well. Comparison of average values of cutting force shows that the analytical relations for predicting the cutting force have 16% average error in CM and 40% average error in UAM. Given that the analytical calculation of undeformed chip thickness and cutting force in UAM and also comparison of experimental forces with the modeled ones has been done in this paper for the first time, the accuracy of proposed relations are acceptable.

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Reduction of cutting force in a machining process offers several advantages including increase in tool life, and improvement in the quality of the machined surface. One the new techniques for reducing cutting force relates to ultrasonic vibration assisted machining. In the present paper, one-dimensional ultrasonic vibration-assisted side milling process of Al7022 aluminum alloy has been studied. In order to investigate the effect of cutting speed, feed rate, radial depth of cut, and vibration amplitude on three cutting force components and their resultant, a special experimental setup has been designed and established which applies one dimensional ultrasonic vibration to work piece. Applying the ultrasonic vibrations on milling process, affects mostly on feed component of cutting force which is unidirectional with the work piece vibration, and decreases it by 33.5% in average. Decrease in cutting speed and increase in vibration amplitude, results to increase the separation of tool and work piece from each other in a portion of each vibration cycle, and larger decrease of the feed force. The average decrease of the resultant cutting force in ultrasonic-assisted milling process is 10.8%.

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Knowledge of broadband transducers is a new technology in the field of sonar science. Considering that Iran has sea water resources, its importance becomes more and more. In this article, after studying the performance of the kinds of transducers in the field of sonar transducers, a proper broadband transducer with the specific impedance and acoustical characteristics that can send and receive signals, is designed, simulated, fabricated and tested. At first, overall dimension of a broadband transducer with lumped parameter model and electrical equivalent circuit model was approximated and then, with increasing the degrees of freedom of analytical models, all characteristics of the optimum transducer parts were obtained in order to have a large bandwidth. By using a finite element software (COMSOL Multiphysics), the designed model was simulated and the obtained results have been compared with analytical design solution. Finally, the transducer was fabricated and tested in order to the modeled and simulated data be validated with practical ones. The obtained experimental results showed that the simulation with COMSOL Multiphysics can predict the resonance frequency and maximum transmitting voltage response (TVR) of the broad bandwidth transducer with a reasonable precision. The prediction error of resonance frequency and maximum TVR by COMSOL is 3.8% and 5.7%, respectively. The use of lumped parameter and electrical equivalent circuit models, however, gives an initial approximation for transducer dimensions, but in determination of the resonance frequency and the frequency of maximum TVR has a higher error in comparison with the finite element method.

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One of the new lubrication methods in machining processes is Minimum Quantity Lubrication (MQL). In this method, a very small amount of fluid by compressed air creates a spray and is used as lubricant. One of the advantages of this method compared to conventional (wet) lubrication is the reduction of environmental pollution and undesired effects on operator health. In the present study, the effect of minimum quantity lubrication on surface roughness in hard turning of 100Cr6 bearing steel has been investigated and compared with dry and wet machining methods. To perform MQL, some equipment have been added to the lathe machine. The tool used for material removal of 100cr6 steel is Nano-CBN that is a new generation of CBN tools with Nano technology. All experimental tests performed in dry, wet and MQL conditions. For investigation of surface roughness, each of cutting parameters include cutting speed, feed rate and cutting depth were selected in three different levels and all possible combinations of these parameters has been tested. According to experimental results and analysis of variance, feed rate 68%, lubrication method 14%, cutting speed 4% and cutting depth less than 1% affected on the surface roughness. The obtained results showed that the surface roughness in MQL method has been averagely decreased 42% and 30% in comparison with dry and wet machining, respectively.

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Machining of hard steels has it’s own problems. According to the recent advances in implementing of new cutting tools, the machining of hard steels with operations such as turning and milling is possible and it can replaced with some of grinding operations. Turning of workpieces with 45 HRC or upper hardness, is said hard turning. The aim of this article is the investigation of the effect of workpiece hardness and cutting speed and feed rate parameters on surface roughness in hard turning of cold work tool steel X210Cr12 or SPK in dry condition. For achieving this goal, the workpieces of X210Cr12 steel where hardened with different heat treatments cycles such that their hardnesses lie in the hard turning range. Then the workpieces were machined with different cutting parameters using CBN tool and the resulted surface roughness were compared. Experimental tests designed with full factorial method and totally 36 tests have been done. According to obtained results of experimental tests and analysis of variance, the effect of feed rate and workpiece hardness on surface roughness was 90.4% and 8.3%, respectively. The effect of cutting speed on surface roughness is negligible. Increasing the feed rate results in the upper surface roughness. Increasing the workpieces hardness to 50 HRC, decreases surface roughness and increasing workpieces hardness from 50 to 65 HRC, increased surface roughness.

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One way of reducing the cutting zone temperature is the use of an appropriate coolant. Common coolants, in addition to the adverse health effects on operator, cause environmental pollution as well. Because of this, interest in dry machining or green cooling methods in recent years has been greatly increased. Cryogenic cooling is one of the green cooling methods where liquid nitrogen is usually used as coolant. In the present paper, the effect of cryogenic cooling by liquid nitrogen on the cutting tool temperature and wear in turning process of AISI 304 austenitic stainless steel has been investigated. Among different methods of cryogenic cooling, the spraying technique due to its direct effect on the cutting zone has been selected. Turning with dry, wet (conventional) and cryogenic cooling methods are done. The obtained results indicated that the cryogenic cooling decreased the tool temperature compared to the dry and wet machining by 83% and 67%, respectively and reduced the flank wear of the tool by 75% and 53%, respectively. Analysis of variance showed that cutting speed relative to feed rate has a much greater impact on the tool temperature and wear. Increase of cutting speed in all cooling cases increased the tool temperature and wear.

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In plasma cutting, a noble gas at high speed is blown from the nozzle and ionized with the help of a frequency spark at high voltage and an electric arc is created which cause the gas changes to the plasma state. Plasma cutting is an ideal process for cutting of the hard metals. In this research, the effect of the input parameters and their optimization in plasma cutting of AISI 309 stainless steel were studied. By conducting the different experimental tests, the effect of input parameters including amperage, gas pressure and the cutting speed of torch on the three output parameters of the width of cut (Kerf), heat-affected zone (HAZ) and surface roughness (Ra) were investigated. Analysis of the results showed that the amperage, cutting speed and gas pressure have the highest impact on the output parameters, respectively. The artificial neural network (ANN)-genetic algorithm was used to predict and optimize the output parameters. The results indicate that the artificial neural networks model trained by the genetic algorithm are able to predict the output parameters accurately. Finally, the optimization of output parameters to achieve the best cutting conditions was carried out using the genetic algorithm. The artificial neural network models were considered as the objective function and also, the parameters of the heat-affected zone, surface roughness, and the width of cut were introduced as inputs of the algorithm. According to results, a combination of the neural network and genetic algorithm is an efficient method for optimization of the plasma cutting process. This method can be easily modified and utilized for other advanced cutting methods.

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