In the present study, experimental investigations were conducted to find out the effect of abrasive water jet Machining (AWJM) process parameters on the surface roughness (Ra) of white Makrana Marble. The approach was based on Taguchi’, s method and analysis of variance (ANOVA) to optimize the AWJM process parameters for effective Machining. Nozzle transverse speed, water pressure, and stand of distance were selected as the input parameters while the other was kept constant. It was found that the water pressure and nozzle transverse speed were significant control factors and the stand of distance was the insignificant control factor in controlling the surface roughness (Ra).

Based on the review of the previous researches, more than 50% of the cost of ceramic parts is related to Machining costs, about silicon nitride (Si3N4), which is one of the most important engineering ceramics, while up to 80% has been reported. This ceramic has a combination of desirable properties such as wear and corrosion resistance and high hardness. Due to the high tool wear in Machining process, the use of traditional methods is not appropriate. The electrical discharging Machining process is a method that can machined all conductive materials without regard to mechanical and metallurgical properties, but Machining of non-conducting ceramics such as silicon nitride is not normally possible by electrical discharging Machining process. Therefore, in this research, the assisted electrode method has been used to perform the electrical discharge Machining of silicon nitride ceramics. After preparing ceramic samples, copper-carbon bilayer and single copper layer were coating on the Si3N4 and they were successfully machined. In order to further examine the machined surface, imaging was performed by SEM. The results show that an increase in material removal rate in two-layer coating compared to single-layer coating. Also, after finishing Machining process, EDX analysis was performed from the surface of ceramic workpiece, which indicates the presence of carbon and copper elements in the machined surface. In addition, the copper tool wear ratio in two-layer coating is less than that of single-layer coating.

In this study, Rotational Chemical Machining (RCM) as a novel Machining process is introduced. The properties such as surface roughness and residual stress as well as fatigue strength of the RCM process are evaluated, discussed and compared to the conventional turning process. In this sense, Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) were utilized. The results show the superiority of the RCM method over the conventional method and eliminate limits of process such as low surface quality and improve fatigue strength. The Amplitude Distribution Curve has a balanced Gaussian shape in RCM indicating the balanced distribution of peaks and valleys on machined surface. Due to the absence of Machining force in the RCM process, in comparison to the turning process, maximum residual stress is significantly decreased from 363Mpa to 71Mpa; surface roughness reduced from 3. 1µ m to 1. 5 µ m as well as the fatigue strength improved 20% approximately.

When working with hardened materials, it's important to control and optimize the surface roughness and Machining force. To achieve this, we can use intelligent methods that are based on prediction and optimization models. In this study, an artificial neural network was used to evaluate the surface roughness and Machining force of hardened steel 4140 by analyzing cutting speed, feed rate, and Machining time. A full factorial method was used to carry out 27 experiments, and an uncoated cemented carbide tool TCMW 16T304 H13A was used to measure surface roughness and Machining force during turning. An artificial neural network model with two hidden layers was selected as the optimal architecture for separately predicting surface roughness and Machining force. The predicted values were then compared with the experimental results, and the average error percentage for validation data was calculated as 4. 25% for surface roughness and 5. 11% for Machining force. Finally, the optimal cutting parameters were selected to minimize surface roughness and Machining force.

AISI H13 die steel is widely used in different industries because of its especial properties. During the Machining of hard materials, some of the mechanical properties of the material are changed due to the generation of intensive thermo-mechanical loads and plastic deformation into the workpiece. Controlling these intensive changes in machined surfaces is an important task and significantly affects the performance of the machined part. In addition, surface roughness is one of the aspects of surface texture and affects the fatigue life of the material. Since Machining of hard materials is a difficult procedure and it is confronted with several limitations, new methods in Machining processes are essential to be developed. One of these methods is using cryogenic coolant where the Machining temperature may be considerably reduced by spraying liquid nitrogen on the cutting region. Based on this, at the present study, the variation of thermal loads and surface roughness at different Machining parameters were evaluated under dry and cryogenic conditions. To do this, a thermal infrared camera and liquid nitrogen delivery system was used during the Machining of hardened AISI H13 steel. Compared with dry condition, the effectiveness of the cryogenic coolant on surface roughness and thermal loads were analysed and discussed at different cutting speed, feed rate, and depth of cut. Finally, it was found that, applying cryogenic coolant in Machining of AISI H13 die steel can be very effective to enhance performance and quality of the machined component in terms of surface roughness and thermal loads.

Near dry Electrical Discharge Machining (EDM) is one of the advanced methods for removing materials environmentally friendly. Combining the minimum quantity of lubricant (MQL) and vegetable oil not only reduces health hazarders and costs, but also improves the process. This research has been conducted on Mo40 steel and the mixture of vegetable oil and air has been used as dielectric. The effect of electric current variables, open circuit voltage, pulse on and off time and air pressure were studied on material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra), using the method of designing the central composition of the response surface. The results showed that the increase in ampere, pulse on time and open circuit voltage increase the MRR; also, increase of the pulse off time improves washing of the environment that prevent short-circuit and all had an effect on the MRR. Also, increasing the ampere and open circuit voltage leads to an increase in the TWR and increasing the pulse on time, as well as the increase in pulse off time, reduces the TWR. Increasing the air pressure reduced the dielectric density and increased the TWR. On the other hand, the increase in the ampere and the pulse on time as well as the open circuit voltage increased Ra and increase in the pulse off time and the air pressure reduced Ra. This method has led to an increase of 200% in MRR, 30% reduction in TWR, and 60% reduction in Ra compared to the kerosene immersion method.

Surface roughness is one of the most important parameters that plays very critical role in determining the quality of engineering components. A good surface quality resulting in improve of fatigue strength, corrosion and wear resistance of the workpiece. On the other hand, increasing cutting speed and decreasing time of Machining are desirable for manufacturers in order to reduce costs and increase rate of production. According to importance of above subjects, having high surface with low cost is required to have proper understanding of cutting parameters of WEDM. In this study, the effect of parameters such as Power, Time-off pulse, Open circuit voltage and Servo voltage on Tungsten carbide is investigated.