Nowadays, in order to reach minimum production cost in machining operations, various optimization methods have been proposed. Since turning operation has different parameters affecting the workpiece quality, it was selected as a complicated manufacturing method in this paper. To reach sufficient quality, all influencing parameters such as cutting speed, federate, depth of cut and tool rake angle were selected as input parameters. Furthermore, both surface roughness and tool life were considered as the objectives. Also, ST37 steel and M1 high speed steel (HSS) were selected as workpiece material and tool, respectively. Subsequently, grey relational analysis was performed to elicit optimal values for the mentioned input data. To achieve this goal, first, degree of freedom was calculated for the system and the same experiments were performed based on the target values and number of considered levels, leading to calculating grey relational generating, grey relational coefficient and grey relational grade. As the next step, the grey relational graph was sketched for each level. Finally, optimum values of the parameters were obtained for better surface roughness and tool life. It was shown that the presented method in the turning operation of ST37 led to high surface quality and tool life.

Machining operation is one of the most applicable processes for the manufacturing of industrial parts. Usually, the quality of finished part in turning operation is measured in terms of surface roughness. In turn, surface quality is determined by machining parameters and tool geometry specifications. The main objective of this study is to model and optimize machining parameters and tool geometry in order to improve the surface roughness in turning operation of AISI1045 steel. Simultaneous optimization of machining parameters and tool geometry was performed using experimental data and statistical methods. A Taguchi approach is employed in order to gather experimental data and then, based on signal-to-noise (S/N) ratio, the best sets of cutting parameters and tool geometry specifications have been determined. Experimental results are provided to illustrate the effectiveness of the proposed approach.

In this paper, Taguchi method is applied to find optimum process parameters for turning UD-GFRP rods using polycrystalline diamond cutting tool. The process parameters considered include cutting speed, depth of cut, cutting environment (dry and wet) and feed rate. The experiments were conducted by L16 orthogonal array as suggested by Taguchi. Signal to Noise ratio and ANOVA are employed to analyses the effect of turning process parameter on the tangential cutting force. The results from confirmation runs indicated that the determined optimal combination of machining parameters improved the performance of the machining process. The percent contributions of cutting speed (2.46%), depth of cut (73.82%), dry and wet (3.89%) and feed rate (8.02%) in affecting the variation of tangential force are significantly larger (95 % confidence level). It has been found that the wet cutting environment reduces the tangential force. Depth of cut is the factor, which has great influence on tangential force, followed by feed rate.

CNC turning is widely used as a manufacturing process through which extra unwanted material is turned to get a high degree of surface roughness. In this research article, Taguchi technique was coupled with Grey Relational Analysis (GRA) to optimize the turning variables, or turning parameters, for the simultaneous improvement of productivity, root mean square roughness (Rq), and average surface roughness (Ra). Taguchi technique L27 (34) orthogonal array was used in this experimental work. Depth of cut, feed, and speed were considered as the controllable process parameters. Root mean square roughness (Rq), average surface roughness (Ra), and material removal rate (MRR) were considered as the performance characteristics; according to TGRA results, the optimum combination in this study found A1B1C1 (Vc=400 rpm, f=0. 06 mm/rev, and DOC=0. 5 mm). The optimum values of Ra and MRR for this study were 6. 86 μ m and 20690. 31 mm3/s, respectively. Further, ANOVA was applied, and showed that depth of cut (DOC) had the most significant effect and followed in line by speed and feed for multi-response optimization. According to the results of Analysis of Variance (ANOA), the %age contribution of DOC (depth of cut), speed, and feed were 38. 71 %, 11. 89%, and 8. 466%, respectively.

In this study, the application of gray relational analysis (GRA) and Taguchi method in multi-criteria process parameters selection of turning operation has been investigated. The process responses under study are material removal rate (MRR) and surface roughness (SR); in turn, the input parameters include cutting speed, feed rate, depth of cut and nose radius of the cutting tool. The proposed approach employs GRA to convert the values of process outputs, obtained from Taguchi method, into a single objective used to determine the best set of process parameters for turning operation of AISI 202 austenitic stainless steel. Analytical results reveal that the combination of higher levels of cutting speed, depth of cut, and nose radius and lower level of feed rate is essential to achieve simultaneous maximization of material removal rate and minimization of surface roughness. Using verification test, these settings would result in more than 14% improvement over those for initial settings. The analysis of variance (ANOVA) and F-tests showed that nose radius is the major factor affecting the gray relational grade (GRG) with 41% contribution.  In general, the proposed procedure is quite efficient in determining the effects of process parameters and finding the best set of process parameters.

In this paper, Ultrasonic assisted cutting (UAT) process has been investigated. The cutting technique is among the advanced machining techniques which improve cutting capability of materials. Vibratory tool is made under longitudinal mode with 10 micron amplitude and 20 KHz frequency, in such a way that vibration is applied in cutting speed direction. Experiment carried out on Al7075; using ultrasonic assisted turning has lead to reduction in the cutting force, versus traditional cutting process. Moreover, further experiments were done aiming at investigating effective parameters in UAT machining process on Al7075 parts. These parameters include cutting speed, feed rate, depth of cut, and vibration amplitude. Statistical analysis on the experiment results were carried out, and different mathematical models for forecasting cutting force and optimizing machining parameters are presented in order to achieve minimum cutting force. At the end, cutting forces were compared for two machining processes namely ultrasonic assisted cutting (UAT) process, and traditional machining.

This paper presents a mathematical model that could assist in measuring, monitoring and controlling temperature variation in cold and ‘red-hot’ metal working conditions of machining. A numerical analysis technique of the temperature distribution, based on the theory of complex applied potential, was carried out using the principles of relationship analysis between the paths of heat supply in Cartesian plane when the heat path supplied to the material is orthogonal. The high level of temperature involved may effectively be predicted if a mathematical relationship that predicts the pattern of temperature distribution in a material is available. A case study example in a machining workshop is given. Simulation experiments are then carried out using Monte Carlo to increase the confidence in decision-making and provide data for significance testing. This was used as an input for testing for significance. Sensitivity analyses were also carried out in order to observe the degree of responsiveness of model parameters to changes in value. In all, five pairs of comparison were carried out among different workpiece materials. There are significant differences between workpiece materials made of steel and copper, copper and zinc, copper and aluminum. However, no significant differences exist in the model behavior of steel and aluminum, steel and zinc. It was observed that parameters are highly sensitive to changes in value. The framework could possibly be applied to milling and surfacing activities in the engineering workshop. This contribution may be helpful to small-scale enterprises that could not afford sophisticated and very expensive facilities.

Background and Aim: Different surgical techniques have been proposed for crown exposure among patients under orthodontic treatment. The aim of this study was to investigate periodontal indices in closed flap operation technique used for impacted teeth crown exposure.Materials and Methods: In this descriptive study (2001-2003) 20 patients (15 females and 5 males), age ranging from 15 to 20 years, were participated. Following the performance of closed flap operation technique, in 12 patients impacted canine and central incisors were exposed and treated orthodontically. Periodontal parameters including sulcular depth, width of keratinized gingiva and attachment loss were recorded. Results: The mean of gingival sulcus depth was 1.50±0.43, the means of keratinized gingival in central incisors and canines were 3.07±0.53 and 2.30±0.42, respectively. In one patient, attachment loss was reported.Conclusion: Considering the optimal sulcular depth and keratinized gingiva, the closed flap operation technique seems suitable.