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Advancement in machining technology of curved surfaces for various engineering applications is increasing. Various methodologies and computer tools have been developed by the manufacturers to improve efficiency of freeform surface machining. Selection of the right sets of cutter path strategies and appropriate cutting conditions is extremely important in ensuring high productivity rate, meeting the better quality level, and lower cutting forces. In this paper, cutting force as a new decision criterion for the best selection of tool paths on convex surfaces is presented. Therefore, this work aims at studying and analyzing different finishing strategies to assess their influence on surface texture, cutting forces, and machining time. Design and analysis of experiments are performed by means of Taguchi technique and analysis of variance. In addition, the significant parameters affecting the cutting force in each strategy are introduced. Machining strategies employed include raster, 3D-offset, radial, and spiral. The cutting parameters were feed rate, cutting speed, and step over. The experiments were carried out on low curvature convex surfaces of stainless steel 1.4903. The conclusion is that radial strategy provokes the best surface texture and the lowest cutting forces and spiral strategy signifies the worst surface texture and the highest cutting forces.

Inclined surfaces are commonly used in the aerospace and die/mold industries. For machining this kind of surfaces, many aspects have to be considered as machinability considerations including milling strategies, machining parameters and etc. In machining, achieving better quality is challenging task. Various tool-path strategies during milling operation leads to variable surface roughness on machined samples. The objective of this study is to analyze different machining strategies in 3-axis milling of a typical curved geometry part. The machining parameters used in this study, are cutting speed, feedrate and stepover. This paper also presents an approach to develop a mathematical model for measuring Scallop height size and distribution for different machining strategies to show that Scallop height size has direct relation with Surface roughness measurements in each strategy. Finally the optimized strategy based on the results was determined.

In order to investigate the effect of different levels of temperature and drought stress on seed germination parameters of nettle roman (Urtica pilulifera L.), an experiment was conducted as factorial in a completely randomized design with three replications at the Department of Agronomy, College of Agriculture, University of Guilan, in 2014. Treatments included different temperature levels (5, 10, 15, 20 and 25 °C) and drought stress levels (0 (control),-2,-4,-6 and-8 bars). The results showed that treatments and their interactions had a significant effect on germination percentage (GP), germination rate (GR), root length and root dry weight. The highest GP (88%), GR (1.8 seed/day) and root dry weight (0.06 g) were obtained as the result of the interaction between the temperature of 25°C and no-stress condition. In this study, with an increase in drought stress and a decrease in temperature, GP, GR, root dry weight, root length and shoot length decreased. The impact of drought stress on GR and GP was lower at 20°C, compared with the temperature of 25°C. A decrease in water potential from-4 to-6 bars at 20°C caused a reduction of 50% and 30% in GP and GR, respectively. However, these reductions at 25°C were 75% and 70%, respectively. According to the results, it could be stated that the significant reduction threshold of seed germination parameters was-2 bars.

Due to outstanding properties of γ–TiAl intermetallic such as high resistance against fatigue, oxidation, corrosion, creep, dynamic vibration, high working temperature and also its application in aerospace, automotive industry and turbojet engines; in this paper, powder mixed electrical discharge machining (PMEDM) of γ–TiAl intermetallic by means of different additive powders including aluminum (Al), graphite (Gr), silicon carbide (SiC), chrome (Cr) and iron (Fe) is investigated to compare the output characteristic of surface quality and roughness. The results indicate that aluminum powder produces the best surface finish, followed by silicon carbide, graphite, chrome and iron respectively. The experimental results show that in the determined settings of input machining parameters, aluminum powder can improve the surface roughness of TiAl sample about 32%.

Nimonic 115 is one of the essential Nickel-based super alloys is known as one of the most difficult-to-cut materials because of its unique properties. Appropriate selection of the machining parameters in milling of this material is so vital for improving the machining efficiency. This paper discusses the use of response surface methodology for modeling of surface roughness in milling of Nimonic 115 with coated carbide tools. The machining parameters used in this study, are cutting speed, feed rate, axial and radial depth of cut. Average Surface roughness was measured in different conditions and analysis of variance (ANOVA)was performed. Then, quadratic model for predicting the surface roughness is established. The results show that the most significant parameter which affects surface roughness is feed rate.

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