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The work describes the statistical characterization of the tensile properties of raw and treated jute yarn fibers. The yarns are treated with various alkaline sodium hydroxide concentrations (0.5, 2 and 5%) and different immersion times at room temperature (30 minutes, 2, 8 and 12 hours). Due to the scattering of the experimental results, statistical analysis was performed using both two-and three-parameters Weibull, and Anova variance methods. In terms of stress, failure strain, and Young modulus, the results obtained from uniaxial tensile yarns show a variation that depends essentially on the immersion time and the NaOH concentration. Optimum mechanical properties are obtained for a concentration of 2% of NaOH and an immersion time of 2 hours. The results are further discussed in view of an extensive Fourier Transform Infrared Spectroscopy (FTIR) analysis carried out on the different classes of yarns.

This experimental investigation was conducted to determine the effects of cutting conditions on surface roughness and cutting forces in hard turning of X38CrMoV5-1. This steel was hardened at 50 HRC and machined with CBN tool. This is employed for the manufacture of helicopter rotor blades and forging dies. Combined effects of three cutting parameters, namely cutting speed, feed rate and depth of cut, on the six performance outputs-surface roughness parameters and cutting force components, are explored by analysis of variance (ANOVA). Optimal cutting conditions for each performance level are established. The relationship between the variables and the technological parameters is determined through the response surface methodology (RSM), using a quadratic regression model. Results show how much surface roughness is mainly influenced by feed rate and cutting speed. The depth of cut exhibits maximum influence on cutting force components as compared to the feed rate and cutting speed.

This paper presents a comparative study of both the surface roughness (Ra and Rz) and the tangential cutting force (Fz) achieved during the machining of EN-GJL-250 cast iron by uncoated and coated silicon nitride ceramics (Si 3 N 4). Experimental tests were planned according to a L 27 Taguchi design. Both the surfaces of response (RSM) and analysis of variance (ANOVA) methods were applied to determine and classify the cutting parameters affecting the surface roughness and cutting forces and for deriving the mathematical models to be used in the optimization stage when implementing the desirability function. Moreover, in order to localize the surface defects in the machined profiles, 2D and 3D topographic analysis based on the Abbott-Firestone curve was employed. The results obtained show that the surface roughness is largely influenced by both the feed rate and the cutting speed, while the depth of cut is the factor that most influenced the cutting force followed by the feed rate. Furthermore, the coated ceramic tool demonstrates a better surface quality and lower cutting force than those obtained by uncoated ceramic. The 3D topographic analysis indicates the generated surfaces as constituted by numerous interrupted ridges. The wear tests show that the CC1690 ceramics are more efficient than the CC6090 ceramics in terms of cutting force, surface roughness and wear resistance.