Dry electrical discharge machining (EDM) is a modification of the oil EDM process in which the liquid dielectric is replaced by a gaseous dielectric. This study investigates the effects of different types of gas (air, nitrogen, and mixture of argon/air) on the machining characteristics of dry EDM of M35 workpiece material. A Taguchi L27 orthogonal array design was applied to investigate the effects of six control factors, including current, pulse on-time, duty factor, gas pressure, electrode rotational speed and specifically type of gas on machining responses, including material removal rate (MRR), surface roughness, and radial overcut. Also, the surface integrity was investigated in different dielectric mediums. Results show that the argon/air mixture can improve the MRR with respect to air and nitrogen. The best dimensional accuracy can be obtained by using nitrogen as the dielectric medium. Also, the machined surface with nitrogen has the fewest small drops and the microcracks in Aagon/air mixture is more than those air one. So, the argon/air mixture is the best dielectric with respect to nitrogen and air mediums for dry EDM of high-speed steel M35.

This article is in two parts describing the analysis and simulation of the disc dressing process and its effect on grinding performance. This part is concerned with the generation of the wheel surface by a diamond disc dresser. A new stochastic model of the prediction of wheel topography by diamond disc dresser is developed. It predicts the number of active grains per unit area and average slope of grains of the alumina grinding wheel. This model is based on the fracture of grits and it considers the kinematical influences of the disc dressing process on wheel surface. It is possible to analyze the effects of changing dressing parameters on the wheel topography. The topography that is generated from this model provides a basis for further prediction of the grinding performance.

In the present study, an attempt was made to analyze the formability of aluminum 5083 fiction stir welded blank through an incremental forming process. Experiments are performed on the joints which were fabricated by optimal welding parameters with 73% strength sufficiency. Firstly, a series of experiments were carried out to compare the formability of welded blank in single-point and two-point incremental forming operations, under different wall angles. Thereafter, an experimental study based on response surface methodology was carried out to find out the effect of incremental forming factors on the dimensional accuracy and minimum thickness. It was found from the results that irrespective of the wall angle, the formability of welded blank (i.e. forming height until occurrence of tear) which formed in two-point incremental forming process is relatively higher than that of single-point incremental forming. Also, statistical analysis revealed that tool rotary speed and step down has a significant effect on the critical thickness, while springback is affected by the sequence of tool rotary speed and feed rate.