In this study, a novel precision finishing process for complex internal geometries using smart magneto-rheological polishing fluid is developed. Magneto-rheological abrasive flow finishing process provides better control over rheological properties of abrasive-laden finishing medium that exhibits changes in rheological behavior in the presence of external magnetic field. The finishing fluid used in this study contains SiC and iron particles with a combination of specific volume percentage of glycerin and liquid paraffin as abrasive, magnetizable and base medium parts, respectively. The smart characteristics of magneto-rheological fluid are utilized to precisely control finishing forces to control surface quality. A hydro-mechanical device is used to provide experimental setup in order to investigate the effects of different parameters on surface roughness. This device consists of a hydro-mechanical power unit, abrasive fluid containers, permanent NdFe magnets, workpiece fixtures and a base frame. Experiments were conducted on austenitic stainless steel (AISI304), aluminum (7075 alloy) and copper (unalloyed) with different magnetic field strength, abrasive particle size and finishing time cycles. It is observed that by decreasing magnetic field strength, the surface roughness decreases in all three materials. Besides, with increase in abrasive particle mesh number, surface roughness tends to be higher. However, there is a slight difference observed through different finishing cycle times. The specific applications of this process are finishing fluid guidelines in precise instruments like capillary tubes in drug delivery setups.

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In recent years, a new generation of composite materials has been introduced as metal matrix composites (MMCs) in order to simultaneously provide higher strength and stiffness. Industrial interests resulted in deep investigations and researches on machinability of MMCs and especially in the field of high-speed machining. High-speed machining processes offer a higher machining efficiency and reduced cost of the process, which made them the process of interest in many manufacturing industries. However, matrix reinforcement by addition of hard particle phases to the MMCs significantly increases machining difficulty, tool wear, surface quality deterioration and overall fabrication costs. In the current research, the cutting speed, feed rate, depth of cut, presence of cryogenic coolant and their effect on the tool wear of high-speed machining of Al/SiC MMC reinforced with 15 wt% SiC particles have been investigated. The results have shown that silicon carbide particles in the aluminum matrix cause a severe tool wear. However, the severity of tool wear has decreased by applying a cryogenic cooling.

Mechanical failure under cyclic and dynamic loading has always been a concern in engineering applications. Many different properties can be achieved by adding different materials to the metal matrix nanocomposites. In this study, steel 316 L is selected as the matrix, and the additive materials of titanium carbide and hexagonal boron nitride in 3.5 wt% for each one are added as the reinforcement particles. The samples are fabricated by powder metallurgy, compacted in pressure of 410 MPa, and sintered in temperature of 1375℃ for 4 h. In addition, some pure steel 316 L samples were provided for comparison purposes. Numerical simulation of bending strength and fatigue life of the notched samples were conducted and verified with experimental tests on the mechanical parts. It appeared that the nanocomposite specimens present a higher mechanical reliability relative to the pure 316 L as a result of adding nanoparticles. Steel 316 L S–N curves of the notched samples are also obtained from numerical analysis.