To overcome the limitation of honing process, the present work proposes magnetic abrasive honing (MAH) process whereby abrasive stones are replaced by magnetic abrasives. This process is combination of magnetic abrasive finishing (MAF) and honing. MAF which is one of the finishing processes can improve the quality of workpiece surface with various geometries, removing the chips in micrometer scale by magnetic field forces. This study set to apply longitudinal vibration to the tube workpiece in MAF process; hence, this process is called MAH. The effects of rotary speed of workpiece, cross-hatch angle, and mesh number were investigated on the surface roughness of AISI 304. Magnetic abrasives were combination of SiC particles as abrasives and iron particles as ferromagnetic particles in lubricant of SAE 40 oil. The results revealed that the longitudinal movement of workpiece is effective on MAH, as the surface roughness decreased with increasing the cross-hatch angle. Surface roughness decreased with increase of rotary and mesh number. The major changes in surface roughness (58%) were obtained in cross-hatch angle of 45º rotary speed of 800 rpm and mesh size of 400. The microscopic picture showed that three-body wear mechanism is dominant for fine grits. پرونده مقاله

Lapping is one of the most important polishing processes which can be used to fabricate flat and smooth surfaces. In this paper, the effect of lapping characteristics and mesh number of abrasive particles are studied on the surface roughness and flatness for the machining of hardened AISI 52100 rings. The most significant lapping characteristics are pressure, lap plate speed and time. Scanning electron microscopy and optical microscopy are used to investigate micro cracks and surface textures. Results showed that surface roughness increased by rising the lapping pressure and plate speed. Also, reduction of the lapping time and mesh number of abrasive particles led to lower surface roughness. Application of lapping process decreased the flatness to 1.2 µm and surface roughness (Ra) from 0.58 to 0.051 µm. The lapping pressure was a significant factor on the surface roughness; and the lapping time was a significant factor on flatness. However, surface roughness increased with rising of mesh number and lapping time, and increased with decreasing the lapping pressure. The minimum surface roughness was 0.051 μm which was obtained in lapping pressure of 7 kPa, lapping speed of 0.164 m/s, time of 15 min and mesh number of 600.The flatness decreased with lapping speed, and reduced with increasing the pressure, mesh number and lapping time. پرونده مقاله

In this study, polyamide 6 (PA6)/ nitrile butadiene rubber (NBR) based hybrid-nanocomposites reinforced with calcium carbonate and organo-clay as nanofillers in various content of 1, 3 and 5 phr were prepared and characterized. The nanocomposite samples were prepared through the melt processing method in an internal mixer. The effect of rubber phase (NBR) content (10, 30, and 50 wt.%), calcium carbonate content (1, 3, and 5 phr), and organo-clay content (1, 3, and 5) was investigated on morphology and mechanical properties of the nanocomposites. The mechanical properties were evaluated by tensile, flexural, and Charpy impact tests. The results showed that adding the NBR reduces the tensile strength, tensile modulus, flexural strength, and flexural modulus, and increases the impact strength. Introducing the nano-clay and calcium carbonate improves the tensile and flexural strength, tensile and flexural modulus, and decreases the impact strength. The nano-clay content from 1 to 3 phr improved the impact strength. پرونده مقاله

During the past decade, polymer nanocomposites have emerged relatively as a new and rapidly developing class of composite materials and attracted considerable investment in research and development worldwide.Direct machining of polymers can be an option for personalized products and for manufacturing product samples. To obtain high quality products and reduce machining costs, it is very important to understand the machining conditions so as to achieve enhanced machining performance. The influence of machining parameters (feed rate) and tool type (cemented carbide, HSS and coated HSS) on thrust force in drilling of epoxy, epoxy/clay and epoxy/TiO2nanocomposites are investigated. Variation of input parameters, feed rate and tool type affects the thrust force. The cemented carbide tool creates less thrust force than HSS and coated HSS tools. The thrust force in drilling process of epoxy/TiO2nanocomposite was more significant than epoxy resin and epoxy/nano clay. The minimum thrust force (13 N) was obtained in feed rate of 0.02 mm/tooth in neat epoxy with carbide tool. پرونده مقاله