فهرس المقالات Surface Quality

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  1 - Evaluation of the Cryogenic Effect on Friction Stir Processed AA7075/Si Matrix Nanocomposites
  Navid Molla Ramezani Behnam Davoodi
  Friction-stir processing is a green manufacturing process for surface composite fabrication and surface modification. To achieve this critical goal, the type of cooling and lubrication are of great importance. Therefore, in this paper, the cryogenic effects were investi أکثر

  Friction-stir processing is a green manufacturing process for surface composite fabrication and surface modification. To achieve this critical goal, the type of cooling and lubrication are of great importance. Therefore, in this paper, the cryogenic effects were investigated on friction-stir processing (FSP) tool wear and surface quality of an aluminum matrix nanocomposite. Silicon carbide (SiC) nanopowder was used as the reinforcing phase. The effects of cooling strategy and tool rotation speed on the tool wear, microhardness, surface roughness, and energy dispersive spectroscopy (EDS) analysis were studied. The cooling procedure was conducted under dry and cryogenic conditions. Additionally, the rotation speed was set at three levels, while other parameters were kept constant. The FSP tools were examined under a scanning electron microscope, and the wear mechanisms were investigated under different conditions. The results showed that tool wear, surface roughness, and microhardness were improved under cryogenic conditions compared to air conditions. Furthermore, in the presence of liquid nitrogen, the metal matrix composite did not exhibit any microstructural defects, such as micro-cracks. Energy dispersive spectroscopy analysis also demonstrated that SiC had better penetration into the base material under cryogenic conditions compared to dry conditions. تفاصيل المقالة
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  2 - The Effect of Artificial Aging Treatment and Lubrication Modes on the Cutting Force and the Chip Surface Morphology when Drilling Al-Si-Mg (A356) Cast Alloys
  Seyed Ali Niknam Keyhan Jabbari
  This article reports the effects of various artificial aging methods and lubrication modes (dry, mist, wet) on the recorded cutting forces and chip morphology in drilling Al-Si-Mg (A356) cast alloys. In the course of this work, the work part sampled were as-received all أکثر

  This article reports the effects of various artificial aging methods and lubrication modes (dry, mist, wet) on the recorded cutting forces and chip morphology in drilling Al-Si-Mg (A356) cast alloys. In the course of this work, the work part sampled were as-received alloy (T0), solution heat-treated alloy (SHT) and then aged alloys at 155°C, 180°C, and 220°C (T4, T6, T61, T7), respectively. The significant effects of artificial aging the recorded cutting forces were noticed. Except minor cases under lower levels of feed rate, in general lower cutting forces were observed in A356-T0 and A356-T7 which are more brittle than other tested alloys. A direct relationship can be formulated among the microcracks on the free surfaces of the chips, brittleness and the recorded cutting forces. The use of MQL led to lower resulting cutting forces under similar cutting conditions. This can be related to less effect of thermo-mechanical stresses on the work part under MQL mode which tends to reduce the cutting forces. تفاصيل المقالة
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  3 - An Experimental Investigation on Surface Roughness and Edge Chipping in Micro Ultrasonic Machining
  Hamid Zarepour
  Surface quality including surface roughness and edge chipping is a key process measure in microultrasonic machining (Micro-USM) as an efficient process for micromachining of hard and brittlematerials. Process parameters such as ultrasonic vibration amplitude, static loa أکثر

  Surface quality including surface roughness and edge chipping is a key process measure in microultrasonic machining (Micro-USM) as an efficient process for micromachining of hard and brittlematerials. Process parameters such as ultrasonic vibration amplitude, static load, type of toolmaterial, type and size of abrasive particles and slurry concentration can influence the surfacequality. However, there is limited study on the parametric effects on the surface quality in micro-USM. The objective of this study is to investigate the effects of the workpiece material as well asprocess parameters including abrasive type, particle size and vibration amplitude on surfaceroughness and edge chipping in micro-USM. Silicon, alumina ceramics and soda-lime glass wereselected as workpiece materials and polycrystalline diamond and alumina as abrasives. Particle sizeranging from 0.3 to 3 μm and vibration amplitude ranging from 0.8 to 3 μm were selected in thisstudy. Results indicate that workpiece material and vibration amplitude have significant effects onsurface roughness. Workpiece material was found to be the most significant parameter with apercentage contribution of about 45 % in the variation of mean Ra, followed by vibration amplitudeand particle size of about 28 % and 5% contributions, respectively. Results also show that aluminaceramic is a material capable of achieving better surface quality in micro-USM as compared tosilicon and soda-lime glass. تفاصيل المقالة
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  4 - Experimental Study on Effective Parameters for Thermal Cutting of Glass Sheets
  سید محمدرضا خلیلی
  The new non-conventional cutting process by the use of thermal shock is a convenient procedure for cutting the brittle materials such as glasses and ceramics. This method is based on the application of localized thermal shock to brittle materials by the use of hot air j أکثر

  The new non-conventional cutting process by the use of thermal shock is a convenient procedure for cutting the brittle materials such as glasses and ceramics. This method is based on the application of localized thermal shock to brittle materials by the use of hot air jet, which induces thermal stresses at the tip of an existed pre-crack. Due to the thermo-elastic behavior of materials, the pre-crack is propagated in the material. By the use of this process, the glass and brittle materials can be cut to any shape without the use of cutting tools. In this paper, based on the presented phenomena and the induced time-dependent thermal shock, the tip of an existed pre-crack in a glass sheet is heated by a moveable point heat source. The effect of parameters such as cutting speed, nozzle orifice diameter, cutting temperature, macroscopic quality of cutting surface on cutting the brittle materials were studied. The results indicated that as far as a pre-defined distance is developed between the moveable heating point and the tip of the existed pre-crack, the crack is propagated in stable manner and under complete control, and hence better cutting surface quality. Based on this distance, the effective cutting parameters are investigated and set to get better cutting process. تفاصيل المقالة