Sharif Digital Repository

This paper presents a surface generation model for sculptured surface productions using the ball end milling process. Dimensional measurement using a coordinate measuring machine (CMM) has been commonly adapted in advanced manufacturing environment to ensure that manufacturing products have high quality and reliability. To conduct dimensional inspection efficiency in a computer integrated manufacturing (CIM) environment, there is an urgent need to derive a sampling strategy which can be used to specify a set of measuring points that lead to accurate sampling while minimizing the sampling time and cost. Owing to the variations in characteristics of geometric feature and manufacturing process,... 

In this study the feasibility of xenon separation from xenon-krypton mixture was investigated by utilizing of the chromatographic column filled with nano and micron sized NaY zeolite. For this purpose the nano NaY with the yield of 100% related to Al2O3 and the average size of 98.6 nm was synthesized through the clear solution method with the mid-adding of NaOH. Furthermore, a novel method for granulation of nano zeolite was developed by utilizing sodium alginate as an external template. In this method the production of uniform spherical granules with the different sizes in the range of several milimiteres to 100 µm was easily performed. Moreover, the results showed that the adding of... 

In recent years magnesium nanoparticles due to their noticeable differences from bulk and their wide applications in various branches including the ability to absorb hydrogen, application in batteries, activation of propellant, different applications in biochemistry and strengthening secondary phase in composites, are well under investigation. The objective of this study is to find an easy, economical and high purity method to obtain magnesium nanoparticles and to introduce an innovative approach of magnesium nanoparticles synthesis in an industrial scale. To achieve this goal, milling process is applied. Micron-sized magnesium powders with different amounts of sodium chloride salt powders... 

In Ultrasonic Assisted Machining (UAM) a mechanical vibration is added to the relative motion of the tool and workpiece. The frequency of vibration is typically from 20kHz to 100kHz and the amplitude is in the range of 10 to 20 microns. Experiments show that using this method improves the machining performance. Reduction in machining forces and tool wear and improving the cooling condition are some of the advantages of UAM. In this work, the forces of ultrasonic assisted milling are investigated. Applying thin shear plane theorem provides an acceptable theoretical base with minimum dependence on experimental data to analyze machining forces. To evaluate the model and find the effect of... 

Finemet soft magnetic alloys in the form of toroidally winded ribbons are not suitable for industrial applications where a large volume of magnetic materials is required. Production of Finemet bulk alloy by powder metallurgy techniques is an applicable method to produce complex component with isotropic magnetic properties which are the same as ribbons. In this research, Finemet bulk magnetic alloy with composition of has been produced by consolidation of amorphous powders obtained by milling of melt-spun ribbons. At the all stages, the structure and magnetic properties were studied using X-ray diffraction, differential scanning calorimetry, transmission electron microscopy, scanning... 

Regenerative chatter is a self-exited vibration that causes poor surface finish, tool wear and breakage and excessive noise. It is, therefore, essential to avoid chatter occurrence passively by selecting cutting conditions that guarantee the stability of the process, or detect and suppress chatter at its onset during the process. The latter has become more important due to the complex and nonlinear dynamics of metal removal and the rising interest in automated systems. Wavelet and Hilbert-Huang transforms are used to detect chatter in machining processes including milling and surface grinding, in this thesis. In the first part of the thesis, chatter detection in milling is studied. The... 

Chatter vibration is a major obstacle in high quality machining. This undesirable vibration decreases the production rate, surface quality, tool life and machine tool life. In the last few decades, a lot of models have been presented to predict chatter. Most of the models, whether linear or nonlinear, have focused on modeling of machine tool dynamics and either disregard the effective parameters of chip formation process or apply some of these parameters through simplified equations. In this research, a finite element simulation of chip formation is combined with the dynamics of machine tool to investigate chatter and its effective factors. The proposed approach, unlike common mathematical... 

Chatter in milling causes problems like damage to the device, losing precision or sleekness, increase in cannibalization, damage to the spindle, higher level of noise, and problem in thin objects. Current theories in regenerative chatter in filing, has a high relation with a work time (ρ~1), but in less deep filing (ρ≪1), these theories have errors (ρ is time per rotation period). Some of the usages of less deep filing are: 1- surfaces that are hard to file 2- creating curve surfaces 3- sleeking surfaces.Formulating these chatters and solving them using nonlinear methods help using the correct filing depth to reduce them. Goal of this project is to solve chatter equations in low depth filing... 

One of the most important parts of designing turbine blades is machining (milling) process of blade root. There is some implementing problem in material removal processing by milling. Because of low heat transferring of inconel 738 in machine parts there is huge amount of heat which cause high temperature in machine and burning, which reduces the efficiency of milling.One of the common way to reduce the temperature of machine is using coolant fluids, which increases expenses and makes environmental pollution, so it is not completely efficient as an industrial work. In this paper Whit using MQL and some new lubricant had been observed more efficient condition in milling process. The main goal... 

Sodium-ion batteries are cost-effective rechargeable batteries which have attracted considerable interest in recent years due to the low cost and abundance of sodium resources on the earth. Na3MnCO3PO4 (NMCP) has been identified as a potential cathode material with a high theoretical capacity of 191 mAh g-1. In order to improve the conductivity and electrochemical properties of NMCP, fabrication of NMCP/reduced graphene oxide (rGO) composite is a novel and interesting research goal. Therefore, in the current study, rGO was produced by using modified Hummers method. Then, the kinetics of NMCP formation through hydrothermal process was investigated. Results indicate that the optimum... 

In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the... 

Machining of Aluminum Metal Matrix Composites faces different problems including adhesive wear, large machining forces, chatter, poor surface quality and therefore low geometric accuracy etc. due to the fact that a ductile matrix is supporting brittle particles. On of the methods used to reduce such difficulties is vibration assisted machining in which a 10 to 20 micron displacement stimulation is applied to the workpiece or tool during machining process. The effect of this method on the milling of the Al/Sic composite is studied through two separate experiments including one and two dimentional vibration assisted milling respectively. Milling forces, tool wear and surface quality are... 

In recent years, the use of high specific strength aluminum alloys in automotive and aerospace industries is in progress due to their energy savings. On the other hand, the carbon nanotubes (CNTs), due to their ultra-high strength and modulus of elasticity, have been considered as an excellent reinforcement for the metal matrix composites used in these industries. For production of these materials, the severe plastic deformation (SPD) has been known as a method of grain refinement to increase the strength and ductility. In this research, the composites of AlMg6 reinforced with CNT were produced by accumulated roll bonding (ARB) known as a SPD technique and their properties were compared... 

This research studies the feasibility of the BK7 optical glass milling process with ultrasonic vibrations. Due to the fragility of glasses, especially optical glasses, machining is very sensitive and complex. For this reason, it is necessary to think for the glass machiners to minimize the defects and failures of the process. So far, efforts have been made to reduce the defects caused by machining on brittle materials, such as increasing the speed of the period, reducing the feed rate of the tool, changing the geometry and the type of tool, the type of process lubrication, etc. In addition, other operations performed to improve the surface of the glass are of better quality, using hybrid or... 

Chattering in cutting process is one of the destructive phenomena in machining, which results in ripple of workpiece surfaces. In this phenomenon, the displacement of the tool tip moves towards instability and the tool vibration continues. Eventually, the tool jumps or breaks out with relatively large shear forces, which leads to a reduction in the rate of production and machining. Since machining processes are very widespread, phenomenological studies of chatter have progressed in the field of modeling and empirical experiments. Research in the field of modeling is mainly intended to examine the dynamics of the tool in two ways: analytic and finite element. In these methods, there are... 

Features with sculptured or free-form surfaces appear frequently in computer-aided design of parts common to aerospace, automotive, and die and mold industries. Because of their ability to machine complex features and to achieve good surface finish, ball-end tools are widely used in the finish milling process of sculptured parts. This research has been devoted to the modeling of cutter-workpiece engagement (CWE) boundaries, cutting forces, and stability prediction in ball-end finish milling process of sculptured parts. In the first step, a new analytical model taking into account the effect of surface curvatures was presented for three-axis and five-axis ball-end milling processes. In this... 

Nowadays, processes with the ability to machine advanced materials are very much needed by industries. Therefore, compare of a rotary ultrasonic-assisted machining process with a conventional machining process is carried out in this study. In order to evaluate this process, the milling and drilling processes are conducted on the carbon fiber-reinforced polymer composite and titanium materials where cutting forces, surface roughness, and fiber pull-out are selected as critical factors for analysis. As a result, it is seen that rotary ultrasonic-assisted machining has a good performance in the milling and drilling of advanced materials. In particular, it is shown that fiber pull-out is... 

Titanium is the most widely used material in medical implants. One of the drawbacks of utilizing titanium in implants, is its biologically inert surface; which hinders the creation of the optimal bond between the implant and the surrounding tissue. This limitation can be addressed by altering the surface texture. As a technology, applying vibration to the tool or workpiece during machining operations is a practical method to create surface micro textures. Upon reviewing the existing literature, it is evident that the impact of the surface texture achieved by vibration-assisted milling, on the interaction of bone cells with the titanium surface has not been investigated. Therefore, this...