Nur  studied the influence of micro end milling process parameters on surface roughness and material removal rate using multi-process micro machine tools with tungsten carbide tool tip to machine methyl methacrylate work pieces. Unapathi  used design of experiments to optimize the tool life, for the machining of 7075 Aluminum alloy, by varying the spindle speed, feed rate and depth of cut. Jagannadha  developed mathematical equations to analyze to effects of parameters on material removal rate and surface finish for machining Al6063 using CNC, by employing regression analysis to find out significant parameters. Atiqah  analyzed the effect of micro end milling process parameters on material removal rate and surface roughness using multi-process micro machining tools by using Taguchi method to design the experiments. Deepika  conducted experiments to enhance surface finish and material removal rate for the machining of Al6082 workpiece on a CNC machine using carbide tool tip. John  conducted experiments using response surface methodology to machine metal matrix composites with Al7075 reinforced with SiC to analyze effects of process parameters on surface finish and material removal rate. Turgay  utilized Taguchi technique and regression analysis to investigate the machinability of Hadfield steel with PVD TiAlN and CVD TiCN/Al 2 O 3 inserts in
There are some materials used in high technology industries which are difficult to finish by conventional machining and polishing techniques with high accuracy and minimal surface defects, such as micro cracks, geometrical errors and distortions on the work surfaces. To solve this problem some new machining methods were developed which are known as ‘Unconventional machining methods'. These were so called so as they do not use conventional edges tools for machining. One such method of machining called ‘Magnetic abrasive machining' (MAF) was developed to overcome difficulties of machining.
Figure 10 plots average surface roughness value, Ra for conventional milling and UAM machined surfaces over 10 m machining length. The longitudinal value of average surface roughness of machined surface shows the roughness values were similar for conventional milling and UAM, however, with the UAM values were just 5% higher. The value of roughness for both machining conditions increased as the machining length increased. The marginally higher surface roughness values for UAM were attributed to the increased tool wear for UAM, Figure 4. In addition, the ultrasonic oscillation in UAM which created more movement of the cutting tool may have contributed to the condition of the machined surface. This result contradicts with Razfar et al.  where they found that surface roughness improved when implementing ultrasonic vibration on the workpiece when milling the AISI 1020 steel. The improvement in surface roughness reported in  was attributed when ultrasonic vibration was applied in the same direction as the feed direction, however, in the present work, ultrasonic vibration was applied perpendicular to the feed direction. Moreover, properties of composite materials were more complicated when comparing with metal. Workpieces of machined surface for both conventional milling and UAM were cleaned using acetone and placed inside the ultrasonic bath and then inspected using the Scanning Electron Microscopy (SEM). Figures 11 (a) and 11 (b) reveal that both machined surfaces experience matrix smearing, fibre pull-out and fibre-matrix debonding. It was observed that the machined surface in conventional machining experienced matrix smearing and fibre pull out. This can be explained by the high machining force in conventional milling that created shearing effect between the cutting tool and the machined surface. It was also found on the machined surface that the matrix resin was plastically deformed suggesting that high machining temperature was a feature of both processes.
Milling is the most extensively used metal machining operation. Most of the finished products undergo milling processes at some stage of fabrication. The widespread use of end milling for machining parts is attributed to its ability to give a faster rate of metal removal as well as a reasonably good surface texture. End milling operating are highly adaptable for both the roughing finishing operation for different product that can be produce with high level of accuracy and surface finish.
Conventional machining or finishing methods are not readily applicable to the materials like carbides, ceramics. Low material removal rate happens to be it’s one serious limitation. Magneto abrasive flow machining is a hybrid machining process comprising of abrasive flow machining (AFM) & Magnetic Abrasive Finishing (MAF) .With the use of magnetic field around the work piece in abrasive flow machining, we can increase the material removal rate as well as the surface finish. To further increase the MRR drill bit can be placed in the flow medium of MAFM, and the process can be named as Drill Bit guided magneto abrasive flow machining (DBGMAFM).
The proper selection of manufacturing conditions is one of the most important aspects to take into consideration in the majority of non-traditional machining processes and particularly, in processes related to Electrical Discharge Machining (EDM). EDM process is based on thermoelectric energy between the work piece and an electrode. Material Removal Rate (MRR), Tool Wear Rate (TWR) and surface finish are important performance measures in EDM process. Despite a range of different approaches, all the research work in this area shares the same objectives of achieving more efficient material removal rate and improved surface quality. The paper researches on EDM relating to MRR and TWR along with surface finish in various work materials like Hot Die Steel (11 / 13) and Aluminium (1100 / 2024) with different tool electrodes (Copper and Brass) and analysis will be carried out for the optimal solution as well as the result.
In addition to that, the teeth prepared with deep chamfer finishing line and planar occlusal reduction showed less mean marginal gap values than the teeth prepared with shoulder finishing line. This might be due to that deep chamfer finishing line design has a more round angle between the axial and gingival seat which enables more accurate seat for the crown restoration. Furthermore, the stress concentrated at the area of the finishing line during the crown seating is more evenly distributed. This is in total agreement with what has been stated by Rosenstiel et al.  stated that “The occluso-axial line angle of the tooth preparation should be a replica of the gingival margin geometry”. In addition this is total agreement with: Wostmann et al.  concluded that the lowest mean value of marginal gap was obtained for the chamfer preparation, while the 90° shoulder finishing line always produced the highest mean value. Comlekoglu et al.  reported that the cervical finish line type had an influence on the marginal adaptation of the tested zirconia crown restorations. This is also in agreement with Alzubaidy and Alshamaa  stated that the deep chamfer finishing line is more preferable than shoulder finishing line for full contour CAD/CAM zirconia crown restorations.
Fig. 1, Fig. 2 and Fig.3 shows the photograph of the tools and work pieces used for the experiments. Oil quenching method was used to obtain the desired properties like hardness of 47 HRc and a density of 7.77 gm/cm 3 . A surface grinding machine is used to grind the top and bottom faces of the work piece before experimentation. The polishing machine is used to remove the carbon deposition on the bottom surface of the tool electrode. The initial weights of the work piece and the tool electrodes were taken by using the digital electronic balance of accuracy 0.005g. The work piece was properly clamped on the fixture and was connected to positive (+) polarity and the tool electrode was connected to the negative (-) polarity of the power supply. The machining time was set to 20 minutes for every experiment. At the end of each experiment the work piece and the tool electrode were unclamped, washed, dried and weighed again on the electronic balance to observe the difference between the weights and hence the WER and TER were obtained. The procedure was repeated for each experiment and required data was collected.
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Projek ini mengenai kesan surfactant kepada ciri-ciri pemesinan (kekerasan permukaan, permukaan topografi dan recast layer) Electric Discharge Machining (EDM) AISI 304 keluli tahan karat dengan menggunakan air dinyah-ionkan dan karbon nanofiber dengan surfactant serta air ternyah-ion dan nanofiber tanpa surfactant. Dua jenis surfactant iaitu Gum Arabic (GA) dan Polyvinylpyrrolidone (PVP) telah digunakan. Keputusan eksperimen menunjukkan apabila penambahan surfactant dalam campuran ia boleh mencegah pemendapan karbon nanofiber dalam cecair dielektrik dan juga boleh meningkatkan kecekapan mesin. Oleh itu, ia akan meningkatkan kekerasan permukaan bahan. Walau bagaimanapun, apabila cecair dielektrik tanpa surfactant, ketebalan recast layer adalah tinggi. Di samping itu, ketebalan recast layer berkurang apabila nisbah di antara karbon nanofiber dan surfactant meningkat ke kepekatan 1: 1 untuk kedua-dua surfactant iaitu PVP dan GA.. Selain itu, untuk permukaan topografi pula , apabila surfactant seperti GA dan PVP ditambah di dalam cecair dielektrik, kemunculan kawah adalah kurang pada permukaan bahan kerja kerana kesan pengedaran. Apabila surfactant digunakan sebagai bahan proses pemesinan dalam cecair dielektrik dengan lebih ketara kesan pengedaran pelepasan diperhatikan. Permukaan licin dengan kawah kecil dan microcrack sukar dicapai. Oleh itu, dengan menggunakan surfactant , kekasaran permukaan bahan lebih baik.
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By adjusting optimal conditions, e.g. the phase difference value ψ and variable σ or the number m of active abrasive grits in the contact zone and spindle speed n of machine-tool off-line, a stable grinding process would be obtained. A series of experiments are performed under specific machining conditions as follows. Monolayer diamond grinding wheel with electroplated grits (average size is 90 μm) is applied to conduct grinding experiments. The sample material is low carbon steel EN8. Abrasive wheel specification takes values of diameter φ 200 mm, width 20 mm, average wedge angle 30°, pack density 5 per mm² in transversal plane, grits spacing 200 μm between adjacent abrasive grits. Depth of cut is 15 μm, grinding speed is 46 m/s, spindle speed is 4456 rev/min, workpiece speed is 100 mm/s. The maximum eccentricity of grinding wheel is examined of 1 μm. Specific grinding energy is approximately 20 J/m 3 . The force ratio between tangential and
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better control of the corresponding processing parameters or machining conditions. However, implementation of surface integrity requirements and relating machining process control needs to accurately measure a large number of surface integrity characteristics from a series of single-factor or multi-factor orthogonally designed machining experiments, which will undoubtedly increase measuring costs and lower production efficiency. Therefore, the surface integrity requirements are normally compulsory to some key parts demanding high performance or only applied to the critical locations affecting the functionality of key parts; for ordinary parts without any specific demands, it is usually unnecessary to adopt the surface integrity machining and measurement standard due to the unwanted time and measurement cost. From an overall optimal perspective in manufacturing, if the manufacturer could manage to ensure the high surface integrity of key parts or at their critical locations and relax the processing requirement for the rest of majority of non-critical parts or locations, then the reliability of and the global production cost for manufacturing this kind of product are likely to be controlled and lowered. For example, the surface roughness requirement for different kinds of linking rods used in aero-engine is within a comparatively large range (such as 0.32~6.1μm); but their concerned fatigue strengths are sometimes found to be insensitive to their processing condition and working environment. According to economical and reliable surface integrity requirement, the manufacturer may relax the surface roughness requirement for many rods from the originally designed R a = 0.8μm to
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necessary. However, these procedures significantly increase surface roughness. Thus, a large number of polishing techniques is available for composites 31. Composite surface roughness is basically dictated by the size, hardness, and amount of filler which influences the mechanical properties of the resin composites. It is also influenced by the flexibility of the finishing material, the hardness of the abrasive and the grit size 16,18,32,33-34 . The hypothesis of this study was that the polishing technique and filler content of the composite resin
Surface finish is another essential output variable of machining process discussed in previous studies.de Oliveira Junior et al. performed tests with input variables such as cutting speed and machining environment with low and high fluid pressure. The study reported that better surface finish can be obtained while turning with PVD-coated inserts under high-pressure cooling . Selvaraj et al. discussed the effect of dry turning process using Taguchi method and optimization of surface roughness, cutting force, and tool wear of nitrogen alloyed duplex stainless steel. The study concluded that t the feed rate is the more critical parameter influencing the surface roughness and cutting force while cutting speed was responsible for more tool wear . A methodology to predict surface roughness in low-speed while turning of AISI316 steel is developed by Acayaba and de Escalona. They used Artificial Neural Network (ANN) model integrated with Simulated Annealing (SA) to predict the surface finish. The model obtained predicted the surface roughness variation of 15% under the same cutting conditions . Coolants play a significant role in achieving lower tool wear rate and better surface finish in a machining process. Sivaiah and Chakradhar compared machining performance during turning of 17-4 PH stainless steel under wet machining and cryogenic conditions. Cutting temperatures, cutting force, chip morphology, tool wear and surface finish under cryogenic machining environment were observed. Cryogenic environment resulted in better values of output compared to wet conditions . Therefore we can conclude that the surface roughness and tool wear depends on cutting speed and feed. As cutting speed increases with low feed rate better surface finish is obtained. Also, to reduce tool wear, cutting speed must be increased. Depth of cut and cutting speed affects material removal rate and cutting force. Literature reviewed suggests that studies were made on the relative performance of machining environment, parameters, and tools on tool wear and surface roughness. However, in the machining of austenitic stainless steel AI 316 studies found to be rarely given attention. Tool wear that adversely impacts the quality of the product and in general machining performance has been overlooked. A number of studies are presented by researchers where cutting parameters were optimized for surface roughness or cutting force(s) or both. However, tool life, which is an essential factor for the economic viability of the machining process, was not considered in most of the studies. Thus, there is a need for the development of a robust model which can predict the machining performance during turning of austenitic stainless steel.
The machining performance (ANOVA-rank factor) for each experiment of the L9 can be calculated by taking the observed values of the MRR as an example from table 3. The taugchi analysis parameter for spindle speed (A) feed (B) depth of cut(C) and width of cut (D).
In our study, when the applied potential was increased, the current density also increased and consequently dissolution was enhanced. At 5 V, the formation rate from the metal ions was relatively low and the quick-flowing electrolyte could effectively transfer the generated ions close to the anodic interface into the bulk electrolyte, resulting in a relatively fresh electrolyte. At 11 V, however, large number of ions are generated at the anodic interface by the increased electric field and thus the ions could not be removed efficiently. Hence, the whole anodic surface was covered by a supersaturated film. We found that the thickness of this film was different above the flat surface and the protrusion. This phenomenon is related to the different electrolyte flow conditions at the flat surface and the protrusion. Compared with the flat surface, the ion transfer effect at the protrusion is more intense because of strong electrolyte flushing, consequently resulting in a thin film. The fluctuation of the film thickness results in a higher local current density at the protrusion than at the flat surface according to Eq. (17), which consequently helps to effectively smooth the surface.
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To evaluate the effect of polishing and finish- ing techniques on the composite resin surfaces at a microscopic level, an additional 5 specimens were prepared using Aelite Enamel composite res- in since this composite resin showed the high- er different values among the subgroups in terms of the polishing and finishing techniques. One of the specimens served as control and had no treat- ment. The surfaces of the 4 specimens were rough- ened with a medium-grit diamond rotary cutting instrument and polished with 1 of the 4 polish- ing and finishing techniques as previously de- scribed. Subsequently, these specimens were gold sputtered with a sputter coater (S150B; Edwards, Crawley, England) and examined under a field emission scanning electron microscope (SEM) (JSM-6335F; JEOL, Tokyo, Japan) at 15.0 kV. The
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From the review of literature, it is clear that number of research was done to optimize the EDM conditions for desired responses. Some researchers made efforts to examine the impact of EDM conditions on the various responses. Very less effort was made to investigate and compare the effect of different type of dielectric fluids on different responses. The AISI 4140 steel is a chromium- manganese-molybdenum grade is used for making the dies for plastic injection moulds, extrusion dies for thermoplastics and for compression moulds. Therefore, this study is focus on the study of the impact of EDM basic parameters with two types of dielectric fluids (Kerosene and deionized water) SR during the machining AISI 4140 steel.
The investigation presented a central composite rotatable second order methodology to develop a mathematical model to predict surface roughness in terms of helix angle of cutting tool, spindle speed, feed rate, depth of cut. were arrived from the results of this research work The increase in helix angle of the end mill cutter resulted in better surface finish and there is no much change in surface roughness for helix angle 45 and 50.The decrease in spindle speed resulted reduced surface roughness and it is very effective at the middle level i.e., at a spindle speed 2500 rpm and 3000 rpm.The decrease in feed rate resulted reduced surface roughness and very effective at the middle level i.e, at a feed rate of of 0.03mm/rev and 0.04mm/rev.The surface roughness is found to be nearly constant for the depth of cut that ranges from 1mm – 2.5mm. Beyond that the roughness value is found to increase at a steady rate and may result in poor surface finish. The surface roughness is minimum when the helix angle and feed rate are respectively at their middle value and maximum when helix angle and feed rate at their lower limits .The increase in helix angle resulted in increased surface roughness for all the levels of depth of cut The surface roughness is better only at low feed and high depth of cut.
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Until recently, the finishing treatment of hardened steels and heat-resistant alloys was performed with grinding operation. The technological characteristics of grinding are excessive heat and force load frequently causing the structural changes and tensile stresses within the surface layer of the workpiece. The practical experience shows that the grinding process is the main source of technological defects like burns on the workpiece surface. Due to use of innovative materials for cutting tools, increase of vibration resistance and accuracy of machine tools, the high-speed cutting machining becomes a good alternative to the grinding .
However, every single material has to be evaluated indi- vidually in regard to their mechanical and aesthetic proper- ties. Limited data are available in the literature on the colour stability and translucency of newly introduced CAD/CAM milling blocks. Thus, the purpose of this study was to determine the effects of staining solutions and surface finishing on the colour stability and translucency of hybrid materials. The null hypothesis of this study was that both staining solutions and surface finishing are not correlated with the stainability and translucency of hybrid ceramics (HC) and resin nanoceramics (RNC).