Features Of Machined Surface Research Articles

Study on friction reduction performance of granular flow lubrication during the milling of Inconel 718 superalloy

PurposeThe purpose of this study is to reveal the friction reduction performance and mechanism of granular flow lubrication during the milling of difficult-to-machining materials and provide a high-performance lubrication method for the precision cutting of nickel-based alloys.Design/methodology/approachThe milling tests for Inconel 718 superalloy under dry cutting, flood lubrication and granular flow lubrication were carried out, and the milling force and machined surface quality were used to evaluate their friction reduction effect. Furthermore, based on the energy dispersive spectrometer (EDS) spectrums and the topographical features of machined surface, the lubrication mechanism of different granular mediums was explored during granular flow lubrication.FindingsCompared with flood lubrication, the granular flow lubrication had a significant force reduction effect, and the maximum milling force was reduced by about 30%. At the same time, the granular flow lubrication was more conducive to reducing the tool trace size, repressing surface damage and thus achieving better surface quality. The soft particles had better friction reduction performance than the hard particles with the same particle size, and the friction reduction performance of nanoscale hard particles was superior to that of microscale hard particles. The friction reduction mechanism of MoS2 and WS2 soft particles is the mending effect and adsorption film effect, whereas that of SiO2 and Al2O3 hard particles is mainly manifested as the rolling and polishing effect.Originality/valueGranular flow lubrication was applied in the precision milling of Inconel 718 superalloy, and a comparative study was conducted on the friction reduction performance of soft particles (MoS2, WS2) and hard particles (SiO2, Al2O3). Based on the EDS spectrums and topographical features of machined surface, the friction reduction mechanism of soft and hard particles was explored.

Grinding characteristics of optical glass in glass molding process

A machined surface study was performed according to the surface roughness post-process polishing operation on the aspheric mold core using a diamond turning machine. Machined surface features in the bokeh image must be removed with a subsequent surface polishing process after the aspheric glass molding pressing, as surface defects are caused by the mechanical resolution of ultraprecision diamond turning machines. Therefore, in this paper, we analyze the interrelationship between surface roughness, interference frequencies, and error-approximation aspherical error values to propose a baseline measure for machined surface removal. From the results of profilometer measurements, the form error accuracy before polishing is 1.3 [Formula: see text]m, and after polishing is 0.2 [Formula: see text]m. As a result of the LUPHOS, the root mean square (RMS) average of interference frequencies before polishing is 20 nm, and after polishing is 3 nm. The machining marks are removed from the bokeh image only when the RMS roughness is maintained at 5 nm or less.

Optimization of process parameters for machining defects of glass fibre reinforced polymer composite machined by AWJM

For the machining of composites like glass fibre reinforced polymers (GFRP), abrasive water jet machining (AWJM) is generally used. AWJM has proven to be a cost-effective and efficient metal removal process of composites, in which a high-speed jet of abrasive and water strikes on workpiece surface to erode the material. In this paper, an experimental investigation is described which is focused on investigating the effect of process parameters on defects like delamination, pulling out of fibres and embedment of abrasive particles of machined samples during AWJM of GFRP composites. For design of experiments response surface methodology (RSM) based on the central composite design (CCD) approach is used. Water pressure (WP), traverse rate (TR), stand-off distance (SOD) and abrasive mass flow rate (AMFR) are considered to study their influence on delamination. The scanning electron microscope (SEM) is used to investigate the microscopic features of machined surfaces. It is revealed that delamination decreases with an increase in AMFR, with a decrease in TR, Further, optimization based on the desirability function is also performed to minimize the delamination. The optimal combination of the cutting parameters (SOD = 2.6 mm, WP = 175-MPa, TR = 104 mm/min and AMFR = 582 g/min) gives the optimized values of Max. DLL is 0.299 mm.

Investigation on the cutting mechanism of SiCp/Al composites in ultrasonic elliptical vibration machining

Aluminum (Al)-based silicon carbide (SiC) material composites are considered as difficult-to-machine materials because of the presence of hard reinforced SiC particles, which results in a greater cutting force and poor surface integrity during the machining process. This paper established micro-anisotropic material mechanical models of SiCp/Al composites with a 10vol% SiC particles, and studied the difference in the machining mechanism between ultrasonic elliptical vibration cutting (UEVC) and ordinary cutting (OC) about SiCp/Al. Moreover, this paper mainly focuses on the influence of UEVC on cutting force, von Mises stress distribution, surface integrity, and chip formation. The models are validated by comparing cutting force, chip shapes, and machined surface features in OC machining SiCp/Al experience from the literature. Simulation results indicate that the cutting mechanism of SiCp/Al on UEVC is different from that of OC and has several good properties. At the same cutting parameters, high-frequency vibration makes the cutting force of UEVC exhibit variable periodicity and reduces average cutting force. The instantaneous impact of tool and fast separation results in a more concentrated von Mises stress distribution, thereby resulting in the particles having a greater break degree than that obtained with OC. A comparison of the surface roughness values from the simulation result shows that UEVC obtains better surface integrity than OC does.

On the material removal mechanism in rotary ultrasonic milling of ultralow-density silica aerogel composites

Silica aerogel composite with ultralow density is a kind of highly porous solid with excellent property of thermal conductivity. It is widely used for thermal insulation in aerospace, national defense and military industries. However, silica aerogel composites are difficult to process, due to the poor mechanical properties, low strength and high brittleness. Therefore, it is necessary to investigate the processing characteristics and material removal mechanism of silica aerogel composites. In this article, a cutting model of silica aerogel composites is established firstly and the fracture mechanism of fiber was analyzed. Then the ultrasonic milling and conventional milling experiments were performed respectively to obtain the features of machined surface. Macro morphology and surface roughness of machined surfaces in different process conditions are compared to investigate the influence of different process conditions on the processing quality. Scanning electron microscope (SEM) was used to obtain the micro morphology of processed surfaces. By comparing and analyzing the micro morphology of processed surfaces, the influence of process conditions on removal mechanism was investigated. The theoretical cutting force and experiment cutting force is compared to verify the cutting model. The results show that the burrs and pits decrease with the ultrasonic vibration amplitude, and increase with the tool diameter. Processing quality of up-milling is better than down-milling. It is indicated that shearing and pulling off are the main removal mechanism of silica aerogel composites. When the silica aerogel composites are processed by rotary ultrasonic milling and up milling, the fibers will be mainly removed by shearing mechanism and the proportion of fibers removed by shearing facture mechanism will be improved with the increase of ultrasonic amplitude.

P-061. Successful vaginal delivery in pregnant women with preeclampsia undergoing labor induction with Prostaglandin

Silica aerogel composite with ultralow density is a kind of highly porous solid with excellent property of thermal conductivity. It is widely used for thermal insulation in aerospace, national defense and military industries. However, silica aerogel composites are difficult to process, due to the poor mechanical properties, low strength and high brittleness. Therefore, it is necessary to investigate the processing characteristics and material removal mechanism of silica aerogel composites. In this article, a cutting model of silica aerogel composites is established firstly and the fracture mechanism of fiber was analyzed. Then the ultrasonic milling and conventional milling experiments were performed respectively to obtain the features of machined surface. Macro morphology and surface roughness of machined surfaces in different process conditions are compared to investigate the influence of different process conditions on the processing quality. Scanning electron microscope (SEM) was used to obtain the micro morphology of processed surfaces. By comparing and analyzing the micro morphology of processed surfaces, the influence of process conditions on removal mechanism was investigated. The theoretical cutting force and experiment cutting force is compared to verify the cutting model. The results show that the burrs and pits decrease with the ultrasonic vibration amplitude, and increase with the tool diameter. Processing quality of up-milling is better than down-milling. It is indicated that shearing and pulling off are the main removal mechanism of silica aerogel composites. When the silica aerogel composites are processed by rotary ultrasonic milling and up milling, the fibers will be mainly removed by shearing mechanism and the proportion of fibers removed by shearing facture mechanism will be improved with the increase of ultrasonic amplitude.

SY5-2. Simplified prediction criteria and management of preeclampsia for LMIC

Silica aerogel composite with ultralow density is a kind of highly porous solid with excellent property of thermal conductivity. It is widely used for thermal insulation in aerospace, national defense and military industries. However, silica aerogel composites are difficult to process, due to the poor mechanical properties, low strength and high brittleness. Therefore, it is necessary to investigate the processing characteristics and material removal mechanism of silica aerogel composites. In this article, a cutting model of silica aerogel composites is established firstly and the fracture mechanism of fiber was analyzed. Then the ultrasonic milling and conventional milling experiments were performed respectively to obtain the features of machined surface. Macro morphology and surface roughness of machined surfaces in different process conditions are compared to investigate the influence of different process conditions on the processing quality. Scanning electron microscope (SEM) was used to obtain the micro morphology of processed surfaces. By comparing and analyzing the micro morphology of processed surfaces, the influence of process conditions on removal mechanism was investigated. The theoretical cutting force and experiment cutting force is compared to verify the cutting model. The results show that the burrs and pits decrease with the ultrasonic vibration amplitude, and increase with the tool diameter. Processing quality of up-milling is better than down-milling. It is indicated that shearing and pulling off are the main removal mechanism of silica aerogel composites. When the silica aerogel composites are processed by rotary ultrasonic milling and up milling, the fibers will be mainly removed by shearing mechanism and the proportion of fibers removed by shearing facture mechanism will be improved with the increase of ultrasonic amplitude.

P-057. Preeclampsia prediction based on urine peptidome study

Silica aerogel composite with ultralow density is a kind of highly porous solid with excellent property of thermal conductivity. It is widely used for thermal insulation in aerospace, national defense and military industries. However, silica aerogel composites are difficult to process, due to the poor mechanical properties, low strength and high brittleness. Therefore, it is necessary to investigate the processing characteristics and material removal mechanism of silica aerogel composites. In this article, a cutting model of silica aerogel composites is established firstly and the fracture mechanism of fiber was analyzed. Then the ultrasonic milling and conventional milling experiments were performed respectively to obtain the features of machined surface. Macro morphology and surface roughness of machined surfaces in different process conditions are compared to investigate the influence of different process conditions on the processing quality. Scanning electron microscope (SEM) was used to obtain the micro morphology of processed surfaces. By comparing and analyzing the micro morphology of processed surfaces, the influence of process conditions on removal mechanism was investigated. The theoretical cutting force and experiment cutting force is compared to verify the cutting model. The results show that the burrs and pits decrease with the ultrasonic vibration amplitude, and increase with the tool diameter. Processing quality of up-milling is better than down-milling. It is indicated that shearing and pulling off are the main removal mechanism of silica aerogel composites. When the silica aerogel composites are processed by rotary ultrasonic milling and up milling, the fibers will be mainly removed by shearing mechanism and the proportion of fibers removed by shearing facture mechanism will be improved with the increase of ultrasonic amplitude.

Dynamic characteristics of abrasive grains and machined surface features for variable axis diamond grinding of quartz glass

There is a fine application prospect for multi-axis grinding of hard and brittle materials with diamond ball end tool. The effects of tool inclination angles and grinding modes of multi-axis grinding of quartz glass on the dynamic characteristics of the diamond abrasives, surface topography, surface fragmentation phenomenon, and surface roughness were investigated in this work. Material removal characteristics and surface formation conditions would be significantly affected by the effective cutting speed, material stress characteristics, and movement space path derived from different grinding modes and tool inclination angles. The surface texture direction is mainly determined by feed direction of the cutter and initial cutting moment and geometry feature of the engaged diamond abrasives. The surface fragmentation phenomenon of the formed surface is apparent when the corresponding surface roughness values are relatively larger. The machined surface with significant surface fragmentation phenomenon is mainly produced by materials' brittle fracture modes, such as larger positive lead and smaller negative tilt under conventional grinding and smaller negative lead angles and larger positive tilt angles under down grinding. Ideal surface evenness could be obtained by using lead or tilt 0° for conventional and down grinding. The ground surface with smaller surface roughness could be produced when employing tool postures, such as negative lead or positive tilt under conventional grinding and positive lead or negative tilt under down grinding condition.

Modeling and prediction of surface roughness using multiple regressions: A noncontact approach

AbstractIn the present work, a machine vision system is introduced, which captures images and extracts surface texture features of machined surfaces. The texture feature parameters are extracted using the gray‐level co‐occurrence matrix and correlated with different surface roughness parameters recorded by a contact‐type surface profilometer. The image acquisition carried out at different roughness levels in order to extract texture features. The variation between each texture features and surface roughness parameter is investigated. Multiple regression models are developed to predict the subjective estimation of surface roughness parameter (Ra) and qualitative detection of the degree of surface roughness. It is observed that the linear detection model shows better performance characteristics compared with a nonlinear detection model. The comparison between measured and predicted results shows that the linear detection model had a maximum relative error of 2.01%, drastically better than nonlinear detection model of −9.60% error parts, hence indicating better surface detection capability over the nonlinear detection model. The results demonstrate that the prediction of surface roughness using linear regression model is a reliable approach of noncontact measurement.

A non-contact approach for surface roughness prediction in CNC turning using a linear regression model

At present, the combination of non-contact type optical techniques and machine vision systems has a huge significance in the assessment of surface roughness. The non-contact measurement methods seem to have greater advantages over the conventional stylus method. Traditionally used contact-type surface roughness measurement technique assesses the roughness of machined component in a single line which is overcome by optical-based techniques and machine vision techniques with the capability to assess the whole machined surface. This paper deals with selected contact type stylus method and non-contact type machine vision methods for components prepared by turning of AISI 1040 steel at a variety of feed rates. The correlations have been developed between two dimensional (2D) surface roughness parameter and texture features for the components. The 2D surface roughness parameters have been recorded using a contact-type surface profilometer. On the other hand, the texture features have been extracted using a Gray level co-occurrence matrix algorithm (GLCM) and machine vision system. The correlation has been developed between extracted texture features of machined surfaces and measured 2D surface roughness parameters. The linear regression analysis has been performed in order to predict the surface roughness of machined components. The comparative results reveal a maximum measurement difference of 15% between contact types and presented a non-contact type assessment.

Comparative investigation of tool wear mechanism and corresponding machined surface characterization in feed-direction ultrasonic vibration assisted milling of Ti–6Al–4V from dynamic view

This paper mainly investigated the wear mechanism of universal coated carbide tools in feed-direction ultrasonic vibration-assisted milling (UVAM) of Ti–6Al–4V alloy through theorical analysis and experimental approaches, where the external ultrasonic vibration excitation was imposed on the workpiece. The rapid intermittent machining features, the generation mechanism of ultrasonic-frequency pulse cutting force and alternating friction, ultrasonic-frequency dynamic impact effect of resonant workpiece and considerable changes in tool trajectory and relative cutting speed in UVAM were analyzed from perspective of tool-workpiece dynamics and kinematics. Due to the ultrasonic-frequency friction between the tool and the workpiece, the minimum quantity lubrication (MQL) with biodegradable cutting fluid was firstly introduced in UVAM to improve the lubrication/cooling performance between tool and workpiece/chips interfaces. Three different machining methods, general milling, feed-direction UVAM and feed-direction UVAM&MQL, were sequentially carried out to comparatively investigate the tool wear mechanism and characterize tool wear and machined surface features. The corresponding machined surface quality including surface topography, surface profile and surface roughness under different tool wear states were presented to evaluate the tool wear condition. The results indicated that the tool wear mechanism in workpiece feed-direction UVAM system was dominated by ultrasonic-frequency dynamic load, where ultrasonic-frequency cutting force, ultrasonic-frequency friction, ultrasonic-frequency vibration impact and cutting inflection points of tool-tip trajectory worked together on the cutting edges. And the tool wear morphology in feed-direction UVAM was mainly characterized by tool-tip fracture, impact crack, friction traces and fatigue crack. The results of machined surfaces indicated that compared with the surfaces obtained in CM and general UVAM, the UVAM&MQL method could significantly improve the finished surface quality, which can also improve the tool wear to a certain extent.

Experimental Investigations on Graphite Mixed Electric discharge Machining of En-19 Alloy Steel

The surface finish of the product machined using EDM can be enhanced by adding special type of semi conductive powder mixed with the dielectric used in the process. In the present research, graphite powder (2 – 6 gm/l of dielectric) is added to the dielectric medium (that is, Kerosene). The experimental investigations are carried out on EN-19 alloy steel as work material and copper rod as electrode. During experimentation, the process parameters such as peak current (Ip), gap voltage (Vg) , pulse on time (Ton) and concentration of the powder (C) are considered as inputs and material removal rate (MRR) and surface roughness (SR) are treated as responses. Detailed analysis of external features of machined surface was observed to study the effect of concentration of Graphite powder during the machining process. Experiments were carried out by using the concept of design of experiments (DOE) and the nonlinear regression modelling is done using Response surface Methodology (RSM). Once the non-linear regression models are developed their statistical validity and prediction accuracy are tested with the help of ANOVA and experimental test cases, respectively.

Experimental Study on Abrasive Water Jet Machining of PZT Ceramic

This paper presents research work involved in abrasive water jet machining of PZT ceramic material. Process parameters namely stand-off distance, water pressure and traverse rate are considered in the present study. Response surface methodology approach is used to design the experiments. Relative significance of process parameters and their influence on kerf properties are identified on the basis of analysis of variance. It is found that water pressure and traverse rate are most significant parameters followed by stand-off distance. On the basis of experimental analysis, regression models are developed to predict kerf taper and depth of cut. The models are developed with respect to significant parameters, interaction and quadratic terms. It is found that model predictions are in congruence with experimental results. Multi-response optimization of process parameters is also performed using desirability approach in order to minimize kerf taper and maximize depth of cut. Kerf wall features of machined surfaces are observed using scanning electron microscope. The findings of present study are useful to improve kerf properties in abrasive water jet machining of PZT ceramic materials.

Surface topography and roughness of high-speed milled AlMn1Cu

The aluminum alloy AlMn1Cu has been broadly applied for functional parts production because of its good properties. But few researches about the machining mechanism and the surface roughness were reported. The high-speed milling experiments are carried out in order to improve the machining quality and reveal the machining mechanism. The typical topography features of machined surface are observed by scan electron microscope(SEM). The results show that the milled surface topography is mainly characterized by the plastic shearing deformation surface and material piling zone. The material flows plastically along the end cutting edge of the flat-end milling tool and meanwhile is extruded by the end cutting edge, resulting in that materials partly adhere to the machined surface and form the material piling zone. As the depth of cut and the feed per tooth increase, the plastic flow of materials is strengthened and the machined surface becomes rougher. However, as the cutting speed increases, the plastic flow of materials is weakened and the milled surface becomes smoother. The cutting parameters (e.g. cutting speed, feed per tooth and depth of cut) influencing the surface roughness are analyzed. It can be concluded that the roughness of the machined surface formed by the end cutting edge is less than that by the cylindrical cutting edge when a cylindrical flat-end mill tool is used for milling. The proposed research provides the typical topography features of machined surface of the anti-rust aluminum alloy AlMn1Cu in high speed milling.

Investigation on an integrated approach to design and micro fly-cutting of micro-structured riblet surfaces

Drag reduction in wall-bounded flows can be achieved by the passive flow control technique through the application of bio-inspired ribleted surfaces. In this paper, innovative design and manufacturing of serrate-semi-circular ribleted surfaces are presented with application to friction and drag reduction on engineering surfaces. Firstly, the design of the ribleted surfaces is described particularly focusing on the serrate-semi-circular shaped structures. Secondly, machining of ribleted surfaces by fly-cutting is investigated, covering the utilization of bespoke CVD diamond tools on a micro-milling machine and the corresponding micro fly-cutting processes. Metrology measurement results show good agreement achieved between the designed and machined surface features. Experiment conducted in wind tunnel shows the machined surface can produce 7% in drag reduction. Compared with conventional micro milling, the micro fly-cutting technique resulted from this research illustrates the unique advantage and industrial significance, particularly for manufacturing micro-structured surfaces in an industrial scale.

Effect of dielectric fluid with surfactant and graphite powder on Electrical Discharge Machining of titanium alloy using Taguchi method

In this paper, Taguchi method was employed to optimize the surfactant and graphite powder concentration in dielectric fluid for the machining of Ti-6Al-4V using Electrical Discharge Machining (EDM). The process parameters such as discharge current, surfactant concentration and powder concentration were changed to explore their effects on Material Removal Rate (MRR), Surface Roughness (SR), Tool wear rate (TWR) and Recast Layer Thickness (RLT). Detailed analysis of structural features of machined surface was carried out using Scanning Electron Microscope (SEM) to observe the influence of surfactant and graphite powder on the machining process. It was observed from the experimental results that the graphite powder and surfactant added dielectric fluid significantly improved the MRR, reduces the SR, TWR and RLT at various conditions. Analysis of Variance (ANOVA) and F-test of experimental data values related to the important process parameters of EDM revealed that discharge current and surfactant concentration has more percentage of contribution on the MRR and TWR whereas the SR, and RLT were found to be affected greatly by the discharge current and graphite powder concentration.

Comparative study of surface integrity aspects of Incoloy 825 during machining with uncoated and CVD multilayer coated inserts

One of the major concerns related to machining of Ni-based super alloy is surface integrity since it directly affects the performance of the machined component during its intended application. In the current study, the influence of cutting speed (51, 84 and 124m/min) and CVD multilayer tool coating (TiN/TiCN/Al2O3/ZrCN) on various aspects of surface integrity such as surface roughness, crystal structure and microstructure of the surface and sub-surface region, thickness of white layer and work hardening tendency have been investigated during dry turning of Incoloy 825. Particular emphasis has been given to understand the mechanism of formation of modified surface layer and the associated process of dynamic recrystallization. The study indicated coated tool resulted in better surface finish compared to that obtained with uncoated tool only at high cutting speed. Various macro features of machined surface included feed mark, material smearing, surface ploughing, re-deposited materials and chip debris. Transformation of crystallographic phase of the machined surface could not be detected compared to that of bulk material. Increase in cutting speed caused gradual refinement of grains, and increased white layer thickness. Coated tool, on the other hand, resulted in the generation of large number of nucleation sites and consequently finer grains at high cutting speed, whereas the uncoated tool promoted growth of sharply defined recrystallized grains. The coated tool prevented the formation of white layer at low and medium cutting speed and also decreased work hardening tendency of Incoloy 825 when compared with that of uncoated tool.

Influence of parameters and optimization of EDM performance measures on MDN 300 steel using Taguchi method

Maraging steel (MDN 300) exhibits high levels of strength and hardness. Optimization of performance measures is essential for effective machining. In this paper, Taguchi method, used to determine the influence of process parameters and optimization of electrical discharge machining (EDM) performance measures on MDN 300 steel, has been discussed. The process performance criteria such as material removal rate (MRR), tool wear rate (TWR), relative wear ratio (RWR), and surface roughness (SR) were evaluated. Discharge current, pulse on time, and pulse off time have been considered the main factors affecting EDM performance. The results of the present work reveal that the optimal level of the factors for SR and TWR are same but differs from the optimum levels of the factors for MRR and RWR. Further, discharge current, pulse on time, and pulse off time have been found to play a significant role in EDM operations. Detailed analysis of structural features of machined surface was done by using scanning electron microscope (SEM) to understand the influence of parameters. SEM of electrical discharge machining surface indicates that at higher discharge current and longer pulse on duration give rougher surface with more craters, globules of debris, pockmarks or chimneys, and microcracks than that of lower discharge current and lower pulse on duration.

Study of the Influence of Cutting Parameters on the Ultimate Tensile Strength (UTS) of UNS A92024 Alloy Dry Turned Bars

High compression forces developed during machining processes -and the subsequent energy transferred - carry on changes in the workpiece surface. These changes are usually evaluated only from dimensional or geometrical viewpoints and less frequently form the point of view of the physicochemical surface properties. Notwithstanding, some works relating geometrical and physicochemical properties of machined surfaces can be found in the literature. It is well known that geometrical features of machined surfaces are strongly related to the cutting parameters. Therefore, it can be thought that physicochemical properties of machined surfaces depend strongly on machining parameters. This work reports on the results of a study of the influence of the turning parameters on the Ultimate Tensile Strength (UTS) of turned bars of UNS A92024 Aluminium-Copper alloy.