Center Line Average Roughness Research Articles

Viability and performance assessment of bipolar linear self-servo mechanism-based Maglev electrical discharge machining by processing Al-6062 alloy

The enhancement of process efficiency and eradication of basic setbacks of the electrical discharge machining (EDM) process has paved the way for its technological advancement. The discharge irregularities observed during conventional EDM operation due to servo-feedback delay have been addressed by implementing a novel bipolar linear self-servo strategy in Maglev EDM. The paper evaluates the viability of the novel Maglev EDM and analyses its performance in machining aluminum (Al) 6062 alloy. The Maglev EDM uses a systematic combination of magnetic repulsive forces to attain tool positioning in the Z-direction, which serves as the servo gap control mechanism. Experiments were carried out on Al-6062 alloy by utilizing brass tools and surrounding air as dielectric. The voltage–current waveforms exhibited stable and uniform discharges devoid of the short-circuiting and arcing phenomenon. Material removal rate, specific energy, and centerline average surface roughness of 6.717 µg/s, 2.397 J/µg, and 3.735 to 4.507 µm were attained at a discharge power of 16.1 J/s, proving the operational viability of the Maglev EDM. The experimental results were further compared with data available in the previously reported literature. Resolidified layers, globules, lumps of debris, melted debris, micro-pores, micro-voids, micro-cracks, and craters were detected from field emission scanning electron microscopy analysis of the processed work surface. The existence of tool material in the processed surface by energy-dispersive X-ray spectroscopy analysis certified the material migration and surface alloying.

Feasibility assessment of manufacturing of heat sink using additive manufacturing techniques

A heat sink is a heat dissipating unit that removes heat with the help of an infusing heat mechanism to a fluidic environment, often atmospheric ambiance or a heat transfer agent where it is imparted away from the system, thereby permitting the control of the device. Commonly the heat sink is manufactured by a process such as forging, casting, stampings, etc. with rectangular or circular fins. The mechanism of heat transfer is mainly relying on the surface area of fins. In this work, the fins are provided with some corrugation to increase the area of transfer of heat. The design change in the rectangular fin makes it complex to produce in conventional methods such as forging, casting stamping, etc. So, the heat sink is manufactured by utilizing 3D printing additive technology. The 3D additive printing design is developed with the Solid works software and the Computational Fluid Dynamics (CFD) analysis is done for finding the optimized design. Then the heat sink is fabricated by powder bed fusion technique. The feasibility study of the fabricated heat sink is done through digital microscopic images, dimensional analysis, roughness measurement, weight analysis and the possibility of porosity by finding the density of the printed material. The microscopic image shows that the surface of the fins has an irregular shape such as crushed foil paper. The dimensional analysis of the fin by profile projector gives the fin thickness variation from 0.98 mm to 1.2 mm. The roughness measurement gives center line average roughness, Ra = 6.910 μm, Root mean square method roughness, Rq = 9.08 μm and Ten point method roughness, Rz = 36.05 μm. Weighing of the specimen shows that the additive-manufactured heat sink has less weight compared to the conventional one.

Topography orientation effects on friction and wear in sliding DLC and steel contacts, part 3: Experiments under dry and lubricated conditions

Surface topography can affect the tribological performance in many applications. The influence of surface roughness and topographic orientation on friction and wear in dry and oil lubricated steel vs steel and diamond-like carbon (DLC) coated steel vs DLC coated steel sliding contacts was investigated. The surfaces had a centerline average roughness (Ra) between 0.004 and 0.11 μm and a topographic groove orientation of 0°, 45° and 90° with respect to the sliding direction. Tests conducted showed that the strongest effect of the orientation of the topographic directions occurs in dry sliding DLC vs DLC contacts. A super-lubricious DLC surface layer was efficiently formed, exhibiting low friction coefficients of 0.04 for smooth surfaces, and rough surfaces with grooves oriented along the sliding direction. The process of surface layer formation was most severely disturbed for average surfaces roughness with grooves oriented at 45° to the sliding direction. For these surfaces, the coefficient of friction was about five times higher (0.21) as compared to smooth samples (0.04). In dry sliding steel contacts, the coefficient of friction decreased with increasing surface roughness. On the other hand, the coefficient of friction increased with surface roughness in oil lubricated steel contacts. Adding a synthetic oil into the DLC vs DLC sliding contact prevented the formation of the super-lubricious surface layer. In tests with rotational steel vs steel sliding the friction coefficient was about 10% lower than in test with linear reciprocal sliding but was higher in DLC vs DLC contacts.

Optimization of Surface Roughness in Turning Operation using Al- 6063 and Effect of Dry Machining

ALUMINIUM-6063 is a widely used alloy material in the production of aerospace, aircraft, gas turbine components. This investigation focuses on the influence of machining parameters, viz., spindle speed, depth of cut and feed rate on the surface roughness obtained in Lathe operation of Al 6063 alloy. In the present study, experiments are conducted for nine different Al 6063 work piece materials to see the effect of work piece material variation in this respect. This roughness parameters, viz., Centre line average roughness, root mean square roughness. The roughness models as well as the significance of the machining parameters have been validated with analysis of variance. In addition, a good agreement between the predicted and measured surface roughness was observed. Therefore, the developed model can be effectively used to predict the surface roughness on the machining of Al6063 within 95% confidence intervals ranges of parameters studied.

The Optimization of Lathe Cutting Parameters Using a Hybrid Taguchi-Genetic Algorithm

In this paper, the multi-objective Hybrid Taguchi-Genetic Algorithm is used to search for the best processing parameters with specified processing accuracy. The experimental cutting parameters used for the L9 orthogonal table process are cutting depth, cutting velocity and feed rate. The surface roughness of the machined workpiece surface was measured according to the standard of centerline average roughness. The Material Removal Rate will be calculated by measuring the diameter of the processed workpiece from the formula to give the Material Removal Rate. A linear regression model is constructed from the processed quality and the processing parameters of the orthogonal table, and the reliability of the model is confirmed by analysis of variance. A Hybrid Taguchi-Genetic Algorithm was used to calculate the optimal cutting parameters for multi-objective processing. The results of the experiments indicate that Hybrid Taguchi-Genetic Algorithm gave better convergence and robustness than the conventional Genetic Algorithm using the same number of iterations. This process produces multiple combinations of optimal cutting parameters for material removal rate and surface roughness. As the enhancement of material removal rate improved efficiency on the production line, the optimal cutting parameters were based on the tolerance range of Ra $1.6\mu \text{m}$ to $3.2\mu \text{m}$ according to the international standard of surface roughness. After actual processing with the selected optimum cutting parameters, the quality of processing is even better than the experimental design of the L9 Orthogonal table.

Optimization of Fractal Dimension of Turned AISI 1040 Steel Surface Considering Different Cutting Conditions

The present work examines the effect of turning process parameters, namely depth of cut and feed rate on the fractal dimension of AISI 1040 steel. Machined surfaces have been characterized using fractal dimensions. Apart from the aforesaid conventional turning parameters, cutting condition has been also considered as a design variable. Three cutting conditions have been considered, e.g. dry, water lubricated, and commercially available water-soluble emulsion lubricated condition. The depth of cut and feed rate has been also been varied at three levels. Experiments were performed following Taguchi's L9 orthogonal array. The optimal setting of process parameters has been achieved through the use of Taguchi's quality loss function represented by a signal-to-noise ratio. The optimal condition predicted from Taguchi's analysis is a 0.4 mm depth of cut, a 0.07 mm/rev feed rate and a water-based emulsion cutting environment. The results obtained for fractal dimensions has been also compared with the more conventional roughness parameter centre line average roughness which is dependent on instrument resolution.

Environmentally friendly machining with MoS2-filled mechanically microtextured cutting tools

This work aims to develop an environmentally friendly manufacturing by avoiding the use of cutting fluids during machining and reducing power consumption. Here, texture was fabricated on the rake face of the plasma-nitrided high-speed steel cutting tool by using a scratch tester. Molybdenum disulfide (MoS2) solid lubricant was filled into this mechanically developed texture to form a self-lubricating tool. Dry turning experiments were conducted using the MoS2-filled textured, unfilled textured, and plain (conventional) cutting tools to evaluate and compare their machining performance in terms of workpiece temperature, machining force, workpiece centerline average surface roughness, coefficient of friction, and chip morphology. Results revealed that filled textured cutting tools considerably improve the machining performance compared with those of plain and unfilled textured cutting tools. Therefore, these tools can eliminate the use of cutting fluids and minimize energy consumption.

Tribo-mechanical and surface morphological comparison of untextured, mechanical micro-textured (MμT), and coated-MμT cutting tools during machining

In machining process, cutting fluids are used to reduce the tool–chip interface temperature and forces, but it causes various health hazards to machine operators as well as increases the associated costs. To improve machining sustainability, researchers are trying to reduce or eliminate cutting fluid usage during machining by various other techniques (development of better tool material, bio-cutting fluids, use of vegetable oils, near-dry machining, process optimization, surface coatings, etc). In recent years, several researchers applied controlled surface modification (surface texturing/engineering) at the tool–chip interface to improve the tribological properties in the machining performance. In the present study, first mechanical microtextures (MµT) are created on the rake surface, and its structural stability is compared with an untextured/virgin cutting tool. The static structural analyses show a negligible effect of mechanical microtextures on the strength of the cutting tool. Afterwards, MµT cutting tools are coated using molybdenum disulphide (MoS2) solid lubricant (i.e. coated MµT, C-MµT). Subsequently, the machining performance studies of C-MµT were carried out to show its advantages over two other types of cutting tools (UC, MµT). Performance of C-MµT is improved by mechanical microtextures (due to the reduction in the actual contact area between tool–chip interfaces) and proper lubrication of the tool–chip contact area. Thus, due to the reduced contact area and formation of lubricant layer by MoS2 at the tool–chip interface, C-MµT experiences 23.75% lower tool–chip interface temperature, 41.06% reduction in the cutting force, and produces 14.37% less workpiece center line average surface roughness ( Ra) compared to untextured cutting tool. C-MµT experiences 9.55% lower tool–chip interface temperature, 19.02% reduction in the cutting force, and produces 5.34% less workpiece center line average surface roughness compared to the MµT cutting tool. Hence, C-MµT cutting tools are the viable alternative to untextured cutting tools.

Some investigations in grindability improvement of Inconel 718 under ecological grinding

This work explores the improvement in grinding characteristics of Inconel 718 (IN718) using soluble oil under minimum quantity lubrication and liquid nitrogen (LN2) environments. The coolant flow rate in minimum quantity lubrication and LN2 grinding has been regulated through indigenously developed setups. Grinding performance has been studied in terms of on-machine measured grinding forces and centre line average surface roughness ( Ra). The obtained grinding characteristics have been compared with the outcomes under dry and wet grinding. Surface integrity of ground surface, wheel morphology, and chip formation characteristics has been studied using scanning electron microscope, energy dispersive X-ray spectroscopy, and atomic force microscopy. Analysis of variance has been carried out to capture the variability in the experimental data for tangential forces and Ra. The main effect of the factors and their first-order interactions have been considered, and second-order regression equations have been developed using response surface methodology. LN2 grinding has been proved to be more efficient as it yielded lowest grinding forces, least oxidation, minimal ground surface damage and better surface integrity. The occurrence of almost circular chips in dry grinding indicates severe oxidation, whereas small C-type chips formed under minimum quantity lubrication and LN2 conditions indicate effective cooling under these environments. The energy dispersive X-ray spectroscopy analysis of the ground surfaces also supports these results through the occurrence of the highest oxidation in dry grinding. From this work, it has been concluded that LN2 and minimum quantity lubrication grinding offer a clean and effective means to improve grinding performance of IN718 compared to dry and wet grinding.

Study the effect of process parameters in plasma arc cutting on Quard-400 material using analysis of variance

Aim of present work is to investigate the effects of process parameters of plasma arc cutting of Quard – 400 material using analysis of variance. Two process parameters, cutting speed and gas pressure are considered and experiments are conducted based on full factorial design. Process responses viz. mean surface roughness (Ra: center line average roughness) and material removal rate (MRR) of machined surface are measured for each experimental runs. Higher material removal rate means industry can cut more metal in same period of time which ultimately results in more profit. And less surface roughness makes finished product more suitable for assembly and easy handling. For minimum mean surface roughness and maximum material removal rate, process parameters are optimized with the help of full factorial design coupled with response surface method. Analysis of Variance (ANOVA) is performed to get the contribution of process parameters on responses and it was found that cutting speed has most significance.

Optimization of Surface Roughness Parameters of Al-6351 Alloy in EDC Process: A Taguchi Coupled Fuzzy Logic Approach

This paper investigates the application of Taguchi method with fuzzy logic for multi objective optimization of roughness parameters in electro discharge coating process of Al-6351 alloy with powder metallurgical compacted SiC/Cu tool. A Taguchi L16 orthogonal array was employed to investigate the roughness parameters by varying tool parameters like composition and compaction load and electro discharge machining parameters like pulse-on time and peak current. Crucial roughness parameters like Centre line average roughness, Average maximum height of the profile and Mean spacing of local peaks of the profile were measured on the coated specimen. The signal to noise ratios were fuzzified to optimize the roughness parameters through a single comprehensive output measure (COM). Best COM obtained with lower values of compaction load, pulse-on time and current and 30:70 (SiC:Cu) composition of tool. Analysis of variance is carried out and a significant COM model is observed with peak current yielding highest contribution followed by pulse-on time, compaction load and composition. The deposited layer is characterised by X-Ray Diffraction analysis which confirmed the presence of tool materials on the work piece surface.

A grey-fuzzy modeling for evaluating surface roughness and material removal rate of coated end milling insert

The prime factor for selecting equipment is its performance capability and reliability without compromising on quality. Materials for aerospace application such as aluminum and its alloys have limited applications because of their complications in machining, effectively and economically. There is no further development in raising the effectiveness above the optimal level in cutting tool materials. The surface roughness influences the determination of the quality of the product. The present study focuses on finding optimal end milling process parameters by considering multiple performance characteristics using grey fuzzy approach. In this work, Aluminum Alloy 6082T6 (AA6082T6) is used as workpiece material which was end milled using Aluminum Chromo Nitride (AP3) coated milling insert. Three process performance parameters namely Centre Line Average Roughness (Ra), Root Mean Square Roughness (Rq) and Material Removal Rate (MRR) were optimized. The grey output is fuzzified into five membership functions and also with twenty-seven rules. Grey Fuzzy Reasoning Grade (GFRG) is developed and the optimal values were found out from the Grey relational grade. The result of the Analysis of Variances (ANOVA) shows that the maximum contribution in the depth cut is (31.785%) followed by feed (28.212%). Moreover, Adaptive Neuro-Fuzzy Inference System (ANFIS) model has been developed with the help of the same input values compared to the performance of the fuzzy logic model. With the help of detailed analysis, it has been found that the fuzzy logic based model gives more reasonable results when compared to ANFIS model.

Erosion modeling in abrasive slurry jet micro-machining of brittle materials

Abrasive slurry jet micro-machining (ASJM) uses a relatively low pressure jet of abrasive slurry to machine features such as holes and channels. This study investigated the effect of alumina particle kinetic energy and jet impact angle on the roughness and erosion rate of channels machined in borosilicate glass using ASJM. A computational fluid dynamics model was used to calculate the local particle impact velocities and angles, and thus the kinetic energies of particles striking the surface. Consistent with earlier work on air-driven abrasive jets, the roughness and erosion rate of the channels machined at perpendicular incidence depended only on the kinetic energy of particles above the apparent cracking threshold of the glass target. Slurry jets of higher kinetic energy produced rougher channels and higher erosion rates since the impacting particles caused larger lateral cracks to form, and thus removed larger chips. The measured erosion rate at various impact angles, and the observed damage due to individual alumina particle impacts, indicated that the dominant mode of material removal was brittle erosion. Two similar analytical brittle-erosion models derived for air-driven abrasive jet micromachining (AJM), were found to predict reasonably well the roughness and the erosion rate of ASJM channels, despite the large differences in the fluid media, flow patterns, and particle trajectories in AJM and ASJM. A key requirement was that the average particle kinetic energy was calculated using the CFD model. With only minor modifications, the models predicted the channel erosion rate and centreline roughness with average errors of 12% and 17%, respectively. In addition, a numerical simulation, previously developed to predict the erosion in AJM of brittle materials, was used to predict the centreline average roughness, shape parameters and depth of ASJM channels for various machining conditions.

초고속 용사 적용 고속 초고압 왕복동 펌프 플런저의 내구성 특성에 관한 연구

The high velocity oxygen fuel spraying (HVOF) is a kind of surface modification process technology to form the sprayed coating layer after spraying the powder to molten or semi-molten state by the ultra-high speed at the high-temperature heat source and conflicting with a substrate. It is desirable to melt completely the thermal spray powder in order to produce the coating layer with an optimal adhesion, however, because a semi-molten powder in a spray process has the low efficiency and become a factor that degrades the mechanical property by the inducement of pore-forming within the coating layer. To improve the wear resistance, corrosion resistance and heat resistance, in this study, the plungers of high-speed and ultra-high pressure reciprocating hydraulic pumps for oil and water used in ironwork are produced with <TEX>$420J_2$</TEX> and the coating layers of plungers are formed by the powders of WC-Co-Cr and WC-Cr-Ni including the high hardness WC. The surface of these plungers is modified by the super-mirror face grinding machine using variable air pressure developed in this laboratory, and then the characteristics of cross-sectional microstructure, and surface roughness and hardness values between no operation and 100 days-operation are examined and made a comparison. The fine tops and bottoms on surface roughness curve of oil-hydraulic pump plunger sprayed by WC-Cr-Ni are molded more and higher than those of water-hydraulic pump sprayed by WC-Co-Cr because the plunger diameter of oil-hydraulic pump is 0.4 times smaller than that of water-hydraulic pump and the pressure of oil-hydraulic pump exerted on the plunger is operated with the 70 bars higher than that of water-hydraulic pump. As a result, it is found that the values of centerline average surface roughness and maximum height for oil-hydraulic pump plunger are bigger than those of water-hydraulic pump plunger.

Surface Roughness of Al - 5Cu Alloy using a Taguchi - Fuzzy Based Approach

The present paper investigates the application of traditional Taguchi method with fuzzy logic for multi objective optimization of the turning process of Al-5Cu alloy in CNC Lathe machine. The cutting parameters are optimized with considerations of the multiple surface roughness characteristics (Centre line average roughness R a , Average maximum height of the profile R z , Maximum height of the profile R t , Mean spacing of local peaks of the profile S a ). Experimental results are demonstrated to present the effectiveness of this approach. The parameters used in the experiment were cutting speed, depth of cut, feed rate. Other parameters such as tool nose radius, tool material, workpiece length, workpiece diameter, and workpiece material were taken as constant.

Optimization of Surface Roughness and MRR in Electrochemical Machining of EN31 Tool Steel Using Grey-taguchi Approach

Electrochemical machining is one of the widely used non-traditional machining processes to machine complicated shapes for electrically conducting but difficult-to-machine materials such as super alloys, Ti-alloys, alloy steel, tool steel, stainless steel, etc. Use of optimal ECM process parameters can significantly reduce the ECM operating, tooling, and maintenance cost and will produce components with higher accuracy. This paper investigates the effect of process parameters on material removal rate (MRR) and surface roughness characteristic (centre line average roughness: Ra, root mean square roughness: Rq, skewness: Rsk, kurtosis: Rku and mean line peak spacing: Rsm) and parametric optimization of process parameters in ECM of EN31 tool steel using grey relation analysis. Experiments are conducted based on Taguchi's L27 orthogonal array (OA) with four process parameters viz. electrolyte concentration, voltage, feed rate and inter-electrode gap. Analysis of variance (ANOVA) is performed to get the contribution of each parameter on the performance characteristics and it is observed that electrolyte concentration is the significant process parameter that affects the responses. The experimental results for the optimal setting show that there is considerable improvement about 48% in the process using confirmation test. The optimal combination is electrolyte concentration 10%, voltage 10V, feed rate 0.25mm/min and inter-electrode gap 0.2mm for maximum MRR and minimum surface roughness. Surface and contour plots are generated to study the effect of input parameters on MRR and surface roughness. Finally, scanning electron microscopy (SEM) images are used to observe the surface morphology.

Optimization of Process Parameters in Plasma arc Cutting of EN 31 Steel Based on MRR and Multiple Roughness Characteristics Using Grey Relational Analysis

This paper investigates the effects and parametric optimization of process parameters for plasma arc cutting (PAC) of EN31 steel using grey relation analysis. Three process parameters viz. gas pressure, arc current and torch height are considered and experiments are conducted based on L27 orthogonal array (OA). Process responses viz. material removal rate (MRR) and surface roughness parameters (centre line average roughness: Ra, root mean square: Rq, skewness: Rsk, kurtosis: Rsk and mean line peak spacing: Rsm) of the machined surface are measured for every experimental runs. For maximum MRR and minimum surface roughness characteristics process parameters are optimized based on Taguchi method coupled with grey relational analysis. Analysis of variance (ANOVA) is performed to get the contribution of each process parameters on the performance characteristics and it is observed that gas pressure is significant process parameter that affects the responses. Confirmation test using optimal setting shows good agreement to the predicted value. This indicates utility of the grey-Taguchi technique as a multi-objective optimizer in the field of PAC. Finally, using scanning electron microscopy, the surface morphology is studied.

Optimization of Electroless Ni–P–Al2O3 Composite Coatings based on Multiple Surface Roughness Characteristics

Electroless Ni–P–Al2O3 composite coatings are popular due to their excellent hardness, friction and wear resistance. The present study tries to investigate the influence of coating process parameters on the surface roughness of electroless Ni–P–Al2O3 composite coating with the help of Taguchi analysis. The different surface roughness parameters considered are, center line average roughness (Ra), root mean square roughness (Rq), skewness (Rsk), kurtosis (Rku), and mean line peak spacing (Rsm). Three parameters, namely, concentration of nickel sulphate as a nickel source, concentration of sodium hypophosphite as reducing agent, and concentration of Al2O3 particles as concentration of second phase particles are considered and fitted into an L27 orthogonal array to find out the optimized condition to minimize the surface roughness of the coating. It is observed that concentration of Al2O3 particles have the most significant influence on Ni–P–Al2O3 composite coating and concentration of reducing agent has moderate influence. The compositional, micro-structural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively.

Optimization of MRR and Surface Roughness in PAC of EN 31 Steel Using Weighted Principal Component Analysis

Abstract In this paper, an attempt has been made to optimize the process parameters for multi-responses (material removal rate, MRR and surface roughness) in plasma arc cutting (PAC) of EN 31 steel using weighted principal component analysis (WPCA). For surface roughness characteristics, five different surface roughness parameters (centre line average roughness: R a , root mean square: R q , skewness: R sk , kurtosis: R ku and mean line peak spacing: R sm ) are considered. Three process parameters viz. gas pressure, arc current and torch height are considered. The experimental plan is based on Taguchi L 27 orthogonal array (OA). To convert the multi-responses problem to a single response optimization problem, WPCA is applied to compute a multi-response performance index (MPI) and then MPI has been optimized using Taguchi method. The optimum combination of process parameters has been found for maximum MRR and minimum surface roughness and verified through a confirmation test. Also, ANOVA is carried out and it is seen that the gas pressure is the most significant factor followed by arc current.

Surface Roughness Minimization in Turning PEEK-CF30 Composites with TiN Cutting Tools Using Particle Swarm Optimization

Poly ether ether ketone (PEEK) composite belongs to a group of high performance thermoplastic polymers and the addition of carbon fibers increases the resistance and rigidity of PEEK. Due to favorable mechanical and thermal properties and potential applications in various manufacturing industries, it is essential to analyze the machining performance of reinforced PEEK composites. The surface roughness is a widely used measure of product quality that could influence the performance of mechanical products and production costs. The present study establishes the relationships between the cutting conditions (cutting speed and feed rate) and three surface roughness parameters (centerline average surface roughness, maximum peak to valley height and root mean square roughness) by developing second order mathematical models based on response surface methodology (RSM). The reinforced PEEK with 30% of carbon fiber (PEEK-CF30) workpieces were machined using TiN-cutting tools. The experiments have been planned as per full factorial design of experiments (FFD). The developed surface roughness models were then employed with particle swarm optimization (PSO) to optimize the cutting conditions. PSO program gives the minimum values of surface roughness parameters and the corresponding optimal cutting conditions.