Increase In Material Removal Rate Research Articles

Mechanism of material removal by fixed abrasive lapping of fused quartz glass

In this paper, a novel fixed-abrasive lapping process to finish off-axis aspheric surfaces efficiently is proposed. The lapping mechanism of fused quartz glass was evaluated using the novel fixed-abrasive pad tool. The applied load and not the rotation speed and feed rate is the key factor affecting the material removal mode of fused quartz glass in the fixed-abrasive lapping process. Analysis of surface characteristic and subsurface damage indicates that lower applied load produces more ductile mode removal and that the removal on fused quartz glass can be changed from brittle fracture to ductile regime if the applied load is less than 25 N. The material removal rate (MMR) increases as the applied load is increased, which further increases the surface roughness. In addition, the MMR increases and the surface roughness decreases as the rotation speed is increased or the feed rate is deceased. A theoretical model for predicting the maximum SSD depth of the specimens during lapping was developed. The model can predict well that the maximum SSD depth increases with increasing applied load.

Effect of Grain Size and Density of Abrasive on Surface Roughness, Material Removal Rate and Acoustic Emission Signal in Rough Honing Processes

Honing processes provide a special cross-hatch pattern to the internal surface of cylinders that favors oil flow. However, along honing operation the abrasive grains wear out and lose their ability to cut material. The honing chips mixed with oil fill the pores of the abrasives and they start cutting in an incorrect way, leading to clogging. In the present paper, honing experiments were carried out according to a 32 factorial design, with different grain size and density of abrasive grains. Roughness, material removal rate, and tool wear were determined. Acoustic emissions were also measured and the chirplet concept was applied in order to detect differences between correct and incorrect cutting operations. As a general trend roughness and material removal rate increase with grain size and with density of abrasive. However, when clogging occurs roughness and material removal rate decrease, because the abrasive grains tend to deform the material instead of cutting it. When the honing process is working appropriately, the chirplet diagram of the harmonic part of the signal shows constant marks. On the contrary, when it does not work properly, marks disappear with time and their frequencies decrease. The results of the present paper will allow monitoring the honing process in order to change the abrasives when they are not working properly.

Study on material transfer and surface properties during fiber laser cutting of A653 galvanized steel sheet

Cut quality is an important factor in laser beam cutting. In the present paper, modeling and optimization of laser beam cutting process parameters during fiber laser cutting of A653 galvanized steel sheet for straight cut by using response surface methodology have been studied. In this experimental work, power, gas pressure, pulse frequency and feed were taken as input parameters and kerf width, kerf deviation and material removal rate were taken as output responses. The experiments were planned using Box–Behnken design, and empirical models have been developed by using response surface methodology. Scanning electron microscope was used to determine the surface characteristics of sample. Confirmation tests were conducted to validate predicted optimum results. Considerable reduction in kerf deviation and increase in material removal rate were revealed by confirmation tests. The percentage prediction error in the case of kerf width was 5.12% and in the case of kerf deviation was 5.88%, which shows that model is adequate. The experimental and statistical results revealed that the most significant laser cutting parameters for kerf width, kerf deviation and MRR is feed followed by gas pressure, frequency and power.

Oscillatory behaviour in the electrochemical jet processing of titanium

When appraising the performance of titanium alloys for corrosion resistance in halide environments researchers have well understood pitting and growth mechanisms through electrochemical corrosion. This knowledge is yet to be exploited for the purpose of electrochemical jet processing, a versatile and selective machining technique that is ideal for high-value manufacturing. The applicability of the method towards processing titanium is hampered by the passivating nature oxides which form. In this study, the process of jet interaction with Ti-6Al-4V in the presence of halide electrolytes is deconstructed to establish the fundamental interactions between the jet and surface. This is used to propose the mechanism by which electrolyte, oxide layer and bulk interact to create unfavourable machining phenomena. These manifest as periodic electrochemical oscillations that are accompanied by aberrations in the resulting cut and are influenced by nozzle diameter, translation, current density and flow velocity. Such oscillations can be avoided completely through processing at current densities >200 A/cm2. Experimentation is also reported here identifying candidate electrolytes for superior processing of titanium considering feature precision at high current densities (>300 A/cm2). This is valuable knowledge in terms of increasing material removal rate. In this regard, cut edge deviation is reduced by >20% and profile deviation is reduced by >40% when applying iodide-doped electrolytes, in comparison to commonly employed chloride solutions.

Multi-objective optimization in WEDM process of graphene – SiC-magnesium composite through hybrid techniques

This paper exhibits a test examination and investigation on the impacts of Wire Electric Discharge Machining (WEDM) parameter on Material removal rate (MRR) and surface roughness (Ra) for the newly developed Magnesium metal matrix composite. Two material parameters (namely reinforcement wt.%, SiC doping %) and three machining parameters (viz. Pulse-On Time (P-ON), Pulse-Off Time (P-OFF), and Wire Feed Rate (WFD)) have been selected to study their effects on the desired output responses (MRR and Ra). The output response variables like MRR and Ra are then analyzed using Taguchi coupled Grey relation analysis. The general belief in any such investigations is that increase in P-ON increases MRR and the same has been revisited through this exhaustive study. Nevertheless, as increased machining time leads to an increase in the manufacturing cost, a trade-off between MRR and Ra, was successfully made by utilizing a Taguchi coupled Grey relation analysis. This gave the best combination of input parameters.

Microhardness and wear behaviour of polycrystalline diamond after warm laser shock processing with and without coating

Cutting tools made of ultra-hard materials such as polycrystalline diamonds offer superior wear resistance in precision machining of Aluminium alloys. However, the wear properties of these materials are dependent on their microstructural characteristics such as grain size and binder percentage. In this context, the present paper evaluates the effects of two low-energy fibre laser processes (nanosecond pulse duration) on microstructural changes of polycrystalline diamond composites and consequently investigates wear and friction characteristics and micro hardness properties. Pockets were first achieved using a single mode SPI pulsed fibre laser (1064 nm wavelength) inducing both laser shock processing (LSP) and laser peening without coating (LPwC) and characterised using a combination of scanning electron microscopy (SEM), white light interferometry, energy dispersive X-Ray (EDX) and micro hardness analyses. The as-received and processed materials were tested on a pin-on-disc for the evaluation of their wear performance. An analytical model based on the asperities of pin and disc after wear test is proposed to predict the trend of wear performance of different laser-processed materials. LSP with vinyl and quartz at a scanning speed of 500 mm s−1 achieved a micro-hardness of 110 GPa at a depth of 632 nm. LPwC at 0.8 GW cm−2 produced hybrid microstructures which share characteristics of laser shock processing and selective laser melted structures. For laser feed speed in the region of 1000 mm s−1, micro-indentation tests revealed an improvement of hardness from 70 GPa to 95 GPa at a depth of 670 nm for LPwC. Tribotest revealed enhanced wear performance for all laser-processed pins and reduced coefficient of friction also validated by increased material removal rate when compared to the as-received material. To the best of authors' knowledge, it is reported for the first time that an improvement of wear performance can be achieved on polycrystalline diamond through LSP and LPwC.

Fabrication and experimental investigation of magnetic field assisted powder mixed electrical discharge machining on machining of aluminum 6061 alloy

Magnetic field assisted powder mixed electrical discharge machining is a hybrid machining process with suitable modification in electrical discharge machining combining the use of magnetic field and fine powder in the dielectric fluid. Aluminum 6061 alloy has found highly significance for the advanced industries like automotive, aerospace, electrical, marine, food processing and chemical due to good corrosion resistance, high strength-to-weight ratio, ease of weldability. In this present work, magnetic field assisted powder mixed electrical discharge machining setup was fabricated and experiments were performed using one factor at a time approach for aluminum 6061 alloy. The individual effect of machining parameters namely, peak current, pulse on time, pulse off time, powder concentration and magnetic field on material removal rate and tool wear rate was investigated. The effect of peak current was found to be dominant on material removal rate and tool wear rate followed by pulse on time, powder concentration and magnetic field. Increase in material removal rate and tool wear rate was observed with increase in peak current, pulse on time and a decrease in pulse off time, whereas, for material removal rate increases and tool wear rate decreases up to the certain value and follow the reverse trend with an increase in powder concentration. Material removal rate was increased and tool wear rate was decreased with increase in magnetic field.

Investigation of the Influence of Reduced Graphene Oxide Flakes in the Dielectric on Surface Characteristics and Material Removal Rate in EDM.

Electrical discharge machining (EDM) is an advanced technology used to manufacture difficult-to-cut conductive materials. However, the surface layer properties after EDM require additional finishing operations in many cases. Therefore, new methods implemented in EDM are being developed to improve surface characteristics and the material removal rate. This paper presents new research about improving the surface integrity of 55NiCrMoV7 tool steel by using reduced graphene oxide (RGO) flakes in the dielectric. The main goal of the research was to investigate the influence of RGO flakes in the dielectric on electrical discharge propagation and heat dissipation in the gap. The investigation of the influence of discharge current I and pulse time ton during EDM with RGO flakes in the dielectric was carried out using response surface methodology. Furthermore, the surface texture properties and metallographic structure after EDM with RGO in the dielectric and conventional EDM were investigated and described. The obtained results indicate that using RGO flakes in the dielectric leads to a decreased surface roughness and recast layer thickness with an increased material removal rate (MRR). The presence of RGO flakes in the dielectric reduced the breakdown voltage and allowed several discharges to occur during one pulse. The dispersion of the discharge caused a decrease in the energy delivered to the workpiece. In terms of the finishing EDM parameters, there was a 460% reduction in roughness Ra with a uniform distribution of the recast layer on the surface, and a slight increase in MRR (12%) was obtained.

Trochoidal milling: investigation of dynamic stability and time domain simulation in an alternative path planning strategy

Trochoidal milling is an alternative path planning strategy with the potential of increasing material removal rate per unit of tool wear and therefore productivity cost while reducing cutting energy and improving tool performance. These characteristics in addition to low radial immersion of the tool make trochoidal milling a desirable tool path in machining difficult-to-cut alloys such as nickel-based superalloys. The objective of this work is to study the dynamic stability of trochoidal milling and investigate the interaction of tool path parameters with stability behavior when machining IN718 superalloy. While there exist a few published works on dynamics of circular milling (an approximated tool path for trochoidal milling), this work addresses the dynamics of the actual trochoidal tool path. First, the chip geometry quantification strategy is explained, then the chatter characteristic equation in trochoidal milling is formulated, and chatter stability lobes are generated. It is shown that unlike a conventional end-milling operation where the geometry of chips remains constant during the cut (resulting in a single chatter diagram representing the stability region), trochoidal milling chatter diagrams evolve in time with the change in geometry (plus cutter entering and exiting angles) of each chip. The limit of the critical depth of cut is compared with conventional end milling and shown that the depth of cut can be increased up to ten times while preserving stability. Finally, the displacement response of the cutting tool is simulated in the time domain for stable and unstable cutting regions; numerical simulation and theoretical results are compared.

Centrifugal and hydroplaning phenomena in high-speed polishing

Super fine polishing with compliant tools can achieve nanoscale roughness, but has limited productivity due to low material removal rate (MRR). Increased spindle speed in high-speed polishing (HSP) might increase MRR, but significant challenges appear above 10,000 rpm because of centrifugal deformation of the tool and pad lifting due to hydroplaning phenomenon. Here, a tool offset compensation strategy is proposed for centrifugal deformation and novel pad patterning design that mitigates hydroplaning. Through this new approach, linear increase in MRR for spindle speed up to 24,000 rpm is demonstrated. This work lays the foundation for future developments of HSP in fabrication of ultraprecision optics.

Process Performance of Low Frequency Vibratory Grinding of Inconel 718

Abstract Inconel is used largely in aerospace industry for the manufacturing of jet engine components, where high heat resistance materials are preferred. Inconel has special properties such as high strength to weight ratio, low thermal conductivity and poor machinability. This has led to numerous researches into the machinability of this material that still poses challenges to unexperienced new manufacturers. The work presented here, employs low frequency oscillation to induce vibratory grinding of Inconel 718 with reduced coolant application at very low pressure. A porous aluminium oxide-grinding wheel was used for the experimental work with and without oscillations. The experimental results showed that the superimposition of vibration improved the overall process performance. A reduction of over 30% in grinding cutting forces was recorded, along with an extended wheel life, increase in material removal rate and improved surface roughness quality.

Interaction of tool and workpiece in ultrasonic-assisted grinding of high performance ceramics

Abstract Ultrasonic assisted grinding processes promise high potential for economical machining of brittle hard materials and improved workpiece qualities. Especially in machining of high performance ceramics as well as ceramic matrix composites (CMC) a significant decrease of process forces and increased material removal rates can be achieved. In previous publications the fundamental effect mechanisms related to ultrasonic assistance in grinding processes were described. However, implicit knowledge about the influence of the tool specifications and geometry on the maximum achievable ultrasonic amplitude is lacking. Furthermore, knowledge about the behavior of the high-frequency tool motions during tool engagement could simplify the design of ultrasonic assisted grinding processes. A targeted utilization of ultrasonic effects can be result in lower process forces, less tool wear and shorter machining times which lead consequently to more sustainable processes. The presented work provides results of the interactions of tool design, tool contact conditions and workpiece in the ultrasonic assisted machining of ceramics with mounted points.

Experimental investigations into rotary magnetic field and tool assisted electric discharge machining using magneto rheological fluid as dielectric

The present study focuses on the development of an electrical discharge machining method using magneto rheological fluid as dielectric and rotary magnetic field assisted electric discharge tool. The work aims to improve the performance of electric discharge machining by utilising the combined effect of magneto rheological fluid with the rotating electrode and magnetic field. This developed hybrid machining process has been designed to attain higher material removal rate to improve the productivity. In this process, the surface roughness has been found higher as compared to when magnetic field and tool was kept stationary. M2 grade high speed steel workpiece was used for the parametric study. The experimentation was performed to evaluate the effect of the percentage contribution of alumina particles, discharge current, duty cycle, and pulse on time on material removal rate and surface roughness. The experimental findings demonstrated that EDM process with rotary magnetic field and tool using magneto rheological fluid as dielectric resulted in an increased material removal rate as compared to EDM with static magnetic field and tool. The findings were found significant for a certain limit of carbonyl iron percentage in magneto rheological fluid.

Micro-EDM performance of Inconel 718 superalloy with and without ultrasonic vibration

Inconel 718 superalloy is an extremely difficult-to-machine aerospace material due to its work hardening nature and poor thermal conductivity. Drilling of cooling holes in this material is much difficult by conventional drilling processes because it has high chemical affinity with cutting tool materials, high welding action of chips at rake face, high strength at high temperature and work hardening nature. In consideration of all these problems, a self-developed setup of drilling ultrasonic assisted micro-EDM (drilling-UA-micro-EDM) has been used to create microholes in this material. A comparative study of machining characteristics of Inconel 718 in terms of material removal rate (MRR), tool wear rate (TWR), hole taper (Ta), and radial overcut (ROC) has been investigated due to drilling-micro-EDM without and with the ultrasonic vibration (UV). Comparative results show that the application of UV in drilling-micro-EDM increases MRR and decreases TWR, Ta and ROC, and gives microholes of good quality and accuracy.

Characterizing the effect of process variables on energy consumption in end milling

Manufacturing processes, such as machining, transform raw materials into finished goods, and these processes consume significant energy. There is an increasing concern about the energy required for such processes and the environmental consequences attributable to the generation of the energy. Reducing the energy required to perform machining operations will not only reduce the environmental footprint, but also provide economic benefits. To that end, the effects of cutting conditions (e.g., feed and speed) and tool geometry (diameter and number of teeth) on the power required for an end milling operation are investigated experimentally. Experimental results are presented from a cutting mechanism perspective with the goal of understanding the role of the process variables. The specific cutting energy (SCE) is found decreasing when material removal rate increases, but there is substantial variation about the general trend. In essence, the cutting parameters and the tool geometry influenced the changes of average chip thickness and cutting speed, which cause the shear deformation energy changes and eventually collectively influence the SCE’s change. Based on the experiments, suggestions on selecting process parameters are provided to improve milling energy efficiency.

Charged-Particle Emissions During Material Deformation, Failure and Tribological Interactions of Machining

Charged particles are emitted when materials undergo tribological interactions, plastic deformation, and failure. In machining, plastic deformation and shearing of work piece material takes place continuously along with intense tool-chip rubbing contact interactions; hence, the emission of charged particles can be expected. In this work, an in-situ sensor has been developed to capture the emitted positive (positive ion) and negative (electron and negative ion) charged particles in real-time in an orthogonal machining process at atmospheric conditions without the use of coolant. The sensor consists of a Faraday plate, mounted on the flank face of the cutting tool, to collect the emitted ions and the intensity of emissions is measured with an electrometer. Positively and negatively charged particles are measured separately by providing suitable bias voltage supply to the Faraday plate. Ion emissions are measured during machining of three different work piece materials (mild steel, copper, and stainless steel) using a carbide cutting tool. The experimental results show a strong correlation between the emission intensity and the variation in machining parameters and material properties. Increasing material removal rate increases the intensity of charged particle emissions because of the increase in volume of material undergoing shear, fracture, and deformation. It is found that emission intensity is directly proportional to the resistivity and strength of workpiece material. Charged particles emission intensity is found to be sensitive to the machining conditions which enables the use of this sensor as an alternate method of condition monitoring.

Material Removal Rate and Tool Wear Rate on Machining of Inconel 718 using Electrical Discharge Machine

Electrical discharge machining is a manufacturing process with a large industrial implementation. The addition of powder particles in suspension in the dielectric modifies some process variables and creates hard and brittle materials with nano surface finish, high tolerance and accuracy to achieve a material removal rate increase. This paper presents a research work to study the performance improvement of material removal rate (MRR) and tool wear rate (TWR)on the nano particle mixed electrical discharge machining. Work piece used is Inconel 718 and tool materials used brass electrode. The electrolyte used is kerosene oil. Titanium carbide nano particle is having high mechanical and electrical properties specifically high electrical conductivity. The input parameters like current, pulse on-time and pulse off-time and outputs MRR and TWR. The experiment results analysis titanium carbide nano particle mixed dielectric fluid to achieve maximum MRR and minimize TWR.

Cutting parameters optimization for MRR under the constraints of surface roughness and cutter breakage in micro-milling process

Selection of cutting parameters in micro-milling operations is essential for improving machining efficiency and quality, and prolonging the micro-milling tool life. The increase of material removal rate (MRR) always means the increase of cutting parameters, which may lead to poor surface quality and micro-milling tool failure, even cutter breakage. An optimization approach based on genetic algorithm is used to achieve the maximum MRR under the constraints of surface roughness and cutter breakage. A theoretical model for predicting micro-milling cutter breakage is presented and micro-milling experiments were conducted to establish statistical models of cutter breakage and surface roughness. The optimized results were achieved under the constraints of the specified surface roughness and compared under the different surface roughness limitation. We find that the optimized results improve the machining efficiency and quality in micro- milling and is affected by constraint conditions complicatedly.

Implementation of MCDM model in lean manufacturing using grey relational analysis in automotive industry

The present economic situation shows the consistent demand for profitable solutions that allow business organizations to gain better ad-vantage. Due to this reason, many organizations search for methodologies that allow them to improve their products and services improve their processes, reduce costs, and improve the profit and customer satisfaction. This has been implemented through lean techniques in their managerial and production methods. As we know Lean production system mainly emphasizes on the waste elimination, using simple and visual techniques. This paper is an attempt to optimize process layout and waste expulsion for automotive powertrain in a leading automo-tive company by using lean manufacturing techniques. In this paper, the existing process in place for machining of cam shaft is analysed and process layout is optimized to reduce cycle time and lead time. In order to reduce the cycle time, the process parameters such a speed, feed and depth of cut are optimized for increased material removal rate (MRR) and decreased surface roughness (RA) by using Grey Relational Analysis (GRA) technique. As MRR is inversely related to cycle time, optimization of parameters for higher MRR reduces the cycle time. Grey Relational Analysis is done by using Design Xpert software.

Preparation of MgO doped colloidal SiO2 abrasive and their chemical mechanical polishing performance on c-, r- and a-plane sapphire substrate

Chemical mechanical polishing (CMP) has been proved to be one of the most important methods to achieve atomic ultra-smooth surface, and it becomes widely used as global planarization techniques. There are some influence factors for CMP processing quality, and abrasive in the slurry is one of the key ones. In order to improve the removal rate and surface quality of sapphire substrate, a new-type MgO doped colloidal silica abrasive was studied Based on the basic principle of chemical thermodynamics, the HSC software was used to analyze the tendency of reactions between MgO doped colloidal silica abrasive and sapphire and between H2O and sapphire to generate solid solutions, compounds and hydrates on the sapphire surface. From the CMP experiment results of a-, r- and c-plane sapphire, it indicated that higher material removal rate (MRR) and lower surface roughness (Sq) were obtained with the slurry containing MgO doped colloidal SiO2 abrasive instead of containing pure SiO2 abrasive under the same conditions. In addition, the action mechanism of MgO doped colloidal SiO2 abrasive on sapphire substrate CMP was studied. From the analyzing result of X-ray photoelectron spectroscopy (XPS), it deduced solid-chemical reaction between sapphire surface and MgO doped colloidal silica abrasive was occurred and Al2Si2O7·2H2O, MgAl2O4 and Al2SiO5 were generated, which can promote chemical effects during CMP and lead to the increase of MRR. Such results have certain guiding significance to practical production.