International Journal of Machining and Machinability of Materials (15 papers in press)
Influence of process parameters on the ultrasonic assisted edge trimming of aerospace CFRP laminates using MQL
by Mohamed O. Helmy, Mohamed El-Hofy, Hassan El-Hofy
Abstract: The use of carbon fibre reinforced plastic (CFRP) composites is increasing rapidly especially in applications demanding high performance such as aerospace structural components. Edge trimming of CFRP parts is essential for controlling the dimensional tolerances and/or the product quality to meet the industrial standards or specification. This article investigates the ultrasonic-assisted edge-trimming of multidirectional CFRP laminates when minimum quantity lubricant (MQL) was employed for the first time. Statistical analysis was conducted to assess the effect of process parameters on the performance characteristics. Cutting speed, feed rate, and radial depth of cut were selected as process parameters while the performance characteristics were cutting forces, bouncing-back, material removal rate (MRR), and surface integrity in terms of surface roughness (Ra, Rz) as well as delamination. The most significant process parameter affecting each performance characteristic was determined using ANOVA test. Regression equations were also developed to predict the magnitude of bouncing back and MRR.
Keywords: Carbon fibre reinforced plastic; CFRP; Edge trimming; Ultrasonic; MQL.
Studies on surface quality of stainless-steel implant material while machining with WEDM process
by S. Sivakumar, M. Adam Khan, B. Muralidharan
Abstract: In this research work machinability studies on stainless steel (SS 107.12) implant by wire electrical discharge machining (WEDM) process was studied. The effect of heat affected zone (HAZ), mechanical load experienced and chemical effects after implantation are the significant factors influencing the degradation of machined surface. The metallurgical behaviour of the machined implant is investigated in detail. The experiments are conducted based on design of experiments by considering the input factors like pulse on time, pulse off time and voltage. The influencing responses measured are material removal rate and surface roughness. Further the machined samples are subjected to metallurgical characterisation, using scanning electron microscope (SEM), spectroscopic (EDS) analysis and atomic force microscope (AFM). From the results it is observed that, increase in voltage has produced better surface finish and reduced the Material removal rate (MRR).
Keywords: implant; steel; WEDM; SEM image; EDS; MRR; Ra.
Investigations on machinability and machining stability of turning super duplex stainless steel
by Subhash N, Jagadeesha T, Mohit Law
Abstract: Super duplex stainless steels (SDSS) combine austenite and ferrite in near equal proportions along with other alloying elements giving these steels excellent mechanical and chemical properties and making them of much use across industries. The same characteristics that give SDSS advantageous properties impair their machinability and make cutting of SDSS prone to unstable process-induced chatter vibrations. The focus of this paper is to hence investigate the machinability and machining stability of dry turning SDSS. Based on systematic experimental characterization, we identify cutting force coefficients that characterize machinability and observe these coefficients to be relatively speed independent. We further observe surface characteristics to improve with cutting speeds. Using identified coefficients and measured dynamics, we predict the stability behaviour. Experimental validation confirms that the nose radius on cutting tools plays a significant role in improving the chatter vibration-free turning of SDSS. Our findings can instruct high-performance strategies for turning of SDSS.
Keywords: Super duplex stainless steel; machinability; cutting force coefficients; dynamics; stability.
Metrological changes in surface profile, chip, and temperature on End Milling of M2HSS die steel
by Balamurugan Karnan
Abstract: The effect of the thermal energy generated during end milling on the surface profile and chip morphology with a change in the spindle speed and feed rate is studied and reported. Steels with 5% Molybdenum have found an amicable application as Molybdenum based high speed die steel (M2HSS). It is used as the machining material. Taguchys L9 orthogonal array machining condition is performed for two different tool diameters of 10 mm and 12 mm. High machining temperatures initiate a local welding zone, creates a weldment between the chip and tool surface, and progress to excess tool wear. This experimental study reveals that the details of increased thermal interaction that allows an excessive deformation of the sample through chip removal. With an increase in the high level of spindle speed and low feed rate, it is possible to get an acceptable level of surface profile roughness with a less tool wear rate. Further, the chip morphological analysis was performed and reported.
Keywords: End Milling; Die steel; Wear; thermal integration; chip formation; chatter growth.
Experimental study of orthogonal cutting of unidirectional CFRP laminates
by BLANCHET Florent, LACHAUD Frederic, PIQUET Robert, LANDON Yann
Abstract: This article relates to the study of orthogonal cutting of unidirectional carbon epoxy composite laminates T800S/M21 with tool angle influences. Many positive and negative values of the cutting angle () and of the angle 2 defined by the direction of the cutting speed and the fibers direction of the workpiece are used. Then this papers focus on the study of the cutting mechanisms, the morphology of the chip (its mode of formation and its shape), and the surface quality obtained according to the cutting forces evolution. Finally, study explains angle influence of surface roughness.
Keywords: Orthogonal cutting; Unidirectional carbon epoxy laminates; cutting forces; surface quality after machinning; cutting mechanisms.
Chamfer Drill Geometric Parameters Optimization by Finite Element Simulation and Experimental Analysis
by Julius Caesar Puoza, Sampson Takyi Appiah, Tainyao Zhang, Bernard Aboagye
Abstract: In this research paper, finite element models for drilling and milling were built respectively for a new chamfer drill tool and simulation results obtained for the best combination of geometric parameters. An orthogonal milling test experiment was conducted using a CNC vertical milling machine to obtain the cutting force and surface roughness. The rake angle of 15
Keywords: Chamfer drill; simulation; optimization; surface roughness; cutting force.
Surface integrity investigation of a Zr52.5Ti5Cu17.9Ni14.6Al10 metallic glass after grinding
by BRUNO LAVISSE, Nassim MENDIL, Georges KAPELSKI, Xavier CERUTTI, Alexis LENAIN, Sébastien GRAVIER, Rémi DAUDIN
Abstract: Crystalline alloys, widely used in the industry, are a topic of important research regarding their integrity resistance towards machining. Such investigations are less intense when dealing with relatively newer and less popular materials such as bulk metallic glasses (BMG). This is even more true when specific machining technics, such as grinding, are involved. As BMG are increasingly promoted to diverse industrial areas, the study of the impact of grinding on their microstructural integrity is necessary. Indeed, the amorphous structure of BMG, at the origin of their remarkable properties, is metastable such that any exterior solicitation (heating, cooling, loading, etc.) can induce structural modifications, for instance local crystallization, and therefore degrade or at least modify their characteristics.rnUsing quick and straightforward characterization technics such as SEM imaging, optical microscopy and X-ray diffraction, the microstructural changes occurring in the BMG after severe grinding passes could be identified. It is shown that crystallization can be detected below the grinded surface even for relatively small depth of cut. The results obtained on this peculiar composition help to propose a more generic methodology to safely use grinding on BMG.
Keywords: Bulk Metallic Glass; Grinding; Surface Characterization; Thermal Damaging.
Innovations in Electro Chemical Discharge Machining process through Electrolyte Stirring and Tool Rotations
by Chandrashekhar Jawalkar, Apurbba Kumar Sharma, Pradeep Kumar
Abstract: Electro chemical discharge machining (ECDM) process is gaining considerable importance in micro-machining of non-conductive and brittle materials like glass and ceramics. Recently it has undergone some innovations in the form of hybrid and variant processes, which have been reviewed and discussed in this paper. To further aid developments, an innovative hybrid process combining electrolyte-stirring and tool-rotation effect has been experimented and reported in this paper. The study was carried out in a phased manner on an in-house fabricated set-up using Taguchis orthogonal array L18. The experimental results illustrate an improvement in the process as compared to normal ECDM (without using electrolyte stirring and tool rotations). The optimum value for material removal was 1.282 mg/min and surface finish (Ra) was 0.4
Keywords: Tool Rotations; Electrolyte Stirring; Material Removal; Surface Finish.
Experimental investigation of surface characteristics and dynamic effects at micro milling of hardened hot-work tool steel
by Barnabas Zoltan Balazs, Marton Takacs
Abstract: One of the main trends in modern manufacturing technology is miniaturization. In this field, micro milling offers the most flexible machining method. Size reduction results in special and unique characteristics with respect to the machining process. The current paper addresses the investigation of the dynamic effects and surface characteristics of micro milled structures. Experiments were carried out on AISI H13 hot-work tool steel with 50 HRC hardness using a 5-axis micro milling centre: cutting force components and the vibration signal were recorded and analysed. By means of Fast Fourier Transform, the dominant frequencies of the process were identified. Time-frequency diagrams were prepared by Short-Time Fourier Transform for studying process changes during cutting time. Also, correlations between surface roughness, burr formation and cutting parameters were investigated. The results of this research provide a deeper understanding of the micro milling process, which ensures well-controlled and reproducible machining of up-to-date materials.
Keywords: micro milling; hot-work tool steel; vibration; signal analysis; burr formation; surface quality.
Mechanistic Modelling of Dynamic Cutting Forces in Micro End Milling of Zr-based Bulk Metallic Glass
by Debajyoti Ray, Asit Baran Puri, Naga Hanumaiah, Saurav Halder
Abstract: This paper presents the mechanistic modelling of dynamic cutting forces in micro end milling of Zr-based bulk metallic glass using empirically determined cutting force coefficients. The cutting force coefficients are determined for the ploughing and shearing dominant regimes from the average cutting forces in full immersion micro milling experiments at different feed rates. The ploughing forces are modelled as proportional to the interactive area between the bottom segment of the rounded cutting edge and the in-flowing work material. The influence of the edge radius of the cutting tool and the effects of minimum uncut chip thickness, elastic recovery, overlapping tooth engagement etc. are considered in the modelling of the cutting forces. The cutting force model uses separate edge coefficients for the ploughing and shearing dominant regimes of cutting. The paper also analyses the effect of low uncut chip thickness on effective rake angle for different edge radii. The proposed model is compared with the results of several micro milling experiments carried on Zr-based bulk metallic glass. The study reveals that the radial ploughing coefficient is larger than the tangential ploughing coefficient. However, the tangential cutting coefficient is found to be larger than the radial cutting coefficient. At lower feed rates, edge radius of the cutting tool influences the cutting forces due to increased ploughing and rubbing effects. The absolute percentage deviation of the prediction from the experimental values of the average peak cutting force components in X-, Y- and Z- directions are in the range of 4.26-6.16%, 3.24-10.44% and 14.67-28.01% respectively for the feed rate range of 0.5-6
Keywords: Micro end milling; Cutting forces; Mechanistic model; Cutting force coefficients; Cutting edge radius; Ploughing; Elastic recovery; Bulk metallic glass.
Optimal cutting state predictions in internal turning operation with Nano-SiC/GFRE composite layered boring tools
by Bonda Atchuta Ganesh Yuvaraju, Bijoy Kumar Nanda, Jonnalagadda Srinivas
Abstract: This paper presents a passive vibration control methodology in internal turning process with the use of hybrid nanocomposite coatings (nano-SiC/GFRE) on the surface of boring bar. Natural frequencies and damping ratio of different composition tool-holders are obtained experimentally using impact hammer test. Three different configuration considered are: (i) conventional (tool-holder 1), (ii) nano-SiC/GFRE with 1% SiC (tool-holder 2) and (iii) nano-SiC/GFRE with 2% SiC (tool-holder 3). A better damping ability is noticed in third configuration of tool-holder compared to others. Furthermore, using single mode data, analytical stability lobe diagrams are constructed for all three tool-holders. Moreover, Box-Behnken design (BBD) is adopted and a set of fifteen experiments are performed with each tool-holder. For third configuration of tool holder, effect of input variables on the surface roughness and tool vibration amplitudes is studied using neural network model. Finally, the neural network regression model is employed as a function estimation tool in simulated annealing for obtaining optimal cutting conditions.
Keywords: boring bar; passive damping; nanocomposites; tool vibration; surface roughness; modal parameters; stability lobes; design of experiments; analysis of variance; neural network; optimization.
An Application of Fuzzy logic with Grey Relational Technique in Grinding Process using Nano Al2O3 Grinding Wheel on Ti-6Al-4V alloy
by PRABHU SETHURAMALINGAM, Stephen Deborah Serenade
Abstract: This investigation is focused on studying grinding of Titanium alloys (Ti-6Al-4V) by using nano Al2O3 grinding wheel as an alternative approach to existing methods of grinding. To evaluate optimum conditions of grinding process output, a full factorial technique has been used. L27 orthogonal array was chosen to arrive at an optimized permutation of grinding depth of cut, speed and feed. Consequently, the optimal combination of parameters was tested and results were compared with those of a conventional grinding wheel. The results show superior surface finish on Ti alloy when ground with nano Al2O3 grinding wheel. Confirmatory tests assured that a great improvement in Grey Relational Grade with fuzzy logic, from 0.551 to 0.749 was observed, which substantiates the progress in the performance at best possible levels of nano grinding parameters. Improvement of 21.47% in surface finish of the ground material using combinations of Fuzzy grey relational analysis have been achieved.
Keywords: Abrasive grinding; MRR; Nano Al2O3 Grinding Wheel; Surface roughness; Grey Relational Analysis (GRA); Fuzzy logic analysis;.
The problem of determining the ploughing forces
by Alexey Popov, Iuliia Krasnikova
Abstract: Currently, two methods are most often used to determine the ploughing forces: the extrapolation on zero uncut chip thickness and the comparison of total forces at different flank wears. These methods assume that the processes occurring on the front surface of the tool cause no effect on the processes transpiring on the rear surface. This study attempted to prove that the processes on the front surface of the tool affect the processes on the rear surface, and both extrapolation and comparison methods cannot be used to find the ploughing forces. This paper presents the experimental measurement results of the ploughing forces obtained in turn by different methods. The comparison of the measurement results was carried out in turning of aluminum alloys and structural steels in orthogonal cutting. The results of experimental studies showed that the increase in the uncut chip thickness causes the increase in the ploughing forces. This finding proves the connection between the processes occurring on the front and rear surfaces. Thus, the extrapolation method on zero uncut chip thickness and the comparison method of total forces at different flank wears cannot be used to determine the ploughing forces. To accurately reveal the ploughing forces, we suggest using the third method, the comparison method of the total forces for different contact areas, which is based on the dependence of the processes on the rear surface on the processes on the front surface.
Keywords: cutting speed; ploughing forces; turning; uncut chip thickness; wear.
Machinability studies on Al7075 based hybrid composites reinforced with SiC, Graphene and CNT
by Ajithkumar J P, Anthony Xavior M
Abstract: This experimental study analyses the machinability of Graphene-based and Multi Wall Carbon Nano Tubes (MWCNT)-based hybrid metal matrix nano-composites by dry turning process using uncoated and Diamond-Like Carbon (DLC) coated carbide inserts. Al7075 matrix was used along with reinforcements such as Silicon Carbide (SiC), Graphene and CNT. Two composites with different weight fraction namely (i) Al7075 - 10%SiC - 0.1% Graphene, and (ii) Al7075 - 10%SiC - 0.1%CNT were fabricated through the united stir and squeeze casting process with ultra-sonification. The effect of Graphene and CNT on cutting force, surface roughness, flank wear, crater wear and chip morphology were quantified and presented. ISO 3685 (1993) tool life testing standards were followed to conduct the experimental study. Graphene-based composite, recorded the highest cutting force (383.4 N) followed by CNT-based (318.6 N) composite at the considered machining parameters. Higher surface roughness of 0.8519
Keywords: Hybrid Composites; Graphene; MWCNT; Surface Roughness; Wear;.
Study on characteristics of AlTiN and TiCN coating layers deposited on carbide cutting tools in hard turning of steel: experimental, simulation, and optimisation
by Armansyah Ginting, Che Hassan Che Haron, Issam Bencheikh, Mohammed Nouari
Abstract: Objective of the present work is focused to study the characteristics of monolayer PVD-coated carbide AlTiN and TiCN cutting tools. Some features related to machinability such as tool wear, tool life, and surface roughness were adopted to study the tools characteristics. Moreover, effort was also paid to determine the cutting condition for both cutting tools that subjected to another feature, namely volume of material removal (VMR). The results of experiment showed that AlTiN gained higher cutting condition than TiCN due to higher usage temperature of its coating material. However, TiCN produced higher VMR than AlTiN and longer tool life. Flank wear and chipping were observed as the wear modes of both cutting tools. Surface roughness was resulted at the quality of medium finish. The finite element method was utilised to provide an orthogonal cutting simulation for resulting the map of cutting temperature distribution at the tool-chip interface. Finally, multi-objective genetic algorithm optimisation was employed for obtaining the optimum yield of VMR.
Keywords: volume of material removal; orthogonal cutting; cutting temperature; finite element method; multi-objective genetic algorithm.