Increase In Depth Of Cut Research Articles

Bonded-cluster simulation of rock-cutting using PFC2D

The influence of hydrostatic pressure on rock-cutting based on Voronoi grain bonded-cluster model is investigated in this paper. Unconfined compressive strength and Brazilian tests are performed to calibrate the relations between micro-properties and mechanical properties of the rock sample. The influences of hydrostatic pressure, cutting velocity and cutting depth on rock-cutting are researched by particle flow code in 2 dimensions. With no hydrostatic pressure, the fractures in the upper area developed rather quickly into the rock along the horizontal direction when the cutter penetrates over 4 mm. The horizontal crack could eventually arrive at the free surface causing a large volume of fragment chips. Hydrostatic pressure could significantly influence the fracture evolution, inhibiting the formation of the long horizontal fracture. The influence of hydrostatic pressure on rock cutting becomes more and more obvious when the hydrostatic pressure is over 5 MPa. High hydrostatic pressure could inhibit the development of the fractures, increasing the energy requirements of drilling and effectively strengthening the rock. The influence of velocity on rock cutting is not obvious when the cutter penetration is less than 1 mm. However, the fracture volume presents a decreasing trend as the cutting velocity is increasing. There is an optimal cutting velocity for rock cutting, the corresponding optimal cutting velocity is 300 mm/s with high rock fragmentation efficiency. As the cutting depth increases, more and more micro-cracks are initiated around the cutter and the volume of the chipped fragmentation is increasing correspondingly. According to the simulation, it is believed that Voronoi grain-based model will contribute to a better understanding for the rock-tool interaction.

On the critical failure mode transition depth for rock cutting with different back rake angles

The failure mode of rock under cutting exhibits a ductile-brittle transition as the depth of cut increases. The critical transition depth, beyond which energy consumed in brittle fracturing surpasses the energy consumed in plastic flow, is the key to differentiating between the ductile and brittle cutting modes and therefore is an important parameter to optimise tool design and operational parameters to meet specific application requirements. This critical failure mode transition depth depends not only on rock properties but also on cutting operational parameters, in particular, the back rake angle. In this work, a series of rock cutting tests were performed to investigate the influence of back rake angle on the critical failure mode transition depth. Size effect law is employed first to identify the critical transition depths, which are then compared with values derived from the analysis of specific cutting energy. It is found that the critical failure mode transition depth increases with the back rake angle. This suggests that the brittle fracture failure induced at large depth of cut can be inhibited by increasing the back rake angle. Cutting at a small back rake angle, on the other hand, is desirable if minimisation of the cutting energy is required in the application.

Effect of Cutting Parameters on the Surface Residual Stress of Face-Milled Pearlitic Ductile Iron

The study determined the effect of cutting parameters on the surface residual stress of face-milled pearlitic ductile iron with a view to enhancing surface integrity of machined parts in the manufacturing industries. The pearlitic ductile iron used for this study was prepared and four cutting parameters were considered. The results obtained showed that the average surface residual stress of the machined surfaces was tensile and increased significantly with increase in depth of cut. Feed rate and cutting speed exhibited some effect, though not statistically significant, on average surface residual stress. The average residual stress was found to decrease significantly and drastically from 605.39 MPa to 101.72 MPa as cutting fluid flow rate increased from 0 ?/min to 4 ?/min. The study concluded that out of all four cutting parameters investigated, the cutting fluid flow rate has most considerable influence on the surface residual stress of the machined pearlitic ductile iron.

Effect of SiC<sub>p</sub> Reinforcement on Machinability of A356 Alloy Metal Matrix Composites

Machining of Aluminum Metal Matrix Composites (AMMCs) is a challenge for manufacturing industries due to their heterogeneous constituents which vary from soft matrix to hard reinforcements and their interfaces. To overcome the difficulties in machining of MMCs, researchers are continuously working to find the optimum process or machining parameters. In this work, End milling studies were carried out in A356 alloy powder-SiC particles (1 μm) in 0, 5, 10, 15 volume % reinforced AMMCs synthesised by vacuum hot pressing (VHP) route.The influence of machining parameters such as cutting speed, feed and depth of cut on the prepared composites in terms of surface roughness (Ra) and material removal rate (MRR) are measured from experimental study. Experiments were conducted as per Taguchi L16 orthogonal array with 4 factors and 4 levels.From the experimental result, it was identified that surface roughness varied from 0.214 μm to 4.115 μm and MRR varied from minimum of 1.11 cm3/min to maximum of 9.65 cm3/min. It is also observed that, MRR increased with increase in machining parameters and reinforcement quantity. Similarly, surface roughness decreased for increase of cutting speed, SiC particle (SiCp) reinforcement and increased for increase in feed and depth of cut. The optimum condition were observed in higher speed, lower feed and higher depth of cut on MMC with higher SiC content (15%) for getting higher machinability.

Investigation of cutting parameters affecting on tool wear and surface roughness in dry turning of Ti-6Al-4V using CVD and PVD coated tools

There are some problems in the machining of titanium alloys with excellent properties such as high strength, good corrosion resistance, long service life and low weight. The leading problem appears to be the fast tool wear and the bad machining surface. Therefore, in this study, it was investigated whether cutting parameters have effect on tool wear and surface roughness by turning under dry cutting condition of Ti-6Al-4V alloy with excellent properties. CVD (TiCN + Al2O3 + TiN) and PVD (TiAlN) coated WC tools were used in the experiments. Then the Ti-6Al-4V alloy turned with the combinations of the different cutting speed, feed rate, cutting long and depth of cut. We observed that the tools wear in both CVD and PVD coated WC tools increased with increasing the cutting speed, feed rate, depth of cut and cutting length. However, while tools wear increased with increasing cutting speed, the surface roughness reduced to an optimum level. Especially, the surface roughness was worsened above the optimum level changing with increasing the feed rate, cutting length and depth of cut. The tool wear with PVD coated WC tools was observed to be less than the CVD coated WC tools. However, the values of the surface roughness obtained with PVD coated WC tools with increase in depth of cut, feed rate and cutting length has given us higher values when compared to CVD coated WC tools.

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2 ABSTRACT: Stability lobe diagram (SLD) helps in avoiding chatter in high speed machining. The stability lobe diagram has been predicted for the spindle of 32kW and 25,000 rpm. The spindle was modelled with beam elements using FEA tool. The natural frequency of the system was found to be 921Hz by modal analysis. A parametric study involving bearing preload, bearing spacing, span, material of spindle, diameter of spindle was done. An experiment was conducted to verify the variation in natural frequency of the system due to the change in spacing. A substantial shift in frequency was observed by altering the spacing. The cumulative effect of all the design variables resulted in a frequency enhancement from 921Hz to 1300 Hz. The variation of spindle stiffness and natural frequency with speed was plotted for various bearing preloads and design variables. A regression analysis is done to develop an empirical relation to predict the natural frequency of the spindle. Pareto chart was plotted to find the most influencing factor among the design variables. The frequency response function of the spindle system was found by Harmonic analysis. Stability lobe diagram was predicted using MATLAB. Real time machining was done to validate the stability lobe. Parametric study of stability lobe has been done and a significant increase in permissible depth of cut has been observed from stability lobe diagram due to the increase in natural frequency.

Investigation on surface formation mechanism in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire based on fractal analysis method

The elliptical ultrasonic assisted grinding (EUAG) method has been proved to be promising in machining of hard and brittle materials, e.g., sapphire and silicon. However, its potential has not been sufficiently developed because the processing mechanism has not been clearly explained. This paper focuses on the surface formation mechanism in EUAG of monocrystal sapphire by investigating the fractal behavior of ground surface. The EUAG experiments on monocrystal sapphire were performed on the constructed apparatus by installing an elliptical ultrasonic vibrator on a CNC surface grinder. For comparison, the conventional grinding (CG) experiments were also carried out on the same experimental apparatus without ultrasonic vibration. The ground surfaces obtained were analyzed by fractal method, and results show that: (1) the great improvement of the surface quality with lower surface roughness is achieved in EUAG compared with those in CG. Moreover, the fractal dimension of ground surface in EUAG is larger than that in CG. It is also found that the fractal dimension is more sensitive to surface defect compared with the surface roughness. (2) The fractal dimension changes differently comparing CG with EUAG as the depth of cut increases from 0.4 to 3.2 μm. From the variations of the fractal dimension with different depth of cut, it is found that there are two variation regions, i.e., steady region and deteriorated region both in EUAG and CG, but the depth of cut in steady-deteriorated transition point of EUAG is larger than that in CG, meaning that the EUAG can achieve a deeper ductile depth of cut. (3) In EUAG, elliptic motion trajectories of adjacent abrasive grains interact with each other, causing the lower side walls of grooves and more exquisite microstructures. Thus the higher surface fractal dimension in EUAG is obtained and a better surface quality is achieved. Therefore, the surface formation characteristics in EUAG of monocrystal sapphire can be investigated by fractal analysis.

Experimental Investigations on Effect of Ceramic B4C Particulate Addition on Cutting Forces and Surface Roughness during Turning of 6061Al Alloy

ABSTRACTAluminium matrix composites are of great interest for researchers in recent years because of their excellent combinations of engineering properties over traditional materials. The machinability of these aluminium matrix composites has become vital for manufacturing industries. During machining of aluminium matrix composites, the cutting forces and surface roughness are dependent on machining parameters (feed rate, cutting speed and depth of cut) and manufacturing parameters (size of the particles, volume fraction, porosity, hardness). With this backdrop, the present work is aimed at investigating the effect of machining parameters, viz. cutting speed, feed rate and depth of cut on the cutting force components, namely, feed force (Ff), radial force (Fd), cutting force (Fc) and surface roughness. The experiments were performed on 0, 5, 7 and 9 wt% B4C particulate of 88 µm size reinforced composite specimens. The prepared specimens were subjected to turning operation on a conventional lathe machine using polycrystalline diamond (PCD) tool to evaluate the effect of B4C particulate addition with varying percentages on cutting forces and surface roughness. Results reveal that the cutting force components decrease with the increase in the wt% of ceramic B4C particulate reinforcement, which can be attributed mainly to increase in porosity, hardness and dislocation densities. SEM image obtained from composite having low wt% of ceramic B4C particulates (5 wt%), which is machined at higher cutting speed and higher depth of cut, has clearly shown the presence of built-up edge (BUE) at the tip of polycrystalline diamond tool. Further, cutting forces increased with increase in feed rate and depth of cut for both 6061Al matrix and 6061Al-B4C composites. It is observed that the surface quality is significantly improved when the cutting speed is increased, and depth of cut and feed rate are decreased.

Optimization of cutting conditions for minimum residual stress, cutting force and surface roughness in end milling of S50C medium carbon steel

Residual stresses are usually imposed on a machined component due to thermal and mechanical loading. Tensile residual stresses are detrimental as it could shorten the fatigue life of the component; meanwhile, compressive residual stresses are beneficial as it could prolong the fatigue life. Thermal and mechanical loading significantly affect the behavior of residual stress. Therefore, this research focused on the effects of lubricant and milling mode during end milling of S50C medium carbon steel. Numerical factors, namely, spindle speed, feed rate and depth of cut and categorical factors, namely, lubrication and milling mode is optimized using D-optimal experimentation. Mathematical model is developed for the prediction of residual stress, cutting force and surface roughness based on response surface methodology (RSM). Results show that minimum residual stress and cutting force can be achieved during up milling, by adopting the MQL-SiO2 nanolubrication system. Meanwhile, during down milling minimum residual stress and cutting force can be achieved with flood cutting. Moreover, minimum surface roughness can be attained during flood cutting in both up and down milling. The response surface plots indicate that the effect of spindle speed and feed rate is less significant at low depth of cut but this effect significantly increases the residual stress, cutting force and surface roughness as the depth of cut increases.

Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

Machining of metal matrix composites: influence of B4C ceramic particulate addition on cutting forces and surface roughness of 6061Al alloy

Amongst advanced materials, metal matrix composites (MMCs) are gaining importance as materials for structural applications. In particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, and high thermal conductivity. The present work aims at experimental investigations on the influence of addition of ceramic particles (B4C particulate) on the machining of 6061Al matrix produced by stir casting method. Cutting forces and surface roughness were evaluated before and after addition of B4C particles to 6061Al matrix. Results suggest that machining forces decreased with increase in cutting speed in both unreinforced and reinforced alloys. However, a drastic decrease in thrust force was noticed at a cutting speed of 43 m/min. The values of cutting forces obtained were high while dry machining at higher feed rate and depth of cut. Results of surface roughness measurements reveal that the higher surface finish is obtained at higher cutting speeds in both cases. Further, the surface roughness increased with increase in feed rate and depth of cut. The role of the reinforcement particles is revealed by the experimental results thus providing a guide for better control of the machining process.

Influence of machining parameters on surface roughness and dry friction

Article history: Received 6 October, 2015 Accepted 7 March 2016 Available online 8 March 2016 Dry friction depends on the surface topography which, in turn, is governed by machining parameters in addition to several other factors,. Therefore, in order to establish a qualitative relationship among these factors, the surface roughness and coefficient of static friction are measured for specimens machined on lathe and shaper machines with different values of machining parameters. For the case of lathe, the measured Ra value is found to increase with increase in feed rate and depth of cut, whereas, a marginal decrease is observed with increasing spindle speed. Similar results with respect to cutting speed have been obtained for the case of shaper machine. On the other hand, the coefficient of static friction, measured on steel substrate using inclined plane method, is found to decrease with increasing Ra values for both the specimen types. © 2016 Growing Science Ltd. All rights reserved.

Optimization of Machining Parameters for Turning of Al6061 Using Robust Design Principle to Minimize the Surface Roughness

The present work aims at optimization of the process parameter such as cutting speed, depth of cut and feed rate on surface roughness produced on the machined component. Analysis is carried out using Taguchi robust design principles. From the analysis, feed rate is found to be the most influential process parameters which influence the surface roughness followed by cutting speed and depth of cut. Increase in feed rate and depth of cut is found to increase the surface roughness.

<i>In Vitro</i> Experimental and Numerical Analysis of Forces in Plane Cutting of Cortical Bone

Bone cutting is a well know procedure in orthopedics. Large cutting force causes overstressing of the bone which may result in trauma. Control penetration of the cutting tool into bone tissue is important to avoid unnecessary damage to the bone tissue. The purpose of this study was to measure and predict cutting force using experiments and Finite Element (FE) analysis when a plane cutter passes over the bone surface in the presence of irrigation. The effect of cutting speed, tool rake angle, depth of cut and width of the cutting face on the cutting force was found. The force was found to decrease with increase in rake angle and significantly rise with increase in depth of cut and width of cutting face. The cutting force was found unaffected by the range of cutting speed used in experiment as well as in simulations. The results obtained from this study strongly recommend the use of irrigation to minimize plane cutting force or force arising from similar cutting action for safe and efficient surgical incision in bone.

Monitoring of Surface Roughness Based on Cutting Force and Cutting Temperature in Ball-End Milling Process by Utilizing Response Surface Analysis

The surface roughness is monitored using the cutting force and the cutting temperature in the ball-end milling process by utilizing the response surface analysis with the Box-Behnken design. The optimum cutting condition is obtained referring to the minimum surface roughness, which is the spindle speed, the feed rate, the depth of cut, and the tool diameter. The models of cutting force ratio and the cutting temperature are proposed and developed based on the experimental results. It is understood that the surface roughness is improved with an increase in spindle speed, feed rate and depth of cut. The cutting temperature decreases with an increase in tool diameter. The model verification has showed that the experimentally obtained surface roughness model is reliable and accurate to estimate the surface roughness.

STUDIES ON MATERIAL REMOVAL RATE OF AL6061 WHILE TURNING WITH COOLANT AND WITHOUT COOLANT USING TAGUCHI METHOD

Material Removal Rate (MRR) is one of the key attribute of machining process which influences productivity. In this work the effect of various turning process parameters on MRR produced on Al6061 (as cast condition) is investigated. Also, the effect of using coolant on MRR while turning is also determined. MRR is found to increase almost linearly with increase in feed rate. Increase in depth of cut and cutting speed is found to increase the MRR by 70.66 % and 16.36 % respectively

INVESTIGATIONS ON THE SURFACE ROUGHNESS PRODUCED IN TURNING OF AL6061 (AS-CAST) BY TAGUCHI METHOD

Surface roughness produced on the machined component is one of the key attribute of machining process. In this work the effect of various turning process parameters on surface roughness produced on Al6061 (as cast condition) is investigated. Also the effect of using coolant on surface roughness while turning is also determined. It is observed increase in cutting speed by 39.29% resulted in decrease of surface roughness by 31.44%. Increase in feed rate and depth of cut leads to increase in surface roughness. Quantitative analysis of surface roughness obtained in machining with coolant and without coolant is also presented.

Formation of Stability Lobe Diagram (SLD) for Chatter Free Milling on Aluminium Alloy

Chatter is a vibrational phenomenon which may cause damage of the tooling structure. The border between a stable (i.e., no chatter) and an unstable (i.e., with chatter) can be visualized in terms of the axial depth of cut as a function of spindle speed. The enveloping curve is a stability lobe diagram (SLD). Using SLD, it is possible to select cutting parameters to perform chatter-free cutting operations. In present study, an experimental methodology is followed based on tests in which a tapered workpiece allows gradual increase in axial depth of cut in feed direction, representing the Y-coordinate of the SLD while speed of the spindle is increased for every pass representing X-coordinate. Experiments are carried on Siemens 828D MTAB CompactMill machine. Acoustic sensor SKF CMAC 5084 is used to collect the milling sound. This work will allow operator to choose the combination of spindle speed and depth of cut for chatter free milling.

Machinability Study on Finish Turning of AISI H13 Hot Working Die Tool Steel With Cubic Boron Nitride (CBN) Cutting Tool Inserts Using Response Surface Methodology (RSM)

Finish turning of hardened die tool steel offers an economical alternative to grinding process. This study investigated the effects of machining parameters including workpiece hardness in a range of 45–55 HRC on cutting forces (F c & F t ), surface roughness (R a ) and cutting edge temperature (T) in finish turning of AISIH13 die tool steel with CBN inserts. Workpiece material AISIH13 has been selected on the basis of its wide applications in die making industries in the range of hardness 45–60 HRC. A central composite design has been used for the design of experimentation, and by using response surface methodology, a mathematical model has been developed. This study reported that the cutting forces are primarily influenced by the hardness of workpiece material. The work material hardness, feed rate and depth of cut are also statistically significant on cutting forces. Also, cutting forces increases, with the increase in workpiece hardness, feed and depth of cut, whereas the cutting speed has least impact on cutting forces. In fact, increase in hardness of work material resulted in better surface roughness as well as increase in tool tip temperature. Furthermore, optimum parameters are obtained through multi-response optimization technique using desirability function approach. The novelty aspect of the present study is that it contributes to practical industrial application of finish turning for the die and mold makers to select the optimum cutting conditions in a range of hardness of 45–55 HRC.

Roughness modelling analysis for milling of carbon fibre reinforced polymer composites

Carbon fibre reinforced polymer (CFRP) composite materials are finding increased application in aeronautical, automobile and structural applications. During post-processing of carbon fibre reinforced plastics, milling is one of the mostly used machining processes. In this study, the relationship between roughness and milling parameters was developed by response surface methodology, and a roughness model for milling CFRP is proposed. The models are found to be adequate through analysis of variance. The result indicates that the increase in feed rate and radial depth of cut increases the roughness. The spindle speed does not show a general trend on roughness in milling of CFRP composites.