Abstract: Grinding requires high specific energy and the consequent development of high temperature at tool-workpiece contact zone impairs workpiece quality by inducing thermal damage to the surface. Finishing grinding process requires component to be cut more than one pass. This paper deals with an investigation on the effect of multipass cutting on grinding performance in term of surface roughness and surface defect. An experimental set-up has been developed for this and a detailed comparison has been done with a single pass and various numbers of cutting pass. Results showed that surface roughness increase with the increase in a number of cutting pass. Good surface finish of 0.26μm was obtained for single pass cutting and 0.73μm for twenty pass cutting. It was also observed that the thickness of the white layer increased with the increased in a number of cutting pass.
Abstract: The objective in this work is to generate and discuss the stability results of fully-immersed end-milling process with parameters; tool mass m=0.0431kg,tool natural frequency ωn = 5700 rads^-1, damping factor ξ=0.002 and workpiece cutting coefficient C=3.5x10^7 Nm^-7/4. Different no of teeth is considered for the end-milling. Both 1-DOF and 2-DOF chatter models of the system are generated on the basis of non-linear force law. Chatter stability analysis is carried out using a modified form (generalized for both 1-DOF and 2-DOF models) of recently developed method called Full-discretization. The full-immersion three tooth end-milling together with higher toothed end-milling processes has secondary Hopf bifurcation lobes (SHBL’s) that exhibit one turning (minimum) point each. Each of such SHBL is demarcated by its minimum point into two portions; (i) the Lower Spindle Speed Portion (LSSP) in which bifurcations occur in the right half portion of the unit circle centred at the origin of the complex plane and (ii) the Higher Spindle Speed Portion (HSSP) in which bifurcations occur in the left half portion of the unit circle. Comments are made regarding why bifurcation lobes should generally get bigger and more visible with increase in spindle speed and why flip bifurcation lobes (FBL’s) could be invisible in the low-speed stability chart but visible in the high-speed stability chart of the fully-immersed three-tooth miller.
Abstract: Present investigations involve a systematic study on the machinability of austempered ductile irons (ADI) developed from four commercially viable ductile irons alloyed with different contents of 0, 0.1, 0.3 and 0.6 wt.% of Ni. The influence of Ni content, amount of retained austenite and hardness of ADI on machining behavior has been conducted systematically. Austempering heat treatment was carried out for 120 minutes at four temperatures- 270oC, 320oC, 370oC or 420oC, after austenitization at 900oC for 120 min. Milling tests were performed and machinability index, cutting forces and surface roughness measurements were used to evaluate the machinability. Higher cutting forces, lower machinability index and the poorer surface roughness of the samples austempered at lower temperatures indicated that austempering at higher temperatures resulted in better machinability. The machinability of samples austempered at 420oC, which contained higher fractions of retained austenite, was superior to that of samples austempered at lower temperatures, indicating that hardness is an important factor in assessing machinability in addition to high carbon austenite content. The ADI with 0.6% Ni, austempered at 420°C for 120 minutes, demonstrated best machinability.
Abstract: This investigation presents the formulation of kerf (width of slit) and optimal control parameter settings of wire electrochemical discharge machining which results minimum possible kerf while machining Al7075/SiCp MMCs. WEDM is proved its efficiency and effectiveness to cut the hard ceramic reinforced MMCs within the permissible budget. Among the distinct performance measures of WEDM process, kerf is an important performance characteristic which determines the dimensional accuracy of the machined component while producing high precision components. The lack of available of the machinability information such advanced MMCs result the more experimentation in the manufacturing industries. Therefore, extensive experimental investigations are essential to provide the database of effect of various control parameters on the kerf while machining such advanced MMCs in WEDM. Literature reviled the significance some of the electrical parameters which are prominent on kerf for machining distinct conventional materials. However, the significance of reinforced particulate size and volume fraction on kerf is highlighted in this work while machining MMCs along with the machining parameters of pulse-on time, pulse-off time and wire tension. Usually, the dimensional tolerances of machined components are decided at the design stage and a machinist pay attention to produce the required dimensional tolerances by setting appropriate machining control variables. However, it is highly difficult to determine the optimal machining settings for such advanced materials on the shop floor. Therefore, in the view of precision of cut, kerf (cutting width) is considered as the measure of performance for the model. It was found from the literature that, the machining conditions of higher fractions of large size SiCp resulting less kerf where as high values of pulse-on time result in a high kerf. A response surface model is used to predict the relative significance of various control variables on kerf. Consequently, a powerful artificial intelligence called genetic algorithms (GA) is used to determine the best combination of the control variable settings. In the next step the conformation test was conducted for the optimal parameter settings and found good agreement between the GA kerf and measured kerf. Hence, it is clearly reveal that the effectiveness and accuracy of the developed model and program to analyze the kerf and to determine its optimal process parameters. The results obtained in this work states that, the resulted optimized parameters are capable of machining the Al7075/SiCp MMCs more efficiently and with better dimensional accuracy.
Abstract: Conventional coagulation, advance oxidation process (AOPs), and the combined process were evaluated and compared for its suitability to treat the stabilized cutting-oil wastewater. The 90% efficiency was obtained from the coagulation at Al2(SO4)3 dosage of 150 mg/L and pH 7. On the other hands, efficiencies of AOPs for 30 minutes oxidation time were 10% for acoustic oxidation, 12% for acoustic oxidation with hydrogen peroxide, 76% for Fenton, and 92% sono-Fenton processes. The highest efficiency for effective oil removal of AOPs required large amount of chemical. Therefore, AOPs were studied as a post-treatment after conventional separation process. The efficiency was considerable as the effluent COD can pass the standard required for industrial wastewater discharge with less chemical and energy consumption.
Abstract: The present paper describes the development of a low cost, highly accurate low capacitance measurement system that can be used over a range of 0 – 400 pF with a resolution of 1 pF. The range of capacitance may be easily altered by a simple resistance or capacitance variation of the measurement circuit. This capacitance measurement system uses quad two-input NAND Schmitt trigger circuit CD4093B with hysteresis for the measurement and this system is integrated with PIC 18F2550 microcontroller for data acquisition purpose. The microcontroller interacts with software developed in the PC end through USB architecture and an attractive graphical user interface (GUI) based system is developed in the PC end to provide the user with real time, online display of capacitance under measurement. The system uses a differential mode of capacitance measurement, with reference to a trimmer capacitance, that effectively compensates lead capacitances, a notorious error encountered in usual low capacitance measurements. The hysteresis provided in the Schmitt-trigger circuits enable reliable operation of the system by greatly minimizing the possibility of false triggering because of stray interferences, usually regarded as another source of significant error. The real life testing of the proposed system showed that our measurements could produce highly accurate capacitance measurements, when compared to cutting edge, high end digital capacitance meters.
Abstract: Quick and qualitative services are not new issues anymore in Logistics but those are still important problems along with cost-cutting. Related to the issues, though advanced information technologies are introduced unceasingly from laboratories, yet there is long way to go for smooth and seamless information flows on physical distribution processes in the industrial field. For the reason, the study aims to seek an advanced information delivery and management strategy through an in-depth case study of a Korea intermodal transportation company. It provides an industrial reference and a way to improve the endemic problems of logistics information systems.
Abstract: Paper is dealing by testing of IN23 ceramic cutting tools at irregular shocks at special fixture - interrupted cut simulator. Standard tests provided at fixture were at regular interrupted cut at 4 slats by 90°. These new tests will be at irregular cut for 1 slat, 2 slats against each other, 2 slats side by side, 3 slats and 4 slats. The main goal is check if irregular shocks have influence at mechanical and thermal shock at tool life of cutting inserts.
Abstract: Abrasive Water Jet Machining is an unconventional machining process well known for machining hard to cut materials. The primary research focus on the process was for through cutting and a very limited literature is available on pocket milling using AWJM. The present work is an attempt to use this process for milling applications considering a set of various process parameters. Four different input parameters, which were considered by researchers for part separation, are selected for the above application, i.e., abrasive size, flow rate, standoff distance and traverse speed. Pockets of definite size are machined to investigate surface roughness, material removal rate and pocket depth. Based on the data available through experiments on SS304 material, it is observed that higher traverse speeds gives a better finish because of reduction in the particle energy density and lower depth is also observed. Increase in the standoff distance and abrasive flow rate reduces the rate of material removal as the jet loses its focus and occurrence of collisions within the particles. ANOVA for individual output parameter has been studied to know the significant process parameters.
Abstract: In this study, WC-Ni-based cemented carbides having different nickel contents were used as the substrate for cutting tool materials. Hardened steel was turned by a (Ti,W,Si)N-coated WC-Ni-based cemented carbide tool, and the tool wear was experimentally investigated. The following results were obtained: (1) In the (Ti,W,Si)N-coated WC-Ni-based cemented carbide, the hardness of the coating film was not much different from the content of the binding material, Ni, and the adhesion strength increased with a decrease in Ni content. (2) There is little difference between the wear progress of the (Ti,W,Si)N-coated WC-7%Ni-based cemented carbide tool and that of the (Ti,W,Si)N-coated WC-6%Co-based cemented carbide tool. (3) The wear progress of the (Ti,W,Si)N-coated WC-Ni-based cemented carbide became slower with a decrease in Ni content.
From the above, it is has become clear that WC-Ni-based cemented carbide can be used as a substrate for cutting tool materials.
Abstract: The article deals with the possibilities of increasing the efficiency of turning thin-walled workpieces. It proposes a new strategy for turning and it proposes new implementation of roughing cycles where a variable depth of cut is applied. Proposed roughing cycles are created in the CAD/CAM system. These roughing cycles are described in relation to their further use in practice.
The experimental research has focused on monitoring the durability of cutting tool and increases its tool life. It compares the turning where the standard roughing cycle is used and the turning where the proposed roughing cycle with variable depth of cut is applied. In article are monitored tool wear during cutting with the sintered carbide cutting edge. The result verifies theoretical prerequisites of tool wear.
Abstract: This paper presents an implementation and performance test of a distributed motion control system based on a master-slave configuration used to move a plasma-cutting torch over a predefined trajectory. The master is a general-purpose computer running on an open source operating system platform and software developer. Software running in the master computer generates commands on real time and we measure performance based on a selected set of differences between expected and observed distances. We are testing the null hypothesis that the outcome trajectory is identical to the input against the alternative hypothesis that there is a shift to the right or left of the input one. We used the Wilcoxon signed ranks test method for the hypothesis test.
Abstract: This study presents a new method for detecting the
cutting tool wear based on the measured cutting force signals using
the regression model and I-kaz method. The detection of tool wear
was done automatically using the in-house developed regression
model and 3D graphic presentation of I-kaz 3D coefficient during
machining process. The machining tests were carried out on a CNC
turning machine Colchester Master Tornado T4 in dry cutting
condition, and Kistler 9255B dynamometer was used to measure the
cutting force signals, which then stored and displayed in the DasyLab
software. The progression of the cutting tool flank wear land (VB)
was indicated by the amount of the cutting force generated. Later, the
I-kaz was used to analyze all the cutting force signals from beginning
of the cut until the rejection stage of the cutting tool. Results of the IKaz
analysis were represented by various characteristic of I-kaz 3D
coefficient and 3D graphic presentation. The I-kaz 3D coefficient
number decreases when the tool wear increases. This method can be
used for real time tool wear monitoring.
Abstract: Jatropha curcas stem was analyzed for chemical
compositions: 19.11% pentosan, 42.99% alphacellulose and 24.11%
lignin based on dry weight of 100-g raw material. The condition to
fractionate cellulose, hemicellulose and lignin in J. curcas stem using
steam explosion was optimized. The procedure started from cutting J.
curcas stem into small pieces and soaked in water for overnight.
After that, they were steam exploded at 214 °C and 21 kg/cm2 for 5
min. The obtained hydrolysate contained 1.55 g/L ferulic acid which
after that was used as substrate for vanillin production by Aspergillus
niger and Pycnoporus cinnabarinus in one-step process. The
maximum 0.65 g/L of vanillin were obtained with the conversion rate
of 45.2% based on the initial ferulic acid.
Abstract: This paper presents a comparative study on dry and wet grinding through experimental investigation in the grinding of CSM glass fibre reinforced polymer laminates using a pink aluminium oxide wheel. Different sets of experiments were performed to study the effects of the independent grinding parameters such as grinding wheel speed, feed and depth of cut on dependent performance criteria such as cutting forces and surface finish. Experimental conditions were laid out using design of experiment central composite design. An effective coolant was sought in this study to minimise cutting forces and surface roughness for GFRP laminates grinding. Test results showed that the use of coolants reduces surface roughness, although not necessarily the cutting forces. These research findings provide useful economic machining solution in terms of optimized grinding conditions for grinding CSM GFRP.
Abstract: Flow field around hypersonic vehicles is very
complex and difficult to simulate. The boundary layers are squeezed
between shock layer and body surface. Resolution of boundary layer,
shock wave and turbulent regions where the flow field has high
values is difficult of capture. Detached eddy simulation (DES) is a
modification of a RANS model in which the model switches to a
subgrid scale formulation in regions fine enough for LES
calculations. Regions near solid body boundaries and where the
turbulent length scale is less than the maximum grid dimension are
assigned the RANS mode of solution. As the turbulent length scale
exceeds the grid dimension, the regions are solved using the LES
mode. Therefore the grid resolution is not as demanding as pure LES,
thereby considerably cutting down the cost of the computation. In
this research study hypersonic flow is simulated at Mach 8 and
different angle of attacks to resolve the proper boundary layers and
discontinuities. The flow is also simulated in the long wake regions.
Mesh is little different than RANS simulations and it is made dense
near the boundary layers and in the wake regions to resolve it
properly. Hypersonic blunt cone cylinder body with frustrum at angle
5o and 10 o are simulated and there aerodynamics study is performed
to calculate aerodynamics characteristics of different geometries. The
results and then compared with experimental as well as with some
turbulence model (SA Model). The results achieved with DES
simulation have very good resolution as well as have excellent
agreement with experimental and available data. Unsteady
simulations are performed for DES calculations by using duel time
stepping method or implicit time stepping. The simulations are
performed at Mach number 8 and angle of attack from 0o to 10o for
all these cases. The results and resolutions for DES model found
much better than SA turbulence model.
Abstract: This paper introduces a novel design for boring bar with enhanced damping capability. The principle followed in the design phase was to enhance the damping capability minimizing the loss in static stiffness through implementation of composite material interfaces. The newly designed tool has been compared to a conventional tool. The evaluation criteria were the dynamic characteristics, frequency and damping ratio, of the machining system, as well as the surface roughness of the machined workpieces. The use of composite material in the design of damped tool has been demonstrated effective. Furthermore, the autoregressive moving average (ARMA) models presented in this paper take into consideration the interaction between the elastic structure of the machine tool and the cutting process and can therefore be used to characterize the machining system in operational conditions.
Abstract: An attempt has been made to investigate the
machinability of zirconia toughened alumina (ZTA) inserts while
turning AISI 4340 steel. The insert was prepared by powder
metallurgy process route and the machining experiments were
performed based on Response Surface Methodology (RSM) design
called Central Composite Design (CCD). The mathematical model of
flank wear, cutting force and surface roughness have been developed
using second order regression analysis. The adequacy of model has
been carried out based on Analysis of variance (ANOVA) techniques.
It can be concluded that cutting speed and feed rate are the two most
influential factor for flank wear and cutting force prediction. For
surface roughness determination, the cutting speed & depth of cut
both have significant contribution. Key parameters effect on each
response has also been presented in graphical contours for choosing
the operating parameter preciously. 83% desirability level has been
achieved using this optimized condition.
Abstract: Chatter vibration has been a troublesome problem
for a machine tool toward the high precision and high speed machining.
Essentially, the machining performance is determined by the dynamic
characteristics of the machine tool structure and dynamics of cutting
process, which can further be identified in terms of the stability lobe
diagram. Therefore, realization on the machine tool dynamic behavior
can help to enhance the cutting stability. To assess the dynamic
characteristics and machining stability of a vertical milling system
under the influence of a linear guide, this study developed a finite
element model integrated the modeling of linear components with the
implementation of contact stiffness at the rolling interface. Both the
finite element simulations and experimental measurements reveal that
the linear guide with different preload greatly affects the vibration
behavior and milling stability of the vertical column spindle head
system, which also clearly indicate that the predictions of the
machining stability agree well with the cutting tests. It is believed that
the proposed model can be successfully applied to evaluate the
dynamics performance of machine tool systems of various
configurations.
Abstract: A new tool path planning method for 5-axis flank
milling of a globoidal indexing cam is developed in this paper. The
globoidal indexing cam is a practical transmission mechanism due
to its high transmission speed, accuracy and dynamic performance.
Machining the cam profile is a complex and precise task. The profile
surface of the globoidal cam is generated by the conjugate contact
motion of the roller. The generated complex profile surface is usually
machined by 5-axis point-milling method. The point-milling method
is time-consuming compared with flank milling. The tool path for
5-axis flank milling of globoidal cam is developed to improve the
cutting efficiency. The flank milling tool path is globally optimized
according to the minimum zone criterion, and high accuracy is
guaranteed. The computational example and cutting simulation finally
validate the developed method.