Machining Forces Research Articles

Determination of the friction coefficients between uncoated WC-Co tools and L-PBF and wrought Ti-6Al-4V alloys for micro-milling simulations

This study aims to determine the friction coefficient in the function of the sliding velocity between uncoated WC-Co tools and Ti-6Al-4V alloys processed by Laser Powder Bed Fusion (L-PBF) and the wrought one. A series of tribological tests combined with numerical simulations were performed under different sliding velocities and a constant contact pressure using spherical WC-Co pins and wrought and L-PBF Ti-6Al-4V. The obtained friction coefficients in the function of the sliding velocity were then integrated into two micro-milling models to predict the cutting forces in machining of wrought and L-PBF Ti-6Al-4V, respectively.

Hybrid-hybrid turning of micro-SiCp/AA2124 composites: A comparative study of laser-and-ultrasonic vibration-assisted machining

Machining of micro SiCp/AA2124 composites remains a challenge with conventional machining yielding poor surface quality with high tool wear. In this paper, we study two distinct and unique hybrid machining processes with the aim of improving the machining outcome of three types of micro-SiC/AA2124 composites with different particulate volume fractions and sizes. The class of composites studied is available commercially and is being used in industrial applications, thus assessing the machining outcomes becomes even more pertinent. Vibratory machining where the tool is made to vibrate at ultrasonic frequencies, known as ultrasonically assisted turning (UAT), is shown to yield some clear improvements in machining. Next, we incorporate laser assistance with the goal of inducing thermal softening in the process zone. This hybrid-hybrid machining process which is referred to as laser-ultrasonic-assisted turning (LUAT) has the potential for improved machining outcomes with significantly reduced machining forces and surface topology improvement. Our studies indicate that an optimum laser power exists for each type of metal matrix composite considering the particle size and volume fraction of the particulate reinforcements yielding benefits in terms of machining force reduction, surface topology improvement and potentially tool life enhancement. In addition, a computational machining model was developed which can be used to predict the machining outcomes with variable machining parameters.

Vibration Reduction Design of Consequent Pole PM Machine by Symmetrizing Local and Global Magnetic Field

The consequent pole permanent magnet (CPM) machine is well known for its high magnet utilization ratio and poor vibration performance. This article focuses on electromagnetic vibration and its reduction design in CPM machines, and the conventional surface-mounted permanent magnet (SPM) machine is used as a benchmark. First, the asymmetrical magnetic field and unbalanced radial force of the CPM machine are investigated with emphasis. The slot-pole combination and force modulation effect are the two reasons for the unbalanced radial force generation. Afterward, two new designs to reduce the vibration caused by the unbalanced radial force are proposed, and the reduction principles are described in detail. Finally, the prototypes of the 12-slot/10-pole SPM and proposed CPM machines are manufactured. The tests are conducted to validate the theoretical analysis and proposed vibration reduction design.

RESEARCH WORK OF RESOURCE FOR USING STRAIN GAGE TO DO CUTTING FORCE MEASURING TOOL

Some measuring tools such as pressure gauges, weight gauges, and the grave of pressure gauges were made by using a Strain gage. Based on the principle of these measuring tools Strain gage is required to carry out the force of the lathe machine. That experiment is determined the power of measuring equipment how to increase electromagnetic current, voltage difference, and the magnitude of the resistance, depending on the relative dimension of the compressive strength of the material, and the relative displacement of the material compares to the change in resistance.

Ultra-high performance recycled steel fiber reinforced concrete segments under the thrust force of TBM jacks and their environmental potentialities

Investigations have indicated that segmental tunnel linings are mainly affected during their installation phase, especially at the stage of applying thrust force. Although these concentrated thrust forces are applied temporarily, they can cause cracks and serious damage to segments. One of the main goals of this research is to evaluate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) using recycled steel fibers (RSF) in tunnel lining segments. An experimental and numerical research program, including small-scaled segments (panel samples), was developed to achieve this goal. In this program, an axial load equivalent to the thrust force of a tunnel boring machine (TBM) is applied to 4 different types of samples. Three common states of defects in the support area have also been simulated to examine the more accurate and realistic performance of segment specimens. Another goal of this research is to present a hybrid design for tunnel segments using UHPFRC with RSF in order to significantly reduce the consumption of reinforcement rebar despite the significant increase in the performance of tunnel segments. Based on the results obtained, it was observed that UHPFRC segments with RSF have a good ability to reduce the opening and growth of cracks caused by the thrust forces. The new hybrid reinforced designs have shown significantly better performance compared to the conventional reinforced segments. Crack openings, the first crack starting force, and the environmental friendliness in the full-recycled fiber UHPFRC segments and two new hybrids reinforced samples were improved compared to the conventional reinforced design.

Machinability investigation of Chromoly steel using TiN/Al2O3/TiCN/TiOCN multilayer coated tungsten carbide tool inserts with artificial neural network methodology

AbstractEnhancing the machining efficiency of hardened steel using four‐layer coated tungsten carbide tools has gained a lot of interest among manufacturing engineers. This paper reports the machining performance of AISI 4140 steel using TiN/Al2O3/TiCN/TiOCN multilayer coated tungsten carbide tool inserts. The impact of cutting speed, depth of cut, and the nose radius on machining force, tool chip interface temperature, surface roughness, and chip forms was ascertained using full factorial machining experiments and artificial neural network (ANN) methodology. The machining force evaluated using Logistic Sigmoid activation function resulted in the highest root mean square error (RMSE) of 4.076 and regression value of 0.998. The maximum error between the ANN predicted results and experimental results for machining force, cutting temperature and surface roughness was about 2.4%, 5.3%, and 2.07%, respectively. The best architecture for ANN was “3‐6‐4” which had a coefficient of regression value of 0.97. However, in case of chip form, some of the ANN predicted values could not be mapped to ISO standard chip form and hence prediction accuracy of 80% was achieved.

Molecular dynamics simulation of the tool geometry effect on nanowire formation behavior during nanoskiving

Au nanowires have been promoted in flexible electronics, micro-nano bioelectrodes, and micro-electrochemical detection benefit from their inherent size effect, unique chemical stability, and biocompatibility. Nanoskiving methodology has been confirmed as a feasible approach to preparing multidimensional nanostructures simply and efficiently utilizing ultramicrotome. However, the morphology, dimension, and microstructure of the nanowires will be altered by the tool geometry under extrusion and shearing during the nanoskiving process. Herein, a molecular dynamics simulation and experiments of cutting polycrystalline Au utilizing nanoskiving were performed, and the nanowire formation behavior caused by the variation of the tool geometry was analyzed. Smaller rake angle and larger tool cutting edge radius favor thicker chip thickness, larger high-stress areas, increased machining forces, as well as a shift in cutting formation mechanism from shear to extrusion shear. The reduction in the clearance angle only increases the high-stress areas and machining forces. The stress state and dislocation density within the chip and plastic deformation zone were closely related to the tool topography. The conclusions provide a thorough technical analysis of the mechanism of polycrystalline Au nanowire formation as well as theoretical guidance for the design and selection of tools for nanoskiving processes.

Experimental Analysis of (triaxial /3D) Machining Cutting Forces and Surface Roughness in Turning Operation OF EN8 Steel

Abstract: The measurement of all machining forces and surface finish during the turning process. All types of machining process the cutting tool, workpiece of surfaces roughness, tool wear, quality, and accuracy of the part of machining the present study.to investigate the effect of machining input parameters (spindle speed, feed rate, depth of cut) on measuring the forces after machining (cutting force, feed force, thrust force) and surface roughness for turning operation. Using of workpieces is EN8 steel and a cutting tool is a carbide tool. experiment stabilized on the lathe machine. The force is measured by a triaxial piezoelectric sensors base dynamometer and data is transmitted by a data aquation system. this is controlled by LAB-VIEW software and stores the forces in the computer. there are 27 experiments, and one parameter is changed and two parameters are constant at an experiment. measured the forces and (Ra) is analyzed is by minitab18 software design a regression equation and (ANOVA). The minimum force and (Ra) the experimental (force &surface roughness is nearest to the predicted value

An improved thermomechanical modeling for orthogonal cutting of AISI 1045 steel

In this paper, two Finite Elements (FE) models with different boundary conditions and mesh constraints were developed for orthogonal cutting of AISI 1045 steel by using an Arbitrary Lagrangian-Eulerian (ALE) approach, which allows the absence of the damage criterion and element distortion. We used a Johnson-Cook (J-C) rheological law for the behavior of the work material and a Coulomb's model for the friction at the tool-chip interface. The simulation results were confronted, on the one hand, with experimental data and, on the other hand, with those obtained by thermomechanical analytic modeling. For this last context, some corrections have been made to Oxley's theory by taking into account a non-uniform distribution of the stresses at the tool-chip interface. For this, the normal stress distribution is modeled with a power-law relationship, and tangential stress is weighted by a corrective coefficient. The models evaluation focused on the components of the machining force, the temperature at the tool-chip interface and chip thickness; close agreements with the experiments were observed.

Analytical model of a fractional slot double‐layer‐winding vernier permanent magnet machine

AbstractThis study presents an analytical model (ANA) for predicting magnetic field and performances of a fractional slot (FS) double‐layer‐winding (DLW) vernier permanent magnet (VPM) machine. Magnetic vector potential equations of a FS DLW VPM machine are analytically solved by the technique of variable separation in three subdomains, that is, regions of permanent magnets (PM), air‐gap, and slots in 2‐D polar coordinate system. Field distributions and performances, such as flux linkage, electromotive force (EMF), torque and inductance of a FS DLW VPM machine are developed. Results from ANA of an 18‐slot/2‐stator‐pole‐pair FS DLW VPM machine prototype have been compared with those from finite element analysis (FEA), which indicates that ANA has a huge advantage in the computing speed in addition to a good accuracy. In the end, a prototype is built and its EMF and torque are tested in experiment platforms in which the results verify ANA. The necessity and importance of the research is that the model is an analytical method which provides a close solution of magnetic field and performances of a FS DLW VPM machine and its calculation time is much less than FEA on the base of a good precision.

Experimental analysis of three essential types of hole making strategies in aircraft assembly technology concerning delamination factor

Large-diameter hole drilling for Carbon-Fibre-Reinforced-Polymer (CFRP) is challenging because of its non-homogeneity and anisotropic features. This research will illustrate the hand-laminated and unidirectional CFRP based on three-hole making strategies for helical milling, large hole and pilot hole drilling. In this article, CFRP analyzes and optimizes axial cutting force and Delamination Factor (DF) based on experimental data collected at different FR (Feed Rate). CFRP's large diameter hole quality analysis includes cutting speed (Rotational Tool Speed) and scanning electron microscopy (SEM) analysis of helical milling, pilot hole and large hole drilling. A comparative study between large hole diameter, pilot hole drilling, and helical milling of CFRP was also conducted to discover the better technology for hole calibration quality by analyzing Machining Force (MF) and DF. According to experimental tests of CFRP laminates, the MF is proportional to the FR. Compared to helical milling, pilot hole drilling with proper cutting parameters can create superior quality holes. As a result, it is recommended that pilot hole drilling be done at a low feed rate and a high rotational tool speed for optimum hole quality. The hole calibration was analyzed to distinguish the cutting parameters (Cutting Speed, FR, and MF) to reduce DF and improve hole quality. Low FR was necessary for CFRP high-speed drilling because delamination at the hole exit was a concern.

Mathematical Prediction of Excavating Force and Power of Chain Type Trenching Machine

Abstract A mathematical analysis was done to find out the factors that affect the excavating force and power of a chain type trenching machine. The mathematical analysis showed that the excavating force and power of the chain type trenching machine are affected by tool cutting speed, tool-cutting angle, angle between cutting movement and vertical direction, trench depth and width, coefficient of friction between soil and metal, soil cohesion resistance, and soil specific weight. The results of field experiments showed that the theoretical excavating force (F tt ) was lower than the actual excavating force by 4.0 kN and 3.5 kN for the 1.2 m and 1.5 m trench depth, respectively. The theoretical excavating power (P r ) was lower than the actual excavating power by 3.8% and 2.8% at a trench depth of 1.2 m and 1.5 m, respectively.

Electromagnetic and Electromechanical Compatibility Improvement of a Multi-Winding Switch Control-Based Induction Motor—Theoretical Description and Mathematical Modeling

The main advantages of multi-winding (multiphase) induction machines include reducing torque ripple, decreasing rotor harmonics losses, reducing the current per phase without increasing the voltage per phase, reducing the current harmonics of the DC voltage source, and high fault tolerance. The authors propose a theoretical description for the harmonic content of the DC-link current, magnetomotive force, and electromagnetic torque of a multi-winding induction machine (IM), and an account of the interaction of the time harmonics for the power supply and the spatial harmonics for winding functions is presented. The proposed theoretical analysis has made it possible to substantiate supply-winding schemes for the compensation of higher harmonics (6th and 12th in the DC-link current and the IM’s electromagnetic torque) and the improvement of the electromagnetic and electromechanical compatibility of the multi-winding machine, which are justified according to the proposed theoretical description. Further, a schematic solution for the multi-winding induction motor with electronic changing of the pole number is proposed to provide a reduction in speed ripples at low rotation speeds. This decrease is ensured by increasing the number of pole pairs and increasing the frequency of the supply voltage. Mathematical models of multi-winding switch control-based induction machines are developed using the method of average voltages in the integration step for an investigation of electromagnetic and electromechanical processes. It is shown that the developed models are distinguished by high speed of response and accuracy. This is confirmed by the comparative analysis using known methods and models in the Matlab environment, as well as a comparison of the simulation results with the known results of physical experiments. The results of mathematical modeling show that the use of a multi-winding IM with appropriate supply-winding schemes stands to significantly reduce the ripples of the IM’s electromagnetic torque and DC-link current in the case of using six-step voltage source inverters. This makes this type of inverter suitable for use in a frequency-controlled electric drive as an alternative to using a PWM inverter, which has a negative influence on the IM’s state.

Effect of Nonlinear Spring Characteristics on the Efficiency of Free-Piston Engine Generator

Piston motion is an important factor in improving the energy conversion efficiency of free-piston engine generators (FPEGs), and an air cylinder is an important component affecting piston motion. In this study, the effect of the air cylinder specifications on the piston drive frequency and energy conversion efficiency is clarified. By considering that the repulsion force of an air cylinder is nonlinear, the main factors that change the piston drive frequency were investigated by simulation. In addition, a piston drive frequency diagram was drawn based on the top surface area of the air cylinder and the compression ratio to discuss the effect of the air cylinder specifications on the piston drive frequency. The results indicate that the air cylinder specifications affect the piston drive frequency and generation force of a linear machine. Moreover, the structure of the air cylinder and the constraints on the maximum generation force of the linear machine narrow the possible operating range in the piston drive frequency. The air cylinder specifications based on the piston drive frequency diagram improved the FPEG energy conversion efficiency by 0.5%.

Digital fingerprints of microstructural variation in titanium alloy hip joint forgings via machining force feedback analysis

Considering actual trends regarding life expectancy, it is forecast that the total number of hip replacements will increase in the next few decades due to an increasingly ageing population. This situation will require an increase in component supply and experience of titanium alloy closed-die forging experience in the manufacturing supply chain. However, the scrutiny of microstructural evolution during processing for orthopaedic implants is not at the same level compared to the aerospace industry. This study is focused on understanding the current microstructure quality in the international forging supply chain by applying standard characterisation techniques, currently used in the aerospace industry for safety critical titanium alloy components, as well as a Sheffield developed machining force feedback technique. Three different manufacturers whose near net shape hip joint forgings all successfully pass the industry standards were studied. Through digital fingerprint reconstructions, the microstructural variation has been shown to be linked to the forging process parameters which could help to determine the individual components' fatigue performance. Furthermore, significant variations have been identified in microstructure quality that could compromise the part performance. The study demonstrates that the materials standards for orthopaedic implants could be more stringent to avoid such large microstructural variations in the supply chain. • Significant variation in the supply chain materials quality has been found. • Hip forgings from 3 manufacturers have been characterised to evaluate material consistency. • Specimens conformed to standards, but important materials quality variation was found. • Texture, microstructure, and machining response variation are linked to final fatigue performance. • Forging Variations have been linked to process variables.

Sustainable Machining of Mg-9Al-1.4Zn Foam Used for Temporary Biomedical Implant Using Cryogenic Cooling.

In this study, the drilling performance of biodegradable grade Mg-9Al-1.4Zn alloy reinforced with hollow thin-walled Al2O3 microspheres is inspected under different coolant environments such as dry, Almag® mineral oil, and liquid nitrogen. Drilling experiments were carried out using titanium aluminum nitride PVD coated and uncoated K10 tools on varying volume fractions of magnesium syntactic foams (5%, 10%, and 15%) reinforced with hollow Al2O3 microspheres. Test results showed a 30–60% higher thrust force generated with liquid nitrogen drilling in comparison to dry and oil-based drilling while cutting higher volume fraction foams. Higher microsphere volume fractions of syntactic foam recorded higher machining forces, which is roughly a 200% increase as the volume fraction raised to 15%. The performance of TiAlN PVD tool coating is reflected through a reduction in thrust forces by 20% during cryogenic drilling. Scanning electron microscope (SEM) investigation of cryogenic-machined bore surfaces showed minimal drilling-induced surface defects compared to dry and Almag® mineral oil conditions. A three-dimensional, thermo-mechanical finite element-based model for drilling Mg-9Al-1.4Zn syntactic foam using AdvantEdgeTM is developed for different sustainable lubrication conditions. Surface finish (Ra) showed a 45–55% improvement during cryogenic drilling of 15% syntactic foams with minimized subsurface damages compared to dry and wet cutting conditions. The higher the volume fraction, the higher the surface roughness (Ra) and thrust force under cryogenic machining.

DEM-continuum mechanics coupling simulation of cutting reinforced concrete pile by shield machine

Based on the discrete element method (DEM) - continuum mechanics coupling method, a numerical simulation analysis is carried out to model cutting some existing bridge piles that have invaded Beijing Metro Line 12. Firstly, the macroscopic parameters of the reinforced concrete pile and the soil stratum where the shield tunneling machine traversed are calibrated using uniaxial compression and Brazilian test through a series of numerical tests. In this paper, the procedure of building up a DEM-continuum mechanics coupling model is presented, then the model is applied to simulate the process of cutting the pile foundation using the earth pressure balanced (EPB) shield machine. The influences of different advancing parameters on the displacement of the pile bottom, the thrust force, and the torque of the EPB shield machine are investigated. The simulation-calculated results, such as thrust force and torque of the shield machine, are in good agreement with the theoretical method in previous studies and the corresponding monitored data in the field. Finally, a method based on the thrust of a single cutter is proposed to improve the theoretical model so that it can consider the effects of cutting bridge piles.

Experimental Analysis of Circular Milling for Material Identification in Aerospace Industry

In the airplane design, thousand holes should be manufactured by machining leading this process in the first place for process optimization. Recently, the stack materials used in this application are sheet layers of Titanium alloy, Aluminum alloy and CFRP, which normally are machined under different cutting conditions. There are two main solutions when drilling stacks: using the more conservative ones or changing the parameters for each layer. In orbital drilling the forces are lower, with better quality but with longer machining time, compared to drilling, allowing the measurement and control of the process. Smart machining techniques can be applied for recognising and adapting the cutting parameters in real time, depending on a database for decision-making. In this paper, a technique is proposed to identify the cutting material based on the cutting and feed components of the machining force in a circular milling process. Experiments consist of machining separately Titanium and Aluminium alloy workpieces in a similar range of cutting speed and feed, measuring forces and the position of the cutting tool (X,Y, SP) using the machine-tool data. The results show that it is possible to identify the materials using the calculated tangential and radial force components in the tool referential frame because the values of specific cutting and feed force are significantly different for each material. An specific force map is used as a signature to distinguish the materials in real time machining which can be used for orbital drilling in the next step of the research.

Study on the Formation Mechanism of Cutting Dead Metal Zone for Turning AISI4340 with Different Chamfering Tools.

Tools with chamfered edges are often used in high speed machining of hard materials because they provide compelling cutting toughness and reduced tool wear. Chamfered tools are also responsible for the dead metal zone (DMZ). Through numerical simulation of orthogonal cutting with AISI 4340 steel, this paper examines the mechanism of the DMZ, the cutting speed, the impacts of the chamfer angle, and the coefficient of friction on the generation of the DMZ. The analysis is based upon the Arbitrary Lagrangian-Eulerian (ALE) finite element method (FEM) for the continuous process of chip formation. The different chamfered angles, cutting speeds, and friction coefficient conditions are utilized in the simulation. The research demonstrates that a zone of trapped material called DMZ has been formed beneath the chamfer and serves as an effective cutting edge of the tool. Additionally, the dead metal zone DMZ becomes smaller while the cutting speed increases or the friction coefficient decreases. The machining forces rise with increasing chamfer angles, rise with increasing friction coefficients, and fall with increasing cutting speed in both the cutting and thrust directions. In this paper, the effect of different chamfering tools on AISI 4340 steel using carbide tools in the simulation environment is studied. It has certain reference significance for studying the formation mechanism of the dead zone of difficult-to-machine materials such as AISI4340 and improving the processing efficiency and workpiece surface quality.

Parasitic Computing

Communication on the Internet is guaranteed by a standard set of protocols, used by all computers. Here we show that these protocols can be exploited to compute with the communication infrastructure, transforming the Internet into a distributed computer in which servers unwittingly perform computation on behalf of a remote node. In this model, which we call 'parasitic computing', one machine forces target computers to solve a piece of a complex computational problem merely by engaging them in standard communication. Consequently, the target computers are unaware that they have performed computation for the benefit of a commanding node. As experimental evidence of the principle of parasitic computing, we harness the power of several web servers across the globe, which-unknown to them-work together to solve an NP complete problem.