Tool Forces Research Articles

Effects of blended vegetable‐based cutting fluids with extreme pressure on tool wear and force components in turning of Al 7075‐T6

ABSTRACTIn this study, performances of four different types of vegetable‐based cutting fluids (VBCFs) over a commercial mineral cutting fluid were evaluated for machinability of Al 7075‐T6. Lubrication properties of VBCFs were improved with additive of extreme pressure. Cutting force and tool wear data were obtained for performance analyses of cutting fluids during longitudinal turning of Al 7075‐T6. Cutting, feed and radial forces indicated 1.70–38.25% improvements for VBCFs over the commercial mineral cutting fluid. The lowest average values of flank and nose wears obtained with blended cutting fluid containing 12% of extreme pressure were 0.09 and 0.10 mm, respectively, whereas these values for the commercial mineral cutting fluid were 0.18 and 0.15 mm. The scanning electron microscope results showed adherence of workpiece material occurred on rake and flank faces, and flank and nose wears were the dominant wear modes. It was found that performances of VBCFs during turning of Al 7075‐T6 were better than that of the commercial mineral cutting fluid. Copyright © 2012 John Wiley & Sons, Ltd.

Finite element modelling and experimental investigation of single point incremental forming process of aluminum sheets: influence of process parameters on punch force monitoring and on mechanical and geometrical quality of parts

New trends in sheet metal forming are rapidly developing and several new forming processes have been proposed to accomplish the goals of flexibility and cost reduction. Among them, Incremental CNC sheet forming operations (ISF) are a relatively new sheet metal forming processes for small batch production and prototyping. In single point incremental forming (SPIF), the final shape of the component is obtained by the CNC relative movements of a simple and small punch which deform a clamped blank into the desired shape and which appear quite promising. No other dies are required than the ones used in any conventional sheet metal forming processes. As it is well known, the design of a mechanical component requires some decisions about the mechanical resistance and geometrical quality of the parts and the product has to be manufactured with a careful definition of the process set up. The use of computers in manufacturing has enabled the development of several new sheet metal forming processes, which are based upon older technologies. Although standard sheet metal forming processes are strongly controlled, new processes like single point incremental sheet forming can be improved. The SPIF concept allows to increase flexibility and to reduce set up costs. Such a process has a negative effect on the shape accuracy by initiating undesired rigid movement and sheet thinning. In the paper, the applicability of the numerical technique and the experimental test program to incremental forming of sheet metal is examined. Concerning the numerical simulation, a static implicit finite element code ABAQUS/Standard is used. These two techniques emphasize the necessity to control some process parameters to improve the final product quality. The reported approaches were mainly focused on the influence of four process parameters on the punch force trends generated in this forming process, the thickness and the equivalent plastic deformation distribution within the whole volume of the workpiece: the initial sheet thickness, the wall angle, the workpiece geometry and the nature of tool path contours controlled through CNC programming. The tool forces required to deform plastically the sheet around the contact area are discussed. The effect of the blank thickness and the tool path on the punch load and the deformation behaviour is also examined with respect to several tool paths. Furthermore, the force acting on the traveling tool is also evaluated. Similar to the sheet thickness, the effect of wall angle and part geometry on the load evolution, the distribution of calculated equivalent plastic strain and the variation of sheet thickness strain are also discussed. Experimental and numerical results obtained allow having a better knowledge of mechanical and geometrical responses from different parts manufactured by SPIF with the aim to improve their accuracy. It is also concluded that the numerical simulation might be exploited for optimization of the incremental forming process of sheet metal.

Recent progress for capillary electrophoresis with electrochemical detection

Abstract Capillary electrophoresis (CE) is an attractive technique in separation science because of its high separation performance, short analysis time and low cost. Electrochemical detection (EC) is a powerful tool for CE because of its high sensitivity. In this review, developments of CE-EC from 2008 to August, 2011 are reviewed. We choose papers of innovative and novel results to demonstrate the newest and most important progress in CE-EC.

A Three-Dimensional Inverse Finite Element Analysis of the Heel Pad

Quantification of plantar tissue behavior of the heel pad is essential in developing computational models for predictive analysis of preventive treatment options such as footwear for patients with diabetes. Simulation based studies in the past have generally adopted heel pad properties from the literature, in return using heel-specific geometry with material properties of a different heel. In exceptional cases, patient-specific material characterization was performed with simplified two-dimensional models, without further evaluation of a heel-specific response under different loading conditions. The aim of this study was to conduct an inverse finite element analysis of the heel in order to calculate heel-specific material properties in situ. Multidimensional experimental data available from a previous cadaver study by Erdemir et al. ("An Elaborate Data Set Characterizing the Mechanical Response of the Foot," ASME J. Biomech. Eng., 131(9), pp. 094502) was used for model development, optimization, and evaluation of material properties. A specimen-specific three-dimensional finite element representation was developed. Heel pad material properties were determined using inverse finite element analysis by fitting the model behavior to the experimental data. Compression dominant loading, applied using a spherical indenter, was used for optimization of the material properties. The optimized material properties were evaluated through simulations representative of a combined loading scenario (compression and anterior-posterior shear) with a spherical indenter and also of a compression dominant loading applied using an elevated platform. Optimized heel pad material coefficients were 0.001084 MPa (μ), 9.780 (α) (with an effective Poisson's ratio (ν) of 0.475), for a first-order nearly incompressible Ogden material model. The model predicted structural response of the heel pad was in good agreement for both the optimization (<1.05% maximum tool force, 0.9% maximum tool displacement) and validation cases (6.5% maximum tool force, 15% maximum tool displacement). The inverse analysis successfully predicted the material properties for the given specimen-specific heel pad using the experimental data for the specimen. The modeling framework and results can be used for accurate predictions of the three-dimensional interaction of the heel pad with its surroundings.

Evaluation of the Enhanced Assumed Strain and Assumed Natural Strain in the SSH3D and RESS3 Solid Shell Elements for Single Point Incremental Forming Simulation

Single Point Incremental Forming (SPIF) is a recent sheet forming process which can give a symmetrical or asymmetrical shape by using a small tool. Without the need of dies, the SPIF is capable to deal with rapid prototyping and small batch productions at low cost. Extensive research from both experimental and numerical sides has been carried out in the last years. Recent developments in the finite element simulations for sheet metal forming have allowed new modeling techniques, such as the Solid Shell elements, which combine the main features of shell hypothesis with a solid-brick element. In this article, two recently developed elements -SSH3D element [1, 2] and RESS3 element [3]- implemented in Lagamine (finite element code developed by the ArGEnCo department of the University of Liège) are explained and evaluated using the SPIF line test. To avoid locking problems, the well-known Enhanced Assumed Strain (EAS) and Assumed Natural Strain (ANS) techniques are used. The influence of the different EAS and ANS parameters are analized comparing the predicted tool forces and the shape of a transversal cut, at the end of the process. The results show a strong influence of the EAS in the forces prediction, proving that a correct choice is fundamental for an accurate simulation of the SPIF using Solid Shell elements.

Atomic Simulation of Multi-tool Nanomachining Process

Multi-tool nanocutting single crystal copper processes are simulated by molecular dynamics. Then, nanomachining mechanism and removal processes are analyzed by atoms energy, and local atomic structures of the workpiece atoms are identified in the nanomachining process. The results show that local atomic structures of stacking atoms near the tool come to phase transition, which transforms from ideal FCC to icosahedra-like structure, closed-packed structure and defective FCC structure. In addition, the cutting force of two-side tools is high in the multi-tool nanocutting process during the preliminary phase of the cutting process. And then, the force of middle tool is higher than others. The removal atoms numbers increase with the increasing tools and the removal ratio of atoms increases when the distance between the tools increases.

Force generation during friction stir welding of AA2024-T3

Force measurement in friction stir welding (FSW) provides a significant insight into the process in terms of machine and tool limitations and design. In the present research the tool forces were investigated experimentally using a rotating component dynamometer and through the development of a finite element model. The model correlated well with experimental temperatures and tool forces and was capable of predicting tool forces for different welding parameters, predicting regions were tool failure is likely to occur and identifying tool pin designs which can process the workpiece more efficiently.

A methodology to estimate the forces on the tool insert in finish hard turning

The work presents a methodology to predict the forces on a worn cutting tool insert in finish hard turning when cutting action is limited to the round nose of the insert. The forces acting on the sharp tool, due to material shear at the cutting edge, were estimated using minimum energy criterion. The induced forces due to chip tool rubbing were estimated using the rake face normal and shear stresses. Instantaneous flank wear was used to estimate the increase in tool forces due to rubbing at the flank-work interface. The flank wear is assumed to be homogeneous all over the tool nose involved in cutting. Machining parameters and the data related to the tool and work piece material used in the model were taken from a previous work that used an equivalent side cutting edge angle to model the worn tool forces. Force estimation from the proposed model was found to be in coherence with the predictions and measured forces from the referred work.

Investigation on Effect of Tool Forces and Joint Defects During FSW of Polypropylene Plate

Friction Stir Welding (FSW) is a solid-state method of joining thermoplastic materials. In this investigation, an attempt was made to join the polypropylene plate of 10mm thickness with different tool pin profiles (square, triangular, threaded and grooved with square pin profile). During FSW, Forces acting on the tool along the travel distance and defects occurred in the joints are observed with respect constant rotational speed and different welding feeds. From this investigation, it is found that the joint fabricated using threaded pin profile tool produce less amount of force and square, triangular & grooved with square pin profile produced defect free welds.

AIPaint: A Sketch-Based Behavior Tree Authoring Tool

Current behavior authoring tools force game designers to split their attention between the game context and the tool context. We have addressed this problem by developing a behavior authoring tool that merges these two contexts. This paper outlines the design and implementation of a gameindependent behavior tree authoring tool, called AIPaint, that allows a designer to create and edit behavior trees via a natural sketching interface overlaid on the game world. We demonstrate the use of AIPaint to author computercontrolled characters in two simple games and report on an observational evaluation.

Effects of the roller feed ratio on wrinkling failure in conventional spinning of a cylindrical cup

In this study, wrinkling failure in conventional spinning of a cylindrical cup has been investigated by using both finite element (FE) analysis and experimental methods. FE simulation models of a spinning experiment have been developed using the explicit finite element solution method provided by the software Abaqus. The severity of wrinkles is quantified by calculating the standard deviation of the radial coordinates of element nodes on the edge of the workpiece obtained from the FE models. The results show that the severity of wrinkles tends to increase when increasing the roller feed ratio. A forming limit study for wrinkling has been carried out and shows that there is a feed ratio limit beyond which the wrinkling failure will take place. Provided that the feed ratio is kept below this limit, the wrinkling failure can be prevented. It is believed that high compressive tangential stresses in the local forming zone are the causes of the wrinkling failure. Furthermore, the computational performance of the solid and shell elements in simulating the spinning process are examined and the tool forces obtained from wrinkling and wrinkle-free models are compared. Finally, the effects of the feed ratio on variations of the wall thickness of the spun cylindrical cup are investigated.

Transient Dynamic Analysis of Maglev Linear Feed Unit

Abstract. The magnetic levitation linear feed unit is a new type of machine features. In machining, the tool and workpiece interaction force will be delivered to the table and make the deformation, resulting in processing errors of machine tools, machining of precision and surface quality. In this paper we established three-dimensional finite element model of the table of feed unit, use the finite element analysis software ANSYS to analysis of the transient dynamic analysis of the pre-designed table and improve the structure of the table at the design stage and forecast performance of the table and provide a theoretical basis for structure optimization.

A study of effects of roller path profiles on tool forces and part wall thickness variation in conventional metal spinning

Sheet metal spinning has seen significant developments in recent years. However, in the present industrial practice, the process design still highly relies on undocumented expertise; trial-and-error approach is commonly used to design the roller path and passes. In this paper, four different roller path profiles, i.e. combined concave and convex, convex, linear, and concave, have been designed and used to carry out spinning experiments and to conduct finite element (FE) analysis. The effects of these roller paths on tool forces, part wall thickness and stress variations in conventional metal spinning have been analysed numerically. The results show that the concave path produces highest tool forces among these four roller path profiles. Using the concave roller path tends to cause higher reductions of wall thickness of the spun part and using the convex roller path helps to maintain the original wall thickness unchanged. A greater curvature of the concave path would result in more thinning in wall thickness of the spun part.

Estimating the variability of tillage forces on a chisel plough shank by modeling the variability of tillage system parameters

In this paper, a probabilistic approach is proposed for quantifying the variability of the tillage forces for the shank of a chisel plough with narrow tines and to estimate the failure probability. An existing three-dimensional analytical model of tool forces from McKyes was used to model the interaction between the tillage tools and the soil. The variability of tillage forces was modeled, taking into account the variability of soil engineering properties, tool design parameters and operational conditions. The variability of the soil engineering properties was modeled by means of experimental observations. The dispersion effect of each tillage system parameter on the tillage forces was determined by a sensitivity analysis. The results show that the variability of the horizontal and vertical forces follows a lognormal distribution ( μ = 0.872, ξ = 0.449; μ = 0.004, ξ = 0.447) and the relationship between these forces is positive and quasi-linear ( ρ( P H , P v ) = 0.93).This lognormal variability was integrated into the estimation of the failure probability for the shank by using Monte Carlo simulation (MCS) and the first-order reliability method (FORM). The results obtained by these two methods, with the assumption of non-correlation between the horizontal and vertical forces, were almost identical. However, the FORM method was faster and simpler, compared to the MCS technique. Furthermore, the correlation between the horizontal and vertical forces has no significant effect on the failure probability, regardless of the correlation strength. Therefore, it is concluded that the FORM method can be used to estimate the failure probability without considering the correlation between horizontal and vertical forces.

Determination of Surgical Robot Tool Force Requirements Through Tissue Manipulation and Suture Force Measurement

Through the use of a cadaveric porcine model, forces necessary for manipulation of the abdominal organs were evaluated using an instrumented probe. Additionally, forces for tissue puncture, knot tightening, and suture breakage have been measured in order to determine the requirements placed upon the design of novel robotic surgical tools. The break forces for a variety of suture sizes and types were evaluated including sizes 3-0 through 7-0 polypropylene, size 1 polybutestor, size 4-0 chromic gut, and size 6-0 braided polyester. Tests of the tissue puncture force and knot tightening forces were carried out using the same instrumented probe, while the suture break forces were measured using a tension testing machine. The measured forces were found to compare well against the literature and provide a good basis from which to design robotic surgical tools with the appropriate capabilities.

Investigation of Interatomic Potential on Chip Formation Mechanism in Nanometric Cutting Using MD Simulation

Nowadays, the nano-machining process is used to produce high quality finished surfaces with precise form accuracy. To understand and analyze the chip formation mechanism of nano-machining process on an atomistic scale, since the experimentation is not an easy task, numerical simulation such as molecular dynamic (MD) simulation is a very useful method. In this paper, MD simulation of the nano-metric cutting of single-crystal copper was performed with a single crystal diamond tool. The model was solved with both pair wise Morse potential function and embedded atom method (EAM) potential to simulate the inter-atomic force between the work-piece and a rigid tool. The chip formation mechanism, dislocation generation, tool forces and generated temperature were investigated. Results show that the Morse potential cannot perform an appropriate defect formation and plastic deformation in nano-metric cutting of metals. Also, tool forces in Morse potential are more than the forces in EAM potential. Furthermore, the fluctuations of resultant forces in Morse potential are greater than that of EAM. In addition, using many-body interaction potentials like EAM can lead to substantial changes in surface energies, elastic-plastic properties and atomic displacement, compared with the pair-wise potentials like Morse. Finally, the atomic displacement investigation shows that in EAM potential study, only the atoms in a local region near the cutting process are displaced, but in Morse potential a large portion of atoms has affected during cutting process. Subsequently, the chip temperature in EAM potential is more than that of Morse potential.

3-D Finite Element Simulation of Friction Stir Welding Process of Non Similar Aluminum-Copper Sheets

The Friction Stir Welding (FSW), a relatively new welding process, was developed in 1991 at the Welding Institute near Cambridge, England. There are two tool speeds to be considered in friction-stir welding; how fast the tool rotates and how quickly it traverses the interface. These two parameters have considerable importance and must be chosen with care to ensure a successful and efficient welding cycle. The relationship between the welding speeds and the heat input during welding is complex. In this paper the friction stir welding (FSW) process of stainless steel alloys has been modeled using a three dimensional finite element method. A coupled thermal viscoplastic model was used for the simulation. Tool speeds and temperature distribution are coupled and solved together using this method. The relationship between the welding speeds and the heat input during welding is obtained by numerical analysis, and the stress contour occurred by temperature field and tool force is surveyed. In addition, the effects of FSW process conditions on heating mainly near the tool pin are investigated in this paper.

Effect of Tool Nose Radius on Nano-Machining Process by Molecular Dynamics Simulation

Today, there is a need to understand the micro mechanism of material removal to achieve a better roughness in ultra precision machining (UPM). The conventional finite element method becomes impossible to use because the target region and grids are very tiny. In addition, FEM cannot consider the micro property of the material such as atomic defect and dislocation. As an alternative, molecular dynamics (MD) simulation is significantly implemented in the field of nano-machining and nano-tribological problems to investigate deformation mechanism like work hardening, stick-slip phenomenon, frictional resistance and surface roughness [1]. One of the machining parameters than can affect nano-cutting deformation and the machined surface quality is tool nose radius [2]. In this paper molecular dynamics simulations of the nano-metric cutting on single-crystal copper were performed with the embedded atom method (EAM). To investigate the effect of tool nose radius, a comparison was done between a sharp tool with no edge radius and tools with a variety of edge radii. Tool forces, coefficient of friction, specific energy and nature of material removal with distribution of dislocations were simulated. Results show that in the nano-machining process, the tool nose radius cannot be ignored compared with the depth of cut and the edge of tool can change micro mechanism of chip formation. It appears that a large edge radius (relative to the depth of cut) of the tool used in nano-metric cutting, provides a high hydrostatic pressure. Thus, the trust force and frictional force of the tool is raised. In addition, increasing the tool edge radius and the density of generated dislocation in work-piece is scaled up that is comparable with TEM photographs [6].

The effect of yarn length and diameter on permeability and compaction response of flax fibre mats

The manufacturing of fibre reinforced plastics using Liquid Composite Moulding (LCM) techniques requires compaction of fibrous reinforcements and flow of liquid resins through them before curing. In the modelling of LCM processes, an accurate description of compaction response and resin flow resistance through the fibrous media (also described as permeability) is required. Permeability and compaction response affect a number of important parameters, such as required tooling forces and mould fill-times. To study the influence of yarn diameter and length, on permeability and compaction characteristics of natural fibre reinforcements, six different types of flax yarn mats were manufactured. Compaction tests were carried out on both dry and saturated samples. Average in-plane permeability was also measured at different fibre volume fractions. It was found that increasing the yarn diameter reduced compaction forces and increased permeability. Long yarn length mats demonstrated higher permeability and compaction response than short yarn length mats.

Process parameter influence on performance of friction taper stud welds in AISI 4140 steel

Friction taper stud welding is a new variant of friction welding which has been developed from the principles of friction hydro-pillar processing. This paper considers the effect of weld process parameters on weld defects, macrostructure and mechanical properties in AISI 4140 steel. It also presents 3D residual stress data for a typical friction taper stud weld. Applied downwards force, rotational speed and plunge depth (equivalent to consumable length) of the stud tool were systematically varied whilst measuring tool torque and temperature at several locations during welding. A simple Taguchi analysis was then used to relate process parameters and weld tensile strength. The combinations of parameters leading to high tensile strength are identified and linked to the occurrence of specific weld defects.