Chip Flow Research Articles

Cutting force model of longitudinal-torsional ultrasonic-assisted milling Ti-6Al-4V based on tool flank wear

The interaction mechanism between the tool flank wear and the cutting force, in milling Ti-6Al-4V, is of significance for its further development. However, the relationship between the tool flank wear and the cutting force should be further investigated under ultrasonic-assisted milling. In this study, the longitudinal-torsional ultrasonic-assisted milling (LTUAM) Ti-6Al-4V in dry cutting was evaluated by comparing with conventional milling (CM). With the consideration of the ultrasonic vibration on the chip flow angle, a novel cutting force model in terms of the tool flank wear was developed by discretizing the side edge to apply the oblique model. Wherein the stress evolution both on the shear plane and the flank plane was analyzed, as well as the swinging range of chip flow angle resulted from ultrasonic vibration. In addition, the coefficients of the cutting force were calibrated through the mechanical method. The model could predict the cutting force evolution with different flank wear bandwidth ( VB ), and optimize the machining parameters. The experimental results indicated the errors between the model and the test were 19.1 % and 12.9 % in the feed ( x ) and the normal ( y ) direction of the tool coordinate system ( o - xyz ), respectively. Through time-frequency transformation, the behavior of the cutting force both in CM and LTUAM was further explained. Besides, the growing amplitude was beneficial to restrain the flank wear apart from the overgrowing amplitude, while the growing helix angles resulted in the serious tool flank wear in LTUAM. For the machined surface texture, the cutter scratches parallel to the feed direction dominated the machined surface in CM while the LTUAM surface featured by the order wave textures.

FE-SPH hybrid method to simulate the effect of tool inclination angle in oblique diamond cutting of KDP crystal

Due to the soft and brittle characteristic, the potassium dihydrogen phosphate (KDP) crystal undergoes a complex process in diamond cutting, which makes the material removal mechanism is still a subject of controversy. In this paper, based on the machining model of oblique diamond cutting of KDP crystal, the effect of tool inclination angles in machining is numerically investigated by constructing a FE-SPH hybrid model, which combines the finite element (FE) method and smoothed particle hydrodynamics (SPH). Subsequently, oblique fly-cutting experiments with the same tool geometries and cutting parameters are performed, and the topographies of uncut shoulder and finally machined surface are measured by the atomic force microscope (AFM). Results show that the distribution of hydrostatic pressure clearly reflects the susceptibility of the processed surface to the cracks formation. With the consideration of hydrostatic pressure, the simulated results of cracks on the uncut shoulder and finally machined surface present a good consistency with the measured results in experiments. Moreover, the chip flow angle in simulation approximately follows the Stabler's chip-flow rule. As tool inclination angle increases, the width of interference zone decreases and the phenomenon of chip tearing is gradually relieved. Finally, the simulation results and experimental observations confirm that the roughness of finally machined surface is influenced by the average slope of uncut shoulder, the width of interference zone and the distribution of cracks.

Modelling and controlling the process of cutting with complex-geometry tools to improve efficiency of mining machines and plants

Constant quality improvement through automation of production processes is an important prerequisite for increased viability of mining machines and plants. Factors that limit the automation of the cutting machining operations include the problem of controlling the chip formation and chip crushing. Solution of this problem necessitates theoretical description of the material cutting conditions for tools with curvilinear surfaces. The paper describes basic principles of modeling the cutting process using complex-geometry tools with curvilinear rake. The theory is based on the concept of chip formation as a process of inhomogeneous strain in the plastic zone where the chip originates. Based on the analysis of the stress-strain state in the cutting zone, criterial relationships were derived that correlate the geometric parameters of the chip shape and machining conditions of the curvilinear-rake tool. Prerequisites for chip breaking are stability of the chip shape during cutting, stable chip-to-obstacle contact, high chip stiffness and low flexibility. The machining conditions leading to chip fragmentation could be found by solving the strength problem. Through establishing the cause-and-effect relationships of the processes of chip formation, curling and breaking, new approaches to achieving favorable chip shape may be found by exerting deliberate impact on the plastic zone of the chip formation through optimizing the conditions for the chip flow off the tool. The established relationships between the output parameters of the cutting process and process conditions of cutting with a complex-geometry tool offer the way to control the chip flow parameters in various machining operations. The research is aimed at creating scientifically informed design codes and optimization of cutting parameters for tools with curvilinear chip-curling and chip-breaking rake surfaces.

Modeling and Characterization of Aisi S-7 Steel Using the Johnson Cook Model – an Explicit Analysis

: A two dimensional, uniformly distributed grains model has been developed for AISI S-7 grade Steel and the orthogonal machining process, in the pursuit of determining the various effects of temperature rise, residual stresses, chip morphology, and strain hardening. A Johnson-Cook material model, along with a numerical, technique was used to simulate the machining process using ANSYS 15 academic license. The machining has been carried out at different velocities: 60, 70, and 80 ms-1 and with depths of cut of 2, 3, and 5 mm. Results revealed that the accumulation of tandem grains offers a maximum resistance ahead of the tool-chip interface due to the strain hardening effect, during the metal removal process. This effect leads to a maximum rise in temperature up to 912.59 °C, which has been observed in the secondary shear zone. Serrated chip flow was observed mainly at a low speed of 60 ms-1. The Strain hardening effect was more substantial at 60 ms-1 and 5 mm depth of cut compared to any other machining parameters. A great deal of discussion has been made on the above material machining process that may serve as a useful resource to the tool designer and manufacturing scientist.

Identification of in vitro and in vivo oncolytic effect in colorectal cancer cells by Orf virus strain NA1/11.

Orf virus (ORFV) is a favorable oncolytic viral carrier in research, and ORFV strain NZ2 has been revealed to have antitumor effects in animal models mediated by immunoregulation profile. However, the antitumor effects triggered by the ORFV in colorectal cancer (CRC) cells is poorly characterized. The in vivo and in vitro roles of ORFV in CRC were determined using western blotting, colony formation, CCK-8, wound scratch assay, qPCR, and animal models. Furthermore, cytokine antibody chip assay, flow cytometry, western blotting, and immunohistochemical (IHC) assays were conducted to explore the potential mechanism of ORFV. The present data revealed that ORFV strain NA1/11 infected and inhibited the in vitro growth and migration of CRC cells. By establishing a CRC model in Balb/c mice, it was revealed that ORFV strain NA1/11 significantly inhibited the in vivo growth and migration of CRC cells. A cytokine antibody array was utilized to obtain a more comprehensive profile revealing the differentially expressed cytokines in ORFV infection. Cytokines, such as IL-7, IL-13, IL-15, CD27, CD30, pentraxin 3, and B lymphocyte chemoattractant (BLC), were upregulated. Axl, CXCL16, ANG-3, MMP10, IFN-γ R1 and VEGF-B were downregulated. The results indicated that ORFV played roles in the regulation of key factors relevant to apoptosis, autoimmunity/inflammation, angiogenesis, and the cell cycle. Finally, data was presented to validate that ORFV infection induces oncolytic activity by enhancing apoptosis in vivo and in vitro. In conclusion, ORFV could be an oncolytic virus for CRC therapy.

Studying endothelial cell shedding and orientation using adaptive perfusion-culture in a microfluidic vascular chip.

Most tissue-engineered blood vessels are endothelialized by static cultures in vitro. However, it has not been clear whether endothelial cell-shedding and local damage may occur in an endothelial layer formed by static cultures under the effect of blood flow shear postimplantation. In this study, we report a bionic and cost-effective vascular chip platform, and proved that a static culture of endothelialized tissue-engineered blood vessels had the problem of a large number of endothelial cells falling off under the condition imitating the human arterial blood flow, and we addressed this challenge by regulating the flow field in a vascular chip. Electrospun membranes made of highly oriented or randomly distributed poly(ε-caprolactone) fibers were used as the vascular scaffolds, on which endothelial cells proliferated well and eventually formed dense intima layers. We noted that the monolayers gradually adapted to the artery-like microenvironment through the regulation of chip flow field, which also revealed improved cellular orientations. In conclusion, we have proposed a vascular chip with adaptive flow patterns to gradually accommodate the statically cultured vascular endothelia to the shear environment of arterial flow field and enhanced the orientation of the endothelial cells. This strategy may find numerous potential applications such as screening of vascular engineering biomaterials and maturation parameters, studying of vascular biology and pathology, and construction of vessel-on-a-chip models for drug analysis, among others.

Numerical Modeling and Analysis of Ti6Al4V Alloy Chip for Biomedical Applications.

The influence of cutting forces during the machining of titanium alloys has attained prime attention in selecting the optimal cutting conditions to improve the surface integrity of medical implants and biomedical devices. So far, it has not been easy to explain the chip morphology of Ti6Al4V and the thermo-mechanical interactions involved during the cutting process. This paper investigates the chip configuration of the Ti6Al4V alloy under dry milling conditions at a macro and micro scale by employing the Johnson-Cook material damage model. 2D modeling, numerical milling simulations, and post-processing were conducted using the Abaqus/Explicit commercial software. The uncut chip geometry was modeled with variable thicknesses to accomplish the macro to micro-scale cutting by adapting a trochoidal path. Numerical results, predicted for the cutting reaction forces and shearing zone temperatures, were found in close approximation to experimental ones with minor deviations. Further analyses evaluated the influence of cutting speeds and contact friction coefficients over the chip flow stress, equivalent plastic strain, and chip morphology. The methodology developed can be implemented in resolving the industrial problems in the biomedical sector for predicting the chip morphology of the Ti6Al4V alloy, fracture mechanisms of hard-to-cut materials, and the effects of different cutting parameters on workpiece integrity.

Development of a novel boring tool with anisotropic dynamic stiffness to avoid chatter vibration in cutting: Part 2: Analytical and experimental verification of the proposed method

In this study, we developed prototypes of boring tools with anisotropic dynamic stiffness, and their chatter stability was investigated analytically and experimentally. In Part 1, a novel design of boring tools with an anisotropic structure was proposed to improve the nominal stiffness in boring operation, thus resulting in higher chatter stability in simulation. In this part (Part 2), anisotropic boring tools with a holder length-to-diameter ratio (L/D) of 4 and 10 designed in Part 1 were prototyped, and their frequency response functions were evaluated. Then, the chatter stabilities were evaluated through turning experiments. With respect to a L/D4 boring tool with anisotropic structure, the nominal dynamic stiffness was significantly improved within the range of machining conditions that satisfies the appropriate combination of cutting force ratio and chip flow direction, compared to a conventional tool with isotropic structure. We confirmed that the proposed boring tool with an anisotropic structure increases the critical radial depth of cut by approximately 17 times compared with conventional tools. Even with an L/D10 anisotropic boring tool, a similar effect was observed wherein the dynamic stiffness of the tool was improved. In contrast, the effect of improving the dynamic stiffness was insufficient; thus, chatter free cutting could not be realized. Analytical investigations verified the importance of further improvement of dynamic characteristics. To realize stable boring with L/D10 boring tools, it is necessary to further reduce the system compliance while also improving the similarity of the frequency response function.

The influence of helix angle of router bits on chip flow, roughness and noise level in milling different grain angle orientation of teak wood

ABSTRACT This study was done to investigate surface roughness, noise level, chip shapes and chip flows characteristic in milling teak wood by conventional and helical router bits. Down-milling process compared to up-milling process produced better surface roughness, lower noise level, and flow chip. Better surface roughness (R a value) was produced by the router bits with higher helix angle compared to lower helix angle. Noise level decreased with increasing in the helix angle of the router bits. The increasing in the angle of the wood grain would increase the values of surface roughness and noise level. With increasing helix angle of the bits the amount of spiral and flow chips increased and granule chips were reduced. The investigations have clearly confirmed that the helical edge is considered to be a valuable design to improve upon the performance of the straight edge for wood milling applications.

Evaluation of Self-Propelled Rotary Tool in the Machining of Hardened Steel Using Finite Element Models.

This paper presents a model for assessing the performance of self-propelled rotary tool during the processing of hardened steel. A finite element (FE) model has been proposed in this analysis to study the hard turning of AISI 51200 hardened steel using a self-propelled rotary cutting tool. The model is developed by utilizing the explicit coupled temperature displacement analysis in the presence of realistic boundary conditions. This model does not take into account any assumptions regarding the heat partitioning and the tool-workpiece contact area. The model can predict the cutting forces, chip flow, induced stresses, and the generated temperature on the cutting tool and the workpiece. The nodal temperatures and heat flux data from the chip formation analysis are used to achieve steady-state temperatures on the cutting tool in the heat transfer analysis. The model outcomes are compared with reported experimental data and a good agreement has been found.

Architecture, Chip, and Package Codesign Flow for Interposer-Based 2.5-D Chiplet Integration Enabling Heterogeneous IP Reuse

A new trend in system-on-chip (SoC) design is chiplet-based IP reuse using 2.5-D integration. Complete electronic systems can be created through the integration of chiplets on an interposer, rather than through a monolithic flow. This approach expands access to a large catalog of off-the-shelf intellectual properties (IPs), allows reuse of them, and enables heterogeneous integration of blocks in different technologies. In this article, we present a highly integrated design flow that encompasses architecture, circuit, and package to build and simulate heterogeneous 2.5-D designs. Our target design is 64core architecture based on Reduced Instruction Set Computer (RISC)-V processor. We first chipletize each IP by adding logical protocol translators and physical interface modules. We convert a given register transfer level (RTL) for 64-core processor into chiplets, which are enhanced with our centralized network-onchip. Next, we use our tool to obtain physical layouts, which is subsequently used to synthesize chip-to-chip I/O drivers and these chiplets are placed/routed on a silicon interposer. Our package models are used to calculate power, performance, and area (PPA) and reliability of 2.5-D design. Our design space exploration (DSE) study shows that 2.5-D integration incurs 1.29× power and 2.19× area overheads compared with 2-D counterpart. Moreover, we perform DSE studies for power delivery scheme and interposer technology to investigate the tradeoffs in 2.5-D integrated chip (IC) designs.

Numerical study on the ceramic tool abrasion in machining superalloy

In this study, a combined finite element method (FEM) and discrete element method (DEM) numerical simulation is proposed to investigate the tool wear evolution in machining superalloy. Firstly, a finite element model for cutting is conducted to obtain the contact stress, the temperature distribution of the cutting tool, and the speed of chip flow. Based on the boundary conditions, a discrete element model is established to display the tool-chip abrasion behavior. The micro-crack number, detached particle number, and wear rate of the ceramic tool are predicted and analyzed by discrete element simulations. Moreover, the effects of cutting speed and depth of cut on tool abrasion are numerically investigated. Subsequently, a cutting experiment is designed to compare simulated results with experimental data. The high consistency of the predicted tool wear and experiments validates that the combined FEM-DEM method is feasible to study the tool wear behavior in machining superalloy. Furthermore, process optimization guidelines are also proposed for improving machining efficiency and tool life in the actual processing. Within a certain range, higher cutting speed notably leads to slighter tool wear. The larger depth of cut causes more severe wear of Sialon ceramic tools.

Investigation on PCD cutting edge geometry for Ti6Al4V high-feed milling

Some new research challenges are connected to new high-feed milling tools, developed recently to reduce the cutting time. The main objective of this article is to analyze if PCD tools could be used for high-feed face milling of Ti6Al4V. As its performance depends significantly on cutting edge geometry, different tool geometries were evaluated regarding tool life and cutting forces. Experimental investigations demonstrate that the tool profile, which has a discontinuity on chip flow direction along the cutting edge, presents an intense local tool wear and, consequently, a smaller tool life. The PCD tool having a straight edge has a longer tool life but, contrarily to the carbide tool theory, local wear behavior on the cutting edge is not constant when depth of cut increases. The cutting force magnitude, and its dynamic, affects drastically the tool life of PCD tools in milling and it is a limitation to the increase of the material removal rate. In conclusion, it is possible to use specific PCD tools for milling titanium alloy in high feed with low depth of cut (smaller than 1 mm), which is not economically practicable.

Three-dimensional turning force prediction based on hybrid finite element and predictive machining theory considering edge radius and nose radius

Abstract Cutting force provides a basis for predicting tool wear and fracture, surface quality of component, as well as vibration and power demand of machine tools during the process of turning. Based on the finite element and mechanical analysis model, a three-dimensional (3-D) cutting force prediction model with consideration given to the edge radius and the nose radius of cutting tool is proposed in this paper. Firstly, combined with cutting force experiment, 3-D cutting simulation is performed in Deform to determine the appropriate Johnson-Cook (J-C) material constitutive model, and the two-dimensional (2-D) orthogonal cutting model is simulated by applying the determined J-C model. By observing the strain rate distribution in the shear zone, the shear angle is obtained, while the nonlinear regression model of shear angle, cutting speed and cutting thickness is conducted. Then, taking into account the impact of nose radius on the cutting process, 3-D oblique cutting is converted into equivalent orthogonal cutting using the chip flow angle and the equivalent cutting edge. The method used to determine the strain rate coefficient of the second deformation zone is redefined in the modified Oxley model, and the chip forming force is calculated. Based on the Waldorf slip line field model, the plowing force generated by the edge radius is predicted. Finally, the cutting force of 3-D oblique turning is obtained by means of coordinate transformation. The proposed model is validated by the excellent consistency between the theoretical predictions and the results obtained after referencing literature data and performing experiment of cutting 304 stainless steel and Inconel 718.

Study of Cutting Forces and Prediction of Surface Quality Analysis Using Neural Network Model, Support Vector Regression Model by Various Textured Tool Condition for Ti-6Al-4V Alloy

To evaluate the performance of the textured tool on surface quality with three different types of the textured pattern using Wire-Cut Electrical Discharge Machining (W-EDM) on tungsten carbide cutting tools with two different groove depth dimensions 100 μm& 200μm respectively and the tools are coated with both TiN and TiAlN using Physical Vapour Deposition (PVD) technique. Surface roughness is predicted using the Support Vector Regression, multilayer Artificial Neural Network model (ANN) model. ANN training is carried out with a pure line transfer function and backpropagation algorithm. Easy off machining and good surface finish are achieved through TiAlN coated tool with linear texture along the perpendicular to chip flow direction than the tools considered for experimental and predicted conditions.

Elasto-Visco behavior of Al7075-T6 using a numerical technique

The transition in temperature and associated stress induced during machining, may affect the structural integrity of the Al7075-T6 alloy. In the present study, Steinberg Guinan material parameters were used to investigate the dynamic behaviour viz chip morphology (fracture mechanism), temperature change and flow stress in the elasto-visco material Al7075-T6. An explicit algorithm, was adopted to investigate the outcomes. Results showed chip formation and the mode of fracture was closely related with depth of cut and can influence the temperature and flow stress during the machining process. Work hardening and edge dislocation slip in the secondary shear zone was observed to have a notable influence. An optimal machining condition was found between 0.6 and 0.7 mm depth of cut.

Partition of Primary Shear Plane Heat in Orthogonal Metal Cutting

When assessing the effect of metal cutting processes on the resulting surface layer, the heat generated in the chip formation zone that is transferred into the workpiece is of major concern. Models have been developed to estimate temperature distributions in machining processes. However, most of them need information on the heat partition as input for the calculations. Based on analytical and numerical models, it is possible to determine the fraction of shear plane heat transferred into the workpiece for orthogonal cutting conditions. In the present work, these models were utilized to gain information on the significant influencing factors on heat partition, based on orthogonal cutting experiments, experimental results from the literature, and a purely model-based approach. It could be shown that the heat partition does not solely depend on the cutting velocity, the uncut chip thickness, and the thermal diffusivity—combined in the dimensionless thermal number—but the shear angle also has to be taken into account, as already proposed by some researchers. Furthermore, developed numerical models show that a more realistic representation of the process kinematics, e.g., regarding chip flow and temperature-dependent material properties, do not have a relevant impact on the heat partition. Nevertheless, the models still assume an idealized orthogonal cutting process and comparison to experimental-based findings on heat partition indicates a significant influence of the cutting edge radius and the friction on the flank face of the tool.

Concept of energy efficient technological system: Machine tool – cutting tool – workpiece

AbstractThis study deals with the concept of increasing energy efficiency by means of decreasing the energetic losses by using advanced composite machine tool components and interfaces characterized by low friction, and high wear resistance. Moreover, this study provides experimental results of damping property measurements and characteristic time domain curves of the fibre, particle, and sandwich composites, underlining the advantages of such composite types in terms of dynamic loading. Furthermore, it provides an analysis on the usage of thin films (coatings) and energy consumption in terms of cutting conditions. The study analyses the cutting tool geometry and shape of cutting edge that positively affect the cutting forces and chip flow direction, and avoid the energy‐intensive restricted cutting effect. Respecting the results of the analyses of mentioned effects contributes to increasing the energy efficiency of the machine tool‐cutting tool‐workpiece system.

Influence of the main cutting edge angle value on minimum uncut chip thickness during turning of C45 steel

Abstract One of the important phenomena of orthogonal cutting process is the occurrence of the minimum uncut chip thickness, as its highly affects the process of cutting initiation and surface roughness. But nowadays non orthogonal i.e., oblique cutting process using special tools with continued cutting edge and high value of cutting angle λs make new possibilities in the field of research. Hence, this paper presents the results of such analyzes and investigations of oblique cutting impact using tool with λs € on the minimum uncut chip thickness during free-radial turning of C45 steel using sintered carbide edges S3OS with rn = 18, 28, 90 μm, respectively. The results show that the experimentally determined minimum uncut chip thickness decreases with the increase of the value of the λs angle and in accordance with the derived theoretical Equations concerning the direction of the chip flow. Moreover, it establishes the possibility of significantly lowering the hmin value with the increase of the absolute value of the angle λs and it opens a new directions of tool edges for oblique cutting to finish machining and sheds new light on abrasive wear issues, during which micro-cutting may occur.

Evaluation of Surface Roughness and Cutting Temperature of EN31 Steel with Varying MQSL Parameters

In the present-day manufacturing industry, achieving machining accuracy, high production rate, high material removal rate and increasing tool cutting life is becoming more vital and a particularly difficult task. Machining of hard material imposes a lot of challenges, mainly high temperature generation between tool-workpiece interface. Enormous heat generation adversely affects surface roughness, tool life, dimensional quality of the workpiece and deteriorates the tool life significantly. The use of proper lubrication in machining processes is critically important to modify the conditions of contact area by effective control over frictional interaction which should ensure change in tool-chip interface and machining mechanics. In the present work an experimental investigation was carried out on various MQSL parameters on surface roughness and tool temperature in turning EN 31 steel and the results are compared with dry turning. In order to apply lubricants at shearing interface (chip flow at the rake face of the tool) high velocity MQSL set-up is fabricated. The present work has achieved significant results and helped in concluding the influence of lubricant parameters of MQSL in turning process.