Cutting Forces Research Articles

Investigation of the Influence of Cutter Geometry on the Cutting Forces in Soft–Hard Composite Ground by Tunnel Boring Machine Cutters

Tunnel Boring Machines (TBMs) are integral to modern underground engineering construction, offering enhanced safety and efficiency. However, TBMs often face challenges in complex geological conditions, such as composite strata, resulting in reduced advancement speed and increased cutter wear. This study investigates the rock-breaking characteristics of TBM disc cutters in composite strata through numerical simulations using the Particle Flow Code (PFC) 5.0 software. Focusing on the Jinan Metro Line 6, the research analyzes cutter forces, rock crack propagation, and the impact of cutter edge shapes on rock-breaking efficiency. The discrete element method (DEM) is employed to simulate microscopic behaviors of rocks, providing insights into crack formation, expansion, and failure. This study’s findings reveal that cutter design and operational parameters can significantly influence cutter lifespan and efficiency. By modifying cutter spacing and penetration depth, enhancing rock-breaking efficiency, and grouting softer layers, TBMs can maintain effective excavation in composite strata. The study establishes a comprehensive understanding of the interplay between TBM cutters and complex geological conditions, offering actionable strategies to enhance TBM performance and mitigate cutter damage.

Influence of Mechanical Factors on the Cutting Performance of an Ultrasonic Bone Scalpel

Abstract The ultrasonic bone scalpel is a cutting-edge surgical instrument that leverages ultrasonic mechanical effects to remove bone tissue with precision, safety, and efficacy. While the adoption of the instrument has surged, the intricate relationship between its mechanical effects and the efficiency of bone removal remains ambiguous. This study aimed to elucidate the quantitative interplay between the mechanical parameters of the instrument and its bone removal performance. To achieve this, we engineered a testing apparatus capable of consistently regulating the scalpel’s cutting force, traversal speed, and depth of cut. The bone removal proficiency of the instrument was then assessed under varying conditions: cutting forces, ultrasonic power outputs, tip traversal speeds, and bone densities. Comprehensive data analysis unveiled a distinct quantitative correlation between the aforementioned parameters and bone removal rates. Furthermore, we identified optimal parameter combinations that maximize cutting efficiency. These insights are pivotal for the design, fabrication, evaluation, and clinical application of ultrasonic bone scalpels, offering a robust reference for future advancements in the field.

On the application of RHT model and SPG algorithm for the analysis of rock cutting process

The linear cutting process in rock poses challenges for verification in field experiments, laboratory investigations, or numerical simulations. This study aims to analyze the rock cutting process and disc cutter force estimation when using linear cutting mode. Three-dimensional numerical simulations using the explicit dynamic finite element method (LS-DYNA software) are conducted to characterize the cutting process. In this regard, two computational algorithms (Lagrangian and Smoothed Particle Hydrodynamics (SPH)) and two material models (Johnson-Holmquist Concrete (JHC) and Riedel-Hiermaier-Thoma (RHT)) are compared, with SPH and RHT identified as more suitable for rock cutting simulation. The results of comparative analyses show that the Lagrangian computational algorithm is highly dependent on the erosion value, hence this method is not suitable for the simulation of the rock-cutting process. Comparing to the RHT material constitutive model, the Johnson-Holmquist model does not well model the post-failure softening strain behavior, which leads to a reduction in the width of the failure area. The comparative analyses also show that the normal and rolling forces predicted by the JHC model are well over 30% higher than the actual experimental results, while the RHT model shows a good agreement between the predictions and the actual results. Overall, the RHT material model with the use of the SPH computational algorithm shows a very good combination in rock cutting process simulation.

Controllable diamond cutting of structured surfaces with subnanometric height features on silicon

Diamond cutting with a controllable depth of cut at the subnanometric scale is desired for next-generation electronics and optics. However, due to the limits of positioning accuracy of the current machine tools, diamond cutting at subnanometric scale depths remains in realm of molecular dynamic (MD) simulations instead of engineering realization. Cutting force feedback and control is regarded as a potential method to improve the positioning accuracy of machine tools. In this study, an ultra-precision force feedback loop with the resolution down to submillinewton is employed and integrated on an ultra-precision machine tool to enable the capability of cutting at subnanometric scale depth. By this way, the relationship between the cutting force and such small depth of cut needs to be well studied. MD simulations are conducted in this study to analyze the mechanism of material removal and influence of the crystallographic effect on the actual cutting depth and force caused by varied cutting directions at subnanometric to nanometric scale depth in diamond turning. Then, the crystallographic effect of silicon with the depth of cut from subnanometric to nanometric scale is compensated experimentally for accurate cutting at such an extremely small scale. Controllable diamond cutting of structured surfaces with actual depths and amplitudes ranging from several angstroms to a few nanometers on silicon is successfully realized.

Modeling of milling forces in facing process of aluminum alloy AL7075 using the square inserts

Cutting forces play very important in designing the tool machine, cutting tool, and in optimization of machining processes. Modeling and prediction of cutting forces by theoretical methods are quite difficult, so, this study was focused on modeling the cutting force in face milling process using combination of theoretical and experimental methods. This study was performed to model the milling forces (MFs) and determine the milling force coefficients (MFCs) in the face milling process of aluminum alloy Al7075 using square inserts. From theoretical and experimental methods, the relationship of average milling forces (AMFs) and feed per flute (ft) were determined as the linear regression. Using experimental data, the linear regressions of AMFs and feed per flute were determined with high values of determination coefficients (larger than 95 %). MFCs were determined including shear and edge MFCs (tangential shear MFC (Ktc) of 538.127 N/mm2, radial shear MFC (Krc) of 185.967 N/mm2, axial shear MFC (Kac) of -691.297 N/mm2, tangential edge MFC (Kte) of 11.253 N/mm, radial edge MFC (Kre) of 6.991 N/mm, and axial edge MFC (Kae) of –32.971 N/mm. The MF models were successfully verified by comparing the measured and predicted MFs in face milling process of Al7075. The tendency and shape of predicted MFs were quite close to the measured ones. The differences between the predicted and the measured MFs can be due to the several reasons such as the influence of vibrations, the influence of cutting heat, etc., and these are also the limitations of this study. The modeling and prediction methods of this study can be used to model and predict the cutting forces in face milling of other milling types and other pairs of cutting tool and workpiece material as well

MatDEM-based study of disc cutter force model in open TBM tunnels: Incorporating installation radius and synergistic effects

The prediction of rock cutting force is critical for tunnel boring machine performance and cutterhead design. This paper presents a novel model for rock cutting force prediction based on the Colorado School of Mines (CSM) model, which incorporates the installation position of disc cutters by introducing installation radius and synergistic effect factors. Linear cutting tests in the laboratory and large-scale rotary cutting simulations in MatDEM software were conducted to examine the impact of these factors. Results indicate that the normal and rolling forces increase and stabilize as the installation radius increases. The synergistic effect produces three force modes in a cutting circle, with mode α having the largest cutting force, mode β having a smaller force, and mode γ having the smallest force. The impact of installation radius and synergistic effect varies with rock-cutter parameters. Multiple regression analysis was used to determine the introduced factors. The proposed model was validated with rock strength and operation data from the Irtysh River conveyance project. The results demonstrate that the proposed model outperforms the CSM model in predicting cutting force in field conditions.

A multiscale finite element modeling for predicting the surface integrity induced by thermo-mechanical loads during high-speed milling of Ti-6Al-4V

High-speed milling (HSM) of Ti-6Al-4V is subjected to complex thermo-mechanical loads, leading to alteration in metallurgical conditions within the cutting deformation zones, adversely impacting the mechanical performances of manufactured products. Hence, inclusive insight into microstructural alterations within the Adiabatic Shear Band (ASB) and the milled surface becomes essential for better service performance. This study first developed a Finite Element (FE) milling model to simulate the machining process of Ti-6Al-4V. The proposed FE model is validated through experimental results regarding cutting forces (CFs), cutting temperature (CT), and chip geometry, where the absolute relative error between simulations and experiments was less than 15 %. Secondly, Zenner-Holloman (Z-H) and Hall-Petch (H-P) equations were incorporated into a user-defined subroutine to simulate dynamic recrystallization (DRX) for grain size and microhardness prediction. Simulation results revealed that the grains became finer in the ASB than on the milled surface. In particular, when the cutting speed and feed rate were increased to 350 m/min and 0.30 mm/tooth, the grain size in the ASB decreased from 14 to 0.68 and 0.44 µm, while in the topmost milled surface, it reduced to 7.06 and 6.75 µm, respectively. Conversely, microhardness exhibited an inverse correlation with grain size and increased with cutting speed and feed rate. Furthermore, the impact of increased plastic strain and temperature on the grains during chip segmentation was also examined. Finally, the proposed FE model validity was established by comparing simulated results with experimental data using advanced characterization techniques. This research significantly contributes to a comprehensive understanding of microstructural evolution and its implications for the mechanical performance of machined titanium components.

Experimental research and optimization based on response surface methodology on machining characteristics of cast Al-7Si-0.6 Mg alloy: Effects of cutting parameters and heat treatment

In this study, structural, mechanical and machining features of Al-7Si-0.6 Mg alloy manufactured by permanent mold casting (PMC) in both as-cast (AC) and T6 heat-treated (HT) conditions were investigated. Structural and mechanical properties were determined using conventional methods. Milling experiments were conducted with titanium aluminum nitride (TiAlN) coated carbide end mills in CNC milling machine under conditions of three different cutting speeds (V: 50, 80 and 110 m/min), feed rate (f: 0.08; 0.16 and 0.24 mm/rev) and constant depth of cut (DoC) (1.5 mm). It was seen that structure of AC Al-7Si-0.6 Mg comprised of aluminum-rich α-Al, coral-like eutectic Al-Si, primary Si, Mg2Si, Fe-rich plate, acicular β-Fe (β-Al5FeSi) and script-like π-Fe (π-AlSiMgFe) intermetallic phases. Eutectic Al-Si, primary Si, β-Fe and π-Fe phases in the structure of the alloy in the HT condition were partially dissolved and turned into an agglomerated and spherical state. While the hardness (HB), yield (YS) and tensile strength (TS) of the alloy raised with HT, the elongation to fracture (EF) reduced. While cutting force (CF), surface roughness (SR), built-up layer (BUL) and built-up edge (BUE) decreased with increasing V, they increased with increasing f in the milling of both cast and HT alloys. Adhered layers and feed marks were consisted of the cutted surfaces of the alloys. While the most adhered layer was observed in AC alloys at a low V (50 m/min) and high f (0.24 mm/rev) combination, the least adhered layer formation was observed at the highest V and the lowest f value in HT alloys. Optimum parameters with Response Surface Methodology (RSM) were determined as V: 125 m/min and f: 0.04 mm/rev in AC and HT cases. The statistical significance of V and f on CF and SR was revealed by analysis of variance (ANOVA), while mathematical models were improved to predict CF and SR.

Research on Rock-Breaking Characteristics of Cutters and Matching of Cutter Spacing and Penetration for Tunnel Boring Machine

Tunnel boring machine (TBM) tunnel construction in composite strata relies heavily on understanding the rock-breaking characteristics of TBM cutters and optimizing cutter spacing and penetration. Utilizing a full-scale rock rotary cutting machine (RCM), this study conducted rock-breaking tests with disc cutters under varying rolling radii. An analysis of rock debris shape and cutter behavior provided insights into rock-breaking mechanisms. Two main types of rock fragments were identified, with both shear and compression failure observed during cutter–rock interactions. The influence of the rolling radius and cutter spacing on cutter forces was analyzed, along with numerical modeling using the particle flow method. Optimal cutter selection in soft–hard composite strata should prioritize cutter force, with the greatest force required in hard rock. Cutter force increases with penetration, while the force difference between cutters decreases with reduced cutter spacing. These findings offer practical guidance for efficient rock-breaking in composite geological formations during tunnel construction.

Optimizing cutter wear in TBM operations through numerical analysis of enhanced rock-cutting interaction

The inevitable wear and degradation of disc cutters during the rock-crushing process significantly impacts the efficacy, timeline, and cost-effectiveness of tunnel construction. Optimizing cutter arrangements and adjusting suitable excavation parameters are crucial to reducing cutter wear in Tunnel Boring Machine (TBM) operations. This study probes the interaction between disc cutters and rock, employing an enhanced Bonding model to more accurately depict the failure behavior of rock specimens. Numerical simulations of the rock-breaking process using two disc cutters were conducted, focusing on highly influential excavation parameters—penetration depth (3, 5, 7, 9 mm) and cutter arrangements—tip width (14, 17, 20, 23 mm) and cutter spacing (50, 65, 80, 95, 110 mm). These simulations analyzed the impact of various factors on cutter force, wear, specific energy of rock breaking, and crushing unit rock cutter wear. The results show that increased penetration depth leads to higher cutter force and wear, with specific energy and unit wear remaining low when penetration is less than 5 mm. A larger cutter tip width incurs higher forces and wear of the first cutter, but when the tip width exceeds 20 mm, the force and wear of the second cutter will be reduced. Optimal specific energy for rock breaking and unit wear of rock volume were identified within a cutter spacing range of 80 to 95 mm. These findings can facilitate the analysis of how excavation parameters and cutter arrangements affect wear behavior, offering superior construction recommendations.

Investigation of the effects of machining parameters on cutting conditions during orthogonal turning of austenite stainless steel

Abstract The 1.4306 austenite stainless steel has been prominently utilized as a material in the automotive and aerospace industry. Considerable interest has been garnered in the machinability of stainless steel owing to its high strength and poor thermal conductivity. The aim of this study is to ascertain the influential cutting parameters, specifically the cutting speed and feed rate, on cut-ting forces, cutting temperature, and chip evaluation. Thus, austenite stainless steel was subjected to free-cutting using a carbide recessing tool under dry conditions. The principle of measuring cutting temperature, a complex procedure due to varying thermal homogeneity, was elucidated. For the turning experiments in question, the standard Taguchi orthogonal array L9 (32), featuring two factors and three levels, was employed. The experimental results were analyzed using MiniTab 17 software. The findings reveal a substantial effect of feed rate on cutting force, cutting temperature, and chip evaluation. The highest cutting force and cutting temperature were observed at a feed rate of 0.15 mm/rev. Conversely, the cutting force was minimized at a cutting speed of 100 m/min, indicating potential for increasing the cutting speed. The augmentation of feed rate led to chip compression and discoloration, attributed to elevated cutting force and a larger chip cross-section that efficiently dissipates heat from the cutting zone.

Experimental and numerical investigations on the force characteristics of cutter in different regions of the TBM cutterhead

The cutters on the cutterhead of a tunnel boring machine (TBM) are usually divided into center cutters, face cutters, and gage cutters, and have significantly different force characteristics. In this study, the authors conduct a series of full-scale cutter rotary cutting tests to compare the differences in the cutter force, the morphology of rock ships, and the efficiency of rock breaking. The results indicate that with increasing cutter spacing, the influence exerted by the cutters on one another in terms of their performance at breaking rocks decreases and their normal force gradually increases, while the rolling force of the cutters is less influenced by the spacing between them. The ratio of the normal force to the rolling force of the gage cutter is less than that of the face cutter, indicating a lower efficiency of breaking rock of the gage cutter. The ratio of rock chips with larger size (>50 mm) and smaller size (<10 mm) gradually decreases while that of rock chips with medium size (about 10–50 mm) gradually increases with increasing installation angle, such that the distribution of the particle size becomes more uniform. Excessive or insufficient penetration rate (PR) will increase the proportion of small rock chips, and a moderate PR will produce rock chips with a larger characteristic size and a more uniform size distribution. Then, a three-dimensional rock-breaking model by all cutters of actual TBM cutterhead is established based on the particle flow method. The results of the simulations indicate that the force on the inner ring of the center cutter is greater than that on the outer ring, and an increase in the installation radius weakens the load difference between the two rings. The normal and rolling forces of face cutters gradually increase, while their side force first increases and then decreases. The side force of the gage cutter significantly increases with the installation angle.

Peridynamics simulation of TBM cutting process in soft and hard composite strata with a simplified loading scheme

In this study, we address the complex geological conditions encountered during tunnel boring machine (TBM) excavation, particularly the challenges posed by soft and hard composite strata. To overcome limitations of conventional numerical methods for analyzing rock fracture in such strata, we employ Peridynamics to simulate rock fragmentation induced by disc cutters. We propose a virtual disc cutter loading scheme that enhances computational efficiency by replacing traditional contact models. Through numerical examples, we demonstrate the efficacy of this loading scheme in simulating rock fragmentation within soft and hard composite strata. With this method, we conduct numerical studies on kerfs-assisted rock fragmentation in such geological conditions, finding that kerfs can help mitigate differences in cutter forces between soft and hard rocks, thus showing potential for improving TBM performance. Our findings offer insights into optimizing TBM operations in challenging geological environments.

Experimental investigation of cutting force of powder metallurgy valve guide rod hole

Aiming at the problem of fast wear of machining tools in the special powder metallurgy valve guide rod hole and gasket seat of a certain engine cylinder head, in order to solve the technical problems in the cutting force (CF) of this kind of powder metallurgy materials, different tools are used and the analysis is carried out under different cutting test conditions. The cutting force law and surface roughness change law of similar powder metallurgy materials are determined to determine the appropriate tool materials and processing parameters. The experimental results show that under the same processing conditions, ceramic tools will suffer less than cemented carbide tools and cutting force can obtain a smaller surface roughness. In addition, the mass production process of valve seat, the blade material is ceramic knife.

A devastating blow: personal reflections on Argentina's scientific decline.

As an Argentine scientist, the defunding of CONICET and INTA feels like a blow to progress and our future. Despite free education, these cuts force talented researchers to seek opportunities abroad. Argentina's history of scientific achievement, from Nobel Prizes to COVID-19 vaccines, is at risk. Defunding science weakens our ability to solve problems and compete globally.

Development of a Parametric Model for Calculating Cutting Forces in External Cylindrical Turning of 16MNCR5 Steel

The paper presents a mathematical model for calculating cutting forces during the machining of 16MnCr5 steel using the Sandvik CNMG 120408 16P25T tool. The modeling process involved the use of a test rig constructed based on the 16Д25 machine, which enabled the measurement of real values of spindle speed, longitudinal feed, cutting depth, and cutting forces. The results transmitted to a computer through the LTR-EU-8 workstation, equipped with galvanic isolated LTR modules and a synchronization interface. Based on the experimental results, the theoretical model demonstrated a deviation from actual measurements of no more than 4.72%. The study provides evidence that the cutting force calculations commonly presented by leading tool manufacturers are inherently overestimated. he difference in cutting forces can be 9%.

Research on dynamic characteristics of cutter breaking frozen soil and optimal drum rotation speed of the new shaft tunneling machine

To improve the efficiency of frozen soil excavation, the new shaft tunneling machine was developed. The new shaft tunneling machine exerts pressure on the frozen soil through the cutter under the joint action of its own gravity, the drum rotational force and the inertia force, and the frozen soil is damaged. By unique way of breaking frozen soil to improve the efficiency of frozen soil excavation, the drum rotation speed is one of the factors affecting the performance of frozen soil excavation. This article applies SolidWorks software to establish the model of cutter breaking frozen soil, takes advantage of Hyper Mesh finite element software coupled with LS-DYNA solver to acquire the regular pattern of change in the force change, frozen soil stress–strain and specific energy of cutter crushing frozen soil, etc., which analyzes the destruction of frozen soil when the drum of the new shaft tunneling machine is rotating at the speed of 25–40 rpm. Combine with field test to investigate the mechanism of cutter breaking frozen soil under the optimal drum rotation speed. The investigation results demonstrate that: when frozen soil's self-bearing capacity is lower than the force of cutter, it breaks up and detaches from the soil body, and frozen soil undergoes tensile, compressive and shear damages. For this research, it is instructive for practical engineering.

Investigation of the effects of machining parameters on cutting conditions during orthogonal turning of austenite stainless steel

Abstract The 1.4306 austenite stainless steel has been prominently utilized as a material in the automotive and aerospace industry. Considerable interest has been garnered in the machinability of stainless steel owing to its high strength and poor thermal conductivity. The aim of this study is to ascertain the influential cutting parameters, specifically the cutting speed and feed rate, on cut-ting forces, cutting temperature, and chip evaluation. Thus, austenite stainless steel was subjected to free-cutting using a carbide recessing tool under dry conditions. The principle of measuring cutting temperature, a complex procedure due to varying thermal homogeneity, was elucidated. For the turning experiments in question, the standard Taguchi orthogonal array L9 (32), featuring two factors and three levels, was employed. The experimental results were analyzed using MiniTab 17 software. The findings reveal a substantial effect of feed rate on cutting force, cutting temperature, and chip evaluation. The highest cutting force and cutting temperature were observed at a feed rate of 0.15 mm/rev. Conversely, the cutting force was minimized at a cutting speed of 100 m/min, indicating potential for increasing the cutting speed. The augmentation of feed rate led to chip compression and discoloration, attributed to elevated cutting force and a larger chip cross-section that efficiently dissipates heat from the cutting zone.

Investigation in optimization of process parameters in turning of mild steel using response surface methodology and modified deep neural network

The turning operation is a traditional and conventional process for machining cylindrical materials to achieve a desired shape. During machining in the turning process, the accuracy and quality of the end product mainly depend on its process parameters. Therefore, this study attempts to achieve a quality product from a conventional lathe machine by optimizing its process parameters for En2-BS970 mild steel. The experiments were designed with the help of response surface methodology (RSM). The most influential turning parameters, such as feed rate, spindle speed, cutting fluid flow rate, and cutting angle, are investigated experimentally. In addition, the machining responses, namely material removal rate (MRR), surface roughness (SR), cutting force (CF), and cutting time (CT), have been optimized using the RSM numerical optimization method. Furthermore, a deep neural network (DNN) machine learning prediction model based on the whale optimization algorithm (WOA) is developed for this experiment in order to predict turning performances for En2-BS970 material. The predicted DNN results showed an accuracy of about 90% compared to experimental results, indicating that the implementation of WOA significantly optimized the DNN weights during training. The RSM optimized responses are obtained as 14.608 mm3/min for MRR, 0.7504 µm for SR, 442.94 N for CF, and 2.48 seconds for CT during the turning operation with input settings of 0.24 mm/rev, 466.535 rpm, 0.075 ml/s and 60.18° for feed rate, spindle speed, cutting fluid flow rate and cutting edge angle respectively.

Comparison of turning process performance using modified cutting inserts under minimum quantity lubrication

ABSTRACT While machining of high-strength alloy steel materials, poor surface quality and decreased tool life are result by an increase in the cutting zone temperature close to the machining region. To overcome this, surface texture with green manufacturing environment is an alternate path to enhancing machining performance. In the present work, novel Parallel Grooved Textured Tools (PGT) was developed and studied the performance of so developed tools. Further, the Untextured Tool (UT) and PGT performance was compared while machining EN24 alloy steel under Minimum Quantity Lubrication (MQL) condition. It was perceived from result that textured tools reduced the cutting temperature (CT), rake wear (RW), flank wear (FW), surface roughness (Ra) and cutting force (CF) up to 18.96%, 18.79%, 24.31%, 12.69%, and18.96% respectively compared to UT.