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30 pages, 4060 KB

Open AccessArticle

Experimental Investigation of Lubrication Effects in High-Feed Face Milling Using DOE-Based Cutting Force and Surface Analysis

by Gyula Varga, István Sztankovics and Antal Nagy

Lubricants 2026, 14(2), 71; https://doi.org/10.3390/lubricants14020071 - 3 Feb 2026

Viewed by 717

Abstract

High-feed face milling is widely adopted in industry for its productivity advantages, especially when machining medium carbon steels. However, the combined effects of lubrication regimes on both the cutting forces and surface quality remain insufficiently explored, creating a research gap in optimizing process [...] Read more.

High-feed face milling is widely adopted in industry for its productivity advantages, especially when machining medium carbon steels. However, the combined effects of lubrication regimes on both the cutting forces and surface quality remain insufficiently explored, creating a research gap in optimizing process parameters for improved performance. This study presents an experimental investigation into the effects of lubrication on cutting forces and surface topography during the high-feed face milling of C45 steel. Using a design of experiments (DOE) approach, eight distinct machining setups were developed by varying the cutting speed, depth of cut, and feed per tooth. Each setup was tested under two lubrication conditions: with flood coolant and under dry machining. Cutting forces in the X, Y, and Z directions were recorded using a dynamometer, while the post-machining surface quality was evaluated using 3D areal surface topography measurements. The results revealed that feed per tooth was the primary factor affecting both the cutting forces and surface roughness, with depth of cut having a moderate effect and cutting speed a minor influence. Flood lubrication reduced the peak forces, stabilized force fluctuations, and improved surface uniformity, particularly in the valley depths and skewness parameters. This work provides (i) a combined analysis of cutting forces and surface topography under high-feed milling, (ii) quantitative evidence of lubrication effects on force and surface consistency, and (iii) identification of dominant process parameters for optimization, offering practical guidance for enhancing productivity, surface quality, and tribological performance in high-feed milling operations. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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30 pages, 12752 KB

Open AccessArticle

Study on Influence of Roller Profile Modification on Wear of Tapered Roller Bearing

by Zhaoxia Luo, Dingkang Zhu, Wenjing Zhang, Weisong Tian, Yu Zhang, Koucheng Zuo and Lai Hu

Lubricants 2026, 14(2), 69; https://doi.org/10.3390/lubricants14020069 - 2 Feb 2026

Viewed by 948

Abstract

Addressing the scientific problem that the profile modification design of tapered roller bearings primarily focuses on contact stress and fatigue life while neglecting its impact on wear evolution, this paper, based on Hertzian contact theory and the Archard wear theory, and considering centrifugal [...] Read more.

Addressing the scientific problem that the profile modification design of tapered roller bearings primarily focuses on contact stress and fatigue life while neglecting its impact on wear evolution, this paper, based on Hertzian contact theory and the Archard wear theory, and considering centrifugal force, gyroscopic effect, and the complex contact state between rollers and raceways, constructed a comprehensive analysis framework integrating a quasi-static model for profiled rollers and a wear depth calculation model. This framework is novel in that it systematically couples roller profile modification parameters with raceway wear evolution under both pure axial and combined radial–axial loads. The validity and effectiveness of the proposed model were verified by comparing the results of the quasi-static model with load distribution data from existing literature and through measurements conducted on a specially designed bearing wear test platform. The main findings are as follows: (1) When the logarithmic modification parameter f₁ increases from 0.7 μm to 3.6 μm, the maximum wear depth of the inner raceway increases by 133% under pure axial load and 144% under combined load, while that of the outer raceway increases by 142% under pure axial load and expands from 0.1–0.2 μm to 0.23–0.52 μm under combined load. (2) Combined load induces significant asymmetric wear on the outer raceway, and the difference between the two wear peaks increases from 0.13 μm to 0.35 μm as f₁ rises from 0.7 μm to 3.6 μm. (3) The wear peak shifts toward the midpoint of the roller generatrix with increasing modification amount. These results provide important guidance for the wear-oriented optimization design of tapered roller bearings. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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24 pages, 4253 KB

Open AccessArticle

Performance Evaluation of a Halbach Permanent Magnet Axial Protection Bearing Under Vertical Magnetic Levitation Flywheel Rotor Drop

by Dengke Li, Jun Ye, Gang Chen, Lai Hu, Zixi Wang, Taishun Qian, Jiahao Zhang, Mengchen Zi and Chao Liang

Lubricants 2026, 14(1), 40; https://doi.org/10.3390/lubricants14010040 - 15 Jan 2026

Cited by 1 | Viewed by 1004

Abstract

This study addresses the issues with traditional rolling protection bearings in vertical magnetic levitation flywheel energy storage systems (FESSs), which are prone to impact, wear, and temperature rise under abnormal conditions, such as drops. It designed a permanent magnet axial protection bearing based [...] Read more.

This study addresses the issues with traditional rolling protection bearings in vertical magnetic levitation flywheel energy storage systems (FESSs), which are prone to impact, wear, and temperature rise under abnormal conditions, such as drops. It designed a permanent magnet axial protection bearing based on a Halbach array, utilizing N42SH permanent magnet material. The five-layer Halbach array achieved a maximum axial magnetic force of 86 KN and a maximum air gap magnetic flux density of 2.2 T, meeting the application requirements. Simulation results, combined with rotor drop dynamics and thermal analysis, show that under an 8000 rpm drop condition, the permanent magnet bearing reduces radial and axial contact forces by approximately 60% and 54%, respectively, and wear by around 70%. Additionally, the maximum system temperature decreases from 109 °C to 74 °C, with a 32% reduction in temperature rise. Friction experimental analysis indicates that low frequency, low load, and moderate temperatures improve friction stability and reduce wear. Overall, the permanent magnet axial protective bearing effectively mitigates drop impact, reduces friction heat and wear, and enhances the safety and reliability of the flywheel energy storage system under abnormal working conditions, providing valuable theoretical support and a design reference for engineering applications. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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23 pages, 3564 KB

Open AccessArticle

Machine Tool Spindle Temperature Field Parametric Modeling and Thermal Error Compensation

by Geng Chen, Lin Yuan, Hui Chen, Chengliang Dou, Guangyong Ma, Shuai Li and Lai Hu

Lubricants 2025, 13(12), 548; https://doi.org/10.3390/lubricants13120548 - 16 Dec 2025

Cited by 1 | Viewed by 920

Abstract

The development of modern machining and manufacturing industry puts forward higher requirements for the machining accuracy of machine tools. The thermal error of the machine tool spindle directly affects the accuracy of the machined workpiece. To improve the accuracy of thermal error prediction, [...] Read more.

The development of modern machining and manufacturing industry puts forward higher requirements for the machining accuracy of machine tools. The thermal error of the machine tool spindle directly affects the accuracy of the machined workpiece. To improve the accuracy of thermal error prediction, this paper conducts temperature field analysis for the thermal error of the machine tool spindle and employs the Whale Optimization Algorithm (WOA) to optimize the temperature field parameters, aiming to establish a spindle temperature field model. This approach avoids the problem that traditional measurement methods cannot obtain the temperature of key rotational positions of the spindle and provides a new method for the selection of temperature-sensitive points in the thermal error measurement process. Initially, a spindle Product of Exponentials (POE) error model is constructed to map the five errors of the spindle to three-dimensional vectors in the machine tool space. Subsequently, the Whale Optimization Algorithm (WOA) is used to optimize the physical parameters of the spindle, and the optimal spindle temperature field model is determined. The calculated spindle thermal error data and temperature field model data are input into the OLGWO-SHO-CNN model for training. Finally, a case study is carried out on a machining center, and the trained model is used to perform compensation verification under constant and variable speed conditions, respectively. The experimental results show that under the constant speed condition, the compensation rates of the X-axis, Y-axis, and Z-axis are 77.2%, 73.1%, and 88.7%, respectively; under the variable speed condition, the compensation rates of the X-axis, Y-axis, and Z-axis are 74.7%, 78.2%, and 88.0%, respectively. The compensation results indicate that the established spindle temperature field model and the OLGWO-SHO-CNN model have good robustness and accuracy. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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18 pages, 2496 KB

Open AccessArticle

Experimental Study on Temperature Rise of New Energy Vehicle Drive Motor Bearings Under Grease and Driving Conditions

by Mengchen Zi, Jun Ye, Haichao Cai, Hongfan Yang, Gang Chen, Jiahao Zhang, Dengke Li and Dongliang Lu

Lubricants 2025, 13(12), 526; https://doi.org/10.3390/lubricants13120526 - 2 Dec 2025

Viewed by 861

Abstract

The temperature rise of drive motor bearings in new energy vehicles is a critical factor affecting their reliability and lifespan, with grease performance and driving conditions being the primary determinants of this rise. Addressing the lack of research on how different grease types [...] Read more.

The temperature rise of drive motor bearings in new energy vehicles is a critical factor affecting their reliability and lifespan, with grease performance and driving conditions being the primary determinants of this rise. Addressing the lack of research on how different grease types affect the temperature rise of drive motor bearings under operational conditions, this study utilizes a high-temperature, high-speed testing machine for drive motor bearings in new energy vehicles. It conducts a comparative analysis of the temperature rise in bearings lubricated with four different types of grease under three typical driving conditions: emergency start–stop, smooth driving, and high-speed driving. Results show that the temperature rise varied from 25.1 °C to 50.3 °C under rapid speed change, 22.7 °C to 40.2 °C at fixed speed, and that grease No.3 achieved the lowest temperature rise and the highest limiting speed (23,000 rpm). These results provide quantitative evidence for selecting grease and optimizing bearing design. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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14 pages, 3369 KB

Open AccessArticle

Influence of Machining Environments on the Burnishing Performance of Aluminum Alloy EN AW-2007

by Irina Beșliu-Băncescu and Laurențiu Slătineanu

Lubricants 2025, 13(8), 368; https://doi.org/10.3390/lubricants13080368 - 19 Aug 2025

Cited by 2 | Viewed by 975

Abstract

The presence of a minimum quantity lubrication (MQL) under the conditions of a burnishing process can contribute to an improvement in the process performance by reducing the heights of the resulting surface asperities, by decreasing the temperature values, and by diminishing the size [...] Read more.

The presence of a minimum quantity lubrication (MQL) under the conditions of a burnishing process can contribute to an improvement in the process performance by reducing the heights of the resulting surface asperities, by decreasing the temperature values, and by diminishing the size of the burnishing force components. On the other hand, there are situations in which it is possible to increase the service life of the parts made of EN AW-2007 aluminum alloy by applying a burnishing process. To verify how the results of applying a burnishing process applied to cylindrical specimens in the aluminum alloy when using and not using a minimum quantity lubrication, an experimental research based on a planned variation between certain limits of the values of the peripheral speed and the feed rate has been conceived and materialized. The experimental results were processed mathematically. It has been found that by using the minimum quantity of mineral oil type Valona MS7023 HC, it was possible to reduce the value of the Sa roughness parameter by up to 18%, a decrease in temperature by about 20 °C, and the size of the burnishing force by up to 45%. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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20 pages, 4979 KB

Open AccessArticle

Investigation of the Effects of Cutting Tool Coatings and Machining Conditions on Cutting Force, Specific Energy Consumption, Surface Roughness, Cutting Temperature, and Tool Wear in the Milling of Ti6Al4V Alloy

by Barış Özlü, Hasan Basri Ulaş and Fuat Kara

Lubricants 2025, 13(8), 363; https://doi.org/10.3390/lubricants13080363 - 15 Aug 2025

Cited by 19 | Viewed by 4609

Abstract

The present study aims to investigate the effects of cutting parameters (cutting speed, Vc: 60–90–120 m/min; feed rate, f: 0.055–0.085–0.115 mm/rev), cutting tool coatings (CVD: TiN/TiCN/Al₂O₃ and PVD: TiAlN), and machining conditions (dry, air, and MQL) on cutting force (Fc), [...] Read more.

The present study aims to investigate the effects of cutting parameters (cutting speed, Vc: 60–90–120 m/min; feed rate, f: 0.055–0.085–0.115 mm/rev), cutting tool coatings (CVD: TiN/TiCN/Al₂O₃ and PVD: TiAlN), and machining conditions (dry, air, and MQL) on cutting force (Fc), specific energy consumption (SEC), surface roughness (Ra), cutting temperature (T), and tool wear (Vb) during the milling of Ti6Al4V alloy. As a result, it was observed that all machining tests conducted with the Al₂O₃-coated cutting tool showed improvements of 4.7%, 10.75%, 3.8%, and 6.3% in Fc, SEC, Ra, and T, respectively, compared to the tests performed with the TiAlN-coated cutting tool. Under dry machining conditions, the average Fc, SEC, Ra, and T values were 302.82 N, 4.88 j/mm³, 0.653 µm, and 241.06 °C, respectively. Compared to dry machining conditions, the air and MQL machining conditions demonstrated improvements in the average Fc by 5.15% and 6.3%, SEC by 10.27% and 17.79%, Ra by 6.23% and 11.17%, and T by 8.9% and 19.68%, respectively. The lowest Fc and Ra values for the Al₂O₃-coated cutting tool were measured at 228.33 N and 0.402 µm, respectively, under the MQL machining condition, at a cutting speed of 120 m/min and a feed rate of 0.055 mm/rev. The lowest SEC value (2.694 J/mm³) was also obtained using the Al₂O₃-coated tool under MQL conditions at a cutting speed of 120 m/min and a feed rate of 0.115 mm/rev. Similarly, the lowest cutting temperature (129 °C) was achieved with the Al₂O₃-coated tool under MQL conditions at a cutting speed of 60 m/min and a feed rate of 0.055 mm/rev. The wear performance of the Al₂O₃-coated cutting tool was observed to be superior to that of the TiAlN-coated tool. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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23 pages, 11067 KB

Open AccessArticle

The Influence of Selected Process Parameters on Wire Wear and Surface Quality of Nickel, Titanium and Steel Alloy Parts in WEDM

by Jarosław Buk, Anna Bazan and Paweł Sułkowicz

Lubricants 2025, 13(8), 356; https://doi.org/10.3390/lubricants13080356 - 12 Aug 2025

Viewed by 1485

Abstract

Research on the WEDM process has traditionally focused on analyzing discharge initiation, material removal mechanisms and surface formation from the perspective of the machined part. However, the same phenomena also affect the tool, namely the wire electrode. A comprehensive understanding of the process [...] Read more.

Research on the WEDM process has traditionally focused on analyzing discharge initiation, material removal mechanisms and surface formation from the perspective of the machined part. However, the same phenomena also affect the tool, namely the wire electrode. A comprehensive understanding of the process requires to examine how these effects impact the electrode itself, particularly in terms of wear. Despite its significance, electrode wear in WEDM is not a topic frequently addressed in the literature. The most common method for evaluating wear involves determining the wire wear ratio (WWR), based on the electrode’s weight before and after machining. However, this approach does not provide insight into changes in the microstructure of the electrode surface. This study presents an alternative approach to interpreting wire electrode wear, using surface roughness parameters in relation to the surface texture of the machined workpiece. Measurements were conducted using an optical focus variation microscope. The influence of selected process parameters—including discharge current I_p, pulse-off time t_off and workpiece height h—on selected surface roughness parameters was investigated. The experimental tests were carried out for three alloys representing distinct material groups: 42CrMo4 steel, Inconel 718 nickel alloy, and Ti6Al4V titanium alloy. The results were compared with the roughness parameters of the corresponding machined surfaces. The presented interpretation of the key factors affecting the electrode surface condition after WEDM serves as an initial step in a broader research initiative. It lays the foundation for further studies on wire electrode wear and the development of new wear assessment parameters such as the electrode wear index based on surface texture parameters. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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23 pages, 5107 KB

Open AccessArticle

Linear Rolling Guide Surface Wear-State Identification Based on Multi-Scale Fuzzy Entropy and Random Forest

by Conghui Nie, Changguang Zhou, Tieqiang Wang, Xiaoyi Wang, Huaxi Zhou and Hutian Feng

Lubricants 2025, 13(8), 323; https://doi.org/10.3390/lubricants13080323 - 24 Jul 2025

Cited by 2 | Viewed by 998

Abstract

As a critical precision transmission element in numerical control (NC) machines, the linear rolling guide (LRG) suffers from surface wear degradation, which significantly impairs machining accuracy and operational reliability. Despite its importance, effective identification methods for LRG degradation remain limited. In this study, [...] Read more.

As a critical precision transmission element in numerical control (NC) machines, the linear rolling guide (LRG) suffers from surface wear degradation, which significantly impairs machining accuracy and operational reliability. Despite its importance, effective identification methods for LRG degradation remain limited. In this study, a hybrid approach combining multi-scale fuzzy entropy (MFE) with a gray wolf-optimized random forest (GWO-RF) algorithm was proposed to identify the surface wear state of the LRG. Preload degradation and vibration signals were collected at three surface wear stages throughout the LGR’s service life. The vibration signals were decomposed and reconstructed using complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), followed by multi-scale fuzzy entropy analysis of the reconstructed signals. After dimensionality reduction via kernel principal component analysis (KPCA), the processed features were fed into the GWO-RF model for classification. Experimental results demonstrated a recognition accuracy of 97.9%. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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24 pages, 15762 KB

Open AccessArticle

Performance of TiSiN/TiAlN-Coated Carbide Tools in Slot Milling of Hastelloy C276 with Various Cooling Strategies

by Ly Chanh Trung and Tran Thien Phuc

Lubricants 2025, 13(7), 316; https://doi.org/10.3390/lubricants13070316 - 19 Jul 2025

Cited by 1 | Viewed by 1704

Abstract

Nickel-based superalloy Hastelloy C276 is widely used in high-performance industries due to its strength, corrosion resistance, and thermal stability. However, these same properties pose substantial challenges in machining, resulting in high tool wear, surface defects, and dimensional inaccuracies. This study investigates methods to [...] Read more.

Nickel-based superalloy Hastelloy C276 is widely used in high-performance industries due to its strength, corrosion resistance, and thermal stability. However, these same properties pose substantial challenges in machining, resulting in high tool wear, surface defects, and dimensional inaccuracies. This study investigates methods to enhance machining performance and surface quality by evaluating the tribological behavior of TiSiN/TiAlN-coated carbide inserts under six cooling and lubrication conditions: dry, MQL with coconut oil, Cryo-LN₂, Cryo-LCO₂, MQL–Cryo-LN₂, and MQL–Cryo-LCO₂. Open-slot finishing was performed at constant cutting parameters, and key indicators such as cutting zone temperature, tool wear, surface roughness, chip morphology, and microhardness were analyzed. The hybrid MQL–Cryo-LN₂ approach significantly outperformed other methods, reducing cutting zone temperature, tool wear, and surface roughness by 116.4%, 94.34%, and 76.11%, respectively, compared to dry machining. SEM and EDS analyses confirmed abrasive, oxidative, and adhesive wear as the dominant mechanisms. The MQL–Cryo-LN₂ strategy also lowered microhardness, in contrast to a 39.7% increase observed under dry conditions. These findings highlight the superior performance of hybrid MQL–Cryo-LN₂ in improving machinability, offering a promising solution for precision-driven applications. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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17 pages, 10204 KB

Open AccessArticle

Effect of Nanographene Water-Based Lubricant (NGWL) on Removal Behavior of Pure Copper

by Ziheng Wang, Zhenjing Duan, Shuaishuai Wang, Ji Tan, Peng Bian, Jiyu Liu, Jinlong Song and Xin Liu

Lubricants 2025, 13(7), 286; https://doi.org/10.3390/lubricants13070286 - 26 Jun 2025

Viewed by 974

Abstract

Pure copper is an important metal material in the fields of integrated circuits, mold manufacturing, and aerospace. Its excellent ductility and plasticity lead to problems such as burrs and tool wear in cutting, which poses great challenges to the improvement of machining accuracy [...] Read more.

Pure copper is an important metal material in the fields of integrated circuits, mold manufacturing, and aerospace. Its excellent ductility and plasticity lead to problems such as burrs and tool wear in cutting, which poses great challenges to the improvement of machining accuracy and surface quality. To achieve high-quality and efficient processing of pure copper, this paper proposes to use nanographene water-based lubricant (NGWL) to regulate its removal behavior. A single-grain diamond scribing test and a micro-milling test were carried out to systematically study the action mechanism of NGWL on removal behavior of pure copper. The results showed that, compared with dry scribing at normal forces of 100, 400, 700, and 1000 mN, the material removal efficiency induced by NGWL was increased by 54.1%, 80.7%, 44.8%, and 30.3%, respectively. Compared with dry micro-milling at feed speeds of 200, 600, 1000, and 1400 μm/s, for the 75°XT4E tool, the surface roughness Sa with NGWL-assisted micro-milling was reduced by 75.5%, 73.1%, 61.4%, and 44.2%, respectively. Similarly, for the 65°UDT4E tool, compared to dry micro-milling, the Sa with NGWL lubrication was also reduced by 28.9%, 52.2%, 54.4%, and 36.9%, respectively. The Sa of pure copper induced by NGWL could be as low as about 20 nm without scales. Overall, NGWL can regulate removal behavior of pure copper by alleviating plastic deformation and promoting ductile fracture, thereby providing a new approach to achieving high-quality and efficient processing of pure copper. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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23 pages, 6061 KB

Open AccessArticle

Monitoring and Prediction of the Real-Time Transient Thermal Mechanical Behaviors of a Motorized Spindle Tool

by Tria Mariz Arief, Wei-Zhu Lin, Jui-Pin Hung, Muhamad Aditya Royandi and Yu-Jhang Chen

Lubricants 2025, 13(6), 269; https://doi.org/10.3390/lubricants13060269 - 16 Jun 2025

Cited by 3 | Viewed by 1552

Abstract

The spindle is a critical component that significantly influences the performance of machine tools. In motorized spindles, heat generation from both the bearings and built-in motor leads to thermal deformation of structural components, which, in turn, affects machining accuracy. This study investigates the [...] Read more.

The spindle is a critical component that significantly influences the performance of machine tools. In motorized spindles, heat generation from both the bearings and built-in motor leads to thermal deformation of structural components, which, in turn, affects machining accuracy. This study investigates the thermo-mechanical behavior of motorized spindles under various operational conditions, with the aim of accurately predicting thermally induced axial deformation and determining optimal temperature sensor placement. To achieve this, temperature rise and deformation data were simultaneously collected using appropriate data acquisition systems across varying spindle speeds. A correlation analysis confirmed a strong positive relationship exceeding 97.5% between temperature rise at all sensor locations and axial thermal deformation. Multivariate regression analysis was then applied to identify optimal combinations of sensor data for accurate deformation prediction. Additionally, a finite element (FE) thermal–mechanical model was developed to simulate spindle behavior, with the results validated against experimental measurements and regression model predictions. The four-variable regression model and FE simulation achieved Root Mean Square Errors (RMSEs) of 0.84 µm and 0.82 µm, respectively, both demonstrating close agreement with experimental data and effectively capturing the trend of thermal deformation over time under different operating conditions. Finally, an optimal sensor configuration was identified that minimizes pre-diction error while reducing the number of required sensors. Overall, the proposed methodology offers valuable insights for optimizing spindle design to enhance thermal–mechanical performance. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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17 pages, 4085 KB

Open AccessArticle

Comprehensive Evaluation of the Rheological, Tribological, and Thermal Behavior of Cutting Oil and Water-Based Metalworking Fluids

by Florian Pape, Belal G. Nassef, Stefan Schmölzer, Dorothea Stobitzer, Rebekka Taubmann, Florian Rummel, Jan Stegmann, Moritz Gerke, Max Marian, Gerhard Poll and Stephan Kabelac

Lubricants 2025, 13(5), 219; https://doi.org/10.3390/lubricants13050219 - 15 May 2025

Cited by 6 | Viewed by 2349

Abstract

Metalworking fluids (MWFs) are crucial in the manufacturing industry, playing a key role in facilitating various production processes. As each machining operation comes with distinct requirements, the properties of the MWFs have to be tailored to meet these specific demands. Understanding the properties [...] Read more.

Metalworking fluids (MWFs) are crucial in the manufacturing industry, playing a key role in facilitating various production processes. As each machining operation comes with distinct requirements, the properties of the MWFs have to be tailored to meet these specific demands. Understanding the properties of different MWFs is fundamental for optimizing processes and improving performance. This study centered on characterizing the thermal behavior of various cutting oils and water-based cutting fluids over a wide temperature range and sheds light on the specific tribological behavior. The results indicate that water-based fluids exhibit significant shear-thinning behavior, whereas cutting oils maintain nearly Newtonian properties. In terms of frictional performance, cutting oils generally provide better lubrication at higher temperatures, particularly in mixed and full-fluid film regimes, while water-based fluids demonstrate greater friction stability across a wider range of conditions. Among the tested fluids, water-based formulations showed a phase transition from solid to liquid near 0 °C due to their high water content, whereas only a few cutting oils exhibited a similar behavior. Additionally, the thermal conductivity and heat capacity of water-based fluids were substantially higher than those of the cutting oils, contributing to more efficient heat dissipation during machining. These findings, along with the reported data, intend to guide future researchers and industry in selecting the most appropriate cutting fluids for their specific applications and provide valuable input for computational models simulating the influence of MWFs in the primary and secondary shear zones between cutting tools and the workpiece/chiplet. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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19 pages, 31637 KB

Open AccessArticle

Effect of Bio-Based, Mixed Ester Lubricant in Minimum Quantity Lubrication on Tool Wear and Surface Integrity in Ultra-Precision Fly-Cutting of KDP Crystals

by Xuelian Yao, Feihu Zhang, Shuai Zhang, Jianfeng Zhang, Defeng Liao, Xiangyang Lei, Jian Wang and Jianbiao Du

Lubricants 2025, 13(4), 156; https://doi.org/10.3390/lubricants13040156 - 1 Apr 2025

Cited by 3 | Viewed by 1593

Abstract

Potassium dihydrogen phosphate (KDP) crystals, vital for high-power laser systems, pose significant machining challenges due to their brittleness, low hardness, and hygroscopic properties. Achieving crack-free, high-precision surfaces is essential but complex. Single-point diamond fly-cutting (SPDF) is the primary method, yet it exposes tools [...] Read more.

Potassium dihydrogen phosphate (KDP) crystals, vital for high-power laser systems, pose significant machining challenges due to their brittleness, low hardness, and hygroscopic properties. Achieving crack-free, high-precision surfaces is essential but complex. Single-point diamond fly-cutting (SPDF) is the primary method, yet it exposes tools to high mechanical stress and heat, accelerating wear. In dry cutting, worn tools develop adhesive layers that detach, causing scratches and degrading surface quality. Traditional wet cutting improves surface finish but leaves residual fluids that contaminate the surface with metal ions, leading to optical degradation and fogging. To address these issues, this study explores mixed-fat-based minimum quantity lubrication (MQL) as a sustainable alternative, comparing two lubricants: biodegradable-base mixed ester lubrication (BBMEL) and hydrocarbon-based synthetic lubricant (HCBSL). A comprehensive evaluation method was developed to analyze surface roughness, tool wear, and subsurface damage under dry cutting, MQL-BBMEL, and MQL-HCBSL conditions. Experimental results show that MQL-BBMEL significantly enhances machining performance, reducing average surface roughness by 27.77% (Sa) and 44.77% (Sq) and decreasing tool wear by 25.16% compared to dry cutting, outperforming MQL-HCBSL. This improvement is attributed to BBMEL’s lower viscosity and higher proportion of polar functional groups, which form stable lubricating films, minimizing friction and thermal effects. Structural analyses confirm that MQL-BBMEL prevents KDP crystal deliquescence and surface fogging. These findings establish MQL-BBMEL as an eco-friendly, high-performance solution for machining brittle optical materials, offering significant advancements in precision machining for high-power laser systems. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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29 pages, 29665 KB

Open AccessArticle

Experimental Research on the Effect of Thermophysical Characteristics of Cutting Fluid on Cutting Performance During Turning Ti-6Al-4V Alloy

by Xiaorong Zhou, Lin He, Sen Yuan, Jing Deng, Zebin Su, Jingdou Yang and Feilong Du

Lubricants 2025, 13(2), 90; https://doi.org/10.3390/lubricants13020090 - 17 Feb 2025

Cited by 3 | Viewed by 1740

Abstract

Cutting fluid has been widely used to enhance the heat dissipation of cutting systems. However, whether cutting fluid can fully play its role is closely correlated with its thermophysical characteristics, such as viscosity, surface tension, etc. In this work, to study the effect [...] Read more.

Cutting fluid has been widely used to enhance the heat dissipation of cutting systems. However, whether cutting fluid can fully play its role is closely correlated with its thermophysical characteristics, such as viscosity, surface tension, etc. In this work, to study the effect of the thermophysical characteristics of cutting fluid on cutting performance, three green vegetable oils (semi-synthetic fluid (L1), rapeseed oil (L2), canola oil (L3)) were selected as cutting fluids of the MQL system, and differences in cutting performance were compared and analyzed under varied lubrication environments. Firstly, the thermophysical characteristics of the vegetable oils were determined by experimental methods. Afterwards, parameters, including tool wear, cutting force, and temperature, as well as the quality of machined workpieces, were selected to evaluate cutting performance, and essential reasons for the difference in cutting performance under varied lubrication environments were clarified. The results demonstrated that the cutting force, cutting temperature, and tool wear produced in the three MQL environments were lower than those in the dry cutting environment, while only the L1 and L2 MQL environments exhibited higher machined surface quality than the dry cutting environment. Moreover, obvious differences in cutting performance under the three MQL environments were also observed due to the different thermophysical characteristics of the three vegetable oils. The best cutting performance was achieved when L2 was used as the MQL cutting fluid. The efforts of this study will give an important reference for the choosing of green cutting fluid in the cutting process of difficult-to-cut materials and be of great significance for accelerating the development of green processing. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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25 pages, 8306 KB

Open AccessArticle

Investigation of the Contact Characteristics of a Single-Nut Ball Screw Considering Geometric Errors

by Jun Liu, Huaxi Zhou, Xiaoyi Wang and Changguang Zhou

Lubricants 2025, 13(2), 57; https://doi.org/10.3390/lubricants13020057 - 29 Jan 2025

Cited by 5 | Viewed by 2284

Abstract

As the critical performance index of ball screws, the contact characteristics have a significant influence on the lubricant properties, tribological properties, and wear properties of ball screws, which further directly affect the service life of ball screws. The non-uniform load distribution induced by [...] Read more.

As the critical performance index of ball screws, the contact characteristics have a significant influence on the lubricant properties, tribological properties, and wear properties of ball screws, which further directly affect the service life of ball screws. The non-uniform load distribution induced by geometric errors results in imbalances among balls along the nut, negatively impacting the service life of ball screws. This study focuses on the load distribution of single-nut ball screws under low-speed working conditions. This paper proposes a self-adjustable model of load distribution that considers the flexibility of the screw and nut with respect to the determination of the non-bearing ball. A refined model for axial stiffness is proposed to systematically analyze the influence of geometric errors on stiffness variations under various loading conditions. The results confirm the ability of the proposed model to reveal the static load distribution in view of geometric errors. The greatest discrepancy observed between the theoretical predictions and the experimental data was 9.22%. The numerical simulations demonstrate variation trends in the normal contact load, the loaded-ball number, and the axial deformation of a nut with geometric errors. Furthermore, the relationship between the axial stiffness of a single-nut ball screw and the geometric error is obtained. The self-adjustable model of load distribution is helpful for studying the carrying capacity of a single-nut ball screw. The findings of the study provide a definite reference for optimization of structural design and wear life prediction. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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18 pages, 12905 KB

Open AccessArticle

Flow Characteristics and Experimental Verification of T-Groove Dry Gas Seal Under Different Flow States

by Lanxia Zhang, Xuexing Ding, Shipeng Wang and Shuai Zhang

Lubricants 2025, 13(1), 9; https://doi.org/10.3390/lubricants13010009 - 30 Dec 2024

Cited by 6 | Viewed by 2098

Abstract

With the improvement of dry gas seal efficiency in high-parameter fields, the flow pattern of gas film lubrication is complicated. Based on gas lubrication theory, the Reynolds equation of compressible gas was established with a bidirectional T-groove dry gas seal as the research [...] Read more.

With the improvement of dry gas seal efficiency in high-parameter fields, the flow pattern of gas film lubrication is complicated. Based on gas lubrication theory, the Reynolds equation of compressible gas was established with a bidirectional T-groove dry gas seal as the research object. The Reynolds equation was solved to obtain a modified turbulent film pressure distribution law that affects gas lubrication. The effectiveness of the calculation program was verified by experimental tests. The results show that with an increase in operating parameters, the turbulence effect caused the gas film pressure fluctuation in the T-groove region to intensify, resulting in gas film flow instability. In addition, the inertia effect improved, which slowed down the leakage and affected the change law of stiffness and the rigid leakage ratio. When the fluid speed and gas pressure were low, the inertia effect could be ignored. When the groove depth was increased to 8 μm, the height difference between the trough and non-T-groove region became larger due to the combination of the turbulence and inertia effects. Further, when the gas film thickness was 3 μm, the opening force and gas film stiffness were high due to the dynamic pressure effect in the small film thickness groove. An increase in the gas film thickness weakened the turbulence effect and reduced the gas film pressure fluctuation. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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32 pages, 10224 KB

Open AccessReview

Precision Machining of Different Metals by Plasma Electrolytic Polishing: A Review for Improving Surface Smoothness and Properties

by Tongtong Yan, Shuqi Wang, Weidi He, Rui Jin, Jiajun Zhao, Yongchun Zou, Jiahu Ouyang, Yaming Wang and Yu Zhou

Lubricants 2025, 13(9), 412; https://doi.org/10.3390/lubricants13090412 - 14 Sep 2025

Cited by 4 | Viewed by 4823

Abstract

The surface quality of metal materials is closely related to their service life and performance. Appropriate polishing techniques can significantly reduce surface roughness and the coefficient of friction, thereby enhancing properties such as wear resistance and corrosion resistance. However, traditional polishing methods have [...] Read more.

The surface quality of metal materials is closely related to their service life and performance. Appropriate polishing techniques can significantly reduce surface roughness and the coefficient of friction, thereby enhancing properties such as wear resistance and corrosion resistance. However, traditional polishing methods have certain limitations. For instance, mechanical polishing has low processing efficiency and fails to ensure consistent product quality; chemical polishing can cause environmental pollution; and electrolytic polishing may result in severe corrosion. In contrast, plasma electrolytic polishing (PEP) has attracted considerable attention for its ability to achieve high-quality surface finishes, its use of environmentally friendly aqueous electrolytes, and its rapid processing speed. It has been successfully applied to the finishing of various metal materials. Hence, this review firstly introduces the basic principles of PEP from two perspectives of macroscopic structure and microscopic mechanism, and summarizes the typical features appearing in the polishing process. Secondly, the key parameters affecting the quality of the polished surface are discussed, including voltage, electrolyte composition and electrolyte temperature, and polishing time. Subsequently, the application of PEP on various metals was discussed, along with considerations regarding the polishing efficiency and removal characteristics of coatings and non-metallic substances. Finally, the challenges and potential future development prospects of PEP are summarized. Full article

(This article belongs to the Special Issue High Performance Machining and Surface Tribology)

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