Purpose The running resistance of the scraper conveyor is a primary factor leading to severe wear of the intermediate trough and a decrease in transmission efficiency. This paper aims to calculate the running resistance more accurately by establishing an improved mechanical model of the scraper conveyor. Design/methodology/approach Using the discrete element model and Plackett–Burman test, the important factors affecting the running resistance are screened out. According to the viscoelastic contact characteristics of coal bulk material and important factors, combined with Box Behnken design test, the improved dynamic model of scraper conveyor running resistance is established. A test bench of scraper conveyor running resistance is established to compare and analyze the running resistance calculated by the improved dynamic model and the test bench under different working conditions. Findings The results show that under the working conditions of no-load starting, heavy-load starting, upward and downward conveying, the errors of the improved dynamic model are reduced by 69%, 76%, 77% and 47%, respectively, compared with the traditional empirical formulas. Originality/value This study provides a more accurate model and technical suggestions for determining the driving power of the scraper conveyor, designing the wear-saving intermediate groove and determining the preloading force of the scraper chain.

Purpose Owing to the presence of unsafe chemical components in many cutting fluids, there is growing concern over their environmental and health impacts. In response, industries and researchers are actively exploring substitute approaches to minimize the use of these fluids in grinding applications. Accordingly, the present study aims to highlight the potential of the minimum quantity lubrication (MQL) technique as an eco-friendly alternative to the conventional flood (wet) grinding method. Design/methodology/approach The review methodology adopted in this study is structured into three core sections. The first section outlines the evolution of the MQL technique and compares its grinding performance against conventional approaches such as dry and flood cooling. The second section reviews existing literature on MQL grinding using single nanofluids (S-NF). Finally, the third section evaluates the performance of MQL grinding when hybrid nanofluids (H-NF) are used. Findings The comprehensive review highlights that MQL provides notable advantages over both dry and traditional wet machining methods. Key benefits include a substantial reduction in cutting zone temperature, lower grinding forces, extended wheel life and enhanced surface quality of the machined parts. In addition, the use of H-NF in MQL grinding exhibits better tribological performance compared to S-NF. Practical implications MQL grinding creates a cleaner, healthier and more environmentally friendly workspace by minimizing fluid usage and reducing pollution, thus promoting sustainable and green manufacturing practices. Originality/value This paper examines the suitability of MQL in grinding operations using S-NF and H-NF. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2025-0498/

Purpose Under high-speed conditions, oil cutoff severely compromises the heat dissipation capacity of bearings, which could trigger a rapid temperature rise and pose a critical challenge to their thermal endurance. This study integrates numerical simulations with experimental validation to investigate the transient thermal characteristics of bearings after oil cutoff. This study aims to provide a systematic framework for evaluating temperature performance under high-speed, oil cutoff conditions. Design/methodology/approach A quasi-static method combined with localized friction modeling is used to calculate frictional heat generation, while the volume-of-fluid method is adopted to accurately capture the oil–gas two-phase flow dynamics within the bearing cavity. The study systematically examines the effects of varying rotational speeds on oil distribution and thermal evolution. Findings After oil cutoff, the oil volume fraction within the bearing cavity rapidly decreases to a steady state, concurrently accompanied by a sharp decline and stabilization of the convective heat transfer coefficient on the cavity wall surface. At a rotational speed of 35,000 rpm, the peak temperature of the inner ring for the bearing reaches 245.46°C after 30 s of oil cutoff. This means that there is a 51% increase compared to steady oil supply conditions. In contrast, the outer ring exhibits a lower peak temperature of 144.88°C, which reflects a 34% increase. Originality/value This study proposes a validated computational method capable of efficiently analyzing internal temperature distributions of bearings, which can provide a practical and reliable alternative for extreme performance design in high-speed bearing systems. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2025-0446/

Purpose This study aims to review the progress in friction and wear experimental research. Design/methodology/approach Initially, it elucidates the evaluation methodologies and classifications of friction and wear testing machines. Subsequently, it consolidates the prevalent methodologies and techniques used in friction and wear experiments, encompassing friction coefficient assessment, wear volume quantification and surface morphology inspection. The discussion then delves into the friction and wear characteristics of friction pair materials under various contact conditions – point contact, line contact and surface contact within diverse environments such as dry friction, lubrication, elevated temperatures and high pressures. This discussion includes the friction coefficient, material removal amount and surface morphology of the friction pair materials. Findings Friction and wear testing serves as a fundamental research methodology within the fields of materials science and mechanical engineering. Based on the distinct forms of contact between friction pairs, these tests can be meticulously categorized into three primary types: point contact, line contact and surface contact. These classifications not only reflect the diversity of geometric characteristics at the friction interface but also profoundly influence the complexity of friction and wear behavior as well as the depth of exploration into underlying mechanisms. This paper summarizes and synthesizes the wear mechanisms of materials and the evaluation of lubricants under varying environmental conditions and different frictional states. Originality/value This paper projects the future trajectory of friction and wear experimental research, pinpointing potential directions and focal points for upcoming investigations. This paper reviews the latest advances in friction and wear experimental research, providing a certain reference value for promoting research and applications in the field of friction and wear. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2025-0322/

Purpose The purpose of this study is to reveal the influence mechanism of centrifugal inertial effect on the dynamic tracking stability of spiral groove dry gas seal (S-DGS) and to explore the interaction between the special effects of the flow field under high-parameter conditions. Design/methodology/approach The real-gas behavior of carbon dioxide (CO2) is expressed by the Virial equation, and the occurrence of exit choked flow is determined when the exit velocity reaches the sound speed. Perturbation and finite difference methods are used to calculate dynamic gas film characteristic coefficients, and then an axial dynamic model for S-DGS is developed considering centrifugal inertia, choked flow and real-gas effects, which is analytically solved to obtain the axial tracking performance of CO2 S-DGS. Findings The centrifugal inertia effect suppresses the axial tracking capability of the stationary ring in pumping-inward S-DGS, while enhancing it in pumping-outward S-DGS. The real-gas effect primarily influences the inertia effect through gas density, and affects the choked flow effect via dynamic gas film characteristic coefficients. The choked flow effect impacts the real-gas effect through the inlet–outlet pressure differential and affects the inertia effect via dynamic gas film thickness. The inertia effect mainly influences both the real-gas effect and the choked flow effect through gas flow resistance. Originality/value Divergent impacts of centrifugal inertia effect on axial tracking performance of two S-DGSs are revealed, and the complex interaction mechanisms of three special effects on dynamic leakage rate are further investigated, providing a critical theoretical foundation for optimizing the sealing performance of S-DGS.

Purpose The present work is a step forward in developing spark plasma sintered titanium alloy (Ti64) and multilayer graphene (MLG) nanocomposites with enhanced mechanical and tribological properties for industrial applications. This study aims to conduct a detailed experimental investigation of the spark plasma process during the fabrication of Ti64-MLG nanocomposites. It gives an insight into understanding the role of adding MLG in influencing the properties of Ti64. Design/methodology/approach Conducts a detailed parametric analysis of the spark plasma sintering (SPS) process during the fabrication of Ti64-MLG nanocomposites. Experimental runs were designed using the central composite rotatable design approach. Findings Analysis of variance predicted Wt.% of MLG as the significant parameter with a contribution of 54.75 % and 48.72 %, followed by the sintering temperature, contributing 43.44 % and 46.22 % in determining corrosion current density and wear rate, respectively. A minimum wear rate of 14.50 × 10–6 g/m, corresponding to a 54.40 % improvement compared to bare Ti64, is achieved for Ti64-0.8 Wt.% MLG fabricated at 1000 °C. Originality/value Ti64-MLG nanocomposites demonstrating improved wear and corrosion resistance have been developed in this study. Additionally, regression models illustrating the relationship between the output responses, that is, wear rate and corrosion current density of the nanocomposites as a function of input parameters, that is, sintering temperature and Wt.% of MLG, have been established.

Purpose This study aims to establish an accurate prediction model for nonuniform tool wear in GH4169 milling by integrating process optimization and intelligent learning techniques. Design/methodology/approach A two-stage approach was used: response surface methodology (RSM) optimized cutting parameters, and a Whale Optimization Algorithm-backpropagation (WOA-BP) neural network model was built using machining angle and time to predict localized tool wear. Findings The proposed RSM–WOA-BP model achieved high prediction accuracy, reducing root mean square error to 1.69µm and mean absolute percentage error to 1.14%, significantly outperforming conventional BP networks in robustness and generalization. Research limitations/implications Because the model parameters are closely related to workpiece machinability, coating wear resistance and tool–workpiece contact geometry, significant changes in workpiece material, coating system, tool diameter, cutting-edge geometry or cooling/lubrication strategy may alter the wear mechanism and the angle-dependent load distribution, leading to systematic bias if the model is directly applied. In such cases, recalibration is required. The proposed workflow is transferable to other materials and tool/coating systems, provided that necessary recalibration and validation are conducted under the new conditions. Practical implications In batch manufacturing, the machining parameters and tool type for a given operation are typically kept stable, so the calibration effort can be amortized over the production batch; the model can thus serve as a practical tool for process planning and wear monitoring. Originality/value This work integrates the strengths of RSM and WOA-BP to develop a high-accuracy model for predicting nonuniform tool wear in ball-end milling, ensuring both modeling precision and experimental efficiency. The model supports precise tool wear prediction in machining nickel-based superalloys with ball-end mills, enabling better control of tool life, cost reduction and improved reliability in complex aerospace and high-temperature applications. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2025-0308/

Purpose This paper presents an experimental investigation into the effect of thrust bearing surface roughness on the performance of a wet rotor circulator pump. The aim of this study is to clarify how different surface roughness levels influence the hydraulic and energy performance characteristics of the pump under controlled laboratory conditions. In contrast to the limited number of existing works addressing thrust bearing surface finish in circulator pumps, this study provides quantitative evidence of its influence on efficiency by explicitly evaluating the Energy Efficiency Index (EEI). Design/methodology/approach Thrust bearings with three distinct levels of surface roughness (Ra ≈ 0.79 µm for stainless steel, Ra ≈ 0.19 µm for alumina ceramic and Ra ≈ 0.08 µm for silicon carbide) were evaluated under consistent operating conditions using a certified test stand in accordance with EN 16297 and ISO 9906 standards. For each bearing type, the pump was operated for 1 h to achieve steady-state conditions, and the tests were repeated four times to minimize uncertainty. Findings The findings reveal that increased surface roughness leads to elevated friction losses between rotating and stationary elements, resulting in higher power demand and reduced overall pump efficiency. Bearings with smoother surfaces demonstrated improved hydraulic performance and lower energy usage. The average EEI values were 0.213 for stainless steel, 0.204 for alumina ceramic and 0.198 for silicon carbide, indicating a clear correlation between reduced surface roughness and improved efficiency. The results provide practical guidance for reducing energy consumption and extending pump lifespan. Research limitations/implications This study focuses on steady-state experimental tests conducted under controlled laboratory conditions to evaluate the effect of thrust bearing surface roughness on pump performance and EEI. While the results clearly demonstrate the influence of surface finish, long-term operation and progressive wear effects were beyond the scope of the present work. In addition, the investigation was performed on a single pump configuration and operating range. Future studies extending the analysis to long-term testing, different pump designs and varying operating conditions would further enhance understanding of the durability and energy performance implications. Originality/value This study offers original quantitative evidence on the effect of thrust bearing surface roughness on the performance of wet rotor circulator pumps by directly linking surface finish to the EEI. Unlike most existing studies focusing solely on lubrication theory or computational models, this work presents real-world performance data, including EEI measurements in accordance with EN 16297. The study isolates surface roughness as the dominant parameter under standardized test conditions, providing practical insights for pump designers and manufacturers on improving energy efficiency through surface finishing without altering pump geometry or materials.

Purpose This study aims to investigate and compare the tribological behavior of two high-performance polymers, ultra-high-molecular weight polyethylene (UHMWPE) and polyetheretherketone (PEEK), under dry sliding conditions against steel and various polyetherimide (PEI)-based polymer counterfaces. Design/methodology/approach Pin-on-disk wear tests were carried out using the UHMWPE and PEEK pins sliding against four different counterfaces of general purposed (GP)-PEI, wear resistant (WR)-PEI, glass fiber-reinforced PEI (PEI + 20% GFR) and AISI 304 L stainless steel. The experiments were conducted under normal loads of 20, 40 and 60 N at a constant sliding speed and distance. The coefficient of friction (COF), specific wear rate (SWR) and dominant wear mechanisms were evaluated based on the experimental measurements and optical microscopy observations. Findings The UHMWPE consistently exhibited lower COF and specific wear rate values than those of the PEEK, under all test conditions. Its best tribological performance was achieved at a load of 60 N against the GP-PEI counterface, yielding the COF and SWR values of 0.0728 and 7.96 × 10–15 m²/N, respectively. For the PEEK, the optimum values of the COF and SWR were obtained as 0.1856 and 8.79 × 10–15 m²/N, respectively also against the GP-PEI. The superior performance of the UHMWPE was mainly attributed to its self-lubricating behavior and the formation of a stable transfer film. However, the PEEK exhibited higher and more unstable friction behavior, particularly when sliding against the PEI + 20% GFR and steel counterfaces. Originality/value Unlike most previous studies focusing primarily on the metal–polymer tribological pairs, this study provides a comprehensive comparative evaluation of polymer–polymer and polymer–metal interfaces. The findings demonstrate that the UHMWPE outperforms the PEEK in the dry sliding applications and offer valuable insights for the rational selection of tribo-pairs in the engineering applications.

Purpose This study aims to reveal the impact of external vibration and frictional surface roughness on the friction-reduction of granular flow lubrication, to further enhance the lubricating effect of granular media, and to promote the wide application of granular flow lubrication technology in industrial fields. Design/methodology/approach The test of vibration-assisted granular flow lubrication with different friction surfaces were conducted on a homemade linear reciprocating vibration friction tester. Based on the test results, the effects of vibration frequency and amplitude on the friction reduction performance of granular flow lubrication were analyzed. Meanwhile, the morphology, size and wear rate of the wear scar on the friction test sample were measured using a white light interference microscope, and the improvement effect of vibration-assisted granular flow lubrication on the anti-wear performance of the friction sample was analyzed. Findings The results indicate that, under the condition of vibration-assisted granular flow lubrication, both ordinary and roughened samples exhibited a significant anti-wear effect. As the vibration frequency was increased, the friction coefficient and the wear amount of the lower specimen initially decreased and then increased. In contrast, with increasing amplitude, both parameters demonstrated a continuous downward trend. Compared with the no-vibration condition, the average friction coefficients with ordinary and roughened samples under vibration-assisted condition were reduced by 16% and 24%, respectively, and the wear rates of the lower specimens were reduced by 20% and 57%, respectively. The result shows that, a roughened surface can store granules, and external vibration facilitates the entry of granular media into the friction interface. Based on the synergistic effect of two above factors, the lubricating effect of granular flow was significantly enhanced. Originality/value This research can enrich the theory of granular tribology, improve the friction reduction effect of granular flow lubrication and ultimately provide theoretical and practical references for the wide application of this technology.