CC BY
2
MEXANIKA
UDK.621.01:677.21
ADVANCED LASER CLADDING TECHNIQUES FOR ENHANCING MINI METAL GEAR PERFORMANCE MADE FROM R6M5 STEEL IN THE TEXTILE INDUSTRY
Elmanov Abbos
Shahrisabz Branch of Tashkent Institute of Chemical Technology, PhD researcher E-mail: abbos.tktishf@gmail.com, Corresponding author.
Tojiyev Davron
Shahrisabz Branch of Tashkent Institute of Chemical Technology, Bachelor, E-mail: davr.toii@gmail.com
Mirzaumidov Asilbek Namangan Institute of Engineering and Technology, Associate professor
E-mail: abdusamatov.alisher@inbox.ru
Abstract. This study explores the enhancement of wear resistance in R6M5 steel gears (10 mm diameter) through laser cladding using a chromium (Cr), boron (B), and molybdenum (Mo) powder mixture. The cladding process significantly improved surface hardness, increasing from 650 HV (untreated) to 1200 HV, due to the formation of martensitic structures, Cr carbides, and borides. Wear resistance tests showed a 49% reduction in wear rate and a 27% decrease in the coefficient of friction. These findings demonstrate that laser cladding with Cr, B, and Mo provides superior wear protection, making it ideal for high-performance gear applications.
Аннотация. В данном исследовании изучено повышение износостойкости зубчатых колес из стали R6M5 (диаметром 10 мм) методом лазерной наплавки с использованием смеси порошков хрома (Cr), бора (B) и молибдена (Mo). Процесс наплавки значительно увеличил твердость поверхности: с 650 HV (без обработки) до 1200 HV, благодаря образованию мартенситных структур, карбидов хрома и боридов. Тесты на износ показали снижение скорости износа на 49% и уменьшение коэффициента трения на 27%. Эти результаты демонстрируют, что лазерная наплавка с Cr, B и Mo обеспечивает отличную защиту от износа, что делает ее идеальной для применения в зубчатых передачах.
Annotatsiya. Ushbu tadqiqotda R6M5 po'latidan tayyorlangan (diametri 10 mm) tishli g'ildiraklarning yeyilishga bardoshliligini xrom (Cr), bor (B) va molibden (Mo) kukunlari aralashmasi yordamida lazer qoplama orqali yaxshilash o'rganilgan. Qoplama jarayoni yuzaning qattiqligini 650 HV (ishlov berilmagan) qiymatdan 1200 HV qiymatgacha sezilarli darajada oshirdi, bu martensit strukturasi, Cr karbidlari va boridlar hosil bo'lishi tufayli sodir bo'ldi. Yeyilishga qarshi sinovlar yeyilish tezligi 49% ga kamayganini va ishqalanish koeffitsiyenti 27% gacha pasayganini ko'rsatdi. Ushbu natijalar lazer qoplamasi tishli g'ildiraklar uchun yuqori darajadagi himoyaviylikni ta'minlashini tasdiqlaydi.
Key words: laser cladding, P6M5 steel, mini metal gears, wear resistance, surface hardness, fatigue life, textile machinery, tribological properties
Ключевые слова: лазерная наплавка, Сталь Р6М5, металлические мини шестерни, износостойкость, поверхностная твердость, усталостная долговечность, текстильное оборудование, трибологические свойства
Kalit so'zlar: lazer qoplamasi, P6M5 po'lat, mini metall tishli g'ildirak, yeyilishga bardoshlilik, yuza mustahkamligi, ishdan chiqish davri, to'qimachilik mashinalari, tribologik xususiyatlar
Introduction
The textile industry relies heavily on machinery that operates under high-speed, high-
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
stress conditions, particularly in components such as mini metal gears that facilitate the transfer of power and movement in various textile processes. These gears, often made from high-speed steel alloys like R6M5, are prized for their hardness and wear resistance [1]. However, continuous exposure to intense mechanical loads, friction, and varying environmental conditions can lead to significant wear and tear, ultimately reducing gear efficiency and lifespan. As a result, there has been a growing demand for surface engineering techniques to enhance the performance and longevity of these gears [2], [3].
Among the advanced surface modification techniques, laser cladding has gained considerable attention for its ability to improve the mechanical properties of steel components, including mini metal gears. Laser cladding involves depositing a layer of material onto the surface of a substrate using a high-energy laser, creating a metallurgically bonded coating that can enhance wear resistance, hardness, and corrosion resistance [4]. The versatility of laser cladding allows the use of various cladding materials, including cobalt-based alloys, nickelbased alloys, and carbide-rich coatings, which are particularly beneficial in improving the tribological properties of R6M5 steel gears [5].
In the context of the textile industry, where gears operate at high rotational speeds and under varying loads, enhancing wear resistance and reducing friction are critical. Research has shown that laser cladding not only increases the lifespan of gears but also significantly reduces the need for maintenance, leading to lower operational costs and downtime[6], [7]. Furthermore, laser cladding allows for localized treatment and repair of worn gear teeth without affecting dimensional accuracy, making it a cost-effective solution for extending the service life of mini metal gears [8]. Recent advancements in laser cladding technology have focused on optimizing laser parameters such as energy density, scanning speed, and powder composition to create defect-free, high-quality clad layers with minimal porosity and dilution [9].
This paper explores the application of advanced laser cladding techniques to enhance the performance of mini metal gears ma de from R6M5 steel, focusing on the optimization of
process parameters, cladding materials, and the resultant improvements in wear resistance and operational efficiency for the textile industry.
Laser cladding involves the deposition of a protective layer onto the substrate material using a high-energy laser beam, resulting in a metallurgically bonded coating that enhances surface properties. This process has been shown to significantly improve the wear resistance and hardness of materials, which is critical for gears operating in high-friction environments, such as textile machinery. Research by Fomin et al. (2016) demonstrated that the laser cladding of R6M5 steel can enhance wear resistance by more than threefold compared to untreated steel, making it highly relevant for applications in the textile industry where gears are exposed to constant mechanical stress[10].
One of the foundational studies in this area by Guo-Ye et al. (2024) investigated the application of laser cladding to enhance the wear resistance of mini metal gears made from various high-speed steels. The authors demonstrated that laser cladding significantly improved surface hardness and reduced wear, making it a promising technique for gears subjected to high friction and load-bearing environments in the textile industry. Their work also highlighted the importance of selecting appropriate cladding materials, such as Cr carbides and h-BN-containing coatings, which offer improved bonding strength and resistance to wear and corrosion[11].
Additionally, the use of Nd-YAG laser technology in manufacturing textile machinery components has been shown to improve their overall performance and longevity. For example, Balasubramanian and Manonmani (2013) demonstrated that laser hardening of bottom rollers in spinning machines not only enhances hardness but also ensures a uniform case depth, leading to better yarn quality and longer roller life[12]. This finding underscores the potential of laser-based surface treatments in improving the efficiency and durability of textile machine
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
components.
Furthermore, laser processing techniques are increasingly replacing traditional methods for treating textile materials, including cutting, engraving, and marking, with applications ranging from creating decorative elements to improving the finishing quality of fabrics. Nemesa and Kaplan (2019) highlighted that different textile materials exhibit varying behaviors under laser treatment, with natural fibers vaporizing and synthetic fibers melting, which allows for high-precision applications without the risk of tearing[13].
The application of laser cladding techniques to mini metal gears in textile machinery offers several advantages, including improved wear resistance, reduced downtime due to fewer maintenance needs, and enhanced overall machine performance. As textile machines operate continuously under harsh conditions, the demand for more durable and reliable components is rising, making laser cladding an attractive solution for gear manufacturers.
In this study, we explore the specific application of advanced laser cladding techniques to enhance the performance of mini metal gears made from R6M5 steel in textile machinery. We will discuss the process parameters, material compatibility, and performance improvements observed in laser-treated gears, drawing on the existing body of research in this field.
Collectively, these studies indicate that laser cladding is a highly effective technique for enhancing the performance of mini metal gears made from R6M5 steel, especially in high-speed, high-wear applications such as textile machinery. The choice of cladding material, alongside the careful optimization of laser parameters, plays a critical role in determining the success of the process. However, further research is needed to explore new cladding materials and methods for even greater improvements in gear performance and longevity.
Materials and methods
This study aimed to improve the wear resistance of a gear made of R6M5 steel with a 10 mm diameter through laser cladding using a mixture of chromium (Cr), boron (B), and molybdenum (Mo) powders. R6M5 is a high-speed steel known for its high hardness and toughness, commonly used for cutting tools and mechanical components. The focus of this methodology is on enhancing the gear's surface durability against wear and friction using the laser cladding technique.
1. Selection of materials: The gear used in this study was made from R6M5 high-speed steel, which contains elements like molybdenum (Mo), tungsten (W), and vanadium (V). These elements impart high hardness and heat resistance, making R6M5 steel ideal for high-wear applications such as gears. A mixture of Cr, B, and Mo powders was selected for the laser cladding process. These materials were chosen for the following reasons:
- Chromium (Cr) improves surface hardness and corrosion resistance.
- Boron (B) enhances hardness and mechanical strength.
- Molybdenum (Mo) contributes to heat resistance and reduces friction.
2. Laser cladding process
The laser cladding process involved applying the Cr, B, and Mo powder mixture to the gear surface and then melting the powder with a laser to form a durable coating. The key steps in the cladding process are outlined below:
- Surface preparation: The gear surface was mechanically cleaned and degreased to ensure the proper adhesion of the coating. This step is crucial for preventing oxidation during the laser process and ensuring a uniform coating.
- Powder mixture preparation: The Cr, B, and Mo powders were mixed in a specific ratio (60% Cr, 30% Mo, and 10% B). The mixture was homogenized using ultrasonic stirring to ensure uniform distribution of particles for optimal cladding performance.
- Laser cladding: The prepared powder mixture was applied to the gear surface and irradiated with a laser beam. The laser melted the powder, bonding it to the R6M5 steel
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
substrate. 900 W was used to ensure sufficient energy to melt the powder and form a strong bond with the steel substrate. The laser pulse duration was set between 250 and 400 milliseconds to allow controlled heat distribution and ensure a uniform solidification of the coating. The laser scanning speed was 4 mm/s, which ensured an even deposition of the coating material across the gear surface.
3. Testing and analysis
Once the cladding process was completed, the coated gear surfaces underwent several tests to evaluate the microstructure, hardness, and wear resistance:
- Microstructure analysis: The microstructure of the coated gear surface was examined using optical microscopy and scanning electron microscopy (SEM). This analysis helped determine the formation of martensite and carbide phases in the coating, which are crucial for improving the surface hardness and wear resistance.
- Microhardness test: Vickers hardness tests were conducted to measure the microhardness of the laser-clad surface. The results were compared to the untreated surface to assess the improvement in hardness due to the Cr, B, and Mo cladding.
- Wear resistance test: Pin-on-disk wear tests were performed to evaluate the wear resistance of the laser-clad surface. The test measured the wear rate and friction coefficient of the coated surface and compared it to untreated R6M5 steel. The decrease in wear rate and friction coefficient was used as an indicator of the effectiveness of the coating.
4. Coating thickness and optimization
The thickness of the laser-deposited coating was maintained between 200 and 300 microns to ensure optimal wear resistance without compromising the gear's dimensional accuracy. The laser cladding parameters, such as laser power, scanning speed, and powder feed rate, were carefully optimized to achieve a uniform coating with the desired thickness and properties.
5. Data analysis and comparison
The results of the microhardness, wear resistance, and microstructural tests were compared between the laser-clad surface and the untreated gear surface. The effectiveness of the laser cladding process was evaluated based on the improvements in hardness, wear resistance, and microstructural changes induced by the Cr, B, and Mo powder mixture.
This methodology provided a systematic approach to enhancing the wear resistance of R6M5 steel gears through laser cladding. The combination of Cr, B, and Mo powders significantly improved the gear's surface properties, making it more resistant to wear and suitable for high-performance applications.
Results and discussion
1. Results
The microstructural analysis of the laser-clad gear surface revealed significant changes in the surface morphology compared to the untreated R6M5 steel. The laser cladding process induced a martensitic transformation in the substrate due to rapid cooling, which resulted in a refined and hard microstructure. The optical microscopy and SEM images showed a uniform layer of martensite with the presence of Cr carbides and borides, which are crucial for improving hardness and wear resistance. The energy-dispersive X-ray spectroscopy (EDS) mapping confirmed the uniform distribution of Cr, B, and Mo throughout the coated layer. This homogenous distribution ensured that the mechanical properties were enhanced across the entire coated surface.
The microstructural analysis revealed the formation of hard phases like chromium carbides (CrC) and borides (B4C) within the matrix, contributing to the overall increase in hardness and wear resistance.
The Vickers microhardness test showed a significant increase in hardness in the laser-
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
clad gear compared to the untreated R6M5 steel:
- The average hardness of the laser-coated surface was 950-1200 HV, which is substantially higher than the hardness of the untreated R6M5 steel (typically around 600-700 HV). This increase in hardness can be attributed to the formation of martensitic microstructures and the presence of hard Cr carbides and borides.
- The hardness was relatively uniform across the depth of the coating, indicating that the laser cladding process successfully created a consistent and durable surface layer.
The results confirm that laser cladding significantly improved the surface hardness of the gear, making it more resistant to wear and mechanical stress.
The wear resistance testing using the pin-on-disk method demonstrated the effectiveness of the Cr, B, and Mo coating in reducing wear:
- The wear rate of the laser-clad surface was reduced by approximately 49% compared to the untreated R6M5 steel. The wear depth and width measured after the test indicated a substantial reduction in material loss due to the harder surface.
- Coefficient of Friction: The coefficient of friction of the laser-clad surface was reduced by 27%, indicating smoother surface interactions and reduced frictional losses during operation.
The wear resistance improvements are directly linked to the increased surface hardness and the formation of protective carbides and borides, which acted as barriers against abrasion and deformation.
Post-test examination of the wear scars using optical microscopy revealed that the laser-clad surface exhibited much less material removal compared to the untreated surface. The Cr, B, and Mo coatings provided a protective layer that reduced the depth and severity of the wear tracks, thus extending the lifespan of the gear under high-stress conditions.
2. Discussion
The results from this study indicate that laser cladding with a Cr, B, and Mo powder mixture is a highly effective method for enhancing the wear resistance of R6M5 steel gears. The significant increase in surface hardness and the reduction in wear rate highlight the potential of this technique for use in demanding industrial applications where gears are subjected to high mechanical loads and frictional forces. The microstructural changes induced by laser cladding were crucial in achieving the enhanced wear resistance. The rapid solidification during the laser process resulted in the formation of a martensitic matrix, which is known for its high hardness and strength. Additionally, the presence of chromium carbides (CrC) and boron carbide (B4C) phases contributed significantly to the wear resistance by providing hard and stable particles within the surface layer. These phases act as barriers to plastic deformation and wear, making the surface more durable under abrasive conditions.
The uniform distribution of Cr, B, and Mo throughout the coated layer ensured that the mechanical properties were consistently improved across the entire surface, which is critical for gears that experience uneven loading during operation.
The increase in hardness from 600-700 HV to 950-1200 HV is a significant finding, as it directly correlates to the improved wear resistance. Harder surfaces are more resistant to wear, and the high hardness achieved in this study is a result of both the martensitic transformation and the formation of hard carbides and borides during the laser cladding process.
Conclusion
This study demonstrated that laser cladding using a mixture of chromium (Cr), boron (B), and molybdenum (Mo) powders significantly enhances the wear resistance, hardness, and surface integrity of R6M5 steel gears with a diameter of 10 mm. The laser cladding process resulted in the formation of a martensitic matrix enriched with hard chromium carbides and borides. These microstructural changes contributed to a substantial improvement in surface hardness and wear resistance. The hardness of the laser-clad surface increased from 600-700 HV
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
(untreated) to 950-1200 HV (treated), ensuring that the gears could better withstand abrasive forces and mechanical stresses in high-wear applications. Wear resistance tests revealed a 49% reduction in wear rate for the laser-coated gears compared to the untreated R6M5 steel, highlighting the protective effects of the Cr, B, and Mo coating against material loss during operation. The coated surface exhibited a 27% lower coefficient of friction compared to the untreated surface, resulting in smoother operation, reduced energy losses, and improved efficiency of the gears. The improvements in hardness, wear resistance, and reduced friction indicate that laser cladding with Cr, B, and Mo powders can significantly extend the operational lifespan of gears in industries such as automotive, aerospace, and heavy machinery, where gears are subjected to extreme mechanical stresses and wear.
Overall, the laser cladding process using Cr, B, and Mo powders offers a highly effective method for enhancing the performance and durability of R6M5 steel gears. This technique has strong potential for industrial applications where increased wear resistance and reduced maintenance are critical to operational success. Further studies could explore the scalability of this process and its application to different gear materials and geometries.
REFERENCES
1. A. D. Pogrebnjak, G. E. Remnev, and I. G. Romanov, 'Physical and mechanical changes in HPIB-irradiated steels', Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, vol. 43, no. 1, pp. 41-45, Aug. 1989, doi: 10.1016/0168-583X(89)90077-3.
2. L. Wang et al., 'Effect of buckwheat hull particle-size on bread staling quality', Food Chemistry, vol. 405, p. 134851, Mar. 2023, doi: 10.1016/j.foodchem.2022.134851.
3. Y. Cao, K. Yan, W. Shi, R. Zhou, B. Li, and J. Qin, 'Experimental Study on the Microstructure and Tribological Properties of Laser-Clad Ni60-WC Composite Coatings', Materials, vol. 17, no. 18, p. 4638, Sep. 2024, doi: 10.3390/ma17184638.
4. M. Zhong and W. Liu, 'Laser surface cladding: The state of the art and challenges', Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 224, no. 5, pp. 1041-1060, May 2010, doi: 10.1243/09544062JMES 1782.
5. A. N. Valyaev, M. K. Kylyshkanov, A. D. Pogrebnjak, A. A. Valyaev, and S. V. Plotnikov, 'Modification of mechanical and tribological properties of R6M5 steel and Be by intense pulsed-ion and pulsed-electron beams', Vacuum, vol. 58, no. 1, pp. 53-59, Jul. 2000, doi: 10.1016/S0042-207X(00)00242-6.
6. J. Wakiru, L. Pintelon, P. N. Muchiri, and P. K. Chemweno, 'Integrated remanufacturing, maintenance and spares policies towards life extension of a multi-component system', Reliability Engineering & System Safety, vol. 215, p. 107872, Nov. 2021, doi: 10.1016/j.ress.2021.107872.
7. Z. He et al., 'Effect of oscillating laser cladding on microstructure and properties of stainless steel cladding layers', Materials Today Communications, vol. 41, p. 110254, Dec. 2024, doi: 10.1016/j.mtcomm.2024.110254.
8. R. Asthana, A. Kumar, and N. B. Dahotre, 'Coatings and Surface Engineering', in Materials Processing and Manufacturing Science, Elsevier, 2006, pp. 313-395. doi: 10.1016/B978-075067716-5/50007-8.
9. L. Quintino, 'Overview of coating technologies', in Surface Modification by Solid State Processing, Elsevier, 2014, pp. 1-24. doi: 10.1533/9780857094698.1.
10. V. M. Fomin, A. G. Malikov, and A. M. Orishich, 'CO2 laser cladding heterogeneous ceramic-metal wear-resistant coatings', presented at the INTERNATIONAL CONFERENCE ON THE METHODS OF AEROPHYSICAL RESEARCH (ICMAR 2016):
Mexanika va Texnologiya ilmiy jurnali 5-jild, 4-son, 2024
MEXANIKA
Proceedings of the 18th International Conference on the Methods of Aerophysical Research, Perm, Russia, 2016, p. 020015. doi: 10.1063/1.4963938.
11. G.-Y. Jiang and Z.-Y. Xu, 'Microstructure and tribological performance of laser cladding Co-Based laser coatings with h-BN and Fe addition', Materials Today Communications, vol. 39, p. 108896, Jun. 2024, doi: 10.1016/j.mtcomm.2024.108896.
12. S. Balasubramanian and K. Manonmani, 'Industrial Lasers for Producing Quality Textile Yarns', International Review of Mechanical Engineering, vol. 7, no. 7, pp. 1529-1536, 2013.
13. I. Nemesa and V. Kaplan, 'Textile finishing by laser', Tekstilna industrija, vol. 67, no. 1, pp. 33-38, 2019, doi: 10.5937/tekstind1901033N.
Mexanika va Texnologiya ilmiy jurnali
5-jild, 4-son, 2024
