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For Inner Ring Rotation

THK Cross Roller Bearings for Inner Ring Rotation represent a specialized class of linear motion components engineered for applications demanding exceptional rotational accuracy, high rigidity, and compact design. These bearings are fundamentally characterized by their unique structural arrangement, where cylindrical rollers are alternately crossed at right angles between the inner and outer rings. This configuration allows the bearing to simultaneously support complex load combinations—including radial loads, axial loads, and moment loads—all within a single, highly integrated unit. The primary design intent for the inner ring rotation variant is to facilitate scenarios where the shaft or the inner ring is the rotating element, a common requirement in many precision machinery setups.

The technical features of these bearings are meticulously crafted to deliver superior performance. The rollers make line contact with the raceways, a critical design aspect that significantly increases rigidity and minimizes elastic deformation under load compared to point contact found in ball bearings. This results in exceptionally smooth and precise rotation with minimal runout. The bearings are available with either a one-piece or split-type inner ring, with the split-type design offering simplified assembly and maintenance, particularly in applications where other components are mounted on the shaft. High-grade bearing steel, advanced heat treatment processes, and precision grinding of all contact surfaces ensure high load capacity, long service life, and consistent performance. Optional sealing units are also available to protect the precision rolling elements from contaminants like dust and moisture, enhancing reliability in harsh operating environments.

The performance advantages of THK Cross Roller Bearings for Inner Ring Rotation are substantial and directly address the challenges of modern industrial automation. Their high rigidity translates into improved machining accuracy and surface finish in equipment like machine tools, as it prevents deflection under cutting forces. The compact cross-section allows for the design of more slender and space-efficient machinery, a crucial factor in robotics and semiconductor manufacturing equipment where every millimeter counts. Furthermore, the ability to handle moment loads eliminates the need for multiple bearing arrangements, simplifying system design, reducing parts count, and lowering overall costs. The high rotational accuracy ensures precise positioning and repeatability, which is paramount in applications like rotary tables, indexing heads, and industrial robot joints.

Typical applications for these bearings are found wherever precision, rigidity, and a compact footprint are non-negotiable. In industrial machinery, they are the core component of rotary tables for machining centers, enabling high-speed, high-precision multi-axis milling and grinding. Within the realm of robotics, they are indispensable in the revolute joints of articulated robot arms, providing the stiff and accurate rotation required for complex assembly and welding tasks. In the automotive sector, they are utilized in advanced manufacturing and testing equipment, such as the rotary indexers for automated assembly lines. Precision equipment, including semiconductor wafer steppers, optical inspection devices, and medical imaging systems like CT scanners, relies on these bearings for their vibration-dampening characteristics and flawless rotational smoothness, ensuring the highest levels of operational fidelity.

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Thin Type Single Split Model RA-C SERIES
THK's Cross Roller Bearing RA C SERIES represents a specialized thin-type, single-split model engineered for inner ring rotation applications where precision, compact design, and high rigidity are paramount. This bearing features a unique cross-roller arrangement where cylindrical rollers are positioned at right angles to each other between the inner and outer rings, alternating direction in a single row. This configuration allows the bearing to simultaneously handle radial, axial, and moment loads with exceptional accuracy. The single-split design simplifies installation and maintenance, enabling straightforward assembly into machinery without complex disassembly of surrounding components. Manufactured from high-carbon chromium bearing steel and subjected to THK's stringent heat treatment processes, the RA C SERIES ensures durability and long-term performance under demanding operational conditions. Key technical features include its ultra-thin cross-section, which minimizes the bearing's footprint while maximizing load capacity and stiffness. The inner ring rotation capability is optimized for applications where the shaft rotates relative to the housing, providing smooth and precise motion control. Precision grinding of raceways and rollers guarantees minimal runout and high rotational accuracy, critical for applications requiring exact positioning. The split construction allows for easy adjustment of preload, enhancing rigidity and reducing backlash during operation. Additionally, the bearing is available with optional seals to protect against contaminants, extending service life in harsh environments. Performance advantages of the RA C SERIES are evident in its ability to deliver high torque rigidity and stable rotation under combined loads, reducing vibration and noise in precision machinery. Its compact design saves space and weight, making it ideal for applications with stringent size constraints. The bearing's low friction characteristics contribute to energy efficiency and reduced heat generation, while its high load capacity supports heavy-duty operations without sacrificing precision. These attributes result in improved machine reliability, reduced maintenance intervals, and enhanced overall system longevity. Typical applications span across industrial machinery, automotive systems, and precision equipment. In industrial automation, the RA C SERIES is commonly used in robot joints, rotary tables, and indexing mechanisms where precise angular positioning is critical. Within the automotive sector, it finds use in electric power steering systems, transmission components, and testing equipment that demand high rigidity and smooth rotation. For precision instruments, such as medical imaging devices, semiconductor manufacturing tools, and optical alignment systems, this bearing ensures accurate motion control and stability. Its versatility also extends to aerospace actuators and packaging machinery, where reliability under dynamic loads is essential. By integrating THK's RA C SERIES, engineers can achieve superior performance in compact, high-precision designs, driving efficiency and innovation across diverse industries.
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Thin Type Model RA SERIES
THK's RA SERIES Cross Roller Bearing for Inner Ring Rotation Thin Type represents a specialized linear motion component engineered for applications demanding high rigidity, precision, and compact design. This bearing features a unique cross-roller arrangement where cylindrical rollers are alternately oriented at right angles between the inner and outer rings, enabling it to withstand complex loads—including radial, axial, and moment loads—simultaneously. The thin-type profile minimizes axial space requirements, making it ideal for machinery with strict dimensional constraints. With the inner ring designed as the rotating element, the RA SERIES ensures smooth, stable motion and is available in various sizes and configurations to suit diverse industrial needs. Key technical features underscore its reliability and performance. The bearing incorporates a compact, lightweight structure without sacrificing load capacity, achieved through optimized roller geometry and high-quality steel construction. Precision grinding of raceways and rollers guarantees minimal runout and high rotational accuracy, critical for applications requiring exact positioning. Optional sealing mechanisms protect against contaminants like dust and debris, extending service life in harsh environments. Additionally, the RA SERIES is pre-lubricated with high-performance grease, reducing maintenance needs and ensuring consistent operation. Its simple mounting design, often including tapped holes for easy installation, streamlines integration into existing systems. Performance advantages of the RA SERIES translate into tangible benefits for industrial machinery, automotive systems, and precision equipment. Its high rigidity and load-bearing capacity reduce deflection under stress, enhancing machining accuracy in CNC equipment, robotic arms, and indexing tables. The thin-type design allows for sleeker assemblies in automotive components such as electric power steering mechanisms and transmission systems, where space efficiency is paramount. Low friction and smooth rotation contribute to energy efficiency and reduced wear, lowering long-term operational costs. In precision devices like medical imaging scanners or semiconductor manufacturing tools, the bearing's exceptional accuracy ensures repeatable movements, minimizing errors and improving product quality. Typical applications span multiple sectors, highlighting its versatility. In industrial automation, the RA SERIES is deployed in rotary tables, swivel joints, and articulated robot joints, where it supports precise angular movement and heavy loads. Automotive engineers utilize it in steering column pivots, brake system components, and electric vehicle drivetrain assemblies to enhance durability and responsiveness. For precision equipment, it finds use in optical instrument stages, measuring device rotators, and laboratory automation systems, enabling fine adjustments and stable operation. By combining compactness with robust performance, THK's RA SERIES Cross Roller Bearing addresses the evolving demands of modern machinery, delivering reliability and efficiency in demanding environments.
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Standard Model RB SERIES
THK's RB SERIES Cross Roller Bearing for Inner Ring Rotation represents a specialized linear motion component engineered for applications requiring high rigidity, precision rotation, and compact design. This standard model features a unique crossed roller arrangement where cylindrical rollers are positioned at right angles to each other between the inner and outer rings, alternating contact directions to handle complex load combinations efficiently. The bearing's construction allows the inner ring to rotate while the outer ring remains stationary, making it ideal for situations where rotational movement needs to be confined to the shaft or internal components. Key technical features include a compact cross-sectional profile that minimizes space requirements while maximizing load capacity. The rollers are precision-ground to ensure uniform stress distribution and are separated by an integrated spacer or cage to prevent skewing and reduce friction-induced heat generation. RB SERIES bearings are available in various sizes and configurations, with options for standard accuracy or high-precision grades to suit different application demands. They typically incorporate sealing mechanisms to protect against contaminants and retain lubrication, enhancing service life in harsh environments. Mounting is simplified through bolt holes on the outer ring, facilitating secure installation without additional complex fixtures. Performance advantages stem from the crossed roller design, which provides simultaneous support for radial, axial, and moment loads. This multi-directional load capacity eliminates the need for multiple bearing assemblies, reducing system complexity and potential points of failure. The RB SERIES offers high rotational accuracy with minimal runout, ensuring smooth and precise motion critical for automated processes. Its rigid structure minimizes elastic deformation under load, maintaining positioning accuracy even during high-speed operations or under heavy loads. Low friction characteristics contribute to energy efficiency and reduced heat buildup, while the optimized lubrication system extends maintenance intervals and operational longevity. Typical applications span industrial machinery, automotive systems, and precision equipment where reliable rotational guidance is paramount. In industrial automation, these bearings are integral to rotary tables, indexing mechanisms, and robotic arm joints, providing the stability needed for repetitive positioning tasks. The automotive industry utilizes them in steering systems, transmission components, and testing equipment rotators, where durability and precision under dynamic loads are essential. For precision instruments, such as medical imaging devices, semiconductor manufacturing tools, and optical alignment systems, the RB SERIES ensures vibration-free rotation and sub-micron level accuracy. Its versatility also extends to packaging machinery, CNC rotary attachments, and measuring device pivots, where compactness and high load-bearing capacity optimize performance in space-constrained designs.
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Standard USP-Grade Series Model RB SERIES
THK's RB SERIES Cross Roller Bearing for Inner Ring Rotation represents a pinnacle of precision engineering, specifically designed to handle complex load scenarios with exceptional rigidity and rotational accuracy. As a standard USP grade component, this bearing series incorporates a unique crossed roller arrangement where cylindrical rollers are positioned at right angles to each other between inner and outer rings. This configuration enables simultaneous support for radial, axial, and moment loads through a single compact unit, eliminating the need for multiple bearing combinations and simplifying mechanical design. The technical architecture features precisely ground raceways and rollers manufactured to exacting tolerances, ensuring smooth motion characteristics with minimal variation in torque. Each roller maintains line contact with the raceways, distributing loads evenly across the bearing structure while providing significantly higher rigidity compared to conventional ball bearing solutions. The inner ring rotation design optimizes performance for applications where the shaft serves as the rotating element, with the outer ring remaining stationary during operation. This orientation enhances stability under rotational stresses and improves mounting flexibility within mechanical assemblies. Performance advantages include exceptional positioning accuracy with minimal elastic deformation under load, making these bearings ideal for applications requiring precise rotational control. The crossed roller design provides approximately 3-5 times greater rigidity than standard ball bearings of comparable size, effectively resisting deflection during operation. Low torque characteristics ensure smooth rotation with consistent resistance values throughout the operational lifespan, while the compact cross-section allows for space-efficient designs without compromising load capacity. The USP grade classification guarantees superior dimensional accuracy and running accuracy, with strict controls on parallelism, perpendicularity, and raceway geometry. Typical implementations span multiple industrial sectors, including precision rotary tables in machining centers where they provide the foundation for high-accuracy indexing and contouring operations. In semiconductor manufacturing equipment, RB series bearings facilitate precise wafer positioning in exposure systems and inspection machinery. Robotics applications leverage their compact rigidity in robot joint mechanisms and rotary actuators, while automotive manufacturing systems utilize them in welding positioners and assembly fixtures. Additional applications include medical imaging equipment requiring smooth gantry rotation, optical instrument positioning stages, and various precision measuring devices where rotational accuracy directly impacts measurement integrity. The series' robust construction ensures reliable performance in demanding environments while maintaining precision characteristics throughout extended service periods.
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