Single Direction Thrust Ball Bearing

I. Product Overview​

Single-Direction Thrust Ball Bearings (abbreviated as SDTBB) are a specialized category within the thrust ball bearing family, designed for scenarios requiring heavy single-direction axial load-bearing, minimal radial load, and a focus on structural simplicity and cost optimization. Their core competitiveness lies in the triple characteristics of "heavy single-axial load capacity + separable compact structure + high cost-effectiveness" - through an exclusive "flat raceway + single-row steel ball" design, they achieve an axial rated dynamic load of 2kN-500kN, dedicated to bearing single-direction axial forces (reverse axial forces will cause steel balls to disengage from the raceway, leading to bearing failure). Adopting a separable three-part structure consisting of a shaft washer, housing washer, and ball-cage assembly, they are easy to assemble and disassemble with low manufacturing costs (40% lower than double-direction thrust ball bearings) and require no complex installation tools. Meanwhile, due to their extremely weak radial load-bearing capacity (only able to bear 1%-5% of the axial load as radial load, requiring pairing with radial bearings such as deep groove ball bearings or cylindrical roller bearings), they accurately match working conditions where "axial forces dominate and radial forces are negligible", completely solving the industry pain points of "complex transmission structures and high costs in heavy single-axial load scenarios".​

The inner diameter of these bearings ranges from 10mm to 300mm, the outer diameter from 25mm to 400mm, and the total thickness (sum of shaft washer and housing washer thickness) from 8mm to 50mm. The limiting speed under grease lubrication is 3,000-15,000 r/min (light-duty models can reach 18,000 r/min). Precision grades are mainly P6 (dimensional tolerance ±8μm) and P5 (dimensional tolerance ±5μm), with P4 grade available for some precision scenarios (e.g., machine tool spindles). Classified by the number and arrangement of steel balls, they include single-row (basic type, no suffix) and multi-row (enhanced type, suffix MA) models. They are suitable for scenarios such as machine tool spindle rear ends, elevator traction machines, automotive gearboxes, precision instruments, and lifting equipment - where "single-direction axial positioning + low-cost compact design" is required. The complexity of the equipment transmission structure is reduced by 30%, and the comprehensive procurement cost is lowered by more than 25%.​

Compared with double-direction thrust ball bearings, although SDTBB can only bear unidirectional loads, they have a simpler structure and are 30% lighter, while adapting to over 80% of single-axial force scenarios, avoiding functional redundancy. Compared with angular contact ball bearings that can bear axial forces, SDTBB have 30%-50% higher axial load capacity of the same size and are 20%-30% cheaper, with no need to consider contact angle matching. Covering over 70% of the transmission field dominated by pure axial forces, they are the optimal choice for balancing "load requirements, structural simplicity, and cost control".​

II. Core Structure and Design Features​

1. Precision Structural Composition​

The three core components of SDTBB (shaft washer, housing washer, ball-cage assembly) are deeply optimized to meet the requirements of "heavy single-axial load-bearing, easy assembly/disassembly, and stable force transmission", ensuring reliable operation under axial force-dominated working conditions:​

Shaft Washer: Adopts a circular thin-disc structure, with its inner hole in an interference fit with the shaft (fit accuracy H7/k6) and no fit requirement for the outer circle. The working surface (the side in contact with steel balls) is a precision-machined flat raceway, with a raceway surface roughness of Ra ≤ 0.04μm and a flatness error of ≤ 1μm. The material used is SUJ2 high-carbon chromium bearing steel (20CrNiMo alloy carburized steel is optional for heavy-duty models), which undergoes "integral quenching + ultra-precision grinding" processes. The surface hardness reaches HRC 60-64, and the core hardness is HRC 30-35, ensuring no deformation or cracking under heavy axial loads.​

Housing Washer: Similar in structure to the shaft washer, it is a circular thin-disc structure, with its outer circle in a transition fit with the housing hole (fit accuracy H7/js6) and no fit requirement for the inner hole. The working surface is also a flat raceway, with a parallelism error of ≤ 0.01mm relative to the shaft washer raceway, ensuring uniform contact with steel balls. The material and processing technology are consistent with those of the shaft washer, providing synchronized surface hardness and wear resistance to prevent bearing failure due to housing washer wear.​

Ball and Cage Assembly: Composed of steel balls and a cage, the steel balls are made of GCr15SiMn high-purity bearing steel. Their diameter is designed according to load requirements (5mm-15mm for light-duty models, 15mm-30mm for heavy-duty models), processed through "vacuum melting + precision grinding + polishing" processes, with a roundness error of ≤ 0.15μm and a surface roughness of Ra ≤ 0.02μm. The cage is divided into stamped cages (SPCC steel plate, suitable for medium-low speed scenarios, rotational speed ≤ 8,000 r/min) and solid cages (HPb59-1 brass or PA66 + 30% glass fiber nylon, suitable for medium-high speed scenarios, rotational speed 8,000-15,000 r/min). The cage pockets adopt a "shallow pocket + positioning boss" design, with the clearance between pockets and steel balls controlled at 0.1-0.2mm to prevent steel ball movement and ensure uniform transmission of axial forces.​

2. Key Design Characteristics​

Heavy Single-Axial Load-Bearing: The combined design of flat raceways and single-row steel balls enables axial forces to be uniformly transmitted to the shaft washer and housing washer through steel balls. The axial rated dynamic load ranges from 2kN to 500kN (e.g., the 51210 model has an axial rated dynamic load of 48kN, and the heavy-duty 51420 model reaches 320kN), which can stably bear single-direction heavy loads such as axial cutting forces of machine tool spindles and axial lifting forces of elevator traction machines. The load capacity increases with the diameter and number of steel balls (multi-row models have a 50% higher capacity than single-row models).​

Easy Assembly/Disassembly with Separable Structure: The shaft washer, housing washer, and ball-cage assembly can be completely separated. During installation, the shaft washer can be pressed onto the shaft first, the housing washer fixed in the housing, and finally the ball-cage assembly installed, eliminating the need for integral installation. During maintenance, worn components (e.g., only the shaft washer or housing washer) can be replaced individually without overall scrapping, improving assembly/disassembly efficiency by 40% and reducing maintenance costs by 30%.​

Low Friction and Adaptable Speed: The point-contact design between flat raceways and steel balls results in a low friction coefficient of 0.0015-0.002 (80% lower than sliding friction bearings) and an operating noise of ≤ 55dB. The limiting speed under grease lubrication is 3,000-15,000 r/min: stamped cage models are suitable for 3,000-8,000 r/min (e.g., elevator traction machines), brass cage models for 8,000-12,000 r/min (e.g., machine tool spindle rear ends), and nylon cage models for 12,000-15,000 r/min (e.g., precision instruments), meeting speed requirements of different scenarios.​

Pairing with Radial Bearings: Due to their extremely weak radial load-bearing capacity (only able to bear 1%-5% of the axial load as radial load), they must be paired with radial bearings (e.g., deep groove ball bearings, cylindrical roller bearings) in practical applications - radial bearings bear the radial load of the equipment, while SDTBB bear the single-direction axial load. The two work synergistically to form a complete "radial + single-axial" load-bearing system, ensuring stable operation of the equipment.​

III. Main Product Models and Classification​

1. Classification by Structural Type (Steel Ball Arrangement)​

2. Classification by Precision Grade​

Grade P6: Dimensional tolerance (shaft washer inner diameter, housing washer outer diameter) ±8μm, raceway flatness ±1μm. Suitable for general precision scenarios (e.g., elevator traction machines, automotive gearboxes), with moderate cost and high cost-effectiveness, accounting for over 60% of the market share.​

Grade P5: Dimensional tolerance ±5μm, raceway flatness ±0.5μm. Suitable for medium-precision scenarios (e.g., machine tool spindle rear ends, precision instruments), capable of meeting axial positioning accuracy of ±0.01mm, accounting for approximately 30% of the market share.​

Grade P4: Dimensional tolerance ±3μm, raceway flatness ±0.3μm. Suitable for high-precision scenarios (e.g., high-end CNC machine tools, aerospace auxiliary equipment), requiring ultra-precision grinding and strict testing, accounting for approximately 10% of the market share.​

3. Classification by Cage Material​

Stamped Steel Plate Cage: Designation with no suffix (or suffix Z), material of SPCC cold-rolled steel plate. Low cost and light weight, suitable for medium-low speed, medium-light load scenarios (rotational speed ≤ 8,000 r/min, e.g., small motors, conveyor equipment).​

Brass Solid Cage: Designation with suffix H, material of HPb59-1 brass. High strength and good heat dissipation, suitable for medium-high speed, medium-heavy load scenarios (rotational speed 8,000-12,000 r/min, e.g., machine tool spindles, large fans).​

Reinforced Nylon Cage: Designation with suffix TN, material of PA66 + 30% glass fiber. Low friction coefficient and wear resistance, suitable for medium-high speed, light load scenarios (rotational speed 12,000-15,000 r/min, e.g., precision instruments, medical devices).

IV. Product Advantages Summary
Single-direction heavy-load bearing, precise fit: Rated axial dynamic load ranging from 2kN to 500kN, dedicated to bearing axial forces in a single direction, precisely matching the "axial force dominant, radial force negligible" working conditions, avoiding performance redundancy of multi-functional bearings, and achieving high bearing efficiency.​
Separable structure, convenient disassembly and maintenance: The bearing ring, seat ring, and steel ball cage components can be separated. Installation does not require overall alignment. Maintenance can replace worn parts separately, increasing disassembly efficiency by 40% and reducing maintenance costs by 30%.​
High cost-effectiveness, significant cost advantage: Simple structure leads to low manufacturing costs (40% lower than double-direction thrust ball bearings, 20%-30% lower than angular contact ball bearings), and long service life (up to 8000-12000 hours under axial heavy-load conditions), reducing equipment comprehensive procurement and operation costs by more than 25%.​
Low friction, low noise, stable operation: Friction coefficient is as low as 0.0015-0.002, operating noise is ≤55dB, and it is compatible with a wide speed range of 3000-15000r/min, meeting the stability requirements of different scenarios.​
Flexible combination, wide application range: Can be flexibly combined with deep groove ball bearings, cylindrical roller bearings, etc., to form a "radial + single-axis" complete bearing system, suitable for multiple industry scenarios such as machine tools, elevators, automobiles, and instruments, with a coverage rate of over 70%.

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