Product Introduction

The 6400 series represents the "heavy" category within single row Deep Groove Ball Bearings; it features the largest cross-section and the highest load-carrying capacity among all standard Deep Groove Ball Bearings. Model numbers begin with "64" (e.g., 6404, 6405, 6406). The 6400 series boasts the largest cross-sectional dimensions of any deep groove ball bearing series, characterized by the largest ball diameters, the highest number of balls, and the thickest rings.

The 6400 series is positioned as a solution for extreme load conditions—considered only when the 6300 series is insufficient but the use of Roller Bearings is not desired. While they account for a small share of overall applications, they are irreplaceable in specific scenarios.

Single row deep groove Ball Bearings are the most representative type of rolling bearing and are widely used. They primarily consist of an inner ring, an outer ring, steel balls (rolling elements), and a cage. In addition to open designs, variants include bearings with steel dust shields (ZZ type), rubber seals (2RS type), or snap rings on the outer ring (NR type). Pressed steel cages are commonly used.

These bearings feature low frictional torque, making them ideal for environments requiring high speeds, low noise, and low vibration. They primarily support radial loads but can also handle moderate bidirectional axial loads. When radial internal clearance is increased, they exhibit characteristics similar to angular contact ball bearings, allowing them to withstand alternating axial loads in both directions.

Structure and Characteristics

Highest Load Capacity: For a given inner diameter, the radial load capacity is approximately 30%–40% higher than the 6300 series and about 100% higher than the 6200 series, making it the "heavyweight champion" of deep groove ball bearings.

Superior Rigidity: With the thickest rings and largest balls, the bearing offers maximum overall rigidity and resistance to deformation.

Excellent Shock Resistance: Large balls and thick rings provide the highest capacity among ball bearings to withstand shocks and overloads. Lowest rotational speed: Features the largest steel balls and generates the highest centrifugal force and frictional heat; it has the lowest limiting speed among all deep-groove ball bearing series.

Largest dimensions: Has the largest outer diameter and width, requiring the most installation space.

Limited selection: Fewer specifications available (starting from 6403; no miniature sizes), limited options for seal types and precision grades, and higher prices.

Dimensional Parameter Table

Common Suffixes

Predominantly open type: The vast majority of standard 6400 series products are open (unsealed), as they are typically used in heavy-duty industrial equipment utilizing oil lubrication or centralized lubrication systems.

ZZ / 2RS: Some domestic manufacturers offer ZZ (metal shield) or 2RS (rubber seal) versions, but the range of options is far more limited compared to the 6200 or 6300 series.

C3 / C4: Larger internal clearances are commonly used for heavy-duty, high-temperature applications; C3 and C4 grades are more common than the standard C0 grade.

M: Solid brass cage; standard or recommended for larger 6400 series models, offering superior strength and temperature resistance compared to pressed steel or nylon cages.

/P5 / P6: High-precision grades require customization; standard products are typically P0 (normal grade).

Application Scenarios

The 6400 series has a relatively narrow application scope, primarily concentrated in heavy-duty, low-speed industrial environments subject to impact loads:

Heavy-duty reducers and gearboxes: Low-speed shafts of large reducers and output ends of heavy-duty gearboxes; subjected to extreme loads.

Mining machinery: Auxiliary drives for crushers, ball mills, and mineral processing equipment; involves heavy-duty, high-impact conditions.

Metallurgical equipment: Auxiliary rolls for rolling mills, conveyor roller tables, straighteners, and coilers; involves heavy loads and high temperatures.

Hoisting and transport machinery: Large crane drums, pulley blocks, and travel wheels; involves heavy lifting capacities and impact loads.

Petrochemical machinery: Support bearings for drilling equipment, oil pumping units, and large pumps; involves heavy-duty, low-speed operation.

Construction machinery: Concrete mixers, large tower cranes, and construction hoists; involves heavy-duty, high-impact conditions.

Heavy-duty conveyors: Drive drums for mining conveyors and large bucket elevators; involves heavy materials and high loads. Hydropower generation equipment: auxiliary supports for turbines and speed-governing mechanisms; characterized by heavy loads and low speeds.

Key Differences

The 6400 series represents an "extreme" variant within the deep-groove ball bearing family, with distinct differences from other series:

6200 series: The most versatile, balanced, and widely used—sufficient for the majority of applications.

6300 series: Higher load capacity and greater rigidity—chosen when the 6200 series is insufficient; the standard choice for heavy-load applications.

6400 series: Highest load capacity, largest dimensions, and lowest speed rating—selected only when the 6300 series cannot handle the load and space permits; rarely used in practice.

Thin-section series (6700/6800/6900/6000): The exact opposite of the 6400 series—thinnest, lightest, and lowest load capacity; used for precision, light-load applications.

Important Note: If the load is heavy enough to require the 6400 series, one should seriously consider switching to roller bearings (e.g., N-type Cylindrical Roller Bearings, Type 3 Tapered Roller Bearings, or Type 2 Spherical Roller Bearings). Roller bearings offer superior load-bearing capacity due to line contact (versus the point contact of ball bearings) and are often more economical and durable under heavy-load conditions. The 6400 series offers advantages only in extreme heavy-load scenarios where ball bearings are mandatory (e.g., due to high speeds, low noise requirements, or mounting constraints).

Selection Recommendations

First, verify if the 6400 series is truly necessary: The 6400 series is bulky, slow, limited in variety, and expensive; consider it only when the 6300 series genuinely lacks sufficient load capacity. The 6300 series suffices for most heavy-load applications.

Consider switching to roller bearings: If loads are extremely high and speeds are low, cylindrical or Tapered Roller Bearings may be superior options—offering higher load capacity and better cost-effectiveness. Choose the 6400 series only when ball bearings are required. Check rotational speed: The 6400 series has a very low limiting speed; it is recommended that the actual operating speed does not exceed 60%–70% of this limit. The 6400 series must not be used for high-speed applications.

Verify installation space: The 6400 series features large outer diameters and widths; carefully check the housing bore dimensions and available axial space during replacement.

Prioritize brass cages: As the 6400 series is typically used in heavy-load, low-speed applications, the "M" design (solid brass cage) is recommended due to its high strength and resistance to impact and high temperatures.

Select larger internal clearance: For heavy-load applications involving interference fits, C3 or C4 clearance classes are recommended to compensate for the reduction in clearance caused by the interference fit and temperature rise.

Lubrication method: The 6400 series comes in an open design as standard; oil lubrication (splash or circulating) is recommended for effective heat dissipation and suitability for heavy loads. If using grease lubrication, avoid overfilling to prevent heat generation caused by churning.