Bearing Block Selection and Maintenance Guide: From Structural Principles to Practical Applications

In linear motion systems, the bearing block-also known as the slider or carriage-is the core unit connecting moving components to the guide rail. It carries loads, guides motion, and directly affects equipment accuracy and life. However, in actual selection and use, bearing blocks are often simplified as "matching parts," with details such as structural differences, preload selection, and lubrication maintenance easily overlooked. For instance, our BF12 Bearing series exemplifies how precise engineering can address these challenges.

BF12 Bearing

1. What Is a Bearing Block?

The bearing block is the moving unit of a linear guide rail system, containing recirculating balls or rollers that move linearly along the rail. It typically consists of the following parts:

• Block Body: Metal base carrying external loads, typically with mounting threaded holes

• Rolling Elements: Balls or rollers that circulate within the raceways

• Retainer/Cage: Guides rolling elements in orderly circulation, preventing collision

• Seals/Scrapers: Prevent dust and chips from entering the interior

• End Caps: Guide rolling elements through circulation turns

Based on rolling element type, bearing blocks are mainly divided into two categories:

2. Five Core Technical Dimensions of Bearing Blocks

2.1 Preload Grade: Determines Rigidity and Motion Resistance

Preload refers to creating pre-tension inside the bearing block by adjusting the fit clearance between rolling elements and raceways. Common preload grades include:

Selection Advice: Higher preload is not always better. Excessive preload leads to increased temperature rise and shortened life. The general principle is: under the premise of meeting rigidity requirements, choose the lowest possible preload grade. For compact applications, the BF12 Bearing offers optimized preload options.

2.2 Accuracy Grade: From Micron to Sub-Micron Level

Linear guides are typically classified into standard, high, precision, and ultra-precision grades. Accuracy is mainly reflected in the following aspects:

• Running parallelism: Height variation as the slider moves along the rail

• Height difference: Height consistency among multiple blocks on the same rail

• Lateral deviation: Fit clearance between slider and rail side

• Data Reference: Running parallelism for precision-grade bearing blocks is typically controlled within 0.005mm/m, while ultra-precision grade can reach 0.002mm/m. Models like the BF12 Bearing achieve these tolerances through advanced manufacturing.

2.3 Sealing and Protection: Key to Extending Life

Standard seals: Suitable for general environments

Reinforced seals: Double-layer or metal scrapers, suitable for cutting environments

Dust cover: Telescopic covers recommended for long strokes

According to statistics, over 80% of bearing block failures are related to foreign object intrusion. Seal selection cannot be ignored.

2.4 Lubrication: The "Blood" of Bearing Blocks

Insufficient lubrication is another main cause of premature bearing block failure. Lubrication methods mainly include:

• Grease: Conventional choice, requires regular replenishment

• Oil: Suitable for high-speed applications or those with automatic lubrication systems

• Self-lubricating design: Some brands offer models with oil reservoirs or solid lubricants

Note: Different lubrication methods should not be mixed; thorough cleaning is required before changing lubricants.

2.5 Installation Method: Determines Final Accuracy

Bearing block installation may seem simple but actually requires strict control:

• Mounting base: Flatness ≤0.01mm/m, surface clean and burr-free

• Bolt torque: Must use torque wrench, tighten in diagonal sequence step by step

• Alignment adjustment: For dual-rail systems, ensure parallelism ≤0.02mm/m

3. Three-Step Selection Method

Step 1: Determine Load Characteristics

Calculate the load types acting on the bearing block:

• Radial load: Perpendicular to motion direction

• Reverse radial load: Opposite to radial

• Lateral load: Parallel to mounting surface but perpendicular to motion direction

• Moment load: Pitch, yaw, and roll directions

Choose ball or roller type based on load magnitude. When equivalent load P > 0.3C (rated dynamic load), roller bearing blocks are recommended.

Step 2: Determine Speed and Acceleration

• High speed (>80m/min) → Ball bearing block

• Medium speed (30-80m/min) → Both acceptable

• Low speed (<30m/min) → Roller bearing block (fully utilize rigidity advantage)

Step 3: Determine Accuracy and Preload

4. Common Application Scenario Recommendations

5. Field Case: Failure Caused by Seal Failure

Background: In mid-2024, a high-speed handling robot at an automation equipment factory in Zhejiang experienced abnormal noise on the Y-axis, with positioning accuracy deteriorating from ±0.02mm to ±0.08mm, forcing equipment shutdown for inspection.

Inspection Findings:

• Bearing block (ball type, C1 preload) showed significantly increased running resistance

• Disassembly revealed damaged seals, with chip powder inside

• Raceway surface had indentations, some balls were worn and deformed

Root Cause Analysis:

The operating environment had cutting dust, and the original standard seals could not provide effective protection. The operator did not follow procedures to check seal status weekly, and by the time the problem was discovered, internal damage had already occurred.

Solution:

• Replaced with reinforced seal bearing blocks (with metal scrapers)

• Installed rail dust covers

• Established daily inspection system to check seal and lubrication status

Results:

After replacement, the equipment ran smoothly, and accuracy remained within ±0.02mm when retested six months later.

Conclusion: Small Component, Big Impact

As the core component of linear guide rail systems, every aspect of bearing block selection, installation, and maintenance deserves serious attention. Preload grade selection, seal protection matching, and lubrication status monitoring-these details collectively determine the final performance of your equipment.

Zhejiang Baili Guide Rail offers a full range of ball and roller bearing block products, covering multiple preload grades, accuracy grades, and seal types to meet different operating condition requirements. All products have undergone ISO standard testing and internal durability validation, including the compact BF12 Bearing designed for space-constrained applications.

If you encounter problems in bearing block selection or use, please contact our technical team. We will provide professional selection recommendations and solutions based on your actual operating conditions.

Choose the right bearing block-make every motion precise and reliable.

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