How to Select the Right Rotary Table Bearing for Your Application

What Are Rotary Table Bearings?

Rotary table bearings are high-precision axial/radial combined bearings designed to support heavy loads while maintaining exceptional rotational accuracy. Unlike conventional bearings that primarily handle single-direction forces, rotary table bearings are engineered to manage three types of loads simultaneously: axial loads, radial loads, and tilting moments. This unique capability makes them essential components in applications requiring stable rotational platforms under demanding conditions.

A typical rotary table bearing consists of an L-shaped inner ring, an axial and radial combined outer ring, one or two rows of axial cylindrical rollers, and a row of radial rollers. The bearing is preloaded and clearance-free after installation, delivering high rigidity, high precision, and heavy load capacity in a compact design. Both inner and outer rings feature mounting holes, simplifying installation and reducing the complexity of the shaft system compared to using multiple conventional bearings.

These bearings are widely used in CNC rotary tables, vertical lathes, indexing tables, medical imaging systems, robotic joints, and industrial automation equipment where stable positioning performance is critical.

BY Bearings manufactures precision rotary table bearings for high-load and high-accuracy applications. Our bearings are produced with strict tolerance control to ensure smooth rotation, reliable rigidity, and long service life under continuous operating conditions. We provide customized bearing solutions based on equipment structure, load requirements, and installation space.

Key Types of Rotary Table Bearings

Rotary table bearings are available in four distinct series, each designed for specific application requirements. Understanding these series is the first step toward making the right selection.

BRT (YRT) Series – Standard High-Precision Rotary Table Bearings

The BRT series represents the standard solution for high-precision rotary tables. These bearings feature two rows of axial cylindrical rollers and one row of radial full-complement cylindrical rollers. The axial component has a cage-guided roller set and is preloaded clearance-free after installation. With a maximum rigidity and high accuracy design, BRT bearings are ideal for mechanically driven precision rotary axes. They are commonly used in CNC rotary tables, indexing heads, boring mills, and vertical lathes where extreme rigidity and machining accuracy are required.

BRTS (YRTS) Series – High-Speed Rotary Table Bearings

The BRTS series is optimized for high-speed applications, particularly those using direct drive motors (torque motors). These bearings offer very low and uniform frictional torque, high continuous speed capability, and maximum tilting rigidity. The nylon cage design reduces friction and heat generation, allowing higher rotational speeds than standard BRT bearings. BRTS bearings are ideal for direct-drive rotary axes in high-speed machining centers and applications requiring dynamic positioning with minimal heat generation.

BRTM (YRTM) Series – Bearings with Integrated Angular Measuring System

The BRTM series integrates an inductive angular measuring system directly into the bearing assembly. This integration enables real-time position feedback with an accuracy of a few angular seconds. The measuring system can be either incremental (MI) or absolute (MA), depending on the application requirements. BRTM bearings are preferred for applications requiring closed-loop position control, such as high-precision CNC rotary tables, indexing tables, and inspection instruments where the exact angular position must be verified.

BLDF (ZKLDF) Series – High-Speed Thrust Angular Contact Ball Bearings

The BLDF series features a bidirectional thrust angular contact ball bearing design, offering low friction, very high continuous speed capability, and low lubricant consumption. These bearings can support axial, radial, and tilting moment loads while maintaining high rotational accuracy and minimal heat generation. BLDF bearings are the preferred choice for high-speed machining applications such as light metal, plastic, and wafer processing, as well as highly dynamic rotary indexing tables in industrial automation. They are particularly suitable for applications where the speed capacity of BRTS bearings is insufficient.

Key Factors to Consider When Selecting a Rotary Table Bearing

Selecting the right rotary table bearing goes beyond choosing a series. The specific configuration of design features directly influences performance under real-world conditions. The following factors require careful evaluation to ensure the bearing meets both mechanical demands and environmental challenges of your application.

Load Capacity

Determine the maximum axial load, radial load, and tilting moment the bearing will encounter. Rotary table bearings must support combined loads simultaneously, so all three force directions must be considered together rather than in isolation. The basic dynamic load rating (C) and basic static load rating (C₀) serve as reference values for sizing. Exceeding rated capacities leads to premature fatigue or deformation. Most applications use the bearing's rigidity curve to determine suitability under specific load conditions.

Precision Requirements

Rotary table bearings are manufactured to P4 and P2 precision grades, with P2 offering the highest level of accuracy. The required precision grade depends on the application—CNC machining centers and inspection instruments typically demand P2 or P4 grades, while automation auxiliary axes may accept lower precision levels. The bearing's radial and axial runout directly affect workpiece quality and positioning accuracy.

Operating Speed

Different series offer different speed capabilities. BRT bearings are suitable for moderate speeds in mechanically driven applications. BRTS and BLDF bearings are optimized for high speeds, with the BLDF series offering the highest continuous speed capacity. The choice of lubricant (grease vs. oil) also significantly impacts maximum allowable speed—oil lubrication supports higher RPMs than grease.

Mounting Space and Design Constraints

Rotary table bearings are designed as integrated units with pre-drilled mounting holes, simplifying the shafting system compared to multiple individual bearings. However, the available space for the bearing—including inner diameter, outer diameter, and width—must match the equipment structure. The bearing's dimensions must accommodate the table size, drive system, and surrounding components.

Environmental Conditions

Temperature range, humidity, corrosive elements, and contamination risk all influence bearing selection. Standard bearings operate within defined temperature ranges, while harsh environments may require specialized seals, coatings, or corrosion-resistant materials. The presence of dust, chips, or coolant requires effective sealing to prevent premature wear and failure.

Lubrication and Maintenance

Rotary table bearings are typically shipped with a high-quality initial grease. Regular maintenance via lubrication grooves on the inner and outer rings is essential for extending service life. Selecting the correct lubricant type (grease for general applications, oil for high speeds) and establishing a relubrication schedule based on operating conditions and manufacturer recommendations are critical to long-term reliability.

BRT vs. BRTS vs. BRTM vs. BLDF: How to Choose?

The following comparison table provides a rapid reference for matching application conditions to the appropriate bearing series:

Selection Criteria	BRT (YRT)	BRTS (YRTS)	BRTM (YRTM)	BLDF (ZKLDF)
Load Capacity	High	Medium-High	High	Medium-High
Maximum Speed	Moderate	High	Moderate	Very High
Friction Characteristics	Moderate	Very Low, Uniform	Moderate	Extremely Low
Integrated Measurement	No	No	Yes	Optional
Typical Drive Type	Mechanical	Direct Drive/Torque Motor	Mechanical or Direct Drive	Direct Drive/High-Speed Spindle
Primary Applications	CNC tables, indexing heads	High-speed direct-drive tables	Closed-loop precision tables	High-speed milling, wafer processing

Quick Selection Guidelines:

• • Standard CNC rotary tables with mechanical drives → Choose BRT (YRT)

• • Direct-drive motor tables requiring high speeds → Choose BRTS (YRTS)

• • Applications demanding closed-loop position feedback → Choose BRTM (YRTM)

• • Ultra-high-speed rotations with low friction requirements → Choose BLDF (ZKLDF)

The selection process should follow a systematic approach: first, define all application parameters including loads, speeds, and environmental conditions. Next, use manufacturer catalogs and load rating tables to identify candidates, and finally, verify the selection using calculation tools or consult with application engineers to confirm the final choice.

Installation and Maintenance Best Practices

Proper installation and regular maintenance are essential for maximizing the service life and performance of rotary table bearings.

Pre-Installation Preparation

Thoroughly clean all mounting surfaces on the shaft and housing to remove burrs, chips, and other residues. The installation area must be clean, dry, and dust-free with adequate lighting. All tools—including torque wrenches, threaded rods, and lifting equipment—must be clean and suitable for the task. The bearing should remain in its original packaging until immediately before installation to prevent contamination.

Installation Steps

1. Step 1: Ensure the surrounding components have the same temperature as the bearing to be installed.

2. Step 2: Align the bearing holes with the mounting holes on the shaft. Two threaded rods can be screwed into the shaft bores to help guide the bearing into position correctly.

3. Step 3: Insert fastening screws evenly distributed around the circumference, tightening them lightly by hand. Remove the threaded rods and install the remaining screws.

4. Step 4: Tighten the fastening screws progressively in three stages (typically 40%, 70%, and 100% of the specified final torque) following a "star" or crosswise pattern. A calibrated torque wrench must be used to ensure accuracy.

5. Step 5: After tightening, manually rotate the table to verify smooth operation before applying power.

Maintenance Practices

• • Regular Lubrication: Establish a strict greasing schedule based on operating conditions. In heavy-duty environments, more frequent relubrication is recommended. Use the correct grease type for the specific temperature range or high-speed environment.

• • Bolt Torque Checks: Periodically verify that mounting bolts meet the specified torque recommendations to prevent loosening or fatigue failure.

• • Condition Monitoring: Watch for abnormal noise, vibration, or increased rotational resistance, which may indicate lubrication issues, raceway wear, or contamination.

• • Seal Inspection: Regularly inspect rubber seals for cracking, wear, or dislodgement to ensure dust and moisture stay out of the raceway.

Why Choose BY Bearings for Your Rotary Table Bearing Needs?

BY Bearings (Luoyang Boying Bearing Co., Ltd.) specializes in high-precision rotary table bearings with over 16 years of manufacturing experience. The company offers comprehensive bearing solutions across all four series—BRT, BRTS, BRTM, and BLDF—with precision grades up to P2 and strict ISO 9001 quality control.

Our rotary table bearings are manufactured with optimized internal geometry to minimize friction and heat generation while maximizing rigidity and load capacity. The integrated mounting hole design simplifies installation, and the multi-row roller structure delivers the stiffness required for heavy-duty machining operations.

With exports to over 100 countries, BY Bearings delivers reliable solutions for both OEM and aftermarket needs. We offer customized bearing solutions based on equipment structure, load requirements, and installation space. For any questions or requirements regarding rotary table bearings, please feel free to contact us.

Frequently Asked Questions About Rotary Table Bearings

Q1: What is the difference between BRT and BRTS series?
BRT bearings are standard high-precision bearings designed for mechanically driven rotary axes, offering maximum rigidity and accuracy at moderate speeds. BRTS bearings are optimized for high-speed applications with direct drives, providing lower, more uniform frictional torque and higher continuous speed capability.

Q2: How to determine the load capacity of a rotary table bearing?
Load capacity is determined by referring to the manufacturer's load rating tables based on calculated axial load, radial load, and tilting moment. Both dynamic and static ratings must be considered. The bearing's rigidity curve provides critical information for assessing performance under specific load conditions.

Q3: What precision grades are available for rotary table bearings?
Rotary table bearings are available in P4 and P2 precision grades, with P2 offering the highest level of accuracy. The choice depends on application requirements—precision machining and measurement typically demand P4 or P2, while automation applications may accept lower grades.

Q4: How to maintain rotary table bearings in high-speed applications?
Regular relubrication is essential, using appropriate lubricants for high-speed conditions. Monitoring temperature rise and rotational resistance helps detect issues early. For BRTS and BLDF series, the specific lubricant type and interval should follow manufacturer recommendations based on speed and operating temperature.

Q5: Can rotary table bearings be customized?
Yes. BY Bearings offers customization of bearing size, precision grade, seal design, and mounting hole patterns based on equipment structure, load requirements, and installation space. Custom solutions are available for both standard and specialized applications.