What is Flanged Slewing Bearings?

At LDB Bearing, we understand that the heart of any robust rotational system is a reliable slewing bearing. Among the various designs available, flanged slewing bearings stand out for their unique advantages in simplifying assembly, enhancing structural integrity, and improving performance. This in-depth guide will explore what flanged slewing bearings are, their key benefits, common applications, and how to select and maintain them for optimal results.

What is a Flanged Slewing Bearing?

A flanged slewing bearing is a large-diameter rotational bearing that incorporates one or more integrated flanges on its inner or outer ring. Unlike standard slewing rings that have a simple rectangular cross-section, a flanged version features a protruding rim that runs circumferentially around the bearing’s profile.

This flange is not an add-on; it is a monolithic part of the bearing ring, manufactured from a single forged or rolled steel blank. It is meticulously machined to provide a precise and robust mounting surface. The primary function of this flange is to serve as an alternative or supplementary mounting point, offering designers greater flexibility and security when integrating the bearing into a machine’s structure. These bearings are engineered to handle combined loads—simultaneous axial, radial, and tilting moment forces—making them indispensable in heavy-duty and precision applications.

Key Design Features and Advantages of Flanged Slewing Bearings

The incorporation of a flange transforms the bearing from a simple component into a multifaceted structural element. Here are the primary advantages that make flanged slewing bearings a preferred choice for engineers:

• Simplified Assembly and Integration: The flange provides a straightforward and secure mating surface. This can drastically reduce the complexity of the host structure, as there is no need to machine intricate steps or shelves to seat a standard bearing. It simplifies the design process and lowers manufacturing costs for the final equipment.
• Enhanced Mounting Stability and Rigidity: By offering an additional vertical mounting surface, the flange resists forces that could cause the bearing to shift or “walk” within its housing. This is particularly crucial in applications with high tilting moments or shock loads, as it ensures the bearing and the structure act as a single, rigid unit.
• Improved Seal Protection: The flange can act as a natural shield for the bearing’s integral seals. By positioning the flange strategically, it can deflect debris, chips, or other contaminants away from the primary seal lips, significantly extending seal life and protecting the internal rolling elements and raceways from premature wear.
• Versatile Mounting Configurations: Flanges can be designed on the inner ring, outer ring, or even both rings simultaneously. This allows for unparalleled design flexibility. For example, an outer ring flange can be used to bolt onto a stationary base, while the inner ring rotates with the machinery above.
• Space Optimization: In some compact designs, the flange can serve a dual purpose, acting as both a mounting feature and a gear teeth carrier (for internally or externally geared bearings), saving valuable space and reducing the component count.

How Flanged Slewing Bearings Work: The Mechanics of Rotation and Load Distribution

Understanding the fundamental working principle is key to appreciating their design. A flanged slewing bearing operates on the same core principle as any slewing ring: it facilitates rotation by using rolling elements (balls or rollers) that run along precision-machined raceways between two concentric rings.

1. Load Transfer Path: The unique role of the flange is to alter and improve the load transfer path. When operational loads (axial, radial, moment) are applied to the rotating structure, these forces are transmitted into one of the bearing rings. The rolling elements then distribute these loads evenly across the raceways and into the opposite ring. The flange, being integrally mounted to the host structure, provides a vastly enlarged and more robust connection point. This ensures that these immense forces are dissipated efficiently into the machine’s framework without causing localized stress concentrations that could lead to failure.
2. Creating a Unified Structure: Essentially, the flange “locks” the bearing into the structure. This transforms the assembly from a simple “component-in-a-housing” into a single, unified, and highly rigid mechanical system. The bearing doesn’t just sit in the machine; it becomes an integral, load-bearing part of the machine itself. This is critical for maintaining alignment, preventing fretting corrosion at the mounting interfaces, and ensuring precise and repeatable rotation under load.

Common Applications Across Industries

The unique benefits of flanged slewing bearings make them suitable for a wide array of industries and machinery. You will typically find them in applications where precision, reliability, and structural simplicity are paramount.

• Robotics and Automation: Robotic arms and rotary indexing tables use flanged bearings for their high rigidity and precise mounting, which are essential for repeatable accuracy.
• Medical Equipment: CT scanners and MRI machines rely on them for smooth, quiet, and absolutely reliable rotation under heavy, precise loads.
• Industrial Turntables: Assembly lines, welding positioners, and material handling turntables utilize flanged bearings for their ease of installation and robust load capacity.
• Renewable Energy: While the main bearing in a wind turbine nacelle is typically non-flanged, flanged slewing rings are often used in solar tracker systems and yaw drives for their straightforward mounting to support posts.
• Construction and Mining Equipment: They are used in compact machinery, conveyor swingers, and drill rigs where the flange provides the necessary stability to withstand harsh operating conditions.

Selecting the Right Flanged Slewing Bearing

Selecting the correct flanged slewing bearing is a critical process that determines the performance and longevity of your application. At LDB Bearing, we recommend a systematic approach:

1. Load Capacity Analysis: The first step is to calculate all the forces acting on the bearing. This includes the axial load (along the axis of rotation), radial load (perpendicular to the axis), and the tilting moment (overturning force). Our technical team can help you analyze these loads to determine the required static (C0) and dynamic (C) load ratings.
2. Flange Configuration: Decide whether you need a flange on the inner ring, outer ring, or both. This decision is driven by your machine’s design—which part is stationary and which part rotates, and how the bearing will be housed.
3. Gearing Requirements: Determine if you need a geared bearing. Flanged bearings can be manufactured with internal or external gear teeth on the non-flanged ring to accommodate a drive pinion for powered rotation.
4. Size and Dimensions: Specify the required bore diameter, outer diameter (including the flange), and overall height. The number, size, and location of bolt holes on both the main mounting surface and the flange are also critical design parameters.
5. Sealing and Lubrication: Choose the appropriate seal type (e.g., rubber seals for general industry, polyurethane for abrasive environments) based on your operating environment. Also, specify the lubrication fitting types and positions for easy maintenance.
6. Environmental Factors: Consider exposure to elements like temperature extremes, corrosive chemicals, or seawater. These factors will influence the material selection (e.g., standard 42CrMo4 steel or corrosion-resistant variants) and surface treatment.

Installation and Maintenance Best Practices

Even the best-designed bearing will fail prematurely if installed or maintained incorrectly.

• Installation:
  • Ensure the mounting surfaces are clean, flat, and free of burrs. Any imperfection can distort the bearing rings.
  • Use high-strength bolts, washers, and thread-locking fluid as specified.
  • Tighten the bolts in a star-shaped, cross-bolting pattern to the recommended torque value. This ensures even clamping force and prevents ring distortion.
  • For bearings with a flange, pay special attention to the bolt sequence for both the main and flange mounting holes.
• Maintenance:
  • Regular Lubrication: This is the most critical maintenance task. Use the correct type and grade of high-performance grease and adhere to a strict relubrication schedule. The interval depends on operating speed, load, and temperature.
  • Bolt Preload Check: After the first 100 hours of operation, re-check the torque on all mounting bolts, as settling may occur. Perform periodic checks thereafter.
  • Visual Inspection: Regularly inspect for signs of wear, damage to seals, grease leakage, or corrosion.
  • Monitor Performance: Be alert to any changes in operation, such as increased noise, vibration, or rotational resistance, which could indicate internal damage.

Why Choose LDB Bearing for Your Flanged Slewing Bearing Needs?

At LDB Bearing, we are not just suppliers; we are your engineering partners. Our flanged slewing bearings are manufactured to the highest international quality standards, ensuring reliability in the most demanding applications.

• Custom Engineering: We specialize in providing custom-engineered solutions. We can design and manufacture a flanged slewing bearing to your exact specifications, including unique flange profiles, special seal arrangements, and custom gear geometries.
• Superior Quality Control: From material forging and heat treatment to final machining and assembly, every step of our manufacturing process is rigorously controlled to guarantee dimensional accuracy, superior metallurgy, and long service life.
• Global Support: With a global supply chain and technical support network, we are equipped to serve clients worldwide, providing expert advice and timely delivery.

Ready to Optimize Your Design? If you are designing a new machine or upgrading an existing one, consider the structural and performance benefits of a flanged slewing bearing. Contact the LDB Bearing team today for a technical consultation and let us help you select the perfect bearing solution for your application.