Are 63 series deep groove ball bearings suitable for applications requiring preload

In the realm of precision mechanical engineering, Preloading is a fundamental technique used to enhance bearing system Rigidity, improve Rotational Accuracy, and effectively Dampen Vibration. However, for the most commonly used rolling bearing type—the 63 Series Deep Groove Ball Bearing—its inherent design characteristics impose professional limitations and unique considerations when utilized in Preloaded Systems.

I. Intrinsic Structure and Radial Design Advantage of 63 Series Bearings

The 63 Series Deep Groove Ball Bearing employs a single-row design where the nominal Contact Angle between the raceways and the rolling elements (balls) is near zero. This specific geometry grants the bearing excellent capacity for handling Radial Load and achieving high Limiting Speed.

• Contact Angle Characteristic: The minimal contact angle implies the bearing is primarily engineered to manage radial forces. Its capacity to withstand Axial Load is comparatively limited, and applying significant axial force leads to a rapid increase in contact stress.
• Non-Separability: The 63 Series Bearing features non-separable inner and outer rings, offering a compact structure and high versatility.

This fundamental design dictates that the 63 Series Bearing is not a typical Angular Contact Ball Bearing, the latter being specifically designed for Preloading Applications.

II. Severe Demands of Preloading Technology on 63 Series Bearings

Preloading involves applying a constant Axial Force before operation to eliminate Internal Clearance and induce initial elastic deformation between the raceways and rolling elements, thereby enhancing the system's dynamic performance.

1. Contact Stress and Bearing Life Reduction

The main risk of subjecting the 63 Series Bearing to a Preload Force lies in the detrimental effect on Bearing Life.

• Stress Concentration: Due to the inherently small initial contact angle, even a moderate preload force causes the Contact Stress between the balls and raceways to rise sharply. Excessive contact stress accelerates Fatigue Spalling of the raceways and balls.
• Raceway Deformation: Preloading alters the internal geometry of the bearing. Given the relatively large Raceway Groove Curvature Radius, the bearing exhibits high sensitivity to deformation changes.

Specialized engineering calculations demonstrate that the reduction in the 63 Series Bearing’s Basic Dynamic Load Rating under pure axial load is significantly greater than that for angular contact ball bearings. Consequently, Preloading will substantially diminish its Rated Life.

2. Heat Generation and Limiting Speed Reduction

The increased contact stress resulting from Preloading directly leads to a considerable increase in the bearing's internal Friction Torque, generating substantial Friction Heat.

• Temperature Rise Effect: Excessive Temperature Rise not only degrades the performance of the Lubricant but can also intensify the differential expansion between the inner and outer rings, altering the Operating Clearance and potentially causing thermal failure.
• Speed Restriction: The Limiting Speed of a 63 Series Bearing under a preloaded state will be drastically lower than the standard values published by manufacturers. Preloading must be strictly avoided in high-speed applications.

III. Application Limits and Professional Alternatives

The 63 Series Deep Groove Ball Bearing is not entirely unsuitable for receiving axial force or minor preloading, but it must be strictly limited to scenarios requiring only minimal force.

1. Applications with Minimal Preload

In certain low-speed, light-load applications where the goal is merely to eliminate internal clearance to slightly improve stiffness, applying a Minimal Preload Force to the 63 Series Bearing may be considered.

• Purpose: The main objective is to prevent Ball Skidding or Rolling Element Slippage at low speeds, rather than achieving high rigidity.
• Control: The preload force must be rigorously controlled, typically through precise adjustment of Internal Clearance or the use of extremely thin shims, ensuring contact stress remains within a safe operating range.

2. Professional Alternative Solutions

For applications demanding high Rigidity, high Precision, or high rotational speed under Preloading, professional engineers should select alternative bearing solutions over the 63 Series Bearing:

• Angular Contact Ball Bearing: The primary choice for preloading. It features inherent contact angles designed to efficiently handle axial loads created by preloading, and allows for precise preload control through Paired Mounting (e.g., DB, DF, DT configurations).
• Tapered Roller Bearing: Suitable for heavy-load applications that require preloading.