Fractured Spherical Bearings

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Fractured Spherical Bearings – Technical Overview

IBSCO supplies high-performance fractured spherical bearings designed for dynamic, high-load, and oscillating applications across the aerospace, military, defense, and heavy industrial sectors. These bearings are manufactured by leading OEMs known for precision, durability, and compliance with military and aerospace specifications, including:

NHBB (New Hampshire Ball Bearings) – Including the Rod-End and Spherical Bearing Division
Kamatics (KAron Bearings Division) – High-load polymer-lined spherical bearings
Aurora Bearing Company – Precision-engineered aerospace and military spherical bearings
RBC Bearings – MS, AS, and MIL-SPEC compliant spherical and rod end bearings
SKF Aerospace, Timken, and FK Rod Ends

All fractured spherical bearings distributed by IBSCO are available with full documentation, traceability, and AS9100/AS9120/ISO 9001-certified processing.

What Are Fractured Spherical Bearings?

Fractured spherical bearings (also called split race spherical bearings) are plain spherical bearings manufactured with a two-piece outer ring that is “fractured” (i.e., split) along a parting line after heat treatment. This construction allows the inner ring (ball) to be installed after final machining, enabling tight radial and axial clearances, extended wear life, and high-performance dynamic operation.

Key Characteristics:

Fractured Outer Ring: Enables assembly around a one-piece spherical inner ring for precise fit and low looseness.
Spherical Inner Ring (Ball): Allows high degrees of angular misalignment and oscillation.
Liner Material: PTFE-based or self-lubricating composite liners for maintenance-free operation in high-load environments.
High Misalignment Capability: Typically ±5° to ±15°, depending on design and clearance.
Maintenance-Free or Re-Lubricable: Available with PTFE liners (self-lubricating) or metal-to-metal for re-lubrication access.

Construction and Operating Principle

Component

Description

Outer Ring

Fractured, two-piece design. Hardened steel or stainless. Can be staked or bonded post-assembly.

Inner Ring (Ball)

Precision-machined spherical surface. May be through-hardened or carburized steel.

Liner (if applicable)

Self-lubricating PTFE or KAron® liner bonded to the inner surface of the outer ring.

Fracture Joint

Ultrasonically inspected mating line; reassembled with precision press fit or staking

Example: In a helicopter rotor pitch link, a fractured spherical bearing allows the linkage to pivot under extreme oscillating loads, while the PTFE liner provides maintenance-free service in corrosive, high-vibration environments.

Bearing Series and Standards

IBSCO supplies fractured spherical bearings conforming to key military, aerospace, and commercial standards:

Specification

Description

PTFE-lined, self-lubricating spherical bearings

MIL-B-81935

Re-lubricable, high-misalignment, fracture race style

SAE-AS81820

Standard aerospace part numbers and interchangeability

NAS / MS / AS Series

Commercial/military qualified equivalents

RBC/KA/KC/KH Series

Technical Specifications

Attribute

Typical Range / Details

0.190 in (4.8 mm) to 3.000 in (76.2 mm)+

Bore Diameter

0.437 in to 4.000 in+

Outer Diameter

-65°F to +350°F (up to 600°F for KAron/metal-to-metal)

Operating Temp Range

±5° (standard) to ±15° (extended inner ring)

Misalignment Capability

Up to 250,000 lbs (varies by series)

Radial Static Load

Radial Dynamic Load

1,000 to 100,000 lbs (varies by liner and size)

Axial Static Load

Typically 10–20% of radial load

Friction Torque

5–25 in-lb typical (varies by liner and clearance)

Liner Life

Seal Options

25,000 to 100,000+ oscillating cycles

Environmental seals, integral shields, grease fittings

Liner Technologies

1. PTFE-Based Self-Lubricating Liners

Maintenance-free operation
Low friction coefficient (µ < 0.10)
Certified to MIL-B-81935 and AS81820 standards
Brands include KAron V, RBC Liners, NHBB self-lube liners

2. KAron® V and KAron® E2

Proprietary fiber-reinforced PTFE liner
High dynamic load capacity
Excellent dimensional stability under thermal expansion

3. Metal-to-Metal

Grease-lubricated or oil-lubricated
Higher friction, but superior load capacity
Re-lubrication via grooves and lubrication ports

Application Examples

Sector

Application

Benefit of Fractured Spherical Design

Aerospace

Control surface linkages, flap actuators

High angular travel, low backlash, self-lubricating

Defense

Turret rings, suspension arms

High shock load capacity, sealed from contaminants

Helicopters

Rotor pitch links, swashplates

High-cycle oscillation, certified aerospace performance

Missile Systems

Fins, pivots, gyroscopic supports

Minimal friction, minimal hysteresis

Rail/Transit

Suspension components, bogie articulation

Durability under vibration and misalignment

Oil & Gas

Articulating joints, valve stems

Long life in corrosion-prone environments

IBSCO Value-Added Services

IBSCO enhances your bearing lifecycle and compliance through the following certified services:

Clean Room Processing & Lubrication

AS9100 Class 6 clean room
Grease control ±0.5mg for high-speed pivot applications
Compatible with aerospace-grade lubricants (e.g., Braycote, Nye, Krytox)

Inspection & Serialization

Part marking, serialization, and certification to customer specs
Ultrasonic and visual inspection of fracture surfaces upon request
Full traceability with material certs and DFARS compliance

Assembly & Packaging

Bearing staking and bonding services
Custom packaging for cleanroom or aerospace line readiness
Private labeling and MIL-SPEC packaging

Inventory & Supply Chain

Multi-year stocking and Just-in-Time delivery
Long-Term Agreements (LTAs)
Government/DoD contract support and cage code traceability

Certifications and Compliance

All fractured spherical bearings and services from IBSCO are delivered under:

AS9100D / AS9120B
ISO 9001:2015
MIL-SPEC (e.g., MIL-B-81935, AS81820, NAS, MS Series)
RoHS, DFARS, and REACH compliant options
Complete material traceability and documentation packages

Contact IBSCO

As a certified distributor and bearing specialist with over four decades of experience, IBSCO provides precision fractured spherical bearings backed by technical support, aerospace-certified processing, and full lifecycle traceability.