Composite Bushings & Self-Lubricating Bearings

Advanced Tri-Layer Construction

The superiority of AIMRSE composite bushings lies in their multi-layered architectural approach. Unlike monolithic metal bearings that rely on a sacrificial layer of grease, our composite structure integrates functional properties into every micron of its cross-section. This "functional layering" ensures that as the bearing operates, it maintains its physical dimensions while providing a constant, renewable lubricating interface.

I. The Structural Backbone (The Metal Shell): At the foundation is a high-strength metal backing, typically composed of Carbon Steel (low carbon), Stainless Steel (316L for corrosive environments), or high-tensile Bronze. This layer provides the mechanical integrity required to withstand static loads exceeding 250 MPa. It ensures a secure interference fit within the housing, preventing bearing migration even under intense thermal cycling or high-vibration conditions.

II. The Sintered Interlayer (The Mechanical Bond): A layer of spherical bronze powder is thermally sintered onto the metal backing. This porous matrix—typically 0.20mm to 0.35mm thick—serves two critical purposes. First, it acts as a mechanical anchor, locking the polymer sliding layer into the structure. Second, it functions as a highly efficient thermal conductor, drawing friction-generated heat away from the sliding surface and dissipating it through the metal shell into the machine housing.

III. The Functional sliding Matrix (The Self-Lubricating Layer): The top interface is a proprietary blend of PTFE (Polytetrafluoroethylene) or POM (Polyoxymethylene), enriched with inorganic fillers such as Molybdenum Disulfide (MoS2) or Graphite. During the critical "bedding-in" phase of operation, a microscopic film of this polymer is transferred onto the mating shaft. This creates a "PTFE-on-PTFE" contact regime, resulting in a coefficient of friction as low as 0.02, effectively making the bearing "self-healing."

Fig.1 Multi-layer construction: Steel backing for structural rigidity, Sintered Bronze for heat management, and PTFE lining for near-zero friction.

Specialized Performance Solutions

Not all friction is created equal. To address the diverse needs of global industry, AIMRSE has developed distinct product lines optimized for specific kinematics—ranging from continuous high-speed rotation to intermittent, high-shock oscillation.

Metal-Backed Series (PTFE & POM): Engineered for Versatility

Our metal-backed series combines a high-strength steel or stainless steel shell with precision-engineered polymer sliding layers, offering two distinct performance philosophies. The PTFE-based variant (Dry-running) is the gold standard for maintenance-free operation, featuring a lead-free PTFE overlay impregnated with friction-modifying fillers that allow the bearing to operate from -200°C to +280°C. It is the preferred choice for clean-room environments, textile machinery, and high-frequency valve actuators where grease would attract contaminants or evaporate under heat. The POM-based variant (Marginally lubricated) offers a thicker, more impact-resistant sliding surface engineered with integrated "grease pockets" that serve as reservoirs for initial lubrication. This series is remarkably resistant to fatigue and ideal for agricultural equipment, truck suspensions, and construction machinery where bearings must withstand heavy shock loads without cracking or deforming.

Fig.2 Filament Wound (FW) series: Designed for extreme shock
and abrasive environments like mining and offshore mooring.

Filament Wound (FW) Series: The Heavyweight for Extreme Environments

When metal-backed bearings reach their limit in corrosive or high-load "dirty" environments, the Filament Wound (FW) series takes over. These bearings are manufactured by winding continuous high-strength glass or carbon fibers impregnated with epoxy resin, resulting in a non-metallic, non-conductive bearing immune to galvanic corrosion. In hydropower applications (such as wicket gate bearings) or offshore mooring systems, the FW series excels because it can tolerate the ingress of silt and sand. The fiber matrix "traps" abrasive particles, preventing them from scoring the shaft, while the inherent elasticity of the resin allows the bearing to absorb edge loading and misalignment far better than rigid metal bushings.

Technical Specifications & Performance Metrics

Selecting the correct composite material requires a deep understanding of the PV value (Pressure x Velocity). The table below outlines the operational boundaries of our primary series, helping engineers match material properties to duty cycles.

Engineering Fits & Dynamics

The successful implementation of a composite bushing is contingent upon the precision of the housing and shaft interface. At AIMRSE, we don't just sell parts; we provide the engineering calculations to ensure system-level reliability.

Housing & Press Fit: Our metal-backed bushings are designed to be press-fitted into housings with an H7 tolerance. During installation, the bushing undergoes a "close-in" effect where the inner diameter shrinks by a predictable amount. Our technical data sheets provide exact formulas to calculate the post-installation ID, ensuring that the necessary running clearance is maintained.

The Importance of Shaft Quality: The "counter-face" (the shaft) is 50% of the bearing system. To maximize life, we recommend a shaft hardness of >50 HRC and a surface finish of Ra 0.4 µm. Using soft shafts (like mild steel) can result in "shaft wear," where the abrasive particles trapped in the polymer actually erode the metal shaft. For marine applications, we recommend ceramic coatings or induction-hardened stainless steel to prevent localized pitting which could shred the PTFE liner.

Fig.3 In-house PV testing: Every batch is validated under simulated loads to ensure zero-defect performance in the field.