A bushing is a cylindrical hollow mechanical component designed to reduce friction, wear, and often even play between two parts in relative motion. It is used as a guide or support for rotating or sliding shafts, or as a mounting element.
Its main function is to improve sliding, absorb loads, protect more expensive parts from wear, and ensure smooth and quiet operation over time. Bushings may be dry, lubricated, or self-lubricating, and may include grooves or inserts depending on the specific operating conditions.
Types
Bushings can be classified by construction shape, each type suited to different mechanical needs.
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Solid bushing: one-piece cylindrical part, ideal for high loads and precise assemblies.
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Flanged bushing: includes a flange for axial positioning and combined load support.
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Split bushing: features a longitudinal cut to ease assembly and accommodate dimensional variations.
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Grooved bushing: includes internal or external grooves for lubrication distribution or debris collection.
Bushings and shafts: how they work
Bushings and shafts operate together as a matched pair within a sliding or rotating system. The shaft is a solid, often hardened component that transmits motion or load, while the bushing acts as the bearing surface that supports and guides it.
During operation, the shaft moves inside the bushing, creating controlled sliding contact. The choice of materials — typically hardened steel for shafts and softer or self-lubricating metals for bushings — allows the system to minimize friction and concentrate wear on the replaceable bushing.
Proper tolerances, lubrication, and surface finish ensure smooth motion, alignment, and extended service life, making this pairing fundamental in applications such as excavators, hydraulic cylinders, presses, and lifting systems.
Main industries
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Automotive: suspensions, steering, engines, transmissions
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Aerospace: landing gears, control surfaces
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Agricultural machinery: arms, joints, implements
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Railway: wagon axles, joints, shock absorbers
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Mining: excavators, crushers, drilling rigs
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Construction and lifting: loaders, buckets, joints, aerial platforms, lifts
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Material transformation: plastic, rubber, paper, cardboard, glass, ceramics
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Food industry: conveyors, mixers, cutters
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Packaging: packaging machines, labelers
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Textile machinery: looms, winders
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Semiconductors: pick & place, micro-mechanisms
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Energy sector: wind, hydraulic and solar turbines
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Woodworking: saws, milling machines
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Amusement and leisure: rides, simulators, attractions
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Test benches and dynamic systems: actuators, load structures, moving platforms
Specific application points
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Hydraulic and pneumatic cylinders
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Mechanical and articulated arms
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Lifts, aerial platforms, elevation systems
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Screw
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Conveyor belts
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Winders and coilers
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Fishing reels
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Bicycle hubs and joints
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Industrial robots and manipulators
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Test benches
Bushing materials
Bushings can be made from a wide range of materials, selected according to working conditions. A useful classification includes metallic, polymeric, and coated/composite materials.
Metals and alloys
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Hardened steel: high mechanical resistance
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Stainless steel: corrosion-resistant, also for food environments
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Bronze: excellent wear resistance and smoothness
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Brass: suitable for light-duty applications
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Sintered bronze: porous, self-lubricating, ideal for mass production
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Sintered iron: cost-effective, moderate load capacity
Polymers and composites
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POM (Polyoxymethylene): low friction, dimensional stability
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PTFE (Teflon): self-lubricating, non-stick
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PA (Nylon): tough and flexible
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Reinforced composites (e.g., PTFE + fiber): suitable for high loads
Terminology
The term bushing is often used with different meanings depending on the context. In addition to its main use as a plain bearing, it may refer to components performing specific mechanical interface or alignment functions:
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a guide or centering sleeve
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a reducer to connect mismatched diameters
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an adapter to couple parts with different sizes or tolerances
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a spacer, to maintain a fixed gap between surfaces
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a fitting insert, used to interface components of different materials or shapes
These are not strict synonyms, but the term “bushing” is frequently adopted when the part performs such functions and shares a similar form.
Sibo Steel Bushings
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