Steel Bushings - Types and Application

Bushing definition

A bushing, also known as bush (typically in American English), is a replaceable lining or sleeve made of metal or other material that is inserted or screwed into an opening (seat) to which it is usually paired with a pin. The bushing is used to limit the size, resist wear and erosion, serve as a guide, and facilitate braking within the hydraulic cylinder. The bushing is a type of bearing, specifically a sleeve bearing. For more information on the terminology and its variants, refer to this article: Differences Between Bushings, Bushes, and Bearings.

Steel Bushings Types

Steel bushings can be categorized based on their shape. Here are the main types:

Plain Bushings
Grooved Bushings
Flanged Bushings

This is a preliminary classification, but there are many different types of bushings. Additionally, it’s clear that a flanged bushing can also be grooved or plain and can be custom-made.

Plain Bushings

Plain bushings are simple hollow cylinders without grooves or flanges. They are very common and installed on various types of machines. This type of bushing, being simpler to manufacture, is suitable for applications where lubrication is less frequent. They are widely used in agriculture and on plows and harrows, and can also be mounted on some models of breakers and clamps.

Flanged Bushings

These bushings have a flange or collar around one end. They can withstand both radial and axial loads in a single direction. There can be different types of flanged bushings, with different grooves and variable sizes. Used in demolition machines, grabs, drilling machines, big buckets, and pile drivers.

They are used to minimize friction between shafts and bushings.

Grooved Bushings

Grooved bushings are bushings that, after internal machining, have various types of grooves. These can be spiral, linear, or more complex patterns like the bushing shown in the photo. The primary function is to collect and distribute grease evenly. They are useful for supporting all equipment that requires precision work and constant maintenance, especially for those operating in harsh environmental conditions to prevent breakdowns and machine downtime. Thanks to the grooves, it is possible to have a small grease reservoir, avoiding frequent maintenance. We can manufacture various types of grooved bushings according to customer drawings and specifications..

Grooved bushings can feature various patterns, such as simple spiral grooves or, as shown in the image on the right, a dense grid-like pattern that ensures constant and uniform lubrication. Knurlings can include different textures like honeycomb, bubble, and spider patterns.

Steel Grooved bushing — Steel bushing with an internal groove.

Material

Hardened Steel Bushings

Hardened steel bushings undergo a heat treatment process that significantly increases their hardness and durability. This makes them ideal for high-stress applications in heavy machinery and industrial equipment, where wear resistance and strength are critical.

Stainless Steel Bushings

Stainless steel bushings are known for their excellent corrosion resistance, making them suitable for harsh environments such as marine, chemical, or alimentary industries. Certain stainless steel alloys can also be hardened for improved durability.

Bushing Size

Metric: 16 mm to 300 mm
Imperial: 0.63 inches to 11.81 inches

Tolerances Bushings

The ISO standard tolerances for Sibo Bushing are u6 for outer diameter and C8 for inner diameter.

Classification by Manufacturing Process

Bushings can be classified based on the manufacturing process used to create them. Each method imparts unique characteristics to the bushings, making them suitable for different applications.

Sintered bushings

Sintered bushings are produced via a process called sintering, where metal powder is pressed into shape and then heated. This creates a solid component with a unique pore structure. These pores are impregnated with lubricating oil, which is released during operation as the bushing heats up, providing lubrication and reducing wear. However, sintered bushings have a lower capacity to withstand heavy loads and strong shocks.

Turned Bushings

Turned bushings are made using a chip removal process. In this method, material is precisely removed from a raw piece to achieve the desired shape. This allows for very tight tolerances and smooth surfaces, making turned bushings ideal for applications that require high precision and can handle heavy loads.

Split Bushings (Spring Bushings)

Split bushings, also known as spring bushings or slit bushings, are created by bending a strip of metal into a cylindrical shape with a slit along its length. These bushings are a suitable solution for facilitating assembly because they can be installed with a hammer blow. They are recommended in applications where the loads involved are low and precision requirements are also low.

Application

Steel bushings are used in various sectors, from construction and mining to agriculture. They are employed in presses and the aerospace industry. In heavy machinery, they can be mounted on buckets, cylinders, drills, and tracks. Steel is particularly recommended for working on rough terrains and with heavy loads, as it is more durable than bronze and traditional plastics.

However, the applications are numerous:

Automotive: Used in suspension systems of heavy-duty vehicles, such as trucks with trailers, to reduce friction and wear.
Industrial Machinery: Serve as guides and wear-resistant components in moving parts.
Hydraulic Cylinders: Facilitate smooth movement and reduce wear in hydraulic systems, aiding in braking and preventing sudden stops.
Construction Equipment: Provide durability and longevity in heavy-duty machinery such as loaders, piling machines, excavators, and their attachments, as well as cranes and aerial platforms.
Mining Equipment: Used in drilling machines, perforation equipment, and machinery for both underground and surface operations.
Agricultural Machinery: Employed in tractors and farming machinery, including specialized machines for olive cultivation and forestry.
Bearing Rings: Used in various applications requiring durable and wear-resistant components.
Hydraulic Pumps: Serve to protect the shaft of the pump in contact with the seal and also function to prevent oil leakage. Integral in ensuring smooth operation and longevity.
Lifting Machines: Provide essential support in various lifting applications.
Amusement Machines: Used in rides and other amusement equipment.
Viticulture and Olive Cultivation Machinery: Essential in specialized agricultural machinery.
Specialized Work Machines: Used in trenchless machines for asphalt, municipal machinery, railway machines, and more.