Polyurethane Bushings: Types, Manufacturing and Uses
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Introduction
The article contains everything you need to know about polyurethane bushings and their use.
You will learn:
What is a Polyurethane Bushing?
How Polyurethane Bushings are Made
Types of Polyurethane
Uses for Polyurethane Bushings
And much more �
Chapter One: What is a Polyurethane Bushing?
A polyurethane bushing acts as a friction-reducing device, situated between stationary surfaces and moving components, providing an alternative to conventional lubricants. Polyurethane is chosen for its extraordinary durability, strength, and resistance to wear and friction. These bushings generally last longer than those crafted from rubber or plastic materials.
Polyurethane is a polymer produced from the chemical reaction involving diisocyanates—which are organic compounds containing two isocyanate groups—and polyols. The phrase "polyurethane" encompasses multiple polymer formulations, each characterized by distinct molecular structures. These variations in hardness and softness make polyurethane adaptable for a range of specific applications.
While both rubber and polyurethane are employed in similar functions, they differ significantly. Polyurethane is notable for its enhanced strength, durability, and resilience in challenging conditions, unlike rubber, which may degrade as time progresses.
Chapter Two: How Polyurethane Bushings are Made?
Polyurethane bushings are highly valued across industries for their exceptional durability, resilience, and vibration dampening properties, making them a popular choice in automotive, industrial, and machinery applications. The production of polyurethane bushings involves several advanced manufacturing techniques, each offering distinct advantages depending on the intended use, required physical properties, and production volume. Common methods include injection molding, polyurethane casting, compression molding, as well as emerging options such as vacuum molding and CNC machining for custom polyurethane bushings. The selection of the ideal polyurethane bushing manufacturing method depends on factors like bushing geometry, tolerances, mechanical strength, and cost-efficiency. In every case, achieving consistent product quality requires precise control over material formulation and molding conditions.
Injection Molding
With the injection molding process, molten polyurethane material is forced under pressure into precision-engineered steel molds, where it is allowed to cool and solidify. Injection molding is favored for high-volume manufacturing of polyurethane bushings due to its repeatability, efficiency, and ability to maintain tight dimensional tolerances. This mass production method utilizes a clamping unit and an injection unit, with the mold positioned between them. The resulting molded polyurethane bushings exhibit excellent uniformity, crucial for industries demanding reliable performance, such as automotive suspension systems, heavy equipment, and machinery assemblies.
Clamping Unit
The clamping unit must endure the stresses exerted on the mold during the injection molding process. Polyurethane is introduced into the injection unit via a hopper located above the screw mechanism. As the screw rotates, it melts the polyurethane and pushes it into the mold, which is secured by the clamping unit, ensuring optimal mold alignment and high surface finish quality of each bushing.
There are three main types of clamping units:
Toggle � Toggle units are used for high-speed production of urethane products and include a toggle link, crosshead connected to the link, and a driving mechanism. These are especially suitable for automotive polyurethane bushings requiring rapid cycle times.
Hydraulic � With a hydraulic clamp, hydraulic fluid pressurized by a pump pushes a piston against the clamp, providing precise force distribution essential for larger or more complex bushing designs.
Magnetic � Clamping force is produced by magnetic force inside the mold clamping plates, often used in applications requiring quick mold changeovers and increased process flexibility.
Injection Unit
The injection unit comprises several components: the hopper, heaters, screw, and motor. Polyurethane pellets or powder are introduced into the hopper positioned above the injection molding assembly. The hopper feeds material into the screw, which advances the material toward the die while increasing pressure. Along the length of the screw shaft, heating elements warm the polyurethane as it moves toward the die. The motor, located at the end of the screw shaft opposite the mold, drives the rotation of the screw, ensuring precise and consistent delivery of the molten material—critical for producing high quality, defect-free polyurethane suspension bushings and vibration control components.
Mold
The mold is designed in the shape of the polyurethane bushing and constructed from durable steel. It includes a sprue that links it to the injection unit, allowing molten polyurethane to be injected into the mold. The mold is meticulously engineered to achieve precise tolerances and dimensions required by automotive, industrial, and off-road polyurethane bushings.
Typically, molds are equipped with multiple cavities to produce several polyurethane bushings simultaneously. For such multi-cavity molds, the sprue is connected to a series of runners that distribute the molten polyurethane evenly to each cavity. To avoid any defects or inconsistencies in the finished bushings, the runners are uniformly spaced from the sprue, ensuring balanced material flow and consistent bushing performance.
Cooling and Ejecting
Once the polyurethane is injected into the mold cavities, it is maintained under pressure. The duration of this holding period can differ based on the type of polyurethane used and the complexity of the bushing design. This step is crucial for ensuring that the bushing solidifies properly and for minimizing defects such as shrinkage or warping. During cooling, the screw retracts to relieve pressure and facilitate adequate material cooling. When cooling is complete, the clamping unit releases, and the finished polyurethane bushing is ejected from the mold, ready for trimming or post-processing. Modern automation further streamlines this process for large-scale production runs of precision mold polyurethane bushings.
Casting
Polyurethane casting resembles the injection molding process but omits the clamping and injection units. Instead, it uses a mold shaped like the bushing and is a more cost-effective method typically employed for short to medium production runs or for custom polyurethane bushings and prototype development. Because polyurethane casting allows for highly flexible mold designs, it is ideal for producing bushings with unique geometries or specialized properties such as high resistance to chemicals, oil, or abrasion. The process begins with preparing a mold for the casting operation and accurately mixing the polyurethane formulation according to the required durometer (hardness) rating.
Polyurethane Compounds
The casting process for polyurethane bushings starts with mixing the necessary compounds to create the specific type of polyurethane required. This involves reacting a polyol with a diisocyanate, along with catalysts and additives for enhanced mechanical properties, thermal stability, or UV resistance. The particular types of diisocyanates and polyols used—such as TDI (toluene diisocyanate), MDI (methylene diphenyl diisocyanate), or polyether/polyester polyols—greatly influence the flexibility, chemical resistance, and hardness of the resulting polyurethane part. Thanks to these varied characteristics, polyurethane can be molded into a diverse range of shapes and configurations, suitable for different industries ranging from automotive and heavy machinery to marine and aerospace applications. Customizing the polyurethane formulation enables bushings manufacturers to meet specific requirements like high load-bearing capacity, longevity under dynamic stress, or resistance to harsh environmental conditions.
Casting Mold
Polyurethane casting molds are made from aluminum, silicone, or steel. The types of casting molds are closed molds, which have two halves that close over the injected polyurethane, and open molds, where the polyurethane compound is poured into the mold, consisting of a single section. In both cases, the heated liquified polyurethane is injected or poured into a mold tailored to the shape and features of a specific bushing. This flexibility in mold design allows for manufacturing performance bushings, heavy-duty industrial bushings, and various high-performance urethane components with complex geometries.
Heating
After the molds have been injected with polyurethane, they are moved into ovens where they are exposed to high temperatures to harden the polyurethane and solidify it. This aspect of the process has to be closely monitored to ensure the quality, physical properties, and structural integrity of the polyurethane bushings. Proper curing is essential for achieving the desired wear resistance, load capacity, and flexibility required for demanding bushing applications, such as vehicle suspension systems or industrial isolators.
Compression Molding
Compression molding is a high temperature process that compresses heated, measured polyurethane—referred to as a charge—into a bushing mold. The molds for the process are produced by machining, die casting, and 3D printing. The process for compression molding is similar to injection molding in that it injects the charge into the mold. Unlike injection molding, compression molding does not include the injection and clamping units, making it especially suitable for lower to medium production volumes, prototyping, and oversized polyurethane bushings with unique design requirements.
Creating the Mold
Creating the mold involves using a precise pattern, achieved through techniques such as CNC machining, 3D printing, or die casting. The crucial aspect of the mold is its capacity to endure the high pressures and temperatures involved in the compression molding process. Die casting is a widely favored method for mold production due to the durability and high thermal conductivity of the metals employed. Additionally, contemporary production methods frequently utilize computerized numerical control (CNC) machining and rapid prototyping using 3D printing to fabricate molds that meet exact engineering specifications and design tolerances.
The Charge
Proper preparation and measurement of the polyurethane charge are essential for ensuring the quality and dimensional accuracy of the molded part. If the charge is excessive, extra material may escape from the mold, resulting in flash that must be trimmed off. This part of the process requires careful monitoring and material control to minimize waste and ensure optimal use of polyurethane resin. After the charge is correctly prepared, it is then placed into the pre-heated mold.
Compressing
The top, movable section of the mold is positioned over the lower, stationary half. The mold is then heated and pressurized to shape the charge into the polyurethane bushing form. As the pressure builds, the polyurethane charge cures and conforms to the mold's intricate design, ensuring precision and structural integrity.
During the compression molding process, several factors are carefully controlled and monitored to ensure consistent quality of the polyurethane bushing. These include temperature, pressure, and compression time. Preheating the charge can enhance its viscosity before it is introduced into the mold, promoting even distribution and preventing air entrapment. The required pressure varies based on the polyurethane type and target durometer, with denser or high-performance formulations needing higher pressures. Additionally, the compression time is tailored to both the type of polyurethane and the unique design specifications of each bushing.
The compression molding process typically operates at 350°F (176°C), with mold pressures ranging from 100 psi to as high as 2000 psi. This compressive force ensures that the charge material is evenly distributed throughout the mold, successfully achieving the complex geometries and high load capacities required of industrial polyurethane bushings and automotive suspension bushings.
Curing
Curing is essential for hardening the molded part and may involve cooling the mold or applying hardening agents and catalysts. The duration of curing depends on the specific type of bushing, polyurethane grade, and post-cure requirements. Typically, curing occurs over 8 to 16 hours in an oven maintained at temperatures exceeding 200°F (93.3°C), resulting in polyurethane bushings with enhanced impact resistance, elasticity, and operational longevity.
Ejection
Once curing is complete, the bushing is removed from the mold either automatically or manually. For small production runs, manual ejection is often used, while automatic ejection involves a mechanism that pulls or pushes the bushing out of the mold. Although not frequently done, a release agent may be applied to the mold’s surface to prevent the bushing from sticking during removal. The ease of ejection depends on the complexity of the bushing design, mold coatings, and finish—factors that contribute directly to process efficiency and product quality.
Casting, injection molding, and compression molding are three common methods for the production of polyurethane bushings but are not the only options. Innovative manufacturing methods, such as vacuum molding and advanced CNC machining, are also used by specialized polyurethane bushing manufacturers for custom and performance applications. Each method offers unique advantages in terms of production speed, accuracy, material property optimization, and part complexity, allowing manufacturers to meet the diverse demands of the automotive, heavy equipment, and industrial markets. When evaluating polyurethane bushing suppliers, consider their technical expertise in various molding technologies, quality control systems, design capabilities, and the ability to customize formulations for your specific performance requirements. As advancements in polyurethane chemistry and bushing manufacturing continue, the industry is able to offer increasingly innovative solutions to meet the evolving needs of engineers, maintenance professionals, and end-users worldwide.
Chapter Three: What are the different types of polyurethane?
By altering the types of polyols and diisocyanates during the polymerization process, manufacturers create various types of polyurethane, each offering unique chemical and physical properties. These adaptable formulations enable polyurethane to be used in a diverse array of commercial, automotive, industrial, and consumer applications. It’s important to note that polyurethane differs significantly from traditional rubber or plastic; as a synthetic polymer, it provides an outstanding balance of rigidity, resilience, and elasticity, making it one of the most versatile engineered materials available today.
Polyurethane materials generally fall into two main categories: polyester-based polyurethane and polyether-based polyurethane. Both are elastomeric polymers (elastomers) known for their superior abrasion resistance, durability, and elastic recovery. The key differences between these types lie primarily in their chemical structure and thermal properties. Polyester polyurethane is better suited for maintaining performance at sustained high temperatures, while polyether polyurethane excels at withstanding extreme temperature fluctuations without becoming brittle. Choosing the right formula hinges on the specific environmental conditions and mechanical demands required for each application.
Polyester Polyurethane
Polyester polyurethane exhibits enhanced strength and rigidity over polyether polyurethane, offering higher tensile strength, improved dimensional stability, and resistance to many chemicals and solvents. Among these elastomers, polyester polyurethane is often the more economical solution, but it can be vulnerable to hydrolysis in the presence of water or high humidity. Engineered with ester groups created by a reaction between acids and alcohols, polyester polyurethane is often preferred in applications where cost-effectiveness, high load-bearing capacity, and surface wear resistance are critical.
Coefficient of Friction (COF)
The coefficient of friction (COF) indicates the frictional force between two interacting surfaces—a crucial factor in dynamic applications where sliding must be controlled or minimized. Polyester polyurethane, owing to its high hardness options, can be engineered for low COF, making it highly suitable for bushing applications, seals, and bearings. Enhanced abrasion properties further ensure consistent performance and reduced wear over time. The kinetic COF for polyester polyurethane typically ranges from 0.2 to 2.5, depending on the specific formulation and hardness selected.
Abrasion Resistance
One of polyester polyurethane’s greatest assets is its exceptional abrasion resistance, which surpasses that of many common plastics, metals, and rubbers. This high sliding resistance translates into longer life cycles, reduced maintenance, and reliable performance in high-wear environments such as conveyor systems, rollers, and protective linings. Industries that require durable, impact-resistant materials for heavy-duty applications frequently select polyester polyurethane for this reason.
Heat Resistance
Polyester polyurethane demonstrates robust heat resistance, maintaining its mechanical integrity even during extended exposure to elevated temperatures. Its molecular structure ensures strong resistance to heat aging—preventing premature material failure and making it ideal for automotive components, industrial machinery, and environments with continual thermal loads.
Hardness
Polyurethane compounds can be custom-blended to cover a broad hardness spectrum, from flexible, sponge-like grades (Shore A) to extremely rigid versions (Shore D). For applications like polyurethane bushings, hardness typically ranges from 80A to 95A, with some specialized products achieving up to 75D on the Rockwell hardness scale. This versatility supports industries from automotive suspension and vibration isolation to machinery pads and heavy-duty wheel treads.
Shock Absorption
Thanks to its advanced energy absorption capacity, polyester polyurethane is an excellent choice for shock absorption and vibration dampening. Industries rely on this material in scenarios where traditional steel springs or metal components are impractical due to excessive noise, severe vibration, corrosion risk, or electromagnetic interference. Polyurethane shock mounts and isolators reduce operational fatigue, extending both equipment lifespan and user comfort.
Tear Resistance
The remarkable tensile strength of polyester polyurethane boosts its resistance to cuts, tears, and mechanical stress, increasing reliability in high-impact and high-load applications where other materials might fracture or fail.
Resistance to Oil, Fuels, and Solvents
Polyester polyurethane’s non-porous structure and chemical composition make it highly resistant to degradation from fuels, oils, greases, and a wide range of organic solvents. This makes it indispensable in sectors such as manufacturing, transportation, and industrial settings where component longevity and resistance to harsh chemicals are vital.
Polycaprolactone (PCL) Polyurethane
Polycaprolactone polyurethane stands out as a specialized type of polyester-based polyurethane. It offers superior ultraviolet (UV) resistance and delivers outstanding tensile and tear strength, outperforming many polyether polyurethanes in demanding environments. Polycaprolactone polyurethane shines in extreme temperatures, demonstrating both high and low temperature flexibility along with robust hydrolytic stability. Frequently, it is used as an additive to resin systems to improve impact resistance, toughness, and longevity, as well as to refine compression set and mechanical integrity. Additionally, due to its biodegradable and biocompatible properties, PCL polyurethane is increasingly used in 3D printing, biomedical devices, scaffolds, and environmentally friendly packaging solutions.
Polyether Polyurethane
Polyether polyurethane is ideal for high-stress, outdoor, or wet-environment applications because of its exceptional hydrolytic stability and resistance to microbial degradation. Unlike polyester grades, polyether polyurethane maintains its flexibility and strength in the presence of moisture, making it well-suited for marine, medical, and food processing uses. This type of polyurethane is also popular for seals, gaskets, flexible foam, and dynamic aerospace parts where resistance to water absorption and biological breakdown are paramount.
Abrasion Resistance
Engineered with high-rebound ether backbones, polyether polyurethane provides remarkable impingement abrasion resistance, especially where surface impacts and particle collisions are common. That makes it ideally suited for high-performance bushings, conveyor scrapers, shot blast linings, and other demanding industrial equipment where durability under impact is critical.
Heat Resistance
Capable of withstanding broad temperature ranges—from sub-zero environments to high-heat zones—polyether polyurethane preserves its flexibility, elasticity, and structural integrity without cracking. Unlike many traditional elastomers, it resists embrittlement and retains resilience during rapid temperature fluctuations, supporting a wide variety of automotive, refrigeration, and construction applications.
Hardness
Both polyester and polyether polyurethane types are manufactured across an extensive hardness range, from soft cushioning foam to hard bearing-grade formulations. Polyether polyurethane commonly ranges from 55 Shore A to 75 Shore D on standardized hardness tests, ensuring compatibility with everything from soft seating to high-wear roller wheels and industrial bushings.
Rebound
Polyether polyurethane excels in applications requiring resilience and energy return. Its outstanding rebound properties mean parts quickly restore their original shape after compression or impact, minimizing energy loss, wear, and material fatigue in dynamic uses such as athletic equipment, flexible couplings, and vibration isolators.
Resistance to the Effects of Water and Moisture
Polyether polyurethane’s superior hydrolytic stability—stemming from its ether linkages—prevents water absorption, swelling, or molecular breakdown in humid or submerged conditions. As a result, polyether polyurethane is routinely chosen for outdoor, marine, and medical applications where extended exposure to water and biological agents demands top-tier long-term performance and durability.
Applications and Selection Criteria for Polyurethane Types
Understanding the key differences between polyester polyurethane and polyether polyurethane is essential when specifying materials for your project. Polyester polyurethane is commonly used in industrial wheels, rollers, high-load bushings, and parts requiring superior abrasion, oil, and chemical resistance. Polyether polyurethane formulations are favored in environments requiring resistance to hydrolysis, such as underwater equipment, medical devices, marine fenders, and food-grade conveyor components. Polycaprolactone polyurethane is increasingly found in biodegradable packaging, tissue engineering, and 3D printing filaments. Selecting the appropriate polyurethane type involves weighing critical factors like mechanical strength, hardness, chemical compatibility, water exposure, thermal cycling, and cost.
When choosing the right polyurethane material, manufacturing methods—including injection molding, casting, and extrusion—should be considered to ensure optimal performance, longevity, and value for any engineered plastic or elastomer application. Additionally, regulatory compliance (such as FDA, RoHS, or REACH guidelines) may be essential for medical, food processing, or export markets. Consult with an experienced polyurethane manufacturer or material engineer to determine the ideal formulation for your application.
Frequently Asked Questions About Polyurethane Types
Is polyurethane rubber or plastic? Polyurethane is a hybrid polymer exhibiting characteristics of both rubber and plastic, but is classified as an elastomer due to its flexibility, resilience, and wear resistance.
Can polyurethanes be recycled? Many polyurethane products, especially thermoplastic polyurethanes (TPU), can be mechanically or chemically recycled to support sustainability initiatives.
How do I know which polyurethane to choose? Factors like operating environment, mechanical stress, exposure to moisture/chemicals, and desired lifespan will determine whether a polyester, polyether, or specialty polyurethane is best suited for your needs.
What industries use polyurethane? Polyurethane is prevalent in the automotive, aerospace, medical device, footwear, construction, electronics, and marine industries, among many others.
Mechanical Properties of Polyester and Polyether Polyurethanes
Polyester
Polyether
Heat Resistance
Higher operating temperature stability.
Greater resistance to heat aging.
Less susceptible to heat build-up.
Lower heat resistance in general
Low Temperatures
Loss of flexibility at lower temperatures.
Will become brittle quicker.
Maintains flexibility at lower temperatures.
More resistant to environmental changes.
Abrasion Resistance
Excellent surface resistance.
Suited to sliding abrasion applications.
Excellent impingement abrasion resistance.
Ideally suited for shot blast applications.
Resilience and Rebound
Excellent shock, vibration, and energy absorption.
Ideally suited for damping applications.
Lower energy absorption.
Higher rebound properties.
Hydrolysis and Chemical Resistance
Higher chemical and oil resistance.
Lower hydrolysis resistance.
Excellent hydrolysis and microbial resistance.
Ideal for water-based applications.
Cut and Tear Resistance
Higher tensile strength.
High cut and tear resistance.
Lower tensile strength.
Lower cut and tear resistance.
Polyurethane's incredible flexibility and processability allow it to be molded or cast into thousands of customized products, parts, and precision components for almost every industry. As a highly adaptable performance material, it can be engineered at room temperature into rigid or flexible forms to meet a broad range of industrial packaging, construction, automotive, medical, and consumer needs. The material's popularity is driven by its ability to be precisely chemically tailored to provide desired properties—such as impact resistance, elasticity, or chemical compatibility—making it a top choice for engineers and manufacturers seeking performance and durability in demanding applications.
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Chapter Four: What are the different types of polyurethane bushings?
Polyurethane bushings come in a diverse range of shapes and sizes, with custom options available for specialized applications. Their popularity is increasing as new technologies and devices emerge that require the durability and reliability of a high-performance material. Bushings serve to minimize friction between moving and stationary components and can replace traditional lubricants due to their durability and low maintenance needs.
Polyurethane bushings are preferred over rubber, plastic, and steel alternatives because of their superior load-bearing capacity and exceptional compression resistance, which contributes to their longer lifespan. These bushings are available in various forms, from soft sponge-like to extremely tough, and can be customized in different colors, shapes, sizes, and dimensions. They offer resistance to environmental factors such as heat and moisture, as well as to solvents, chemicals, and wear.
Suspension Bushings
Suspension bushings were among the first applications of polyurethane bushings due to their effectiveness in minimizing friction and absorbing shocks, ensuring a smoother ride over rough terrain. They help regulate the movement of steering joints to reduce sway during turns. These bushings are typically found in control arms, ball joints, tie rods, sway bars, shock absorbers, and strut mounts.
Polyurethane bushings combine the strength and durability of materials like wood and plastic with the flexibility and resilience of rubber. Their standout feature is their exceptional durability, which makes them particularly suitable for automotive use. Suspension bushings are subjected to continuous stress and deformation, and their hardness enhances road feel and vehicle control for drivers.
Flange Bushing
Flange bushings, sometimes referred to as flange bearings, do not actually contain bearings. Instead, they serve as a protective interface between components, absorbing and redirecting energy through the bushing. Featuring a shoulder on one end, they are often used to facilitate the mounting and alignment of bearings, simplifying the installation process. Unlike standard sleeve bushings, flange polyurethane bushings are equipped with this additional shoulder. The key dimensions of a flange bushing include the inner diameter (ID), outer diameter (OD), overall length (OAL), flange outer diameter (FLOD), and flange thickness (FLTH). These measurements are crucial for manufacturers during the production of flange bushings.
Motor Mount Bushings
Polyurethane motor mount bushings are engineered to minimize the transfer of noise, vibrations, and movement that can lead to wear on engine parts. They serve as aftermarket replacements for factory-installed rubber mounts, which tend to deteriorate over time. These bushings offer flexibility and anti-vibration properties. Unlike rubber mounts, polyurethane motor mount bushings are resistant to oil, coolants, and grease, and they can endure rapid temperature changes.
The appeal of polyurethane motor mount bushings lies in their extended lifespan, which is typically three to four times longer than that of rubber or plastic mounts. Due to their superior durability and strength, these bushings do not crack, dry out, or fracture. They are preferred over metal bushings because they do not damage surrounding components and do not generate vibrations or noise.
The design of polyurethane motor mount bushings is tailored to fit various vehicle makes and models, as engine bays and frames differ significantly. Consequently, manufacturers offer a range of motor mounts, including custom options, to accommodate different vehicles. An essential aspect of producing polyurethane motor mount bushings is rigorous testing to ensure their durability and performance.
Hydraulic Cylinder Bushings
Hydraulic cylinder polyurethane bushings function as wear-resistant liners designed to minimize friction between pins and connecting parts. These bushings are preferred over standard bushings because of their self-lubricating capabilities. They feature a metal base coated with polyurethane, which ensures ongoing lubrication throughout their use.
Split Polyurethane Bushings
Split polyurethane bushings are designed to minimize friction in heavy machinery and feature a longitudinal split that simplifies installation. This split provides both flexibility and a secure fit. Additionally, the slit allows for easy shaft replacement without the need for retooling, making them ideal for applications where exact boring is not required.
Clench Polyurethane Bushings
Clench polyurethane bushings are similar to split polyurethane bushings but include interlocking tabs along the split edges. These tabs are specifically designed to eliminate gaps in the slit, ensuring a more secure and gap-free fit.
Sleeve Polyurethane Bushings
Sleeve polyurethane bushings are among the most basic types of bushings, featuring a cylindrical shape akin to a small tube. They are designed to handle radial loads and can be paired with thrust washers to accommodate heavier loads. Like other bushings, they reduce friction between moving parts and help absorb vibrations. Engineered for durability, sleeve bushings are suited for high-temperature environments and are compact in design.
DOM Sleeve Polyurethane Bushings
DOM sleeve polyurethane bushings combine a polyurethane sleeve with metal cylinders, which can be crafted from materials such as bronze, steel, or stainless steel. The polyurethane sleeve offers lubrication, while the metal cylinders enhance the bushing's stability. These bushings are frequently used as motor mounts and suspension links. Available in standard sizes, they are also often custom manufactured to fit a range of vehicles and heavy-duty machinery.
Chapter Five: What are the differences between rubber and polyurethane bushings?
When selecting materials for bushings, customers can choose between rubber and polyurethane, each offering distinct advantages. The decision largely depends on the bushing's intended use and performance requirements. Several factors influence this choice, and various types of plastics may also be considered as alternatives.
There is often confusion surrounding terms like polyurethane rubber or polyurethane plastic, but these do not accurately describe polyurethane. The key advantage of polyurethane lies in its unique properties, which set it apart from other materials.
Rubber
Rubber bushings have been used for years in its synthetic and natural form. It is valued for its flexibility, shock resistance, and durability. Rubber is capable of absorbing shock and compressing under a load due to it being a soft material that gives under pressure. It can be damaged by heat, oil, and chemicals and does not wear well. When exposed to certain environmental conditions, rubber can be significantly damaged.
Synthetic rubber, an elastomer known for its elasticity, durability, toughness, and resilience, is available in several types including styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), silicone rubber, and ethylene propylene diene monomer (EPDM). Each type of synthetic rubber has specific properties that make it suitable for different applications.
Rubber is favored in bushing production primarily due to its cost-effectiveness, which contributes to its widespread use in the automotive industry. However, rubber does have a downside: it tends to degrade under repeated stretching, deformation, and stress.
Marring � Rubber contains carbon that leaves black marks on the components it comes in contact with.
Chemical and Water Resistance � Rubber is unable to be constantly exposed to water since it will rot.
Abrasion Resistance � Rubber deteriorates when exposed to constant abrasive forces.
Formulations and Colors � Rubber, synthetic or natural, has standard formulations and colors.
Longevity � The life expectancy for rubber bushings is 10 to 15 years.
Tensile Strength � Although rubber is a strong and durable material, it ruptures, cracks, and breaks when confronted with heavy loads.
Temperatures � Rubber tends to harden at very low temperatures and breaks down and melts in extremely high temperature conditions.
Polyurethane
Polyurethane stands out as a superior bushing material compared to rubber primarily due to its exceptional durability. Its strength and toughness enable polyurethane to outlast rubber by five to ten times. Typically, when rubber bushings reach the end of their service life, they are replaced with polyurethane bushings.
Polyurethane is particularly well-suited for applications involving constant stress thanks to its carbamate linkages. It combines the elastic qualities of rubber with the rigidity of plastic, making it versatile for similar uses as rubber and plastics. Moreover, polyurethane bushings can be produced in a wide range of colors, whereas rubber bushings generally come in only a few color options.
Non-Marring � Polyurethane bushings do not mark the components they make contact with.
Chemical and Water Resistance � Polyurethane bushings are resistant to chemicals, solvents, petroleum products, oxygen, and exposure to ozone. It retains all its properties when submerged or exposed to humid and moist environments.
Abrasion Resistance � The abrasion resistance of polyurethane is one of the reasons that it is so widely used to produce bushings. In the face of severe abrasions, it can last five to ten times longer than rubber or plastics.
Load Bearing � Polyurethane can withstand more pounds per square inch than rubber without fracturing or breaking.
Formulation and Colors � Polyurethane compounds are very flexible and can be adjusted to meet hardness levels from soft as tissue to as hard as metals. The formulation process makes it possible to produce polyurethane in a wide array of colors.
Longevity � This is the key aspect of polyurethane. While rubber bushings can last for 10 to 15 years, polyurethane bushings can last as long as an application is in operation.
Chapter Six � What are the advantages of polyurethane bushings?
Originally, polyurethane bushings were developed for use in military equipment and racing vehicles. They remained exclusive to these applications until the 1930s when they began to be used more broadly. By the 1990s, polyurethane bushings quickly became a popular alternative to rubber bushings. Today, they are widely recognized as the benchmark for high-quality bushings. Polyurethane is a polymer created by reacting diisocyanates with polyols. The term "polyurethane" refers to a range of materials that can be engineered and combined in various ways to produce diverse properties. The distinctive molecular structure of polyurethane provides it with exceptional resilience, strength, durability, and longevity.
Durometer Rating �
Resilience �
Adaptable �
Reliable �
Absorption �
Load Capacity �
Cost � The cost of polyurethane bushings is higher than rubber bushings, which is amortized over their long life of usefulness.
Conclusion
A polyurethane bushing is a friction reducing bushing that is placed between moving and stationary components as a replacement for lubricants.
Polyurethane is a polymer produced by combining diisocyanates, an organic compound consisting of two isocyanate groups, and polyols.
Polyurethane bushings are produced using different methods, including casting, extrusion, and injection molding. The choice of method is dependent on the type of polyurethane material, the type of bushing being produced, and the quantity, which can vary from a few hundred to thousands.
The two general types of polyurethane are polyester and polyether, which are elastomers with elastic properties and are resistant to abrasion.
Polyurethane bushings are available in a wide variety of shapes and sizes with custom bushings for special and unique applications. Their use is constantly growing as new devices are being introduced that require the support, security, and strength of a resilient and reliable material.
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Molding is a manufacturing process that uses a mold - the latter being a solid container used to give shape to a piece of material. It is a forming process. The form is transferred from the mold to the material by...
Fiberglass Molding
Fiberglass molding is a method for forming complex and intricate parts using fiberglass resin. Though there are several reasons for producing parts and components from fiberglass, the most pressing reasons are the...
Fiberglass Sheets
Fiberglass is a plastic reinforced material where glass fiber is used as reinforcement, and the glass fiber is flattened into a sheet. It is also known as glass fiber reinforced plastic or glass reinforced plastic...
Overmolding
Many of the products used daily are made possible by producers and suppliers of rubber and plastic. These substances are robust, adaptable, and capable of practically any shape required for various industrial purposes. Several varieties are...
Plastic Bottles
Plastic bottles are bottles made of high or low-density plastic, such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), or polyvinyl chloride (PVC). Each of the materials mentioned has...
Plastic Caps and Plugs
Plastic caps and plugs are two distinct ways for sealing the ends, tops, and openings of tubes and containers. Caps are placed over the opening, and plugs are placed in the opening. Due to the many varieties of...
Plastic Coating
Plastic coating is the application of liquid polymers or plastic on the surface of a workpiece by dipping or immersion. The result is a thick plastic finish for protective and decorative purposes. This gives the material additional resistance against...
Plastic Injection Molding
Plastic injection molding, or commonly referred to as injection molding, is a manufacturing process used in the mass fabrication of plastic parts. It involves an injection of molten plastic material into the mold where it cools and...
Plastic Overmolding
Plastic overmolding has a long and interesting history, dating back to the early 1900s. The first overmolding process was developed by German chemist Leo Baekeland, who invented Bakelite, the first synthetic plastic. Baekeland used a...
Rotational Molding
Rotational molding, commonly referred to as "rotomolding", is a plastic casting technique used to produce hollow, seamless, and double-walled parts. It uses a hollow mold tool wherein the thermoplastic powdered resin is heated while being rotated and cooled to solidify...
Rubber Injection Molding
Rubber injection molding is when uncured rubber is transformed into a usable product by injecting raw rubber material into a mold cavity made of metal. The applied pressure produces a chemical reaction like...
Rubber Molding
Rubber molding is a process of transforming uncured rubber or an elastomer into a usable product by transferring, compressing, or injecting raw rubber material into a metal mold cavity...
Rubber Overmolding
There are several methods to perform rubber overmolding, and each method has its own unique advantages and disadvantages. The choice of method typically depends on the design and material requirements of the product being...
Silicone Rubber Molding
Silicone rubber molding is a method for shaping, forming, and fabricating silicone rubber parts and products using a heated mold. The process involves compressing or injecting silicone rubber into a mold...
Thermoplastic Molding
Thermoplastic molding is a manufacturing process that works to create fully functional parts by injecting plastic resin into a pre-made mold. Thermoplastic polymers are more widely used than thermosetting...
Grommet Edging
A grommet edging is a flexible rubber or plastic strip that covers rough and sharp surfaces found in openings and edges of panel walls to protect the passing electrical cables, wires, and other sensitive components...