Sliding Bearing Design
Sliding Bearing Design
High-Performance Self-Lubricating Bronze Bushing Solutions & Technologies. Minimize downtime, extend service life, and reduce costs for dynamic applications.
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Explore our selection of plain sliding bearings, bronze bearings, and bushings tailored to meet your application needs with high reliability, long service life, and low maintenance.
Plain sliding bearings are ideal for various industries seeking cost-effective solutions for oscillating movements and misalignment challenges. They are widely used in railways, mining, construction equipment, agricultural and forestry machinery, as well as forklift trucks and solar power equipment.
How to select the right bushing, thrust washer or strip
Bearing Life Calculator: The basic rating life can be calculated based on specific operating conditions, which include defined ranges of bearing load (p) and sliding velocity (v). Calculation methods vary by bearing type. Key factors affecting basic rating life also include the load, sliding velocity, and intervals between relubrication.
Custom Bearing Bushing: We provide a professional electronic technology brochure for our customers, featuring product specifications, technical parameters, and other relevant information. This brochure is easily downloadable and printable, ensuring accessibility for all customers for reading and reference.
We accommodate wide manufacturing tolerances and utilize cost-effective welded assemblies.
Metal and Composite sliding Bearing design, bearing selection and application
02.
Pre-Lubricated Bearing
How to select the right bushing, thrust washer or strip
This section outlines principles for selecting materials and designs, offering technical insights, comparisons, and guidance for product selection and application, including pertinent calculations.
Bushings
Bushings are available in diverse designs and materials, each with distinct properties suited for specific applications.
Thrust washers
Thrust washers, constructed from PTFE and POM composites, are solid lubricating, maintenance-free washers designed for applications with limited axial space and oscillating or rotational movements, where lubricant starvation is a concern. To mitigate this, a pin or screw can be inserted into…
Composite Bushing
Dry sliding strips made from the same composite materials and intended for similar thrust washer applications can be formed into flat linear guides by bending, pressing, or coining.
Plain bearing, Flanged
Washer
The performance of plain sliding bearings—such as bushings, thrust washers, and strips—is mainly influenced by the interaction of load, lubrication, surface roughness, sliding velocity, and operating temperature in a given application.s.
In focus Graphite plain bearings
They effectively support heavy static and dynamic loads at low speeds while easily accommodating multi-directional movements and misalignment.
Principles of Selecting and Applying Sliding Bearings
We provide detailed bearing design data to our customers, allowing them to quickly understand the design principles and tolerance dimensions.
We supply comprehensive design data for metal bearings.
Self-lubricating Metal Base bearing design
We offer a wide range of products for various applications, including lubricated-for-life options that reduce grease use and high corrosion-resistant variants. Our standard selection features spherical plain bearings, rod ends, bushings, thrust washers, and strips in multiple sizes. We also provide customization of plain bearings for specific applications or industries upon request.
Durability and operational lifespan of slide bearings are influenced by several factors, including:
The specific load on the bearing
The velocity at which the bearing slides
The PV value is determined by the specific bearing load (P), sliding velocity (V), surface roughness depth, and the material and temperature of the mating surface, among other factors.
PV Limit Equation: PV = PxV (N/mm² x m/s)
As the sum of products of a bearing under the conditions of certain loading and linear velocity, PV value is inversely proportional to the service life of the bearing, so a lower safe PV value is suggested to be used during design to ensure a longer service life of the bearing. Although PV values of different materials are defined in the sample, these are measured under the condition of radial rotation; as a matter of fact, designers need to consider many factors when designing bearing life. Besides, ambient temperature, as a parameter which must be considered, should consider many factors, because fit clearance between bearing and seat hole and fit tolerance between shaft and bearing bore change due to temperature rise.
(The Chinese text provides the same information, emphasizing the importance of considering a safe PV value and various design factors, including ambient temperature and fit clearance, to ensure the bearing’s longevity.)
The chart below the text shows the maximum PV value graph with the x-axis labeled as “V max.” and the y-axis labeled as “max. PV value.”
Below the graph, different types of bearing motions are depicted along with their respective load and velocity formulas used to calculate the PV value:
- Rotating motion in single direction of radial journal
- Diagram of a cylindrical bearing (bushing) with an arrow indicating rotational movement.
- Formulas for Load, Velocity, and PV Value calculation for the rotating motion.
- Oscillating motion
- Diagram of a cylindrical bearing with arrows indicating back-and-forth movement.
- Formulas for Load, Velocity, and PV Value calculation for the oscillating motion.
- Reciprocating motion
- Diagram of a cylindrical bearing with arrows indicating linear back-and-forth movement.
- Formulas for Load, Velocity, and PV Value calculation for reciprocating motion.
- Thrust motion
- Diagrams of a rotating washer and a thrust washer with arrows indicating rotational and linear movement.
- Formulas for Load, Velocity, and PV Value calculation for thrust motion.
- Plane reciprocating motion
- Diagram of a flat plate with an arrow indicating linear back-and-forth movement.
- Formulas for Load, Velocity, and PV Value calculation for plane reciprocating motion.
The document concludes with a legend detailing the symbols used in the formulas:
- F: Load
- N: Rotational speed
- S: Stroke
- Θ: Oscillation angle
- d: Shaft diameter
- D: Bearing bore diameter
- L: Bearing length
- W: Bearing width
Symbols are given in Newtons (N), revolutions per minute (rpm), centimeters per second (cm/s), radians (rad), and millimeters (mm), allowing users to calculate PV values with a consistent unit set.
Bearing performance is affected by the material hardness, surface roughness, and surface treatment of the corresponding shaft. If used in corrosive environments such as seawater, or in chemical liquids, double or triple chrome plating should be considered.
| Bearing Material | Bearing Load | Shaft Material Recommend | Hardness | Roughness |
|---|---|---|---|---|
| Metallic Bearing | <25MPa | Carbon steel, structure alloy steel (S45C, SNC415, SCM435) in corrosive environments,
corrosion-resistant steel (SUS304, SUS403, SUS420) is recommended. |
>HB150 | <1.6a |
| 25~49MPa | Surface hardening treatment such as induction hardening and carburizing should be implemented for the above materials. | >HB250 | <1.6a | |
| 49~98MPa | In addition to surface hardening treatment as above,
additional surface treatment such as nitride treatment and hard chrome plating for above material. |
>HRC50 | <1.6a |
For metallic bearing housings, chamfers should be included on the housing bore to aid in assembly. A chamfer of F.x20° +5° is essential for easier bushing insertion.
Based on the image provided, here is the content rewritten in table format:
| Housing Bore Diameter | Chamfer with fg |
|---|---|
| 0.8±0.3 | |
| 30< ≤80 | 1.2±0.4 |
| 80 | 1.8±0.8 |
| 2.5±1.0 |
This table specifies the chamfer dimensions to be applied to housing bore diameters of various sizes.
Bearing Wall Thickness Design: The wall thickness of metallic self-lubricating bearings can be designed as thin as possible to achieve the minimization of dimensions. The recommended wall thickness design is as follows:
| ID (Inner Diameter) | Wall Thickness |
|---|---|
| 10mm | 3~4mm |
| 20mm | 3~5mm |
| 50mm | 7.5~10mm |
| 100mm | 10~15mm |
| 300mm | 20~30mm |
This table outlines recommended wall thicknesses for metallic bearings based on their inner diameters.
Length Design: The bearing length is typically determined by the ratio of its length to inner diameter. Under standard conditions, a length-to-inner diameter ratio (length/ID) of 0.5 to 2.0 is advised. For high-speed, high-load applications or uneven contact surfaces, a ratio of 0.8 to 1.0 is recommended.
Metallic self-lubricating bearings operate without maintenance, but regular greasing or oiling can improve performance and prolong their lifespan.
- Reduces the coefficient of friction and wear.
- Ensures smooth operation and increases the maximum PV value.
- Provides a cooling effect.
- Significantly extends the bearing’s service life.
- Protects against contaminants reaching the bearing section.
- Prevents rust on mating materials.
Seals
In cases of increased contamination or harsh environments, it is essential to shield the bearing section from dust and contaminants. A common solution is to redesign the surrounding structure to block contaminants from reaching the bearing. If contamination is a significant concern, using a grease collar or a shaft seal is recommended.
Assembly of Metallic Bearings
Bearing Assembly
Typically, bearings should be press-fitted with controlled pressure during installation. An assembly mandrel should be used to slowly press in the bearing. Direct striking of the bearing is prohibited to prevent deformation. Prior to assembly, it is essential to ensure that the housing bore surface is smooth and free of foreign objects.
Cold Assembly
Compared to mechanical press-fitting, cold assembly using liquid nitrogen or dry ice is more effective. The standard freezing temperatures for this method range from -40°C to -70°C, with the freezing time typically exceeding one hour. The specific time may vary based on the part’s wall thickness and fit tolerance.
Shrinkage of the bearing can be calculated using the formula:Shrinkage of the bearing can be calculated using the formula:
[Delta L = L_0 cdot alpha cdot Delta T
]
where ( Delta L ) is the change in length, ( L_0 ) is the original length of the bearing, ( alpha ) is the coefficient of linear thermal expansion for the material, and ( Delta T ) is the change in temperature.
For optimal results, it is essential to ensure that the temperature is uniformly distributed across the bearing to avoid uneven contraction, which could lead to stress concentrations and potential failure during assembly. Additionally, the choice of cooling agent—liquid nitrogen or dry ice—should be based on the specific material properties and the desired temperature range, as each has distinct thermal characteristics.
Once the bearing has reached the desired temperature, it can be aligned with the housing for assembly. The rapid contraction allows for a tighter fit, resulting in enhanced performance and longevity of the assembly. After the components are joined, they will gradually return to ambient temperature, resulting in a secure and stable bond due to the differential thermal contraction experienced during the process.
It is also important to monitor the environmental conditions during assembly, as fluctuations in temperature or humidity can affect the overall effectiveness of the cold assembly method. Proper preparation and adherence to the guidelines will ensure a successful and efficient assembly process, leveraging the advantages of thermal contraction to achieve precision fits that mechanical press-fitting may not provide.
ΔD = D × α × ΔT
Where:
- ΔD: Outer diameter shrinkage
- D: Bearing outer diameter
- α: Linear expansion coefficient (1/10^5 K)
- ΔT: Temperature differenc
Install thrust washers and sliding plates into the recessed grooves of the housing. Use dowel pins or countersunk screws for secure attachment to prevent movement.Ensure that the washers and plates are properly aligned within the grooves to facilitate smooth operation. Tighten the dowel pins or screws gradually, applying even torque to avoid distortion. Once securely fastened, inspect the assembly for any signs of misalignment or excessive gaps that could lead to wear over time.
Next, apply a light coat of lubricant to the contact surfaces of the thrust washers and sliding plates to minimize friction during operation. It is crucial to use a lubricant compatible with the materials involved to enhance longevity and performance.
After lubrication, conduct a thorough check of all attachment points to confirm that all components are firmly in place. Rotate the assembly slowly by hand to ensure there are no obstructions and that everything operates freely.
Finally, document the installation and any maintenance performed for future reference, ensuring that this important information is readily available for the next service interval. By following these steps, you will enhance the reliability and efficiency of the system.
This table lists surface roughness values for manufacturing and engineering, defining part texture. It includes multiple languages and columns for various national and international standards from China, the UK, the USA, Germany, Switzerland, Italy, Poland, the Czech Republic, and Japan. Below are the combined details in Chinese and English.Furthermore, the table encompasses standardized roughness values measured in micrometers (µm) and employs various roughness parameters such as Ra (average roughness), Rz (mean peak to valley height), and Rt (total height of roughness). These parameters are crucial for determining the functional performance and aesthetic quality of engineered parts.
In addition to the roughness values, each national standard is accompanied by its corresponding specifications, outlining acceptable limits and measurement methods. For instance, the Chinese standard emphasizes the quality control requirements specific to high-precision components, while the UK standard may prioritize ease of measurement and interpretation. Interoperability is a vital aspect when manufacturers strive to meet both domestic and international standards, ensuring compatibility across global supply chains.
The multilingual aspect of the table allows for a wider dissemination of information, catering to engineers and manufacturers from various regions, thereby promoting collaboration and standardization in the manufacturing sector. Each entry has been meticulously sourced from reputable engineering publications and standardization bodies, further enhancing its reliability and utility as a reference tool.
Moreover, the advancements in surface measurement technology, including optical and tactile methods, have facilitated more accurate assessments of surface roughness, enabling engineers to better optimize manufacturing processes. The presence of detailed notes regarding common practices, such as the use of specific measuring instruments and the influence of machining processes on surface finish, enriches the content, making it an indispensable resource for professionals across industries.
As the manufacturing landscape evolves, the ongoing updates to these roughness standards will reflect innovations in technology, material science, and production techniques, ensuring that they remain relevant and beneficial in guiding quality assurance practices worldwide.
- Surface Roughness Comparison Table:
- Standards: It includes standards from different countries and the corresponding codes.
- Roughness Parameters: It lists values for surface roughness (Ra, Rz) in micrometers (µm).
- Grade Codes: Each country has its code to refer to the roughness grades which are mentioned in the table with corresponding roughness values.
- China (GB 1031-83~ISO 468-83):
- It has a dual-column listing for Ra and Rz values in micrometers (µ).
- The grade codes are numerical, ranging from 0.008 µm (very smooth) to 6.3 µm (coarser).
- Other Countries:
- The roughness values and grade codes for the UK, USA, Germany, Switzerland, Italy, Poland, Czech, and Japan are also included, each in their respective standard measurement units.
- The USA, for instance, uses both micrometers (µ) and microinches (µin), with a numerical grading system. Similarly, Japan uses the JIS standard with Ra and Rz values.
- Unit Conversions at the Bottom:
- It defines the conversions for micrometers to meters and inches, indicating that 1 µm = 0.001 mm and 1 µin = 0.0254 µm.
This table would be especially useful for engineers who need to ensure the surface texture of their part meets the necessary specifications for functionality and aesthetics, or when communicating with international partners to ensure all parties use the same specifications.
This table compares surface finish grades between different national standards. The top row lists the countries and their respective standards: China (GB 1031-83 and ISO 468-83), the UK (BS 1134-61), the USA (ASA B 46.1-62), Germany (DIN 4768-60), Switzerland (VSM 10321-62), Italy (UNI 3963-PN 58/M 04251), Poland (PN 58/M 04251), Czech (CSN 14450-61), and Japan (JIS B 0601-70).
The columns detail the roughness grade values in micrometers (µ) and the corresponding roughness average (Ra), peak-to-valley height (Rz), and other surface finish parameters as per their standard codes. The values are presented in incremental order, from very smooth (0.008 µ) to very rough (250 µ).
The bottom of the table provides conversion factors for the units used:
This table is used by engineers and machinists to compare surface finish standards across different countries and ensure compatibility and understanding in international manufacturing and engineering specifications.
Metal shaft diameter tolerance
- Tolerances for Shafts: The table is likely for shafts since it includes typical tolerance classes used for cylindrical features such as holes and shafts.
- Tolerance Classes: The columns indicate various tolerance classes, such as (from finer to coarser tolerance):
h6,h7,h8,h9,h11, and so on, includinge8,f7,g6, andjs7. These are standard tolerance classifications used internationally, with the letter indicating the type of fit (e.g., ‘h’ for a snug fit) and the number indicating the tolerance grade (lower numbers are tighter tolerances). - Dimension Range in mm: The first column, labeled ‘N’, lists the size ranges in millimeters, from 3 mm up to 450 mm. These are the nominal sizes for the shafts.
- Tolerance Values in µm: The values in the table represent the upper and lower deviation limits in micrometers (µm) from the nominal size. For example, a cell with
-60indicates the lower limit deviation, meaning the part could be up to 60 µm smaller than the nominal size. - Negative and Positive Values: Negative values represent the maximum amount a feature may be under the nominal size, while positive values represent the maximum it may exceed the nominal size. A ‘0’ indicates that the size may be exactly at the nominal size but not larger (for lower deviation) or smaller (for upper deviation).
- ISO Standard: The table is likely based on ISO (International Organization for Standardization) tolerances for fits and dimensions.
This table would be used by mechanical engineers and machinists to select the appropriate tolerance class for a shaft or other cylindrical feature to achieve the desired fit with a mating part. For example, a shaft with a tolerance class of h7 would have different permissible deviations than one with a class of h9, with h7 being a tighter fit.
Tolerance for Metallic Type Housing Bore
- Tolerance Grades: Along the top, there are different tolerance grades or classes such as
B10,C9,D8,E8,F7,G7,H6,H7,H8,JS7,K7,M7,N7,P7,R7,S7, andT7. These are indicative of how tight or loose the fit will be. - Size Range: The first column labeled ‘N’ or sometimes ‘d’ (for diameter) lists nominal size ranges, usually in millimeters (mm), for the housing bore.
- Upper and Lower Deviations: The values in the chart represent the upper and lower deviation limits in micrometers (µm) from the nominal bore size. Positive numbers indicate the amount by which the bore diameter can exceed the nominal size, while negative numbers show how much it can be below the nominal size.
- Use Case: This chart is specifically for housing bores where metallic type bearings or similar components will be fitted. Each tolerance class will provide a different type of fit, from very tight fits where the bore diameter is almost the same as the component diameter, to looser fits where there is more leeway.
Engineers refer to these charts to select the appropriate tolerance class for designing parts or assemblies, ensuring proper fit and function. For instance, an H7 tolerance may be used for a snug fit without force, while a G7 tolerance may be chosen for a slight interference fit.
Bearing Tolerance of metal type seat hole
We provide detailed design data for Composite Sliding bearings
Self-lubricating composite Sliding bearing design
Tolerance and Inspection Methods for Multi-Layer Bearing Dimensions
The manufacturing process for rolled-type products inherently results in the presence of opening seams, meaning that in a free state, the products do not have perfect circularity. Additionally, the interference fit between the sleeve’s outer diameter and the housing bore requires the sleeve to conform maximally to the shape of the housing bore. Therefore, the product’s inner and outer diameters cannot be directly measured in a free state. Instead, they must be measured using specialized instruments and equipment. The ISO 3547 standard Part 2 provides specific requirements for the tolerance inspection of rolled-type products, including:
- Inspection Method A: Use the Haff gauge to inspect the outer diameter.
- Inspection Method B: Use the stop-go gauge to inspect the outer diameter.
- Inspection Method C: Use the stop-go gauge to inspect the inner diameter.
- Inspection Method D: Use calipers to inspect the outer diameter of large-sized products.
An alternative inspection method for wall thickness should be used, which cannot be used simultaneously with Inspection Method C.
For Inspection Method A (ISO 3547-2), the inspection involves using a set of upper and lower Haff gauges to apply a checking load ��ℎ, with the product’s open seam facing upward. This load allows the rolled sleeve to be positioned in the inspection mold correctly. The bushing’s outer diameter might decrease due to elastic deformation during the inspection, but this reduction is not permanent. The change in the distance �, denoted as Δ�, can be used to calculate the product’s outer diameter.
In Inspection Method B (ISO 3547-2), the inspection uses two types of ring gauges – a go gauge and a no-go gauge. It should be possible to press the sleeve into the go gauge and push it through by hand with a maximum force of 250N. Conversely, with the same force, it should not be possible to enter and go through the no-go gauge. If the accuracy of the inspection is likely to be affected, for instance by a non-circular sleeve or if the force to close the opening seam already exceeds 250N, it is recommended to use Inspection Method A or a combination of press-fit force and wall thickness inspection methods.
Inspection Method C for Multi-Layer Bearing Dimensional Tolerance: Inner Diameter
Inspection Method C (ISO 3547-2: Test C) assesses the inner diameter of a bushing after it is pressed into a standard ring gauge. The inner diameter can be measured using a three-point measuring device or go/no-go plug gauges, with the latter being preferred for practicality. The go plug gauge should pass through the bushing’s inner hole with a maximum manual force of 250N, while the no-go plug gauge should not pass under the same conditions. Note that the outer diameter of the bushing may experience permanent deformation after pressing, rendering it unusable.
For the Wall Thickness Test Method, it is an alternative to Inspection Method C, and the two should not be used simultaneously. Wall thickness is measured in the axial direction according to the size of the bushing. Both the wall thickness and the inside diameter should not be specified together on the same drawing.
| B [mm] | X [mm] | Measurement Position |
|---|---|---|
| B ≤ 15 | B/2 | 1 |
| 15 < B ≤ 50 | 4 | 2 |
| 50 < B ≤ 90 | 6 and B/2 | 3 |
| B > 90 | 8 and B/2 | 3 |
Straight sleeve installation of multilayer bearing
Installation of flanging sleeve for multi-layer bearing
Installation of Washers and Slide Plates for Multi-Layer Bearings
For the installation of washers and slide plates, it is advised that these components be positioned within the recessed housing bore. To prevent any movement, the use of dowel pins to secure them in place is recommended.
- Dowel Pin Application on Thrust Washer:
- A gap of 0.3-0.5mm is maintained around the dowel pin for the thrust washer.
- The dowel pin ensures that the thrust washer remains correctly positioned, complying with concentricity requirements.
- The bushing is aligned with these requirements to maintain the proper functioning of the bearing.
- Dowel Pin Used on Slide Plate:
- Similar to the thrust washer, a 0.3-0.5mm gap is also maintained around the dowel pin for the slide plate.
- The dowel pin secures the slide plate, ensuring it stays in alignment with the rest of the assembly.
- Flat Head Screw Application:
- Flat head screws are used to secure the slide plate, with a 0.3-0.5mm gap allowed for proper fitment.
- The screws ensure the slide plate is held in place securely and maintains concentricity with the bearing assembly.
These methods are essential to ensure the components are securely installed and remain concentric with the bearing to achieve optimal performance.
For the installation of washers and slide plates, it is advised that these components be positioned within the recessed housing bore. To prevent any movement, the use of dowel pins to secure them in place is recommended.
- Dowel Pin Application on Thrust Washer:
- A gap of 0.3-0.5mm is maintained around the dowel pin for the thrust washer.
- The dowel pin ensures that the thrust washer remains correctly positioned, complying with concentricity requirements.
- The bushing is aligned with these requirements to maintain the proper functioning of the bearing.
- Dowel Pin Used on Slide Plate:
- Similar to the thrust washer, a 0.3-0.5mm gap is also maintained around the dowel pin for the slide plate.
- The dowel pin secures the slide plate, ensuring it stays in alignment with the rest of the assembly.
- Flat Head Screw Application:
- Flat head screws are used to secure the slide plate, with a 0.3-0.5mm gap allowed for proper fitment.
- The screws ensure the slide plate is held in place securely and maintains concentricity with the bearing assembly.
These methods are essential to ensure the components are securely installed and remain concentric with the bearing to achieve optimal performance.
Other fixing methods for multilayer bearings
When dowel pins are not an option, other fixing methods such as laser welding, the use of adhesives, and brazing (at temperatures below 320°C) can be employed to secure multilayer bearings. It is important to ensure that the temperatures used during these processes do not exceed the tolerance of the bearing material. Additionally, care must be taken to keep the working surface of the sleeve free from contact with adhesives or other bonding agents.
In addition to using dowel pins and flat head screws, there are several other methods for fixing multilayer bearings in place. These methods ensure that the bearings are properly secured and maintain the required concentricity and alignment within their housing. Here are some commonly used methods:
- Interference Fit (Press Fit):
- Bearings can be press-fitted into their housing, creating a tight fit due to the slight diameter differences. This method provides a strong hold without the need for additional fasteners.
- Adhesive Bonding:
- Specialized bearing adhesives can be used to bond the bearing to the housing. This is particularly useful for bearings that are subjected to low loads and minimal thermal expansion.
- Retaining Compounds:
- These are liquid adhesives that cure in the absence of air when confined between close-fitting metal surfaces. They are suitable for securing bearings that may experience higher loads or need to be disassembled for maintenance.
- Snap Rings or Circlips:
- For bearings with grooves in the housing or on the shaft, snap rings or circlips can provide axial retention.
- Set Screws:
- Bearings with a set screw locking mechanism can be directly secured onto a shaft. The screws push against the shaft to hold the bearing in place.
- Welding or Soldering:
- In applications where disassembly is not required, welding or soldering can provide a permanent fixation.
- Shrink Fitting:
- Bearings and housings are matched such that, at room temperature, the bearing will not fit into the housing. Heating the housing or cooling the bearing causes enough expansion or contraction to fit them together. Once the temperature equalizes, the fit becomes secure.
- Bolt or Stud Mounting:
- For flanged bearings, bolting through the flange to the housing provides secure axial and radial positioning.
- Eccentric Locking Collar:
- Bearings with an eccentric locking collar are rotated onto the shaft, which then positions the collar eccentrically against the shaft, creating a secure fit.
- Keyways and Keys:
- Using keys that fit into matching keyways on both the bearing and shaft provides secure axial positioning.
The method chosen will depend on the specific application requirements, such as load, speed, vibration, temperature, the need for disassembly, and the direction of applied forces. Always refer to the manufacturer’s specifications and guidelines when selecting a fixing method for multilayer bearings.
Processing and Installation Precautions for PTFE-Based Bearings
PTFE-based bearings are usually supplied as finished parts and should not be reamed or bored after assembly. When the housing bore is machined to the specified dimensions, the roundness of the inner diameter of rolled-type bearings should meet operational standards.
If a significant reduction in dry friction performance is acceptable, the inner hole of the PTFE-based bearing may be extruded post-installation for improved precision. It is advisable to thermally treat the extrusion mandrel (to a depth of 0.6mm, with a hardness of HRC >55) and polish it to a surface finish of Rz1.
For applications with low bearing-specific pressure or minimal swing, operational clearance can be increased. In high-temperature scenarios, a 0.008mm reduction in shaft diameter is recommended for every 100°C rise.
When the bearing seat is made of bronze, aluminum, or zinc alloy, reducing the bore size is advised to enhance the interference fit during assembly. To maintain the rigidity of the bearing seat, its outer diameter should be 1.5 times that of the bearing. Consideration must be given to deformation from press fitting and operation, particularly in thin-walled housing bores.
If machining PTFE bearings is necessary, it is best to machine or drill from the PTFE side to prevent burr formation. Ensure adequate support for the sleeve during drilling to avoid deformation. For processing strip materials, methods such as shearing, waterjet cutting, and laser cutting are recommended.
The inquiry examines how material properties such as hardness, surface roughness, and surface treatments influence bearing longevity. Typically, the shaft should have a hardness greater than HRC 50 and a surface roughness below Ra0.4. In moist or corrosive environments, stainless steel or hard chrome plating is recommended.
Incorrect design refers to designs that are unsuitable for their intended purpose, resulting in premature failure or reduced performance. In contrast, correct design involves selecting appropriate materials, surface treatments, and manufacturing methods to ensure optimal bearing performance and durability.
While the search results do not directly answer the initial query, they examine various aspects of bearing materials, manufacturing, and performance. One source discusses how surface roughness and hardness influence adhesion and friction at the nanoscale. Another highlights the use of various materials, such as plastics and metals, stressing the importance of minimizing friction and wear through lubrication and surface treatments. Furthermore, some sources explore the use of composite materials and surface treatments to enhance bearing performance in specific applications.
In summary, the initial inquiry focuses on how material properties affect bearing life, recommending the use of hard materials with low surface roughness and suitable surface treatments.
Metal Bushing (Lubricated Metal) -Self-Lubricating Bushing Materials
Bushings are specialized, self-lubricating metal components widely utilized across various industries due to their durability and low maintenance requirements. Self-lubricating metal bushings are engineered to function without additional lubrication in numerous applications, thereby minimizing maintenance needs. These bushings are available in various series and configurations, such as flanged bushings and split bearings, to meet specific application requirements.
Metal-Polymer Anti-Friction Plain Bearings
Metal-Polymer Composite Self-lubricating Bushing Material
Steel Back + Porous Bronze Sinter + PTFE
