5 Types of Spring Lock Washers: Properties and Uses
In the world of mechanical assemblies, small components often play the biggest roles, and spring lock washers are no exception.…
Helical spring lock washers, commonly known as split lock washers, are essential components used to ensure the security and integrity of bolted assemblies. These washers are designed to apply greater bolt tension per unit of applied torque, resulting in more uniform torque control and load distribution. The primary function of split lock washers is to prevent fasteners from loosening due to vibration and corrosion, making them ideal for applications involving hardened bearing surfaces.
Building on the benefits discussed, the mechanism of action of helical spring lock washers is critical to their performance. The split in the washer plays a crucial role. As a screw or bolt is tightened, the washer flattens, creating tension within the joint. This tension helps counteract the effects of vibration and minor movements, which can otherwise lead to loosening. The trapezoidal cross-section of the washer undergoes deformation under load, contributing to a high spring rate that helps maintain the clamping force in the assembly. This mechanism ensures that the fastener remains secure even under dynamic conditions.
Standard split lock washers are versatile and used in a broad range of industrial applications. They are suitable for general-purpose fastening where moderate vibration and shock loads are present.
Designed for metric fasteners, these washers offer the same functionality as standard split lock washers but are sized according to metric standards. They are commonly used in international applications and machinery that adhere to metric specifications.
These washers adhere to stringent military standards, guaranteeing reliability and performance in critical applications. They are used in defense and aerospace industries where failure is not an option.
Also known as high-collar lock washers, these have a smaller outside diameter to fit under socket head cap screws. They are used in applications where space is limited and a low-profile washer is required.
These washers are thicker and have larger outside diameters than standard split lock washers. They provide additional security and are used in applications that require enhanced locking capabilities.
While helical spring lock washers are effective in many scenarios, their performance can vary based on specific conditions. For instance, they may not always prevent self-loosening under extreme vibration or dynamic loads. The Junker test, which simulates transverse vibrations, has shown that these washers can fail to maintain the clamping force under such conditions. In this test, a bolted joint is subjected to cyclic transverse loads, demonstrating that split lock washers may not always be sufficient to prevent loosening.
In real-world applications, consider the specific requirements of the assembly and choose the appropriate type of washer for optimal performance. For example, in high-vibration environments, additional locking mechanisms or washers with different designs may be necessary.
In summary, split lock washers are a widely used and versatile solution for maintaining the integrity of bolted assemblies. Their ability to counteract vibration and corrosion makes them suitable for numerous industrial applications. However, it is crucial to select the right type and size based on the specific needs of the assembly to ensure maximum effectiveness.
External tooth lock washers, commonly known as star washers, feature serrated or toothed edges that extend outward from the center. This design allows them to bite into the surface of the material they fasten, creating a secure grip that prevents loosening due to vibration and movement.
Enhanced Grip: The serrations dig into surfaces, ensuring a firm hold. For example, in automotive assemblies, external tooth lock washers outperform flat washers by maintaining secure fastenings even under constant vibration and dynamic loads. This is especially beneficial for components like engine mounts or suspension systems.
Corrosion Resistance: External tooth lock washers are often made from stainless steel grades such as AISI 304 and AISI 316. These grades are highly resistant to rust and corrosion, making them suitable for harsh environments. For instance, AISI 316 is ideal for marine applications due to its superior resistance to saltwater corrosion, while AISI 304 is often used in industrial settings exposed to chemicals and moisture.
Electrical Bonding: These washers ensure reliable electrical continuity by piercing through coatings like varnish or anti-corrosive agents. This feature is critical in grounding systems, where maintaining a consistent electrical path is essential for safety and functionality. For example, in circuit protection, they ensure that electrical connections remain intact despite environmental challenges.
Vibration Reduction: By securely locking the fastening device in place, external tooth lock washers help mitigate vibrations. In automotive applications, this property is leveraged to maintain the integrity of fasteners in engine compartments and chassis components, where constant vibration is a concern.
Automotive Assembly: External tooth lock washers are commonly used in automotive components where secure fastening is critical. Their vibration-reduction properties are particularly valuable in areas subject to constant movement and dynamic forces, such as engine mounts and suspension systems.
Electrical Equipment: In devices where maintaining electrical contact is crucial, these washers provide both mechanical locking and electrical conductivity. They are essential in grounding systems and other electrical assemblies to ensure reliable performance.
Appliances and Consumer Products: Many household appliances utilize external tooth lock washers to ensure that fasteners remain tight despite regular use and vibration. For example, they are used in washing machines and refrigerators to maintain the integrity of internal components.
When selecting external tooth lock washers, consider the following factors:
Material Compatibility: Ensure that the washer material is compatible with the substrate (the material to which it is fastened) to prevent galvanic corrosion, a type of corrosion that occurs when two different metals are in electrical contact in a corrosive environment.
Surface Condition: The effectiveness of these washers can be influenced by the surface finish of the materials being joined. Smooth surfaces may reduce the locking effectiveness, while rougher surfaces can enhance the grip.
Load Requirements: Assess the load and vibration conditions of the application to determine if external tooth lock washers are the most suitable choice or if other locking mechanisms are needed. For instance, in high-vibration environments like machinery, the serrated edges of these washers can provide a more secure hold compared to split lock washers.
External tooth lock washers are an effective solution for preventing the loosening of fasteners in various applications. Their design provides strong grip and stability, making them essential components in both mechanical and electrical assemblies.
Internal tooth lock washers are essential components used to secure fasteners and prevent loosening under various conditions. These washers feature teeth on their inner circumference, designed to grip the threads of a bolt or nut. When a fastener is tightened, the teeth engage with the mating surface, creating friction that effectively locks the fastener in place. This locking mechanism is particularly effective in scenarios involving vibration, dynamic loads, or thermal expansion and contraction.
The design of internal tooth lock washers is focused on maximizing grip and stability. The internal teeth allow for a more compact installation, making them suitable for applications where space is limited. Unlike external tooth washers, which can protrude and interfere with surrounding components, internal tooth washers maintain a smooth exterior, ensuring that they do not obstruct other parts of the assembly.
When a fastener is tightened, the teeth of the washer bite into the surface of the bolt or nut, enhancing friction and preventing loosening. This feature is particularly beneficial in applications where mechanical vibrations are prevalent, such as in automotive or aerospace industries. For instance, in automotive assemblies, internal tooth lock washers are often used to secure critical components like engine mounts and transmission housings, where reliability is paramount.
Internal tooth lock washers are versatile and can be used across a wide range of industries. Their applications include:
The use of internal tooth lock washers offers several advantages:
Internal tooth lock washers are made from various materials to suit different applications:
To ensure optimal performance of internal tooth lock washers, consider the following during installation:
Wedge lock washers, such as Nord-Lock washers, are engineered to provide exceptional security for bolted joints, ensuring their reliability even under extreme vibration and dynamic loads. Their unique design offers a mechanical locking solution that prevents loosening, making them indispensable in industries where safety and durability are paramount. The innovative wedge-locking mechanism distinguishes these washers from conventional fasteners by relying on tension rather than friction.
Nord-Lock washers utilize a specialized design comprising two interlocking washers. One side features cams, while the other has serrations. When tightened, the cams create a wedge effect that locks the washers in place. This mechanism is based on the principle that the cam angle is greater than the thread pitch angle. As a result, any loosening attempt increases the clamping force, preventing the joint from loosening due to vibration or transverse loads.
The thread pitch angle refers to the incline of the bolt threads, while the cam angle is the incline of the washer’s internal cams. The difference between these angles ensures that any attempt to rotate the bolt in reverse tightens the joint further. This design eliminates reliance on friction, making these washers highly effective in high-vibration environments such as construction machinery, automotive assemblies, and mining equipment.
In applications where exposure to extreme temperatures or saltwater is a concern, stainless steel washers are preferred. Conversely, for standard industrial use, steel washers are more cost-effective while maintaining high performance.
SP washers are designed with an enlarged outer diameter, making them suitable for flanged bolts, nuts, oversized or slotted holes, and soft materials. They distribute the load evenly across sensitive surfaces, preventing material deformation or damage. SP washers are frequently used in industries like automotive manufacturing, where slotted holes or lightweight materials are common, and in electrical applications requiring load distribution on softer materials like aluminum.
Nord-Lock washers are designed for straightforward installation and removal using standard tools. Their wedge-locking mechanism remains effective regardless of lubrication. Washer reusability depends on the environmental conditions and level of wear. For instance, exposure to heavy corrosion or mechanical wear may necessitate replacement after prolonged use. Regular inspection is recommended to assess the washers’ condition and ensure continued functionality.
Nord-Lock washers are rigorously tested to meet international standards, ensuring their reliability under demanding conditions. Certifications include:
These certifications validate their effectiveness, making them trusted components in industries such as aerospace, mining, and renewable energy.
By combining a robust mechanical locking mechanism with exceptional material properties, Nord-Lock washers offer a secure and durable solution for bolted joints in critical applications. Their design ensures peace of mind in industries where joint failure is not an option.
Internal tab lock washers feature tabs bent inward on their inner circumference. These tabs engage with the fastener’s threads, providing a locking action from within the assembly. This design ensures that the external surfaces remain smooth and free from obstructions.
Internal tab lock washers are commonly used in various industries and applications:
The internal tabs dig into the fastener’s threads, creating a secure locking action without impacting the external surface of the assembly.
External tab lock washers have small tabs or tangs bent outward from their circumference. These tabs dig into the mating surface and the fastener, providing a positive locking action.
External tab lock washers are often used in critical and demanding environments:
The external tabs bend against the fastener’s side or the mating surface, maintaining a fixed position and preventing the fastener from rotating. This design is particularly effective in harsh environments where other types of lock washers might fail.
Split lock washers rely on a spring force generated by the split ring to prevent loosening. They are more suited to applications with moderate vibrations and smaller loads.
Toothed lock washers, either internal or external, use teeth to grip the fastener and the mating surface. They are effective in applications where there is a risk of loosening due to vibration or thermal cycling but may leave scratches on the surfaces they contact.
Belleville washers provide a constant spring force and are used in applications requiring high load capacity and compensation for thermal expansion. Wave washers, with their wavy shape, are used where axial play is required, such as in ball bearings and suspension systems.
When choosing between internal and external tab lock washers or other types of lock washers, consider the following factors:
Understanding these differences and selection criteria ensures that the chosen lock washer type provides the necessary reliability and security for your specific application.
Below are answers to some frequently asked questions:
Split lock washers, also known as helical spring washers, offer several advantages, particularly in applications where vibrations and dynamic loads are a concern. One of the primary benefits is their ability to prevent bolts from loosening due to vibrations. The washer’s split and twisted design creates a spring-like action that pushes back against the mating surface when the bolt is tightened, helping to maintain the bolt’s position over time.
Additionally, split lock washers enhance load distribution. They compress and act as a spring when the bolt is driven in, spreading the load more evenly and protecting the joined workpiece from damage. The split design also provides a frictional locking mechanism, where the sharp edges bite into the mating surface, adding security against rotational movement of the bolt and making it less likely to loosen.
These washers are easy to install, as they are placed between the bolt head or nut and the mating surface and tightened like any other washer. Their versatility makes them suitable for various industries, including transportation, household appliances, and any scenario where vibrations and torque could cause fasteners to loosen. Overall, split lock washers are a reliable choice for maintaining the integrity and stability of bolted joints in dynamic environments.
External tooth lock washers prevent loosening by utilizing sharp teeth around their outer diameter that bite into the material and the fastener head when tightened. This design creates a mechanical interlock between the washer, fastener, and the bearing surface, which resists rotation and loosening.
The washer’s teeth grip securely onto the joint material, increasing friction and providing a robust resistance to torque and vibration. This makes them particularly effective in dynamic environments where movement or vibration might otherwise loosen a standard fastener. Their design is especially advantageous when used with fasteners that have larger heads, such as round or pan head screws, as the increased surface area allows for a stronger hold.
By maintaining constant contact and biting deeper into the material under vibration or stress, external tooth lock washers ensure the fastener remains secure over time, making them an ideal choice for applications in automotive, aerospace, and other industries where reliable fastening is critical.
Internal tooth lock washers are most effective in several specific applications due to their unique design and functionality. They excel in lighter-duty jobs and with softer materials like aluminum and plastic, as their discrete locking effect minimizes damage to the material. These washers are particularly suited for fasteners with smaller heads, such as fillister head fasteners, where the inward-facing teeth grip securely under the bolt head without needing large external teeth. In electrical applications, internal tooth lock washers enhance the electrical connection by providing a stable contact point, making them valuable for grounding purposes. Additionally, their clean, streamlined appearance makes them ideal for applications where aesthetics are important. Lastly, they are effective in low to medium torque applications, providing a reliable hold without being overly aggressive. Overall, internal tooth lock washers are best utilized in contexts requiring secure fastening on softer materials, smaller head fasteners, clean appearance, and electrical connections.
Wedge lock washers are highly suitable for high-vibration environments due to their unique wedge-locking mechanism that secures bolted joints through tension rather than friction. These washers come in pairs, with cams on one side and radial teeth on the other. When subjected to vibration or dynamic loads, the radial teeth grip the bolt or nut and the material surface, while any loosening movement is redirected into the cams. The cam angles are steeper than the thread pitch, creating a wedge effect that counteracts loosening.
This design ensures exceptional resistance to loosening under severe vibration and heavy loads, as demonstrated by tests like the Junker test (DIN 65151), which consistently show wedge lock washers outperforming other locking methods. Their reliability makes them a preferred choice in industries such as automotive, construction, aerospace, energy, and mining, where high vibrations and dynamic stresses are common.
Additionally, wedge lock washers are valued for their ease of installation, corrosion resistance, and reusability. These features, combined with their proven performance in critical applications, make them indispensable for maintaining the safety and integrity of bolted joints in challenging environments.
Internal tab lock washers should be used over external tab lock washers when maintaining a smooth and unobstructed external surface is important, such as in applications where aesthetics or a clean finish is critical, like in electronics or small appliances. They are also preferable when working with softer materials that could be damaged by the external tabs, as internal tabs distribute the locking force without marring the external surface. Additionally, they are ideal for applications requiring electrical grounding, as they ensure secure fastening without interfering with other components. In contrast, external tab lock washers are better suited for high-vibration environments or applications involving dynamic loads where their broader locking surface provides enhanced stability.
