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What Are the Differences Between Spring Washers and Flat Washers?

Mar. 29, 2024

What is the function of a flat washer?


Flat washers serve an essential role in various mechanical applications, providing support, distributing load, and preventing damage to surfaces. Typically stamped out of iron plates, these washers come in round or square shapes with a central hole. The size of this hole is typically standardized based on the bolt diameter or customized to meet specific requirements.


When it comes to choosing flat washers, it's important to match the washer's hole diameter with the bolt size. For instance, flat washers designed for M10 bolts will have a 10mm hole diameter. However, the outer diameter and thickness of the washer can vary, allowing flexibility in usage. This means that flat washers with the same bore diameter can accommodate bolts of the same size but may differ in their outer dimensions and thicknesses.


The main functions of flat washers are:


1. Enhancing the contact area between the screw and the machine, thereby promoting stability and even distribution of force.


2. Safeguarding the machine's surface from damage caused by spring washers during screw removal. Proper usage entails positioning the flat washer adjacent to the machine's surface, with the spring washer placed between the flat washer and the nut. The flat washer serves to augment the screw's load-bearing capacity, while the spring washer provides a buffer against loosening when subjected to stress.


3. It's important to note that flat washers do not provide anti-vibration functionality nor do they prevent loosening on their own. Therefore, their application requires careful consideration and proper use in conjunction with other components for optimal performance.


spring washer

What is the function of the spring washer?


The function of a spring washer is to prevent the nut from loosening once it's installed beneath it.


Commonly used spring washer sizes include M3, M4, M5, M6, M8, M10, M12, M14, and M16, which are widely utilized specifications.


The primary functions of the spring washer include:


Its main purpose is to prevent loosening. Once the nut is tightened, the spring washer applies elastic force, pressing against the nut. This pressure helps secure the nut in place, preventing it from easily coming off and enhancing the friction between the nut and the bolt.


For instance, bolts connecting the motor and the base typically require spring washers. This is essential because the motor's vibrations can cause the nut to loosen without the presence of a spring washer.


Consequently, spring washers are commonly installed on fasteners in equipment prone to vibration.


All in all, the spring washer can prevent loosening and increase the preload. The flat washer does not have this function, and can only be used to increase the tightening contact area, prevent friction between the bolt and the workpiece, and protect the surface of the connector.


In certain special connections, particularly those relying heavily on compression for generating frictional force to transmit power, spring washers are unsuitable as they may diminish connection rigidity. In such cases, where connected part strength is low, flat washers or flange bolts prove useful in increasing contact area. However, in scenarios involving vibration, spring washers are recommended for optimal performance.


When should a flat washer be used and when should a spring washer be used?


1. Flat washers are suitable for applications with minimal loads and minimal exposure to vibrations.


2. When dealing with substantial loads and vibration, a combination of flat washers and spring washers becomes necessary.


3. Spring washers are typically utilized in conjunction with other washers rather than being used independently.


What are the installation sequence of spring washers and flat washers?


The flat washer should be installed first, followed by the spring washer. This order is crucial due to the rotational movement of the washer when the nut is tightened. Installing the spring washer first risks scratching the connector due to its sharp corners. In contrast, the flat washer's smooth, flat surface ensures no damage occurs during rotation. Thus, it is advisable to install the flat washer before the spring washer for optimal connection integrity.


Bolt assembly


Bolt assembly involves combining bolts with spring washers and flat washers to ensure robust hardware connections.


For rigorous connections, particularly with crossbar nuts, spring washers are essential. Gaps between bolts and nuts, if present during tightening, can lead to loosening over time.


During use, the nut's tendency to rotate along the thread direction after tightening can exacerbate this issue.


Spring washers address this by providing pre-tension. When the nut presses against the spring washer, pre-tension prevents loosening.


Ordinary washers support the spring washer's pre-tension, expanding its effective pressing area.

spring washer