Why is a metal washer called a washer?
Washers are small, flat metal discs with a hole in the center. They are commonly used in various applications to distribute the load of a fastener, such as a bolt or a screw, and to prevent damage to the surface being fastened. The term "washer" seems simple enough, but have you ever wondered why they are actually called washers? In this article, we will dive into the etymology of the word and explore the origins and significance of this commonly used fastening component.
Origins of the Term "Washer"
The term "washer" originated in the English language during the 14th century. It comes from the Middle English word "waschen," which means "to wash." Initially, the term was used in relation to the action of cleaning or laundering clothes. However, over time, the term "washer" began to be associated with other objects and functions beyond laundry.
The adoption of the term for the metal disc with a central hole is believed to be influenced by the concept of cleaning or separating different materials. As a washer is placed between the fastener and the surface, it can be seen as a barrier that keeps these two elements apart, preventing them from coming into direct contact. In a way, the washer performs a similar function to that of separating and cleaning laundry, hence the name "washer" stuck.
Significance and Function of Washers
Washers may appear simple, but they play a crucial role in various mechanical and construction applications. Let''s explore their significance and functions in more detail.
1. Load Distribution
One of the primary functions of a washer is to distribute the load exerted by a fastener over a larger area. When a bolt or a screw is tightened, it creates pressure on the surface being fastened. Without a washer, this pressure is concentrated in a small area, which can cause damage to the material or make it vulnerable to loosening over time.
By using a washer, the load is spread out over a larger surface area, reducing the pressure on any single point. This helps to prevent damage, increases the stability of the connection, and enhances the overall strength and longevity of the fastening.
2. Surface Protection
In addition to load distribution, washers also provide surface protection. When fastening materials together, there is a risk of scratching, marring, or deforming the surface. A washer acts as a protective barrier between the fastener and the material, minimizing the contact and reducing the chances of surface damage.
For example, if you are attaching a metal bolt to a fragile plastic component, the washer will prevent the metal from directly touching and potentially cracking or deforming the plastic. This is particularly important in applications where aesthetics or the structural integrity of the material is paramount.
3. Preloading and Spring Action
Washers can also provide preloading and spring action. Preloading refers to applying a tension or compression force to a fastener before its intended use. This can help compensate for any anticipated settling, loosening, or thermal expansion that may occur over time.
Certain types of washers, such as Belleville washers or disc springs, exhibit spring-like properties. They can absorb and release energy, thereby improving the resilience and ability of the fastened joint to withstand dynamic loads, vibrations, or thermal stress. These washers can act as shock absorbers, compensating for the natural play or movement that may occur in the connected components.
Types of Washers
Washers come in a variety of shapes, sizes, and materials to suit different applications and requirements. Some common types of washers include:
1. Flat Washers
Flat washers are the most basic and commonly used type of washer. They have a flat surface on both sides and a hole in the center. Flat washers are primarily used for load distribution and surface protection.
2. Spring Washers
Spring washers, also known as lock washers or split washers, are designed with a split or helical shape. This shape provides a spring-like action, which helps maintain tension and prevent loosening due to vibrations or other external forces. Spring washers are often used in high-vibration applications or where regular tightening and retightening may be required.
3. Belleville Washers
Belleville washers, also known as conical spring washers, are conically shaped and provide high spring loads within a small space. They are designed to handle high loads, high temperatures, and potential stress relaxation. Belleville washers find applications in industries such as automotive, power generation, and aerospace.
4. Wave Washers
Wave washers, as the name suggests, have a wave-like shape and provide axial flexibility and vibration damping. They are often used in applications where there is a need for compensating for misalignment, thermal expansion, or maintaining tension in bolted joints under varying conditions.
Conclusion
The humble metal washer may seem like a simple component, but it serves a significant purpose in many mechanical and construction applications. The term "washer" originated from the concept of cleaning or separating materials, and the function of keeping two elements apart is equally important in fastening applications. Washers distribute load, protect surfaces, provide preloading or spring action, and come in various types to cater to specific needs. So, the next time you come across a metal washer, you''ll know there''s more to it than just a name.