Washers may appear to be small and inconspicuous components in the world of fasteners and hardware, but they play a vital role in ensuring the integrity and longevity of various structures and assemblies. These seemingly simple circular disks, typically made of metal or plastic, serve a primary purpose that extends far beyond their modest appearance. In this comprehensive guide, we will delve into what washers are, explore their primary purpose, and elucidate their significance in a wide range of applications.
What Are Washers?
Washers are flat, typically disk-shaped pieces of material with a central hole. They are designed to be placed between a nut, bolt head, or another fastening element and the surface of the material being fastened. Washers come in various sizes, materials, and configurations, but they all share the same fundamental design—a flat, circular shape with a hole in the center.
Just like with nuts, it’s important to match the strength of the flat washer with the strength of the bolt to reduce likelihood of failure. Common pairings are: Low Carbon washers with Grade 2 or Grade 5, and High Alloy washers with Grade 8.
The Primary Purpose of Washers
Washers serve a crucial primary purpose in mechanical and structural assemblies:
The primary purpose of washers is to distribute the clamping load or force applied by the fastener (e.g., a bolt or nut) over a larger area of the material being fastened. When a fastener is tightened, it exerts pressure on the material, which can cause deformation or damage, particularly in softer materials like wood or plastic. Washers act as a buffer, spreading this load more evenly to prevent damage or deformation, thus preserving the structural integrity of the material.
The Significance of Load Distribution
Load distribution is essential for several reasons:
- Preventing Surface Damage. Without washers, the concentrated force from a fastener can cause dents, impressions, or even cracks in the material. Washers help prevent such damage.
- Enhancing Structural Integrity. Washers contribute to the longevity and stability of structures by minimizing the risk of material failure due to excessive localized stress.
- Improving Fastener Performance. Proper load distribution ensures that fasteners, such as bolts and nuts, perform optimally by maintaining a secure and stable connection.
- Alignment Correction. Washers can also be used to correct alignment issues in assemblies. In situations where components are not perfectly aligned, washers can be strategically placed to compensate for misalignment and ensure that the fastener engages correctly.
Reducing Friction. In some cases, washers may include specialized materials or coatings to reduce friction between the fastener and the material being fastened. These washers are often used in applications where controlled friction is essential.
- Sealing and Insulating. Specialized washers, such as rubber or neoprene washers, can provide sealing and insulating properties. They create a watertight or airtight seal and can also act as electrical insulators in certain applications.
When Not to Use Washers
While washers are invaluable in many applications, there are situations where they may not be necessary or even advisable:
Precision Machined Surfaces
In applications where the surfaces to be fastened are precision machined to meet tightly toleranced specifications, adding washers may disrupt the precision fit.
Engineered Fastening Systems
Some modern fastening systems, especially in aerospace and automotive industries, use engineered solutions that are designed without the need for traditional washers.
Cost and Space Constraints
In applications where cost or space is a significant concern, adding washers may be deemed unnecessary if the structural integrity of the assembly is not compromised.
Types of Washers
Washers come in various types, each tailored to specific applications and requirements. Some common types of washers that we provide include:
These are the most basic type of washers and are used for general-purpose load distribution. They help maintain structural integrity, correct misalignments, and reduce friction between fasteners and materials.
Split Lock Washers
Also known as spring washers, these have a split design that provides spring-like tension to prevent fasteners from loosening due to vibration or thermal expansion and contraction.
Fender washers are large-diameter washers with a relatively small central hole. They are often used to distribute loads over a wider area, such as when fastening thin materials or where a decorative or finished appearance is desired.
Copper washers are used for their excellent electrical conductivity and resistance to corrosion. They create reliable electrical connections and are ideal for applications requiring airtight seals.
Nord Lock Washers
Nord-Lock washers secure bolts with tension instead of friction. The system cannot loosen unintentionally as it creates a wedge-effect underneath the bolt head or nut. The system comprises a pair of wedge-lock washers with cams on one side and radial teeth on the opposite side. When the bolt is tightened, the teeth grip and seat the mating surfaces. The washers become locked into place.