Different Types of Washers and Their Application

A washer is a round piece of hardware essential for uniformly distributing the load from a screw or nut. These components not only alleviate friction but also help prevent corrosion and leaks.

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Washers can preserve tension, function as spacers, and are indispensable in numerous construction endeavors.

Choosing the proper washer type for your specific needs may prove more complex than anticipated. This guide will discuss the various washers and their suitable applications.

Understanding Washers

A washer is characterized as a thin plate featuring a circular hole at its center. They are mainly employed to distribute the weight of threaded fasteners, such as bolts or nuts.

In addition to providing load distribution, washers serve as spacers, springs, wear pads, pre-load indicators, locking devices, and vibration reducers.

Typically composed of either metal or plastic, high-quality bolted joints necessitate hardened steel washers to avert the loss of pre-load due to brinelling after torque application. Washers play a crucial role in mitigating galvanic corrosion, particularly by isolating steel screws from aluminum surfaces.

They could also be utilized in rotating applications as bearings. Thrust washers are utilized where rolling element bearings are unnecessary due to cost-performance constraints or spatial limitations.

Various coatings can reduce wear and friction, either by hardening the surface or acting as solid lubricants.

Types of Washers

There exists a wide range of washers suited for different applications.

• Structural Washer
• Belleville Washer
• Countersunk Washer
• Fender Washer
• Flat Washer
• Sealing Washer
• Slotted Washer
• Spherical Washer
• Split Lock Washer
• Tooth Lock Washer
• Wave Washer
• Torque Washer

#1. Structural Washer

Structural washers are robust, thick washers employed in demanding construction projects. For outdoor applications, they are generally coated or galvanized for enhanced corrosion resistance.

• The top bearing surface is angled to accommodate non-parallel surfaces
• Shape: Round or square
• Use: Leveling and shim applications

#2. Belleville Washer

Also known as conical spring washers or disc springs, Belleville washers have a unique conical shape allowing for axial loading both statically and dynamically.

The Belleville name traces back to the inventor Julien Belleville, who patented a spring design that laid the groundwork for these washers. Over the years, various profiles have been established with the most common being those featuring or lacking contact flats.

The slight dish shape with edges parallel to the centerline enhances elasticity.

Shape: Round

Application: Effective for projects involving thermal expansion, shock absorption, and maintaining tension under dynamic loads.

#3. Countersunk Washer

Countersunk washers function similarly to flat washers but provide a bearing surface for flat head screws. They also offer sealing functionality.

Often referred to as finishing washers, they have countersinks that secure the fastener head, resulting in a flush surface available in various shapes like 90-degree countersunk and flanged types.

• Allows flat or oval head countersunk screws to sit flush.
• Shape: Round
• Use: For a neat finished appearance

#4. Fender Washer

A fender washer is a flat washer with a larger outer diameter relative to its center hole. Made from thinner metal, they are designed to distribute load effectively on thin sheet metal. Common applications include plumbing, electrical work, and sheet metal.

Originating from automotive usage, these washers are particularly prevalent for mounting fenders, as they evenly distribute the load across a broader surface area.

• Enhanced outer diameter for a wider bearing surface.
• Shape: Round
• Used to alleviate force/stress and to cover oversized holes

#5. Flat Washer

Flat washers are crucial in protecting surfaces by evenly distributing torque when a bolt or screw is tightened. They prevent corrosion between steel screws and aluminum surfaces. Nylon washers can help reduce noise and abrasion while providing electrical insulation.

Commonly known as Type A plain washers, flat washers possess a standardized circular shape and centrally located holes, and they are available in both imperial and metric dimensions.

• Most widely used with two flat surfaces.
• Round or square Shape
• Used to distribute nut or bolt force/stress while reducing friction during installation

#6. Sealing Washer

Sealing washers, typically rubber or neoprene with options for metal backing, are placed on fasteners to curb water intrusion.

When installed for sealing purposes, sealing washers compress against flexible or rigid surfaces to effectively seal any environments, whether natural or industrial.

A tight fit against surfaces assists in sealing minor fastener diameters and surface imperfections.

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Sealing washers are typically circular seals made of annealed copper, aluminum, or fiber, used widely for creating seals on hydraulic couplings where pressure levels are not extreme.

#7. Slotted Washer

Slotted washers have a slot extending from the center to the perimeter, permitting removal, replacement, or insertion without detaching the fastener.

This design facilitates assembly and disassembly of bolted joints without completely removing bolts, nuts, and washer installations. They are often thicker for added strength.

#8. Spherical Washer

Spherical washers are engineered to create an exact parallel surface between the bolt head and nut face, adjusting for angular deviations to prevent bolt bending.

• Automatically compensates for angular discrepancies.
• Evenly distributes bolt tension.
• Minimizes bend fatigue in bolts.
• Enhances bolt stretching due to longer clamping length.
• Surface treatment for protection against humidity and harsh conditions.

#9. Split Lock Washer

Split lock washers utilize friction to hold bolted joints in place. Their split and twisted design create sharp edges.

Installed between the bolt head/nut and the mating surface, the joint gains additional tightness through standard tightening. Due to experimental evidence, split washers are recognized as ineffective as locking devices and may worsen self-loosening over time.

For lighter applications, they may suffice; however, utilizing tooth lock washers is advisable in more significant load scenarios due to their enhanced gripping design.

#10. Tooth Lock Washer

Tooth lock washers, also known for facilitating electrical contact, prevent loosing joints through friction. With either internal or external serrations, these washers bite into the mating surface upon tightening.

• External tooth lock washers feature a cylindrical inner diameter and are designed for use with wide-headed fasteners.
• Internal tooth lock washers have a cylindrical outer diameter intended for shallow-headed fasteners.

#11. Wave Washer

Wave washers, or coiled wave springs, absorb axial compressive loads and cushion stress. The wave structure provides multiple contact points for superior load-bearing capability.

Height and material thickness govern their load properties. Commonly used for thrust-loading applications where space is limited, wave washers help manage assembly tolerances and vibe-induced loosening.

• Available in carbon and stainless steel.
• Offered with various finishes like clear zinc, yellow zinc, and black oxide.
• Require lesser operating space compared to traditional coil springs.
• Distributes applied loads uniformly.
• Minimal sharp edge interference or galling.

#12. Torque Washer

Torque washers are designed specifically for soft materials where bolts may come loose over time. A prime example is softwoods, as environmental factors may induce significant warping.

To mitigate bolt loosening, torque washers employ:

• Four prongs that embed into the material, anchoring the bolt.
• Enhanced surface area contact between all interfacing components.
• Manufactured from a single metal sheet to prevent breakage.
• Square holes fitting carriage bolt square shanks.

Optimal Situations for Washer Utilization

Washers are particularly advantageous in two scenarios:

Firstly, when the bolt and nut assembly lacks adequate tightness, washers can increase spacing between the nut and the joining item, improving leverage and enabling a tighter joint.

Secondly, washers are essential for waterproofing assemblies at risk of leakage.

Employing Washers Effectively

The initial step in using washers is to ascertain the appropriate thickness. A thicker washer can enhance tightness, necessitating possibly multiple washers in some cases. For waterproofing functions, a thinner washer might be sufficient.

Carefully measuring washer size is critical. Incorrectly sized washers can adversely affect joint integrity. Greasing washers is also advised, which simplifies fastener placement and hinders corrosion.

Using washers is generally straightforward when these guidelines are adhered to, significantly contributing to secure assemblies and prolonged durability.

Related Posts

Nuts and bolts work in conjunction with washers to join components. Although the terms nuts and bolts might be interchanged, their functions differ significantly. This section will examine various types of each hardware piece, when to utilize them, and the fundamental principles of how they connect components.

Bolts possess a head with a driving surface, typically hexagonal for wrench compatibility, along with a cylindrical shaft running through the work pieces. The shaft is threaded but may feature an unthreaded section known as the shank, which alleviates shear or snap risks with load-bearing strength coming from this portion. The shank contributes to quicker and simpler installation of lengthier bolts.

In most assemblies, a washer is necessary—a thin, unthreaded component positioned onto the bolt shaft. Its role includes distributing connection load across a greater area and assisting in preventing fastener loosening upon installation.

The nut serves to draw the work pieces together along the bolt shaft. While nuts are threaded like bolts, they have internal threads allowing them to engage with the external threads of a compatible bolt. A nut designed for a specific bolt exhibits a matching driving surface (thus a hexagonal nut works with a hex-head bolt).

A typical use case for a combination of bolt, washer, and nut involves inserting a bolt into aligned holes in the work pieces and subsequently tightening the nut. As the nut is tightened, it compresses the components, drawing the washer against one element and the bolt head tightly against the other. It is often necessary to use two wrenches to hold the bolt head steady while tightening the nut.

To appropriately match a nut and washer to a bolt, it is essential to consider factors such as material, finish, size, and thread type.

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