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Nuts and Washers

Nuts and Washers
Nuts and washers may seem like small, simple components, but these little pieces of hardware can be an integral part of many different fastening applications. Once you take a look at the large variety of nut and washer types, you will be amazed at all your options. In most cases, making a selection is simply a matter of determining what function you need them to perform and choosing accordingly. Therefore, it is helpful to know a little bit about the different types available so you can find the right fit for your next project. Consider the following questions as you contemplate which nuts and washers to purchase:
        • What types of nuts are available?
        • What types of washers are available?
        • What is the function of each?
        • What materials can nuts and washers be made from?
        • How are they sized?

Uses, Materials, Nuts and Washers

Generally speaking, nuts are used to secure a bolt or screw while washers distribute pressure, relieve friction and prevent leaks. Not every nut and washer is appropriate for every situation, however. Some are designed to excel at different activities. Flat washers, for instance, are good for general use, but finishing washers are best used for ornamental effects with flat or round screw heads. Both nuts and washers can be made from an array of metal and nonmetallic materials, and each are sized in both U.S. and metric measurements. In most cases, you’ll need tools to secure them, but some pieces, such as wing nuts, can be twisted into place with your bare hands.
Uses and Materials: Nuts feature threaded holes and perform the relatively simple function of keeping a bolt or screw in place. Just as there are a large number of different bolts and screws, there are many nuts to match. Some are best used for clamping applications, some are designed for marine use and others can be used to join lengths of threaded rods together. Washers are thin disks that can be used to support loads and evenly distribute stress created by fasteners. They can also be used as a spacer, spring, wear pad or locking device.
          • Nuts are made from brass, stainless steel, zinc-plated steel, silicon bronze, chrome and more
          • Hexagonal nuts are the most frequently used type
          • Washers help prevent galvanic corrosion by insulating screws          
          • Washers may be made of metallic materials including aluminum, brass, copper, bronze or stainless steel, 
             or nonmetals, including ABS, leather, nylon, PVC and rubber
Nut Types: When it comes to purchasing nuts, the best way to make sure you have the right one for the job is to check and see if its classification matches the screw or bolt you’re using. Specialty hardware may not be as easily classified, but many pieces will be marked to indicate their grade. Consult the chart below to learn more about the different types of nuts available:
Nut Type Description Applications
Acorn • Features a pointed top • Covers protruding fasteners
Cap • Features a rounded top • Covers protruding fasteners
Coupling • Long and slender • Joins together lengths of threaded rods
Hex • Available in a wide range of sizes • General uses Clamping and joining
Knurled • Round, textured exterior allows for
  easy gripping
• Attaching diffuser shields on electrical fixtures

• Available in different types

• Nylon-insert locking nuts feature a 
  nylon interference washer

• Prevents bolts from loosening under vibration
Machine Screw • Used with smaller screws • Secures and joins machine screws
Serrated Flange • Features a built-in washer • Combines the qualities of a locking nut and a hex
Speed • Thin and flat • Secures fasteners where there is low clearance
Square • Square-shaped • General applications
T • Features three sharp prongs with
  short barrel lengths
• Fastens wood, particle board and composite
  materials to leave a flush surface
Tensilock • Features ratchet teeth inside the
• Distributes loads during fastening Holds tightly
  under vibration
Wing • Features wings that allow you to twist
  it by hand
• Easy-on, easy-off fastenings

Washer Types: Some washers can be used for general tasks while others are used for more specific applications. SAE washers, for instance, are approved by the Society of Automotive Engineers for use on automobiles. Washers are also a key component in boatbuilding. Most washers have a constant thickness, but some, like spring washers, feature an open construction that allows the thickness to vary. The chart below provides details on some commonly used washers:
Washer Type Description Applications
Bonded • Provide a low-profile
• Used in conjunction with a gasket
Countersunk • Available in a number of
  shapes, including angle,
  flanged, 90° and more
• Removes the need to drill a countersunk hole with
  flat-or oval-head screws
Dock • Has a larger outside
  diameter and thickness
• Distributes force evenly
Fender • Has a large outside diameter • Covers large and oddly sized holes
Fiber • Made of vulcanized fiber • Used in conjunction with an insulating washer or
Finishing • Available in brass and stainless
• Provides a finished look with round or flat screw
Flat • May be regular or high strength • General uses Prevents marring of surfaces
Lock • Provides spring action
• May have a high collar
• Prevents loosening due to vibration
Machinery Bushings • May be made of flexible,
  nonmetallic material
• Takes up slack between machinery parts
Rubber • Made of hard rubber • Sealing
SAE • Has a small outside diameter • Automotive
Spiral Split • Often used in conjunction with a
  flat washer
• Locking
Spring • May be helical or conical • Increases elastic properties of a joint
Tension • Made of spring steel • Eliminates rattles, side play and lost motion in
• Connects levers and gear shift rods
Tooth Lock • Teeth may be internal or
• Bites into surface to lock into place



Gaskets: While washers can sometimes function in a similar manner, gaskets are ideally suited for sealing areas where there is a possibility of gas or liquid leakage.
Single-Thread Nuts: These nuts can be used in lieu of multiple-thread nuts for lighter-duty applications. They require less torque and reduce the number of parts you’ll need, making jobs faster and less complicated.
Kits: Nuts and washers are often available in kits that provide large numbers of several different types of each. These kits can be ideal for general-purpose home improvement needs.