Figure 1: A complete guide on fasteners. Source: National Bolt & Nut Corporation

All fasteners perform the same function — mechanically joining and securing two or more parts together. However, differences in type, quality, shape and material significantly influence the fastener’s performance and service life. Understanding the functional varieties of the different types available, including nuts, bolts and washers, is essential to selecting the appropriate fastener (and fastener supplier) for a project.

The following guide outlines a small selection of the types of fasteners available in National Bolt & Nut Corporation’s total inventory to help customers choose the optimal product for their fastening application.

Types of fasteners

Bolts

Bolts are one of the most versatile structural fasteners, available in a vast array of configurations to suit different materials and strength requirements. These fasteners differ primarily in thread specification, length and head shape, with varying combinations of these characteristics resulting in bolts with different functions. They typically require a drilled hole and a complementary nut, or tapped mating part for installation, and, unlike screws, they are generally not tapered. The terminology distinguishing between the types of bolts is often inconsistent and incorrectly used interchangeably for screws, so it’s best to select bolts based on project specifications rather than the exact name indicated on a supplier’s website.

Some of the types of bolts manufactured at National Bolt & Nut Corporation include:

• Carriage bolts: Carriage bolts feature a domed or countersunk head with a square underside that prevents turning post-installation. They are often used with wood and masonry.
• Flange bolts: Flange bolts are a specialized type of hex head bolt that has an integrated flange that serves as a washer component to more evenly distribute the load.
• Plow bolts: Like carriage bolts, some plow bolts have a square-shaped countersunk top. Others have a domed design. These bolts are ideal for heavy-duty applications like industrial machinery.
• Hex head bolts/hex head cap screw: Characterized by their hexagonal head shape, hex head bolts are a broader category of bolts that requires installation with a wrench. They are available in many lengths and threading varieties. Hex head cap screws have tighter tolerances and are the most common hex bolt category.
• Square head bolts: Like hex head bolts, square head bolts are defined by their head shape — i.e., square. This head design facilitates tooling gripping, allowing for easier installation.
• Socket head cap screws/Allen bolt: Socket head cap screws have a flat chamfered top surface with a smooth or knurled cylindrical sides. Forged heat-treated alloy examples are high strength fasteners intended for the most demanding mechanical applications, with special alloy formulations.
• Additional bolt types: The other bolt types that the company can custom manufacture include anchor, belt (e.g., eye, hook, J and U), countersunk, lag and T-handle bolts.

Types of nuts

Figure 2: Nuts are available in a variety of shapes, sizes and materials. Source: National Bolt & Nut Corporation

Nuts are available in a variety of shapes, sizes, materials and thread patterns. While selection of a nut is somewhat constrained by the choice of bolt—particularly in terms of size and threading — users still should select the nut head shape and material that is most suitable for their application.

• Coupling nuts: A coupling nut is a longer, cylindrical nut that joins two male threads. This component can be used to add length to an installation.
• Flange nuts: Similar to flange bolts, flange nuts feature a round flange that acts as an external washer and allows for a more even load distribution.
• Hex nuts: Hex nuts are hexagonally shaped. These nuts are extremely versatile but require a wrench for installation. The types of hex nuts that the National Bolt & Nut Corporation supplies include finished hex, semi-finished hex, hex flange, hex jam, heavy hex and slotted hex.
• Lock nuts: Lock nuts are available in a range of shapes and are used to secure other nuts and prevent them from loosening. Types of lock nuts include all metal lock nuts with top or side locking features, serrated hex flange, and nylon inserts.
• Slotted nuts: Slotted nuts are designed and constructed such that they can form a locking mechanism with a cotter pin or a safety wire.
• Square nuts: Square nuts are characterized by their square shape. This head shape increases the surface area of the fastener and the amount of friction it experiences, reducing the risk of it loosening.

• Wheel nuts: Wheel nuts are a broad category of nuts that are used in automotive wheel applications.
• Additional nut types: The other nut types that the company can custom manufacture include cap, castle, conical, Keps, thumb and wing.

Types of washers

Figure 3: Washers are disk-shaped components that provide enhanced control over locking and friction when used with other fasteners. Source: National Bolt & Nut Corporation

Washers are disk-shaped components that provide enhanced control over locking and friction when used with other fasteners. These fasteners may also feature teeth, indentations and other unique structural mechanisms for use in more specialized applications. In general, they serve a variety of functions, including preventing loosening of the fastener assembly, protecting the surface under a fastener and distributing the pressure more evenly during installation and use.

Compared to nuts and bolts, washers have much fewer variants available. However, among the washer types, there remain important distinctions. Like nuts, washers should be complementary to the selected bolt and chosen to suit the user’s unique fastening application.

• Beveled washers: Beveled washers are formed with a slightly angled surface, allowing them to join materials that are not parallel to one another.
• Flat washers: Flat washers are the most common type of washer. They provide a larger surface area for better load distribution. Different thicknesses are available for a variety of hold strengths.
• Lock washers: Lock washers come in many shapes, such as helices, toothed rings, conical or spring, each designed to prevent slippage of fasteners in demanding applications. They are commonly used in environments that experience high levels of vibration.
• Structural washers: Structural washers are one of the most heavy-duty washer options available. These thick fasteners are designed to withstand the high load pressures of construction.

Other fasteners

In addition to these three types of fasteners, National Bolt & Nut Corporation offers other fasteners, such as dowels, hose and shaft couplings, nails, pins, rivets, rods, screws, shackles, and studs— as both stock and custom fastening solutions.

Figure 4: National Bolt & Nut Corporation offers other fasteners, such as dowels, hose and shaft couplings, nails, pins, rivets, rods, screws, shackles, and studs— as both stock and custom fastening solutions. Source: National Bolt & Nut Corporation

Figure 5: Washers: National Bolt & Nut Corporation

National Bolt & Nut Corporation suggests that customers consult with an engineer to best identify which fasteners to call out in a specific application. There are many factors to consider when selecting a fastener. Other important considerations include understanding how individual fasteners work together to form a joint, use cases, thread patterns, and material and finishing options, employing an engineer will save money and headache in the long run.

Right-handed versus left-handed thread patterns

Many fasteners, including nuts and bolts, feature threads to facilitate their fastening function. Threads are available in both right-handed and left-handed patterns. Although most applications use right-handed (i.e., clockwise running) threads, special circumstances require left-handed (i.e., counterclockwise running) threads to resist forces that would otherwise loosen the fastener.

Fastener material selection and plating guide

Fasteners are available in a wide range of materials and finishes. Choosing the right material and material finish for a fastening application is as essential as selecting the proper type, size and shape.

The most common fastener materials are aluminum, carbon steel and other alloys. However, manufacturers also use alternative materials, such as brass and plastic, for fasteners intended for specialized applications. For instance, silicone bronze is appropriate for aquatic environments.

Finishing options are also available to improve aesthetic or functional properties, such as increasing material strength or corrosion resistance. Some of the types of finishing that the company provides include black oxide, hot dip galvanizing, zinc plating and chrome plating, to name a few of the many plating options that are available.

Figure 6: Fasteners are available in a wide range of materials and finishes. Source: National Bolt & Nut Corporation

National Bolt & Nut Corporation

Your source for quality fasteners

National Bolt & Nut Corporation’s experience allows them to offer high-quality products and services to meet the fastener needs of a diverse set of industrial clients. They serve industries ranging from construction and transportation to alternative energy and mining, in each case, meeting and exceeding customer requirements. The company prides itself on offering a full range of stock and custom fasteners that provide durability and high performance at competitive prices.

National Bolt & Nut Corporation is a woman owned ISO 9001:2015 manufacturer and distributor of custom non-standard and standard fasteners. They have been supplying quality fasteners since 1996 and guarantee all of their products. Providing full certs and traceability to ensure customer peace of mind, National Bolt & Nut Corporation offers warehouse and release options spread out over 12 months, giving customers complete control over their ever changing release schedules. Eliminate future line down situations with all necessary fasteners “complete on the shelf awaiting your release.”

To learn more about their standard and custom fastener products and how they can benefit future projects, contact National Bolt & Nut Corporation or request a quote today.