Choosing the Right Fasteners

Mechanical fasteners come in many standard and custom varieties. These are the most common types:

• Bolts: Bolts come in many designs and are used to hold threaded components together. Double-end bolts, eye bolts, and carriage bolts are just a few common bolt kinds. Each type of bolt features threads and is typically used with a nut to hold components firmly in place.
• Screws: Screws are a durable tool for achieving excellent holding power. Like bolts, screws feature a threaded end; however, they do not require a nut or other component to hold them in place.
• Nuts: Nuts are threaded onto bolts to create a strong connection between components. They come in several designs, such as cap nuts, castle nuts, and weld nuts.
• Washers: These flat, circular discs are used with nuts and bolts to protect components from friction. They can isolate components, prevent leaks, and maintain tightness even when exposed to vibrations.
• Rivets: Typically installed using a rivet gun, rivets are a type of permanent fastener that protects components from shearing forces. Each end of a rivet has a head to support axial loads.

While fasteners are just a small component within a larger assembly, they play an important role in how products function and hold together over time. In fact, selecting the wrong fastener material or design can lead to a product not performing correctly or experiencing a shortened operating life. Each type of fastener comes in several design subtypes and material options that need to be matched carefully to your intended application.

It’s important to identify the right solution for each project to prevent costly product redesigns. Since fasteners not only hold assemblies together but also protect them against vibration, quality should be a more important consideration than cost. To ensure reliability, fasteners should be at least the same quality as the products they’re used with.

There are many factors involved in fastener selection. The most suitable type depends on the end-use environment, required strength, size, and other considerations. Follow the steps below to better understand your needs and match them to the right fasteners.

1. Know How the Fastener Is Being Used

When selecting the most suitable fastener for your project, consider how your product will be used. Fasteners that must frequently open and close should be made from durable metal materials. In applications involving less wear and little to no vibrations, a lower-priced plastic fastener may be suitable.

Another factor is durability. Different types of fasteners can withstand varying levels of torque. Know the weight of your product’s mating components so that your chosen fasteners can hold them together properly. You’ll also need to ensure the fasteners and their respective threads are appropriately sized for your project’s load. These considerations will ensure your end product is durable and operates safely.

2. Consider the Fastener’s Operating Environment

Environmental factors play a large role in fastener selection. Unlike products for indoor applications, products that will be used outdoors require more durable and robust components that can withstand UV light, temperature changes, and other corrosive conditions. It’s important to note any other application-specific conditions your fasteners will need to endure, such as saltwater exposure, high levels of vibration, or extreme temperatures.

For example, 18-8 stainless steel (8% nickel, 18% chromium) will corrode in saltwater environments and quickly lose integrity. Products exposed to saltwater should be constructed from 316 stainless steel to better prevent rust. If extreme temperatures are involved in your project, you’ll want to select a material that will not significantly expand or contract.

Fastener expansion or contraction, as well as vibration, can all result in loose connections over time. If your fasteners will be used in high-vibration areas, implement a specialized solution, like a prevailing torque locknut. Our team can always advise you on the best types of metal fasteners for challenging applications.

3. Select the Proper Material

Fastener material plays a crucial role not only in your project’s cost but also in its strength and durability. Understanding where a fastener will be used and what role it will play are the biggest factors in material selection. Some of the most common fastener materials include:

• Aluminum: A lightweight, corrosion-resistant material that’s also cost-effective.
• Brass: Highly corrosion-resistant, yet softer than steel and bronze.
• Bronze: Performs better than stainless steel in corrosive marine applications but is more costly.
• Steel: Offers high tensile strength and excellent durability. Stainless steel, carbon steel, and alloy steel are common choices for fasteners.
• Nylon: This lightweight, cost-effective material is ideal for nonconductive applications.

Each of these material options has multiple grade options to choose from, allowing for highly specialized material selection. The material you choose can be further tailored to your needs with plating services. Black nitrate and black oxide are common plating options for fasteners used within the gun and agriculture industries, as these treatments help prevent corrosion.

4. Size Your Fastener

Where and how your fasteners will be used plays an important role in the size you’ll require. For example, heavy-duty applications typically require large, durable fasteners. Small products, on the other hand, have tighter spaces that require more compact fasteners.

For every application, there is a wide range of standard sizes. Metric bolts come in sizes that range from M5 to M30, and hole sizes range from just 5.5 mm to 32 mm. Some of the smallest standard-sized bolts are used in eyeglass frames, while the largest can weigh up to 15 lbs and are used in wind turbines. No matter what size fastener your project requires, we can deliver what you need, including custom options from our global sourcing network.

5. Determine Your Fastener Type

Among the various fastener categories and subcategories, a multitude of choices are available. For example, if your project requires a screw, you’ll have to further identify the most suitable head type: flat, oval, hex, pan, truss, socket, or button. There is also an equally diverse variety of nuts, bolts, rivets, rods, pins, clips, and other fasteners.

How your fastener will be used, what materials your project involves, and where your fastener will fit into your overall product design are key factors that influence the selection process. For many applications, you’ll find an in-stock, off-the-shelf option that meets your needs. More demanding projects may require custom fastener design. While off-the-shelf options are more cost-effective, a custom design will ensure all your project-specific requirements are met.

With the many types of fasteners available, identifying the right products can be overwhelming. With Associated Fastening Products, Inc., you can be certain you’ll find the ideal solution for your needs. In addition to our comprehensive catalog of standard products, we also specialize in sourcing hard-to-find components and developing quality custom solutions. To discuss your needs, reach out to our team or request a quote today.