Top 10 Questions Every Fastener Buyer Should Know

Fasteners come in all kinds of shapes, sizes, and finishes and each one can be used for a variety of applications. To help you navigate the complex world of specialty fasteners, we have put together a list of the most commonly asked questions from fastener buyers.

1. What is the difference between a bolt and a screw? 

This is a very common question, as the terms are often used interchangeably. In general, bolts are intended to be used with a nut to fasten two components together, while screws are designed to thread into a tapped hole. However, a screw can be used as a bolt with a nut, while a bolt may not always be suitable as a screw. The distinction lies in their intended use and manufacturing tolerances.

2. What are the most common fastener materials and finishes? 

Fasteners are typically made from various materials, including steel, stainless steel, and aluminum, each with different strength and corrosion resistance properties. They also come in various finishes, such as zinc plating, hot-dip galvanizing, and PTFE coatings, which provide additional protection against corrosion.

3. What is the difference between coarse and fine threads? 

Understanding thread series is crucial, as it influences the fastener's strength, assembly process, and resistance to loosening. Coarse threads (UNC) have fewer threads per inch than fine threads (UNF), making them suitable for rapid assembly in construction due to their resistance to damage and compatibility with thicker coatings. Fine threads, however, are preferred in applications demanding strength and vibration resistance, like automotive and machinery.

4. What are the different types of mechanical anchors and when should I use them? 

Mechanical anchors are used to connect materials to concrete and masonry. The provided sources highlight several types, including wedge anchors, sleeve anchors, masonry screws, screw bolts, drop-in anchors, and Sammy's®. Each type has specific applications and benefits, and understanding their differences is crucial for making the right choice. For example, drop-in anchors require a separate setting tool for installation.

5. What is the significance of grade markings on fasteners? 

Grade markings indicate the tensile strength of a fastener. For instance, SAE Grade 5 fasteners have three radial lines on the head, while Grade 8 fasteners have six radial lines. Metric fasteners use property classes like 8.8, 10.9, and 12.9, directly indicating the tensile strength in megapascals (MPa).

6. What type of nut should I use with a particular bolt? 

Choosing the correct nut for a bolt is vital for ensuring a secure and reliable connection. The sources emphasize nut compatibility, highlighting that specific nut grades are designed for particular bolt grades. For example, ASTM A193 Grade B7 studs should always be paired with A194 Grade 2H heavy hex nuts.

7. How do I determine the correct length of an all-thread stud? 

There are two ways to measure the length of an all-thread stud: overall length and first thread to first thread. Continuous thread studs are measured from extreme end to extreme end, including the chamfer, while flange type studs are measured from the first fully formed thread to the next to last fully formed thread, excluding the chamfer.

8. What are Rivnuts, and how are they used? 

Rivnuts, also known as rivet nuts, are threaded inserts installed into thin materials to provide a strong threaded connection point. They are typically used in applications where access is limited to one side of the material, such as paneling in truck trailers.

9. What is a structural bolt? 

Structural bolts are heavy hex bolts with a full body diameter and a shorter thread length than a standard hex bolt.

10. What is an anchor bolt? 

Anchor bolts usually secure a steel structure to concrete.  One end is submerged in concrete while the threaded portion is above the surface. Available anchor bolt grades are typically 35, 55 and 105.

Big Bolt Has Big Inventory

Do you have an upcoming project but aren't sure what type and quality of fasteners you should use? Well, Big Bolt has you covered! We can manufacture specialty fasteners or let you pick from our large inventory. We are also equipped to rush-manufacture and customize different products upon request to meet your schedule and ensure your project succeeds. Get in touch with us today to get a quote.