Types of Nuts and Bolts – Head Styles, Threads, Materials & Industrial Applications

Introduction

Nuts and bolts are the backbone of modern fastening systems, essential in everything from small appliances to large-scale infrastructure. Understanding the types of nuts and bolts used in different industries helps engineers, suppliers, and end-users make the right selection based on performance, material, and budget.

Common Bolt Head Types

• Hex Bolt (Hexagonal Bolt): Standard six-sided head used in mechanical and structural applications.
• Carriage Bolt: Smooth domed head with a square neck for wood and metal fastening.
• Socket Head Cap Bolt: Used in high-torque, low-clearance areas, fastened with Allen keys.
• Flange Bolt: Includes a built-in washer flange beneath the head for better load distribution.
• Eye Bolt: Has a looped head for lifting or anchoring.

Types of Nuts

• Hex Nut: Most common; used with all standard bolts.
• Wing Nut: Easy to tighten/loosen by hand without tools. Ideal for temporary assemblies.
• T-Nut: Used in wood, has a flat base with prongs for hammering into material.
• Flange Nut: Integrated flange acts like a washer to spread load and resist loosening.
• Square Nut: Traditional four-sided design for tight grips in old or heavy-duty assemblies.
• Self Locking Nut: Includes nylon inserts or deformed threads to resist loosening from vibration.
• Cap Nut: Aesthetic nut with a dome that protects the bolt threads.

Specialty Nut & Bolt Types

• Coupling Nut Bolt: Used to join two threaded rods together, often in extension or tension applications.
• Stud Bolt: A threaded rod with no head, used with two nuts. Common in flanges and pressure systems.
• Flange Nut Bolt: Combines a flange on the nut and the bolt for better torque transfer and resistance.
• Square Nut Bolt: Ideal for grip-heavy applications with square-headed bolts for mechanical advantage.

4Thread Types & Standards

Threads define the compatibility and load-bearing ability of a nut-bolt pair. Standard thread types include:

• Unified National Thread (UNC/UNF): Used mostly in the US and mechanical components.
• Metric Thread: ISO standard (M4, M6, M8, etc.) used globally in automotive, manufacturing, and heavy equipment.
• Acme Threads: Wide flat threads for linear motion and load applications (like in vises and jacks).
• Left-Hand Thread: Tightens counterclockwise; used in reverse force applications (like gas cylinders).

Nut & Bolt Material Types

Industrial Applications by Type

• Automobile Industry: Uses high-strength metric bolts and flange nuts with locking threads.
• Construction: Structural hex bolts, GI nuts, and anchor bolts for steel frame connections.
• Electrical Equipment: Small M4 to M10 bolts with washers and nuts for terminal fixtures.
• Woodworking: T-nuts, carriage bolts, and wing nuts for furniture assembly and support beams.

Download PDF Reference

Want a quick reference? Download our full PDF guide covering types, materials, sizes, and pricing.

FAQs – Types of Nuts and Bolts

Q. What is the difference between a nut and a bolt?

A bolt is a threaded fastener with a head, used with a nut to secure objects. The nut is internally threaded to fit over the bolt.

Q. Which types of nuts are best for vibration resistance?

Self-locking nuts (nylock or distorted thread) are ideal for vibration-heavy environments like engines and machines.

Q. Can I reuse nuts and bolts?

Most can be reused if not damaged, but critical load-bearing fasteners (like flange bolts) should be replaced to avoid failure.

Q. What is a coupling nut used for?

It connects two threaded rods or bolts, often used in tension systems or to extend threads.

Related Pages

• Nut Bolt Price Per KG – Updated Market Rates
• Nut Bolt Manufacturers in India – Verified 2025 List
• Nut Bolt Size Chart – All mm & Inch Dimensions

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