The Complete Guide on Hexagonal Bolts
Hexagonal bolts, commonly called hex bolts, are among the most widely used fasteners in construction, engineering, and industrial applications. Their six-sided head design allows for easy wrenching, making them a preferred choice for assembling metal, wood, and composite materials. Available in a variety of materials, including stainless steel, high-tensile steel, and brass, hex bolts provide strong and secure fastening solutions. They are often used in conjunction with hex nuts and washers to ensure stability in structural frameworks, machinery, and vehicle assemblies.
Hexagonal Bolt Head Sizes
Hex bolts are manufactured in both metric and imperial sizes to suit different applications. Hexagonal bolt head sizes are determined by three key measurements: the diameter, thread pitch (for metric) thread per inch (for imperial), and length. Common metric sizes range from M5 to M64, with diameters measured in millimetres, while imperial hexagonal bolt head sizes are measured in inches and include sizes such as ¼”, ⅜”, ½”, and ¾”. The length of a hex bolt is measured from the underside of the head to the end of the threaded portion, ensuring accurate fitting based on the required fastening depth.
Hexagonal Head Bolt Dimensions
Hexagonal head bolt dimensions conform to specific standards to ensure compatibility across industries. The most recognised standards for hex bolts include DIN 931 / ISO 4014 (partially threaded) and DIN 933 / ISO 4017 (fully threaded) for metric bolts, while imperial versions follow ASME B18.2.1. The width across flats (AF) – the distance between opposite faces of the hex head – varies based on diameter, with an M10 bolt typically having a 17mm AF measurement and an M16 bolt having a 24mm AF measurement. Additionally, the head height is proportional to the bolt size, ensuring an optimal wrench grip for tightening.
Hexagonal Bolt Specifications
Hex bolts are classified based on material composition and strength grades. In metric fasteners, common strength grades include 8.8, 10.9, and 12.9, with higher numbers indicating greater tensile strength. For example, an 8.8-grade hex bolt is made from medium-carbon steel and is heat-treated for improved durability, while a 12.9-grade bolt is alloy steel, capable of withstanding extreme loads. Stainless steel variants such as A2-70 and A4-80 offer excellent corrosion resistance, making them ideal for marine and outdoor environments. In the imperial system, hex bolts are graded using markings such as Grade 2, Grade 5, and Grade 8, with Grade 8 being the strongest, often used in automotive and heavy-duty applications.
Understanding the flexibility and strength of fasteners, sizes, dimensions, and specifications of hexagonal bolts is essential when selecting the right fastener for your project. Whether used in machinery, construction, or general engineering, choosing the correct hex bolt ensures structural integrity and long-term performance. Dinstock is a trusted supplier of high-quality industrial fasteners, specialising in precision-engineered solutions for various sectors. With an extensive range of products, including hexagonal bolts, we provide reliable fastening solutions that meet industry standards for strength and durability. If you’re looking for the right hex bolts for your project, get in touch with us today to discuss your requirements.
