Hex Bolts

A hex bolt is a threaded fastener with a six-sided (hexagonal) head designed for tightening with a spanner, socket, or wrench. Also referred to as a hexagonal bolt, hexagon bolt, hex head bolt, or hex bolt screw, these fasteners are widely used across machinery, construction, automotive, and general assembly work.

At RS Philippines, you will find hex bolts in fully threaded, partially threaded, and flanged configurations across multiple materials, grades, and sizes.

What is a Hex Bolt?

A hex bolt is a mechanical fastener with an external hexagonal head and a threaded shaft. It is typically used to join components by passing through pre-drilled holes and securing them with a nut, or by threading directly into a tapped hole. The six-sided head of a hexagonal bolt allows secure tightening from multiple angles using standard spanners, wrenches, or socket tools, providing secure and repeatable tightening for structural and mechanical assemblies.

A hex screw, or hex head screw, usually refers to a fastener manufactured to tighter tolerances and often fully threaded, commonly used in tapped holes. Their names vary across suppliers and applications, so check the thread length and installation method against the product specification before ordering.

How Hex Bolts Work

A hex bolt secures two or more components through a simple mechanical process:

• Clamping Force Generation: When tightened, the bolt applies tensile force along its shank, creating a clamping force between joined components that holds the assembly together.
• Thread Engagement: The mating threads between the bolt and nut (or tapped hole) convert rotational torque into axial force, securing the joint.
• Load Distribution: The bolt head and any washers distribute compressive load across the joint surface, reducing local stress concentrations.
• Joint Integrity: Proper tightening ensures sufficient preload to resist loosening under vibration and operational loads.

Uses of Hex Bolts

A hex bolt or hex bolt screw can be used with a nut, in a tapped hole, and tightened using a hex key or wrench. Common applications include:

• Construction and Structures: A hex bolt is used to fasten beams, columns, brackets, frames, and structural supports in bridges, buildings, and road infrastructure.
• Machinery and Equipment: Hex head bolt applications include securing base plates, housings, guards, and mechanical joints in industrial equipment and production line assemblies.
• Automotive and Maintenance: Hex bolt screws are used in engine assembly, chassis connections, body panels, and general workshop repair and mounting work.
• Furniture and Fixtures: Where a strong, serviceable fastener is needed in place of smaller screws, hex bolts provide reliable clamping force in furniture frames and fixture installations.
• General Fabrication: Hex bolts are suitable for metal-to-metal and wood-to-metal assemblies requiring nuts, washers, and through-bolt connections.

Materials Used for Hex Bolts

The material of a hex bolt directly affects its strength, corrosion resistance, and suitability for a given environment. Never substitute a hex head bolt without first checking if the replacement meets the original specification requirements. Common options include:

• Steel: The most widely used hex bolt material, this is available in strength classes such as 8.8, 10.9, and 12.9 (as defined by ISO standards). Higher grade numbers indicate greater tensile strength, and plain steel may require a coating or plating for corrosion resistance in exposed environments.
• Stainless Steel: These are available in A2 (304) for general outdoor and humid environments, and A4 (316) for higher corrosion resistance in marine, chemical, or washdown applications. A4 includes added molybdenum for better resistance to chloride attack.
• Zinc-Plated Steel: Carbon steel bolts with zinc coating provide moderate corrosion protection for indoor or dry environments. The coating reduces oxidation but is less suitable for highly corrosive conditions. It also has moderate anti-corrosive properties without the higher cost of stainless steel hex head bolts.
• Brass: This is a copper-zinc alloy that offers good corrosion resistance and electrical conductivity. It’s used in applications where non-magnetic or non-ferrous fasteners are required.

Types of Hex Bolts and Hex Head Screws

Hex fasteners are available in various configurations, such as:

• Partially Threaded Hex Bolts: Featuring an unthreaded shank beneath the head, these hex screws improve alignment and increase shear strength in connections that experience lateral forces. They are best suited to assemblies where the smooth section needs to pass through clearance holes in mating parts.
• Fully Threaded Hex Bolts (Hex Screw): Threads run the entire length of the shaft, providing consistent grip and thread engagement at any fastening depth. A fully threaded hex bolt screw is commonly used where the bolt threads into a tapped hole or where grip length varies across applications.
• Hex Head Cap Screws: These are hex head screws that are manufactured to tighter tolerances (e.g. ISO 4017, DIN 931/933) than standard hex bolts, with a washer face under the head for better load distribution. These are used in precision mechanical assemblies and tapped hole applications.
• Flanged Hex Bolts: An integrated washer-like flange beneath the head distributes clamping load over a wider surface area, removing the need for a separate washer and making them well suited to vibration-prone assemblies.
• Stainless Steel Hex Head Bolts: Available in A2 and A4 grades, these stainless steel hex head bolts are the ideal choice when corrosion resistance is a priority in outdoor, humid, or chemically exposed environments.

How to Choose the Right Hex Bolt?

Selecting the correct hex bolt for your application involves matching several key parameters:

• Size and Thread: Match diameter, length, and thread pitch exactly to the nut, tapped hole, or mating component to ensure proper fit and load distribution.
• Material and Coating: Use steel for general-purpose strength and choose stainless steel hex head bolts for outdoor, humid, or corrosive environments.
• Strength Class: Choose the appropriate strength class (e.g. 8.8, 10.9) based on load requirements and safety factors. Using an incorrect grade can result in insufficient strength or unnecessary cost.
• Thread Type and Length: Use partially threaded bolts where shank alignment and shear resistance matter. Use fully threaded bolts where full thread engagement along the grip length is required.
• Access and Tool Clearance: Ensure that there’s sufficient clearance for a wrench, spanner, or socket to tighten the hex bolt properly.
• Washers and Nuts: Use compatible washers and nuts where required to distribute load and prevent loosening.
• Budget: Compare hex bolts prices across material, grade, and size to find the ideal product for your budget.

Hex Bolt Installation Tips

Follow these practical steps to ensure a secure and reliable hex bolt installation:

• Use Correct Tools: Always use the correct socket or spanner size to ensure proper engagement with the hex head bolt. Incorrect tools can round the corners and reduce tightening effectiveness.
• Tighten Evenly: For assemblies with multiple hex bolts, tighten gradually in a cross or sequential pattern to distribute clamping force evenly across the joint.
• Avoid Over-Tightening: Excess torque can strip threads on the hex screw or damage mating components. Use a torque wrench where specified torque values apply.
• Check Thread Engagement: Ensure enough threads are engaged in the nut or tapped hole before applying full torque.
• Inspect Before Use: Replace any hex bolt showing signs of corrosion, damage, or deformation before installation.

Why Buy Hex Bolts from RS Philippines?

RS Philippines offers hex bolts in various sizes, materials, thread types, and finishes from trusted brands including RS PRO, ABB, and Parker. Browse steel, stainless steel hex head bolts, zinc-plated, and brass options by grade, diameter, thread pitch, and length. You will always find the ideal product at reasonable prices.

While at it, add complementary products such as hex nut drivers to your order and enjoy fast delivery across the Philippines. For delivery details, check out our Delivery page.