Hex Head Cap Screws: Why Do You Need Them?
When you need a lot of holding power and the ability to apply high torque, hex head cap screws give you the strength and reliability for heavy-duty applications.
These types of screws handle the toughest jobs in construction, manufacturing, mining, and machinery where standard fasteners fall short.
Here's everything you need to know about hex head cap screws: what they are, different types, what industries use them, and how to choose the right screws for your project.
What Is a Hex Head Cap Screw?
A hex head cap screw is a threaded fastener with a six-sided head and chamfered point, built for high-torque applications. The hex head gives you a solid grip for your wrench or socket, allowing you to apply the force needed to create secure connections in demanding environments.
Many other screws need a nut on the receiving end, but hex cap screws thread directly into tapped holes or nuts, depending on your application.
You tighten them by turning the head itself, which makes installation straightforward when you have the right tools.
You'll find these screws throughout construction sites, manufacturing facilities, mining operations, crane work, industrial applications, and machine parts where components need to stay locked together under stress, vibration, and heavy loads.
Types of Hex Head Cap Screws
Hex head cap screws come in multiple grades and materials to match different strength requirements and environmental conditions:
Standard Grades
Grade 2 (plain, plated, galvanized)
Grade 5 (plain, clear zinc plated)
Grade 8 (plain, clear zinc plated, zinc yellow plated)
Grade 9 (zinc yellow plated)
Metric Grades
8.8 (plain, clear zinc plated)
10.9 (plain, clear zinc plated, zinc yellow plated)
12.9 (plain, clear zinc plated, zinc yellow plated)
Specialty Materials
Stainless steel (18-8, 316, and special grades)
Silicon bronze
Brass
Aluminum
Structural Applications
A325 (plain and galvanized)
A490 (plain and galvanized)
Each grade and material has different strength levels and corrosion resistance to handle different job requirements, depending on what you need.
Learn more about self-tapping vs self-drilling screws.
What Industries Use Hex Head Cap Screws?
The following industries use hex head cap screws:
Automotive: Engine assemblies, transmission mounts, chassis connections, and suspension components all rely on hex head cap screws for secure, high-torque fastening.
Construction: Structural steel connections, heavy equipment mounting, and framework assembly require the strength these screws provide.
Mining Industry: Underground and surface mining equipment operates in harsh conditions with extreme vibration and stress, so they need hex head cap screws.
Crane Industry: Boom connections, counterweight mounting, and structural joints depend on hex head cap screws to handle massive loads and dynamic forces safely.
Manufacturing: Production equipment, conveyor systems, and heavy machinery use these screws for assemblies that must maintain alignment and connection integrity during operations.
Machining: Machine tool construction and workholding fixtures require the precise, high-strength connections that hex head cap screws deliver.
At D&T, we supply hex head cap screws to businesses in all of these industries.
How to Choose Hex Head Cap Screws
Here's how to choose hex head cap screws:
Measure your requirements by getting the diameter and length from your existing screw or application specifications.
Determine whether you need coarse or fine threads based on your specific application.
Select the grade that matches your strength requirements. Higher grades handle more stress and demanding applications.
Choose the finish based on your environmental conditions. Pick plain, plated, galvanized, or stainless steel depending on corrosion resistance needs.
The finish protects against specific environmental challenges your application will face.
How to Measure Hex Head Cap Screw?
Use calipers or a tape measure to get accurate measurements. For diameter, place the calipers across the threaded shank. This gives you the nominal diameter size. For length, measure from directly under the head to the tip of the screw.
These measurements give you the basic size, like ¾" diameter x 3" length. To determine thread pitch, test-fit a nut of known thread specification (coarse or fine) with the same diameter. The nut that threads on smoothly tells you whether you have coarse or fine threads.
What Is the Difference Between a Hex Head Cap Screw and a Hex Head Tap Bolt?
Hex head cap screws can be partially or fully threaded and work two ways: they either thread directly into a tapped hole or use nuts and washers on the opposite end to clamp components together.
Hex head tap bolts are fully threaded and designed to screw into pre-drilled, tapped holes that match the bolt's thread size. They rely on the threaded hole for their holding power.
How Do You Unscrew a Hex Head Screw?
For right-hand threads (the standard), turn the screw counterclockwise using your hand or a wrench. If the screw uses a nut on the opposite end, hold one side steady with a wrench while turning the other side counterclockwise to loosen the connection.
Why Choose Our Hex Head Cap Screws
At D&T, we keep extensive stock of hex head cap screws in the grades and materials that heavy industries need. We're knowledgeable and get our customers high-quality hex cap screws at a competitive price.
Got a project that needs hex head cap screws? Give us your specifications and we'll handle the rest. We'll take your order, give you a quote, and organize pickup.
Ready to get the right hex head cap screws? Request your quote today!
