In the world of industrial fasteners, the terms
cap screw,
tap bolt, and
hex head bolt are often used interchangeably. While these fasteners look very similar at first glance, they have important differences in threading, manufacturing standards, and typical applications.
Understanding these differences helps ensure you select the correct fastener for strength, fit, and reliability in construction, manufacturing, and industrial equipment.
What Is a Hex Head Bolt?
A hex head bolt, often called simply a hex bolt, is one of the most commonly used fasteners in construction and industrial applications. It features a six-sided head designed to be tightened with a wrench or socket.
Most hex bolts are partially threaded, meaning a portion of the shank beneath the head is smooth and unthreaded. This smooth section can help provide alignment and improved shear strength when fastening materials together.
Hex bolts are typically installed by passing the bolt through two or more materials and securing it with a nut and washer on the opposite side.
What Is a Tap Bolt?
A tap bolt looks similar to a hex bolt but has one key difference: it is fully threaded from the head to the tip.
Because the entire length is threaded, tap bolts are designed to be threaded directly into a tapped (pre-threaded) hole. This eliminates the need for a nut, making them ideal for applications where the back side of the connection is not accessible.
Tap bolts are commonly used in machinery, equipment frames, and maintenance applications where components must be secured directly into threaded metal parts.
Since they engage threads along their entire length, tap bolts can provide strong thread engagement within the receiving material.
What Is a Cap Screw?
A cap screw, specifically a hex cap screw, is very similar in appearance to a hex bolt but is manufactured to stricter dimensional tolerances and higher strength standards.
Hex cap screws typically include a washer face under the head, which helps distribute the load and provides a smoother bearing surface during tightening.
Unlike standard hex bolts, cap screws are often used in precision mechanical assemblies and are commonly installed into tapped holes rather than with a nut.
Cap screws are frequently produced in specific strength grades such as Grade 5 or Grade 8, making them suitable for applications where fastener strength and reliability are critical.
How to Choose the Right Fastener
Selecting the correct fastener depends on several factors including load requirements, access to the connection, and the materials being joined.
General guidelines include:
- Use a hex head bolt when the fastener will pass through materials and be secured with a nut.
- Use a tap bolt when threading directly into a tapped hole and full threading is required.
- Use a cap screw when a higher precision or high-strength fastener is needed for mechanical assemblies.
FAQ
Are tap bolts fully threaded?
Yes. Tap bolts are fully threaded from the head to the tip, allowing them to be threaded into tapped holes without a nut.
Are hex bolts and cap screws the same?
No. Cap screws are manufactured with tighter tolerances and higher strength specifications, while hex bolts are generally used with a nut and washer.
When should you use a tap bolt?
Tap bolts are commonly used when the fastener must thread directly into a tapped hole and access to the back side of the assembly is limited.
If you're sourcing cap screws, hex bolts, or tap bolts for construction, manufacturing, or industrial equipment, Marovato supplies a full range of fasteners and pipe support hardware to contractors and industrial buyers across the Tri-State area of New York, New Jersey, and Connecticut.
Contact
the knowledgeable team at Marovato Industries, Inc. at
718-389-0800 to discuss your project requirements and get the right components for your application.
