Bolts, as well as screws, are available in a vast variety of head shapes. These heads are made in order to grip the tools that are used to tighten them.
The most common types of bolt heads include square, hex, slotted hex washers, and socket caps.
The earliest bolt heads in use were the square heads. Square heads consist of a square indentation on the head followed by a shaft that withstands rotation when a torque is applied to it.
Square heads are still in use today but hex heads have become more common. Hexagonal heads are used with a wrench or a spanner to provide torque.
Type Of Bolt Heads
There are numerous other head shapes in use as well, namely:
#1. Flat bolt head.
A counter shank head with a flat top. A flat head is designed to be countersunk into the material it is being used with.
Flat heads are often used when a low-profile fastener is desired, as the head sits flush with the surface of the material it is being used with.
#2. Oval bolt head.
A counter shank head with a rounded head top. An oval bolt head is a type of bolt head with an oval-shaped head, rather than a hexagonal, square, or round head.
They may also be used in applications where a low-profile fastener is desired, as the head of the bolt sits flush with the surface of the material it is being used with.
#3. Pan bolt head.
A slightly rounded head with a short vertical side. A rounded head with a flat top is often used in decorative applications.
Pan’s heads are similar to round heads in that they are often used for decorative purposes, but they have a flatter top and a more rounded shape.
#4. Truss bolt head.
An extra-wide head with a rounded top. A truss bolt is a type of bolt with a flat, triangular head that is used to join trusses in construction and engineering applications.
The flat, triangular shape of the head allows for high clamping force, which is necessary for these applications to ensure the structural integrity of the truss.
#5. Round bolt head.
A Dome’s head. A round head is often used for decorative purposes.
Round heads are not as common as some of the other types of bolt heads, but they can be used in applications where a more decorative appearance is desired.
#6. Hex bolt head.
A hexagonal head. A hexagonal head that can be tightened or loosened with a wrench or socket.
Hex heads are very common and are often used in a wide range of applications, including construction, automotive, and machinery.
They are easy to grip with a wrench or socket, and their shape allows for high torque to be applied.
#7. Hex washer bolt head.
A Hexagonal head with a round washer at the bottom. A hex washer bolt is a type of bolt with a hexagonal head and a built-in washer.
The washer is typically located under the head of the bolt and is designed to distribute the load of the bolt more evenly across the surface of the material it is being used with.
#8. Slotted hex washer bolt head.
A hexagonal head with a built-in washer and slot. The slot allows the bolt to be tightened or loosened with a screwdriver, rather than a wrench or socket.
The built-in washer helps to distribute the load of the bolt more evenly across the surface of the material it is being used with, and the hexagonal head allows for high torque to be applied.
#9. Socket cap bolt head.
A small cylindrical head using a socket driver. A cylindrical head with a hexagonal recess, designed to be tightened or loosened with a socket.
Socket heads are similar to hex heads in that they can be tightened or loosened with a socket, but they have a cylindrical shape rather than a hexagonal shape.
They are often used in applications where a high level of torque is required and where a low-profile fastener is desired.
#10. Button bolt head.
A low-profile rounded head with a socket driver. A small, flat head with a low profile, is often used in applications where a low-profile fastener is desired.
Button heads are similar to flat heads, but they have a smaller head size and a lower profile.
However, there are many similarities between bolts and screws, there are some differences too.
FAQs.
What are the 6 different types of heads for machine screws?
The most common types of machine screw head shapes are pan head, flat head, round head, oval head, truss head and hex head. Most of the various head types are available with either slotted or Philips screwdriver compatibility, and some come with a combination head that is compatible with both.
What is a bolt without a head called?
If the bolt doesnt have a head at all just being a threaded rod, its referred to as a stud or a stud bolt. If it has a head on it but no slot, socket or any mechanism to grip that end it’s called a carriage bolt.
What is the most common bolt head?
Hex heads are very common and are often used in a wide range of applications, including construction, automotive, and machinery. They are easy to grip with a wrench or socket, and their shape allows for high torque to be applied.
What do bolt numbers on heads mean?
The measurement of an inch nut or bolt will be listed as the thread size — a number between one and 12 or an inch increment followed by the threads per inch (TPI). If the diameter is less than 1/4 inch, the diameter will be listed as a number between zero and 12; the larger the number, the closer it is to 1/4 inch.
The numbers which are written as 4.8, 8.8, 10.9 or 12.9 refer to Tensile Strength on the first digit and Yield Strength on the second digit to make users be able to choose the right fasteners that fit to the application.
How Are Bolt Heads Measured?
Flat head, countersunk screws are flat on the top of the head. They are measured from the top of the head to the tip. Hex and hex washer head screws and bolts, although flat on the top and the bottom, are measured from the bottom of the head.