Types of Fasteners

Varieties of Screws/Bolts

Wood Screw

• Has a sharp point.
• Generally has an unthreaded shank below the head.
• Designed to attach 2 pieces of wood.

Sheet Metal Screw

• Use sharp points and threads and are designed to be driven directly into sheet metal. They can also be used in softer material like plastic, fiberglass, and wood.

• Self Drilling Sheet Metal Screw

  • Sheet metal screw with a self-drilling point.

Machine Screw

• Smaller fastener threaded the entire length of the shank.
• Usually has a recessed drive type.
• Has a thread class

• Thread-Cutting Machine Screw

  • Machine screw with a thread-cutting (self-tapping) point.

Set/Grub Screw

• Is headless.

• Fix a rotating part to a shaft.

• Used only for transmitting very light loads.

Socket Screw

• A machine screw with an internal hex socket (Allen) drive. longer lengths may have a smooth upper shank.

Shoulder Screw/Bolt

• Shank is ground to a precise diameter and threaded portion is smaller in diameter then the shoulder. These fasteners can be used to create a pivot point.

Barrel Nut/ Mating Screw

• Used for through-bolting applications where a head is desired on both sides of the joint.

Fastener Heads

• Flat Head

  • A countersunk head with a flat top.

• Round Head

  • A domed head.

• Oval Head

  • A countersunk head with a rounded top.

• Hex Head

  • A hexagonal head, can have a washer or flange modification.

• Slotted-Hex-Washer Head

  • A hex head with a built-in washer and slotted drive.

• Button Head

  • A low profile rounded head using a socket drive.

• Socket Head

  • A small cylindrical head using a socket drive.

Drive Types

• Socket/Hex/Allen Drive

  • Hexagonal hole for use with an Allen wrench.
  • Often used in bicycle maintenance and furniture.

• Phillips and Frearson Drive

  • An X shaped drive.
  • Designed to cam-out after a certain torque limit.

• Slotted Drive

  • A slot in the head, used with a flathead installation tool.
  • Most popular.
  • Less likely to have rounded or stripped slots.

• Combination Drive

  • A combination of slotted and Phillips drives.

• Square/Robertson Drive

  • A square-shaped drive type.
  • Often used in automotive and furniture industries.
  • Has the highest torque tolerance.

• Star/Torx Drive

  • A six-pointed star pattern specifically designed to prevent cam-out and stripped heads.

• One-way Drive

  • Installs with a normal slotted or "flathead" installation tool but can not be removed without special tools.
  • Often used on barrel nuts and mating screws.

Additional Reading:

Rivets (Page Link)

References

Contributors: