One important area of fastener design that you may have overlooked is the specification of the fastener drive head configuration. Different than the actual shape of the fastener head (see post on Fastener Screw Head Types here), the drive type is the fastener feature by which the user applies torque to the fastener and drives the fastener into the joint. The drive head is an important part of the fastener and greatly impacts the characteristics of the fastened joint.
Most Common Drive Types
Everyone probably knows the two most recognizable drive head types: the slotted drive head and the Phillips drive head. Indeed, you probably have at least one of these screwdrivers in your garage and could identify them easily from a lineup of fastener drive types. However, you may not be aware of the nuanced functionality of the drive head or the variety of specially designed types of drive heads available.
Hexagonal Socket Head
This drive head is more commonly referred to as an “Allen Drive” and many people are aware of the tool used to tighten these joints which is called an “Allen Wrench”. This drive profile is easy to understand, it’s simply a hexagonal-shaped profile. The advantages of this drive head are similar to the Torx head, in that they can handle large torque applications. However, these drive profiles are more commonly used in high-torque applications that must be easily disassembled such as bolted connections in weight-bearing or safety-critical joints.
Hexagonal socket head drives are typically used in consumer products that have joints that serve some safety functions but must be designed to be lightweight and easily disassembled. The socket head screws can withstand high torques to ensure the joints stay clamped. Probably the most recognizable examples of consumer products that almost exclusively employ hexagonal socket head joints would be bicycle equipment or residential furniture.
Slotted or Flat Head
The slotted head drive takes its name from the single slot on top of the fastener. This drive type is also sometimes referred to as a “flat head” screw. These screw heads are designed to easily accept the flat head drive and are great for hand-driven applications. Slotted drive heads are not typically used in applications that require large torque applications. This is because the flat drive head is susceptible to slipping out of the drive slot on the ends when the screw is being driven under even medium torque. Anyone who has ever used a slotted head drive knows this phenomenon very well. However, the slotted drive head is designed to be unfastened quickly and easily in applications that do not require large torques to secure the joint.
The patent on the iconic Phillips head drive expired back in 1966, but the drive is still extremely prevalent today. The joint was invented to prevent the drive head from slipping out of the flat-head screw under large torque applications. The Phillips drive head is probably the most widely used fastener drive head in simple equipment joints because the fastener drive type is so widely penetrated, the market and everyone has a Phillips head screwdriver. If you’re looking for a medium-duty fastener that can easily be disassembled and can accept medium to large torque values, then the Phillips is probably the right fit and you need not look any further.
The Torx drive head is another step up, in a manner of speaking, from the Phillips drive head. Instead of a four-point cross, like the Phillips head, this drive head features a six-pointed star shape. The Torx name is the trademarked name for this drive head. This star shape fastener is designed to transmit much larger torques into the joint when compared with that of a standard Phillips or slotted head drive. This drive head is best for high-volume screw applications where many screws are to be quickly fastened into the joints at medium to high torque values.
The most common application for the Torx drive head is in weight-bearing wood structures such as deck planks. These drives can quickly and easily transmit the high torques that are required to clamp these structural wood pieces together. The Torx drive head helps the joint stay clamped under the adverse mechanical loading and environmental conditions seen during the life of such structures.
This survey of fastener drive head types should have cracked the door open for you to the wide world of fastener drive heads. MISUMI carries a variety of fastener drive types for your application, explore them here.