How does a fastener's drive design affect torque capacity, holding power, and function? Learn how in this guide to the most common drive types.

What is a fastener drive?

The drive is the feature in a screw or bolt head that connects with a tool, enabling the fastener to be turned.

Although screws were initially made with only one drive type, there is now a multitude of styles available, such as flathead, Phillips, Robertson, Torx, and hex. The drive type affects how the entire fastener performs, and it's an important piece to consider when selecting a fastener.

What does drive type affect?

A fastener's drive influences:

• Torque capacity: How much force can be applied before cam out or slippage.
• Holding power: The amount of clamping force that can be created through tightening.
• Installation and removal: How easy it is to drive the fastener and whether it can be removed later.
• Security: Whether specialty tools are required to remove the fastener.
• Appearance: The final look after installation.

How drive type affects torque and holding power

The shape of the drive affects how well tools can transfer torque to the fastener. Drives with more contact area and even force distribution can handle higher levels of torque. However, high concentrations of force created by sharp corners or small connection areas increase the likelihood of damage during installation, limiting the amount of torque that can be applied.

Higher torque increases clamping force, which is what gives fasteners their holding power. In general, drive types that resist stripping and cam out can handle higher levels of torque, creating stronger connections.

Flathead/Slotted

The slotted drive type, also called flathead, was the first design used when screws were developed. This drive has a single recessed line across the head and is best driven by a handheld flathead screwdriver. The slotted design stands out by its simplicity—it's easy to manufacture and easy to install.

The flathead design has a low torque capacity and easily cams out. It's an affordable and accessible option for lightweight applications that can be installed by hand, but it's not suited for projects that need significant holding power.

Common flathead applications

The flathead drive type is commonly used in lightweight or delicate applications, such as:

• Electrical cover plates
• Antique furniture
• Decorative hardware
• Restoration projects

Phillips/Cross

The Phillips drive type, named after the first manufacturer, has a cross-shaped recess with smooth inner corners. It offers slightly higher torque capacity than flathead drive, but not enough for any structural applications. This design cams out easily, which can sometimes be beneficial to help prevent overtightening.

The symmetrical design of the Phillips drive helps center the driver and reduce slippage. These screws are good for general purpose applications where moderate holding power is sufficient.

Common Phillips applications

Phillips drives are common in general purpose fasteners without a significant needs for high torque, such as:

• Drywall installation
• Consumer electrics & devices
• Lightweight construction & furniture

Phillips vs. Frearson

The Frearson drive is similar to Phillips but less common. These two drives are frequently confused because they look similar, but there are slight differences between them.

The Frearson driver has a sharp tip, which allows it to fit all size screws with a single bit. The cross in this drive has sharp angles that make it less prone to camming out.

Torx/Star

The Torx drive has a star-shaped, six-lobed recess with increased bit engagement, torque capacity, and resistance to cam out. This drive comes in multiple sizes, and it's important to use the right one to prevent stripping the socket.

Pros:

• High torque capacity
• Low likelihood of cam out
• Self-centering design
• Slightly resistant to tampering

Cons:

• Requires a specific driver for use

Common Torx applications

Because the Torx drive allows for higher torque transfer and, therefore, higher clamping force, it is a strong choice for heavy-duty or structural applications that earlier designs cannot accommodate, such as:

• Automotive assembly
• Structure and framing applications
• Appliances & machinery

Robertson/Square

The Robertson drive has a square-shaped socket in the head. This design is mostly used in the United States and Canada and is unlikely to be found outside of North America.

The Robertson drive has a high torque capacity and resistance to cam out. The square shape allows for better attachment to the driver, making one-handed driving a possibility.

Pros:

• Strong bit engagement
• Self-centering design
• Low likelihood of cam out

Cons:

• Less common, especially outside of North America
• Requires a unique driver

Common Robertson applications

For its high torque capacity, Robertson drive screws can be used in a variety of heavy-duty and general applications alike, such as:

• Structure and framing applications
• General woodworking
• Furniture assembly
• Electrical devices

Allen/Hex

The Allen drive has a hexagonal socket that can handle higher levels of torque, but may still strip if the wrong size driver is used. These screws can be turned by hand with an Allen wrench or with a power driver.

Pros:

• Strong bit engagement
• Allen wrenches sometimes allow for more accessible installation

Cons:

• Requires a specific driver for use

Common Allen applications

The Allen drive is highly versatile and used in a variety of applications, such as:

• Furniture assembly
• Machinery
• Automotive parts
• Bicycles

External drive designs

Some drives protrude above the screw head, or the entire head may act as a drive. These are turned with an adjustable wrench or a female driver socket. External drive designs have high torque capacities and are unlikely to strip, making them an excellent option for heavy-duty applications.

These fasteners are great for outdoor applications as the head is unlikely to corrode or deform beyond use, whereas recessed drives may rust or fill with debris, rendering them unusable.

External Hex

A hexagonal head, often called "hex head," is very common in construction and machinery assembly.

Pros:

• Excellent torque transfer
• Low likelihood of deformation
• Compatible with sockets and impact tools

Cons:

• Head protrudes above material surface

Common hex head applications:

• Heavy-duty structural and framing fastening
• Automotive assembly
• Outdoor construction
• Metal roofing and siding installation

External Square

A square-shaped head is somewhat easier to grip with a wrench and extremely resistant to deformation, making it great for applications where frequent adjustments may be needed.

Pros:

• Easy to grasp and turn with a wrench
• Strong and durable design
• Highly unlikely to deform
• Compatible with sockets and impact tools

Cons:

• Head protrudes above material surface

Common square head applications:

• Heavy-duty structural and framing fastening
• Plumbing fittings
• Machinery assembly

Key differences between drive types

Each drive type has unique advantages. Alongside cost and availability, you should consider the security, torque capacity, and cam out resistance when choosing a fastener. The chart below compares these features among common drive types.

Keep in mind that these ratings are relative, and there are many other factors that contribute to a fastener's performance. Contact your fastener manufacturer for exact specifications.

Other drive types

This guide covered some of the most common drive types, but there are many others available in the fastening world. Some other notable drive types include:

• One-way drive: These feature breakaway heads or sloped wings that make it easy to install the fastener but impossible to remove without special tools.
• Combination: These drives combine features of two or more traditional styles, typically Phillips and flathead. These screws can be turend with multiple tools, making them a more convenient fastener to use.
• Thumbscrew: These are screws that can be turned by hand, eliminating the need for extra tools.
• Security: There are a multitude of drives with varying levels of tamper resistance, possibly through complex drive designs or even custom drives.

Check out our blog for more fascinating fastening information or reach out to our in-house experts if you have additional questions. Give us a call at (406)752-5253 or send us an email at tom@jakesales.com.

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