The Evolution Of Torx Screw Heads: Understanding The Different Types

Torx is a trademarked type of screw head developed by Camcar Textron in 1967. It is characterised by a 6-point star-shaped pattern and is often referred to as a 'star screw'. The official generic name is hexalobular internal, standardised by the International Organization for Standardization as ISO 10664. Torx screwdrivers have a distinctive 6-point star-shaped head that perfectly mates with appropriately sized screw heads. The unique Torx design reduces the likelihood of the screw head being stripped and increases the screwdriver's resilience. Torx screw heads are commonly used in vehicles, motorcycles, bicycles, computer systems, hard disk drives and consumer electronics.

Torx Plus

The Torx Plus design features more square lobes, which allow for higher torque and minimise wear. The name is shortened to IP (Internal Plus) with sizes ranging from 1IP to 100IP (sometimes listed as IP1 to IP100) and EP (External Plus) with sizes ranging from 1EP to 42EP, as well as smaller sizes ranging from H7EP to H2EP. The specifications for these licenses are held by Textron.

Standard Torx drivers can be used to drive Torx Plus screws, but not to their full torque due to the loose fit. Torx Plus drivers will not fit into standard Torx screws.

A tamper-resistant version of Torx Plus also exists, featuring five lobes rather than six, plus a solid post in the centre. This version is used for security as the drivers are uncommon.

Torx Paralobe

The TORX PARALOBE™ Drive System is the latest member of the TORX® family, featuring increased strength and other benefits. It was developed by Acument Global Technologies to address customer needs and concerns with other drive systems. The system improves upon the benefits of the TORX® and TORX PLUS® drive systems, offering increased drive bit strength, life, and torque—20% over the TORX PLUS® system and 50% over the TORX® system.

The unique geometry of the TORX PARALOBE™ Drive System results in 'full surface drive contact', reducing drive bit/recess contact stresses. It features vertical straight sidewalls and reduced bit/recess wobble, producing a more solid 'fit'. The lobe geometry area is approximately 6% larger than the TORX PLUS® drive system, resulting in 20% greater drive bit torsional strength and drive system strength, and 100% greater finite drive bit fatigue life.

The TORX PARALOBE™ AUTOSERT® feature is designed for assembly situations where the driver bit is continuously rotating. The compound angle ramps guide the driver bit into the recess, creating a self-centring and engaging action. This feature allows for higher rpm engagement, speeds up engagement, reduces assembly time, increases productivity, and eliminates the need to slow down the driver bit.

The TORX PARALOBE™ Stick Fit offers a stable stick fit between the drive tool and the recessed part. It is suitable for manual and automated applications where the orientation of the fastener changes between the time the fastener is engaged on the bit and when it enters the nut thread.

Torx ttap

The Torx ttap drive system combines the high torque capability of the Torx drive system with added stability and Frixion Fit of the ttap stability button. This makes it ideal for the wood screw market, as it offers high torque transfer, wobble-free installation, single-hand installation, and avoids stripped-out recesses. The patented recess design allows the fastener to stick to the bit before driving.

Standard Torx drivers can be used to drive Torx ttap screws, but Torx ttap drivers will not fit standard Torx screws.

Standard and Security Torx Heads

Standard Torx heads are characterised by a distinct, 6-point star-shaped pattern and often referred to as 'star screws'. They require a 'star screwdriver' with a 'star bit' to tighten and loosen them. Standard Torx screwdrivers have a distinctive 6-point star-shaped head that mates perfectly with appropriately sized screw heads. The unique Torx design reduces the likelihood of the screw head being stripped or the screwdriver being damaged.

Security Torx heads, on the other hand, are designed to provide an additional level of security. They are often called Pin Torx due to the extra pin located in the centre of the six-point star socket head. This centre pin prevents the use of a standard Torx screwdriver, making these fasteners tamper-proof. Security Torx screws are also known by various other names, including 6 lobe screws, tamper-proof Torx, 6 lobe pin Torx, Torx TR, Torx pin, and star pin drive screws.

To work with Security Torx screws, you need specialised tools that accommodate the additional security pin. These screws provide a higher level of security than standard Torx screws as they require a specific security Torx screwdriver to loosen them. Security Torx screwdrivers have a unique design that allows them to mate with the security pin in the screw head.

Both standard and security Torx heads come in various sizes, and it is important to match the size of the screwdriver to the size of the screw for a proper fit and to avoid damage.

Torx Screwdriver Sizes

The Torx screwdriver is a type of screwdriver with a distinct 6-point star-shaped pattern, often referred to as a "star screwdriver" or "star bit". The official generic name is the hexalobular internal, standardised by the International Organization for Standardization as ISO 10664. The Torx screwdriver is designed to perfectly mate with appropriately sized screw heads, with the unique design making it less likely that the screw head will be stripped or the screwdriver damaged.

Torx screwdrivers come in a range of sizes, denoted by a capital "T" followed by a number, ranging from T1 to T100. Some manufacturers may also use "TX" or "Tx" before the number. The number following the "T" indicates the point-to-point dimension of the screw head, with smaller numbers corresponding to smaller dimensions.

Some common Torx screwdriver sizes include:

• T10
• T15
• T25

These sizes are commonly used for a variety of applications, from automobiles to computers.

It is important to note that the size of the Torx screwdriver must match the size of the Torx screws being used. For example, T15 Torx screws require a T15 Torx screwdriver.

In addition to the standard Torx sizes, there are also external Torx sizes, denoted by a capital "E" followed by a number, ranging from E4 to E44. The "E" sizes do not directly correlate to the "T" sizes, so it is important to refer to the correct sizing when selecting a Torx screwdriver.

Another variation is the Security Torx or Tamper-Resistant Torx, often shortened to Torx TR. This type of Torx screwdriver contains a post in the centre of the head, preventing the use of a standard Torx screwdriver. This type of screwdriver is used for added security and is commonly used in prisons, security locks, or computer parts.

When choosing a Torx screwdriver, it is important to select one of high quality to reduce the risk of breakage and cam-out.

Frequently asked questions