Torx refers to a type of screw head with a star-shaped recess. Torx screws come in various sizes and are commonly used in automotive, electronics, and other applications that require precise torque control.
Sometimes Torx screw heads have a hole drilled in the center of the recess. This hole serves an important function depending on the application.
In this article, we will discuss what a Torx screw head with a hole in the center is called, the reasons for the hole, and the different types and uses of Torx screws with holes.
What is a Torx Screw Head with a Hole Called?
A Torx screw head that has a hole drilled in the center is specifically called a tamper-resistant Torx or a security Torx.
The hole makes it more difficult for people to unscrew or remove the fastener without the proper Torx driver bit. This prevents unauthorized access and tampering.
Some other names for a Torx screw with a hole include:
- Torx Pin-In
- Torx Plus
- Torx Tamper
However, Torx with a pin, Torx plus, and Torx tamper refer to variants of security Torx fasteners and not just a regular Torx with a hole. We will explain these specialized security Torx types later on.
Reasons for the Hole in Torx
There are a few key reasons why some Torx screw heads have a hole in the recess:
To Prevent Tampering
As mentioned earlier, the central hole prevents the use of a standard Torx driver bit to remove the screw. Only a specialized security Torx bit with a hole that matches the screw head hole can grip and turn the fastener.
This tamper-resistant feature is useful for:
- Automotive wheel lug nuts
- Electronics like gaming consoles, laptops, and mobile devices
- Appliances
- Public infrastructure like bathroom fixtures
The security Torx screw makes it difficult for unauthorized people to open up devices and access internals.
To Allow Pin Alignment
In some applications, a pin is inserted into the hole in the Torx screw head before tightening. The receiving part has a matching hole.
As the Torx driver turns the screw, the pin engages in the alignment hole ensuring proper fastening.
This pin alignment ability makes security Torx suitable for:
- Automotive suspensions, brakes, gears
- Aircraft assemblies
- Medical equipment
Proper hole alignment is critical in these applications for safety. The pin secures tightening accuracy.
To Enable Rotation Prevention
Certain applications require preventing any rotation of the tightened Torx screw for optimal function.
In such cases, the hole is filled with a plastic or metal pin after tightening the screw. This is done using specialized equipment.
The pin lodged in the hole blocks any possibility of screw rotation.
Rotation prevention using security Torx is common in:
- Motorcycle engines
- Bicycle parts
- Machinery joints
Here, vibration forces could otherwise loosen an ordinary screw. The pin eliminates that risk.
Types of Security Torx Fasteners
There are several types of tamper-resistant and security Torx screw heads available:
Torx Pin-In
This is the basic version of a security Torx with a hole. It simply requires a matched Torx driver bit with a hole to fit the head recess.
Torx Pin-In provides minimal tamper resistance and is also the easiest to remove later on, just requiring a Pin-In driver bit.
Torx Plus
Torx Plus screws have a raised plus-shaped metal pattern in the center hole. The recessed Torx walls also have a waved profile.
Corresponding Torx Plus driver bits have a hole with inner ribs to grip the screw head better. The waved walls provide extra torque transfer.
Torx Plus is more tamper resistant than Torx Pin-In due to its complex drive recess shape.
Torx Tamper
Torx Tamper screws have a hole filled with a free-spinning metal insert that keeps turning even if someone tries to engage it with a flathead screwdriver.
Specialized Torx Tamper driver bits have a hole and projecting ribs that can engage and turn the metal insert and screw.
This is one of the most secure versions of anti-tamper Torx available. The spinning metal insert prevents most tampering attempts.
Torx Tamper-Resistant TS
This is similar to standard Torx Tamper but with increased tamper resistance. Torx TS screws have an inner diameter that is non-standard.
So common Torx Tamper driver bits will not fit them. Only Torx TS bits with matching non-standard sizing can turn the screws.
Sizes of Security Torx Screws
Security Torx screws are available in all the standard Torx drive sizes:
| Torx Size | Torx T-Number |
|---|---|
| Small | T1 – T20 |
| Medium | T25 – T55 |
| Large | T60 – T100 |
The smaller size pins are more delicate and require careful handling and tightening. Large security Torx are robust for applications like automotive wheel lugs.
In general, make sure to use the correct size security Torx driver bit for the screw size. This avoids damage to the pins and receptacles. Using excessive force with an ill-fitting bit can also ruin the tamper-resistant properties.
Materials Used for Security Torx Fasteners
Security Torx screws, bolts, and other fasteners are fabricated from:
- Stainless steel – Offers high corrosion resistance and strength for long life in demanding environments like marine applications.
- Steel – Common choice that combines good strength and cost-effectiveness. Steel Torx are suitable for most applications.
- Brass – Provides excellent chemical resistance while being softer to avoid damage to delicate equipment. Used for instruments, valves, and electrical fixtures.
- Aluminum – Lightweight yet strong aluminum provides strength without adding a lot of weight. Used for aircrafts and high-end equipment.
- Plastic – Cost-effective option for light duty uses. Plastic security Torx are common in consumer electronics and appliances.
The material matches the expected operating conditions and cost considerations of the application.
Pros and Cons of Security Torx Fasteners
Security Torx screws with a hole offer some notable advantages:
Pros:
- Enhanced tamper-resistance compared to standard Torx
- Prevents accidental loosening from vibrations
- Allows precise control over tightening angle and hole alignment
- Wide range of sizes available including small micro Torx
- Made from various hardened materials including stainless steel
Some potential disadvantages to consider:
Cons:
- Can only be driven by specialized security Torx drivers
- Higher cost than regular Torx
- Pin heads may wear out over time
- Small broken pins could damage equipment
- Improper installation can compromise tamper-resistance
Despite the minor downsides, security Torx offer tangible benefits for critical applications that justify their use.
Uses of Security Torx Fasteners
Some common uses of tamper-resistant Torx screw and fastener types include:
Automotive
- Wheel lug nuts
- Brakes and transmission assemblies
- Suspension components
- Fluid valves
- Door locks and latches
Aerospace
- Aircraft engines and landing gear
- Access panels
- Interior components
Appliances
- Securing covers and access panels
- Tightening screws on circuit boards and components
Computers and Consumer Electronics
- Hard drive enclosures
- Mobile device screw covers
- Game console casings
Construction and Hardware
- Bathroom fixtures like toilet paper holders
- Door hinges
Buying Guide for Security Torx Tools and Fasteners
Here are some tips when shopping for security Torx products:
Torx Driver Bits
- Get driver bits with durable, hardened steel construction to minimize wear
- Choose drivers with high torque capacity for grip and control
- Buy screwdriver sets with multiple Tamper Torx bit sizes
- Look for bits with holes, ribs, and other features to suit the fastener
- Ensure the driver bit hole pattern matches the screw heads
Security Torx Screws
- Verify the level of tamper resistance required
- Check that the pin size and type suits the application
- Match the screw head size to the specifications
- Choose a material like stainless steel for harsh environments
- Buy from reputable brands for quality and correctness
Investing in high-quality security Torx drivers and fasteners ensures the best performance and protection.
Conclusion
A Torx screw head with a hole drilled in it is specifically termed as a security Torx or tamper-resistant Torx. The hole allows driving by special Torx drivers only, prevents loosening from vibration, and enables precise alignment during tightening.
Security Torx versions like Torx Pin-In, Torx Plus, and Torx Tamper offer increasing levels of tamper resistance for critical applications. Security Torx screws are available from micro sizes to large variants in hardened metal for optimal strength.
Carefully choosing the right Torx drivers and fasteners as per the specifications and operating environment is important to gain the anti-tampering benefits of security Torx. With the proper installation, they provide reliable and robust fastening.