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What are Security Screws?

A 6-lobe flat head pin sealing screw.

What Are Security Screws?

Security screws are similar in design to conventional screws. However, there is one main difference: security screws come in many different shapes and sizes and tend to have a unique drive style, for which you require specific tools. The unique drive style is because a security screw's primary purpose is to deter tampering and avoid removal by unauthorized personnel. Excellent examples are assemblies or systems in public areas, exposing them to vandalism or sabotage. If you imagine a simple slotted head screw, it is very easy for someone in public to undo that screw with a simple flat-headed screwdriver or even with a small coin in their pocket. The security screw's purpose is to prevent this and deter vandals from attempting to undo the screw.

Security screws can be split into two different types: tamper-resistant and tamper-proof. At first glance, these different types can be confused about having the same meaning. However, there is a difference.

Tamper-resistant screws

They are installed or removed with a specialized tool, made specifically for them. These screws are the more common type and are often used in situations where authorized personnel requires regular access. Your average person may carry a flat-headed or Phillips headed screwdriver but will struggle to remove the screw without causing significant damage without the correct specialized tool.

Tamper-proof screws

A step up from tamper-resistant screws, these screws are designed to be next to impossible to remove without the correct tooling; perhaps even drilling or cutting of the screw may be required for extraction. Depending on your needs, tamper-proof screws may be more suitable than tamper-resistant screws as these tend to be used in more permanent situations.

To summarize, you have your basic conventional screw, a step up from that is your tamper-resistant security screw, another step up from that is your tamper-proof security screw

Where Would You Find Security Screws Being Used?

Security screws are used throughout the world in all kinds of industries and areas. You will find tamper-resistant screws in public areas to deter casual or opportunistic temptation. Some examples of this use are bathroom stalls, license plates, public benches, school tables, lamp posts, electrical boxes, and security systems. Other industries have tighter security requirements with more sensitive information and therefore require more expensive measures to protect their assets from sabotage or unlawful entry.

As technology in the modern world is advancing so quickly, we find ourselves surrounded by autonomous technology such as LiDAR (Light Detection and Ranging) - the technology used in autonomous vehicles, robots, aerial drones, and public transportation. As these systems evolve and become more complex, they become critical to the operation and become a bigger target for cybercriminals, thus being more exposed to security breaches. Keeping the systems secure from tampering and vandalism in public areas is vital to ensure safety and continued operations. The use of security screws in these critical and sensitive areas is highly advantageous as it is a simple deterrent for vandals and criminals. Not having the correct, unique tooling required to undo these security screws would help delay unwanted access and raise suspicion. Another reason for using security screws is to prevent owners from carrying out their own maintenance on products, particularly in the automotive industry. As cars become more and more complex, end-user maintenance could cause more damage than good. Security screws limit how much maintenance the owners can do themselves and ensure that the contracted manufacturer or a specialized third party carries out maintenance.

What Are the Different Types of Security Screws?

Generally speaking, the main way security screws are differentiated from conventional screws is by their different drive styles: security screws tend to have different head designs that require a specific tool to turn the screw. Let's take a look at a simple example:

Here we have a picture of a standard Torx screw and a more secure version of the Torx screw below. Now the Torx screw itself can be considered more secure as the star-shaped drive is less common than a slotted drive or a Phillips drive. However, as you can see in the picture, the lower Torx screw has a pin located in the center of the star-shaped drive. This simple change now makes all the original star drive tools obsolete as they can no longer be used to install or remove this new type of screw.

Below is a list of different head types for security screws:

Another type of security screw is the security/tamper proof sealing screw. This combines the types of security screw heads, mentioned above, along with the sealing capability of a sealing screw. This is achieved by adding a rubber O-ring which sits in a specifically designed groove under the head of the screw, resulting in performing a perfect 360 degree seal between the two mating surfaces. These type of screws are used when you are looking to deter any threats of tampering whilst also protecting from the threats of the environment, such as fluids and gases. For more information on sealing screws, please visit the Ultimate Guide to Sealing Screws.

Which Industries Tend to Use Security Screws?

Security screws are used in any industry where there would be a threat of tampering or unwanted removal. Vandalism in public is the most obvious threat, particularly as we evolve in a world where complex, safety-critical technology is integrated into everyday life. Below is a list of industries that use security screws:

  • Aerospace
  • Automotive
  • Hospitals and Medicine
  • Correctional Facilities
  • Schools and Universities
  • Military
  • Retail Outlets
  • Utility Companies
  • Marine
  • Transport Providers

Which Materials Should I Use?

The materials of security screws depend on the nature of the application. There are a few considerations to keep in mind when choosing the correct security screws:

What is the purpose of this screw?

What is the purpose and operation of the system the security screw is supporting? Do you need a small machine screw to protect sensitive electronics from sabotage or vandalism, or do you need something stronger and robust to withstand the extreme conditions you would find, for example, in the marine or aviation industries? The screw will need to have the correct mechanical properties to be successful. Design factors include the metal it is made from, thread depth, thread thickness, diameter, and head size.

Is there corrosion?

This is when you need to think about what the screw will be in contact with (water, saltwater, lubricants, air) and how much that will affect the corrosion rate. The longer you can delay that corrosion process, the better. If a security screw is subject to corrosion, it potentially loses its purpose of maintaining the system's security. For example, stainless steel and titanium are used a lot in the marine industry due to the saltwater's high corrosion rate. Another example is galvanic corrosion. This type of corrosion occurs when two dissimilar metals meet together. Therefore, the higher the rate of corrosion, the more corrosion resistance required.

How is the screw manufactured?

Screws are made by cold heading and machining processes. The material chosen can influence how the screw is made, which can be important as some fabrication methods can create weaknesses in the required design. Some examples are: machine cut screws which are literally cut into the blank during the thread rolling process resulting in lost material and weakness in the metal, dissimilar metals between the screw and the contact surface can result in galvanic corrosion, cheap or incorrect materials used can cause cracking of the screw due to the pressure applied. All these examples essentially lead to the same result: failure. If the security screw fails, then the whole system or operation can fail, resulting in breached systems, increased vandalism, additional maintenance and repairs, poor reliability, new materials required, and reduced operating time. These all lead to an increase in operational costs.

What is the cost?

When considering the overall cost, it is essential to think about the longevity of the security screw. Does the screw need regular removal and installation to perform specific tasks where a tamper-resistant screw would be preferable, or would a more permanent tamper-proof screw be better suited where it doesn't plan to be removed once it's installed? Sometimes it can be financially beneficial to spend a bit more on the security screw to get better performance, longevity, and reduce the risk of damage.

What is the availability?

When choosing your materials, it is vital to think about how readily available those materials are and how much it will cost to use. Some metals are rarer than others making the availability low and the cost higher. For example, titanium has some excellent properties by being lightweight and highly corrosion-resistant; however, it is rarer than other metals and is in high demand, making it more expensive.

Once you have evaluated what properties you require for your sealing screw, you then need to select the material it is to be made from to perform these tasks. Below is a list of metals:

What Are Self-Locking Screws?

One last thing to consider is the use of self locking screws. This is when a screw is applied with a specific treatment, such as nylon, to provide extra locking capability of that screw and is used in areas of constant vibration. As the vibration continues, it can slowly reduce the grip of the screw over time. There are different ways of achieving this self locking feature, below are a few examples:

  • Strip - A milled slot is formed in the threads of the screw and a bar of nylon, Kel-F or Vespel is inserted, offering a wide adjustment range and working area.
  • Vibratite - A vibration resistant coating that is added to the threads and are adjustable, removable and reusable.
  • Pellet - A hole is drilled into the threads of the fastener and a firm nylon plug is inserted, it is vibration resistant and adjustable. This process is a good option for bearing retainer nuts.
  • Epoxy - A powerful sealing element and is known to out-perform most nylon locking elements in first-off torque evaluations. It is suitable for sealing automotive parts from fluids such as oil, water, antifreeze and gasoline.
  • Patch - A powdered nylon is sprayed onto the threads, creating self-locking characteristics. They are chemical resistant and reusable, even when exposed to chemicals such as alcohol, gasoline, oil and jet fuel.
  • Precote 30 - A varnish like pre-coat that comes in epoxy and acrylic formulations. It is of medium strength for sealing and locking threaded fasteners that require controlled friction, such as those used in an assembly line.

What Is the Overall Cost?

To summarize, the overall cost that needs to be weighed up is if the potential risk of sabotage, vandalism, or unauthorized maintenance outweighs the additional cost the security screw has over conventional screws. You need to assess what your goals are and how safe your equipment needs to be, and then balance this with the relevant type of available security screws.

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