What are Security Screws?

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:

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

• Pin Torx head (as shown above) - A star-shaped, 6-lobe recess like a conventional Torx screw. But this head has a pin located in the center, which prevents removal with a standard Torx tool.
• Pin Hex head - Following the same philosophy as the pin Torx head, the Pin Hex head is similar to your conventional Hex head screw but has a pin located in the center, preventing removal with a standard Hex head tool. These screws are also known as 'security Allen screws.
• Oval pan screw head - At first glance, it can look more like a circular stud or rivet. The oval shape design requires specific tooling to remove the screw and is a good deterrent for vandals as an attempt at removal without the correct tooling could cause significant damage.
• Snake eye head - Sometimes referred to as pig nose head, have two holes located on the head which require a unique 2-pin driver. They tend to be more visually appealing and are more suitable for low torque applications.
• Clutch head - Also known as one-way screws, they come in many different designs. They allow you to install the screw in a usual manner, perhaps with a simple flat-headed screwdriver but do not allow you to remove it. This makes installation very simple, providing the screws are never intended to be removed again.
• Tri head - A more familiar example you would see in everyday life (lamp posts, bins, electrical boxes). A triangular-shaped head that requires a specific triangular screwdriver to install/remove.

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:

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:

• Aluminum - Silvery-white in color, this common metal is lightweight and non-magnetic. It is soft, ductile, and has a high corrosion rate in the proximity of acids or alkaline.
• Steel - Steels are produced differently, depending on their purpose. They are broadly categorized into four groups: carbon steels, alloy steels, stainless steels, and tool steels. In general, steel is relatively corrosion resistant. It's three times heavier than aluminum, common, tough, strong, durable, malleable, and silver in color. They are non-magnetic but can sometimes become magnetic after certain metalwork processes. The variety of steels can contain other elements such as tungsten, cobalt, silicon, nickel, chromium, and many more, depending on the desired properties.
• Copper - Pinkish/brownish in color, ductile, soft, malleable, and very high in thermal and electrical conductivity.
• Brass - As this is an alloy of copper, it has similar properties, like being soft, a good conductor of heat, and malleable. It is also resistant to corrosion and non-magnetic.
• Monel - Excellent corrosion resistance in many environments such as saltwater. However, it is susceptible to galvanic corrosion, meaning if aluminum, zinc, or iron are used around it, it can quickly corrode. It is high in strength and uncommon.
• Titanium - Very high corrosion and thermal resistant. It is lightweight, low density, and very tough. It is rare and quite expensive, also suitable for use in medical instruments and devices.

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:

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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