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b. ThreeLock : Mechanical threadlocking
Pre-coated screws and bolts : three processes, different applications
28/09/2026
Smartphones, computers, batteries, motors and industrial machinery all have something in common: they rely on screws and bolts to hold their components securely together.
But when an assembly is exposed to vibration, shocks, temperature changes or repeated mechanical stress, simply tightening a screw may not always be enough to keep it securely in place.
Have you ever removed the back of your computer to clean the fans and noticed that some of the screws had a distinctive colored coating ?
That coating is not just there for appearance. It is a pre-coating designed to give the screw additional functionality. .
Pre-coated screws and bolts are fasteners that have been treated with a specially formulated resin before they are delivered to the assembly line.
Instead of applying a liquid locking or sealing product during assembly, the functional coating is already applied directly to the threads.
Depending on the technology and formulation used, this coating can provide threadlocking, sealing, lubrication or a combination of these functions.
This means that the fastener itself becomes a functional component of the assembly, helping improve process consistency and reliability.
At ThreeBond, different pre-coating technologies are available depending on the required performance, including MEC, ThreeLock and Sealock.
Liquid threadlockers and pre-coated screws can both be used to prevent loosening and improve the reliability of threaded assemblies. However, they work differently and are suited to different manufacturing processes.
With a liquid threadlocker, the product needs to be applied during assembly. This adds an additional step to the production process and requires the correct amount of product to be dispensed onto the thread.
With a pre-coated screw, the functional coating is applied in advance and controlled during the coating process. The fastener can then be supplied ready for assembly. This can provide several advantages :
ThreeBond has developed several pre-coating processes, each designed for different requirements.
a. MEC : Reactive locking and sealing
MEC stands for Micro Encapsulated Coating. In the MEC process, a reactive resin is contained within microscopic capsules and applied to the threaded surface.
But when an assembly is exposed to vibration, shocks, temperature changes or repeated mechanical stress, simply tightening a screw may not always be enough to keep it securely in place.
Have you ever removed the back of your computer to clean the fans and noticed that some of the screws had a distinctive colored coating ?
That coating is not just there for appearance. It is a pre-coating designed to give the screw additional functionality. .
01. What are pre-coated screws and bolts ?
Instead of applying a liquid locking or sealing product during assembly, the functional coating is already applied directly to the threads.
Depending on the technology and formulation used, this coating can provide threadlocking, sealing, lubrication or a combination of these functions.
This means that the fastener itself becomes a functional component of the assembly, helping improve process consistency and reliability.
At ThreeBond, different pre-coating technologies are available depending on the required performance, including MEC, ThreeLock and Sealock.
02. Why using pre-coated screw instead of threadlockers ?
Liquid threadlockers and pre-coated screws can both be used to prevent loosening and improve the reliability of threaded assemblies. However, they work differently and are suited to different manufacturing processes.
With a liquid threadlocker, the product needs to be applied during assembly. This adds an additional step to the production process and requires the correct amount of product to be dispensed onto the thread.
With a pre-coated screw, the functional coating is applied in advance and controlled during the coating process. The fastener can then be supplied ready for assembly. This can provide several advantages :
- Consistent coating : the amount and position of the coating can be controlled in advance.
- Simplified assembly : no additional liquid dispensing step is required.
- Cleaner handling : there is no liquid threadlocker to apply manually on the production line.
- Integrated functionality: depending on the process, the coating can provide locking, sealing or lubrication.
- Process control : the pre-coating is prepared before the fastener reaches the assembly line. ThreeBond's technical documentation specifically highlights the quality and process-control advantages of precoating technology.
03. Types of pre-coated screws
ThreeBond has developed several pre-coating processes, each designed for different requirements.
a. MEC : Reactive locking and sealing
MEC stands for Micro Encapsulated Coating. In the MEC process, a reactive resin is contained within microscopic capsules and applied to the threaded surface.
When the screw is tightened, the friction between the threads breaks the microcapsules and releases the reactive components. This initiates the curing process, creating a strong bond between the threaded parts. The result is both threadlocking and sealing performance.
MEC formulations are available in different strength levels and chemistries, including acrylic and epoxy types. ThreeBond's current product range includes water-based MEC products ranging from low to high strength.
MEC is therefore particularly suited to applications where a strong and reliable connection is required, including automotive, electronics and industrial applications.
TB2448
MEC Process Epoxy resin
- High strength
- M2 to M40
ColourBlue
Locking+150°C
Sealing+170°C
TB2448B
MEC Process Epoxy resin
- High strength
- M2 to M40
ColourOrange
Locking+160°C
Sealing+170°C
TB2448
MEC Process Epoxy resin
- High strength
- M2 to M40
ColourBlue
Locking+150°C
Sealing+170°C
TB2448B
MEC Process Epoxy resin
- High strength
- M2 to M40
ColourOrange
Locking+160°C
Sealing+170°C
TB2458
MEC Process Acryl resin
- Low strength
- M3 or larger
ColourOrange
Locking+100°C
Sealing+170°C
TB2468
MEC Process Acryl resin
- Medium strength
- M3 or larger
ColourPink
Locking+100°C
Sealing+170°C
b. ThreeLock : Mechanical threadlocking
Unlike MEC, ThreeLock is a non-reactive coating. A nylon resin is applied to the threads to create mechanical resistance when the screw is assembled. Rather than chemically curing after assembly, the coating acts between the threads to help prevent loosening.
This makes ThreeLock particularly suitable for applications where reliable threadlocking and the possibility of disassembly are required. Its characteristic smooth, glossy appearance also makes it easy to distinguish from some other pre-coating technologies.
ThreeLock can be used for applications including small screws in electronic equipment, automotive components, eyeglasses and other assemblies where resistance to loosening is required.
TB2365B
Threelock Nylon resin
- Repeated usage
- Assembly / Disassembly
- M1.6 to M40
- Pre-coated locking agent
ColourGreen
Service temperature-50 to +120°C
TB2365C
Threelock Nylon resin
- Repeated usage
- Assembly / Disassembly
- M1.6 to M40
- Pre-coated locking agent
ColourRed
Service temperature-40 to +200°C
c. Sealock : Sealing and lubrication
Sealock focuses on sealing and lubrication rather than threadlocking. Its coating is designed to fill the small gaps between threaded surfaces, helping prevent leakage while also facilitating assembly.
This makes Sealock particularly suitable for applications where leak prevention and smooth assembly are essential, such as pipes, fittings and other fluid-related components.
Unlike MEC, Sealock is non-reactive: it does not rely on a curing reaction after assembly.
TB2358
Sealock Fluoropolymer
- Excellent chemical resistance
- Magnet bonding
ColourWhite
Sealing170°C
So, in simple terms :
MEC → Lock & Seal
ThreeLock → Prevent Loosening
Sealock → Seal & Lubricate
Three technologies, three different ways to make a simple screw do much more.
Related pages
04. Why water-based resins ?
Pre-coating fasteners requires a coating solution that can be applied evenly to the threaded surface. Traditionally, organic solvents have been used in pre-coating processes. During drying, however, these solvents can evaporate into the atmosphere, contributing to VOC emissions.
To address this issue, ThreeBond has developed water-based pre-coating technologies, using water as the medium instead of relying on conventional organic solvents. ThreeBond's technical documentation highlights water-based pre-coating as a way to reduce VOC emissions and respond to increasingly stringent environmental regulations.
Water-based formulations can therefore offer an alternative to conventional solvent-based processes while maintaining the performance required for pre-coated fasteners. Today, ThreeBond offers a range of water-based MEC products, including acrylic and epoxy formulations with different strength and heat-resistance levels.
A screw may look like a simple mechanical component, but its coating can fundamentally change the way it performs.
Whether the priority is strong locking and sealing, resistance to loosening, or sealing and lubrication, choosing the right pre-coating technology allows the fastener to be adapted to the application.
With MEC, ThreeLock and Sealock, ThreeBond's pre-coating technologies turn standard screws and bolts into functional fastening solutions.
TB2365B
Threelock Nylon resin
- Repeated usage
- Assembly / Disassembly
- M1.6 to M40
- Pre-coated locking agent
ColourGreen
Service temperature-50 to +120°C
TB2365C
Threelock Nylon resin
- Repeated usage
- Assembly / Disassembly
- M1.6 to M40
- Pre-coated locking agent
ColourRed
Service temperature-40 to +200°C
Sealock focuses on sealing and lubrication rather than threadlocking. Its coating is designed to fill the small gaps between threaded surfaces, helping prevent leakage while also facilitating assembly.
This makes Sealock particularly suitable for applications where leak prevention and smooth assembly are essential, such as pipes, fittings and other fluid-related components.
Unlike MEC, Sealock is non-reactive: it does not rely on a curing reaction after assembly.
TB2358
Sealock Fluoropolymer
- Excellent chemical resistance
- Magnet bonding
ColourWhite
Sealing170°C
So, in simple terms :
Three technologies, three different ways to make a simple screw do much more.
MEC → Lock & Seal
ThreeLock → Prevent Loosening
Sealock → Seal & Lubricate
Three technologies, three different ways to make a simple screw do much more.
Related pages
04. Why water-based resins ?
Pre-coating fasteners requires a coating solution that can be applied evenly to the threaded surface. Traditionally, organic solvents have been used in pre-coating processes. During drying, however, these solvents can evaporate into the atmosphere, contributing to VOC emissions.
To address this issue, ThreeBond has developed water-based pre-coating technologies, using water as the medium instead of relying on conventional organic solvents. ThreeBond's technical documentation highlights water-based pre-coating as a way to reduce VOC emissions and respond to increasingly stringent environmental regulations.
Water-based formulations can therefore offer an alternative to conventional solvent-based processes while maintaining the performance required for pre-coated fasteners. Today, ThreeBond offers a range of water-based MEC products, including acrylic and epoxy formulations with different strength and heat-resistance levels. A screw may look like a simple mechanical component, but its coating can fundamentally change the way it performs.
Whether the priority is strong locking and sealing, resistance to loosening, or sealing and lubrication, choosing the right pre-coating technology allows the fastener to be adapted to the application.
With MEC, ThreeLock and Sealock, ThreeBond's pre-coating technologies turn standard screws and bolts into functional fastening solutions.
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