In every piece of dynamic machinery—from automotive engines and heavy equipment to complex electronic enclosures—threaded fasteners are constantly under attack. Shock, vibration, and thermal cycling cause even the tightest nuts and bolts to loosen, leading to system failure, costly downtime, and potential safety hazards.

While mechanical solutions like lock washers and nylon inserts offer some resistance, the definitive industrial solution for securing threaded assemblies is Anaerobic Threadlocker.

Threadlocking adhesives are liquid or semi-solid compounds applied to the threads of a fastener. They cure into a solid, durable plastic that fills the microscopic gaps between the threads, preventing movement and corrosion. This guide demystifies the different types of threadlockers and details how the Incure Re-Lok™ Series helps you choose the perfect strength level for your application.

The Universal Standard: Understanding Threadlocker Strength Codes

Industrial threadlockers are universally color-coded by their final cured strength. This classification is the single most important factor in product selection, as it dictates whether the fastener can be removed during maintenance.

1. Low Strength (Purple Threadlocker)

• Primary Function: Securing small fasteners (typically M6 and smaller) that require easy, quick disassembly with standard hand tools. Prevents loosening due to mild vibration.
• Ideal For: Adjustment screws, calibration screws, and fasteners in delicate electronic equipment where excessive torque could cause damage.
• Incure Example: Re-Lok™ B22 (Low-strength, Purple)

2. Medium Strength (Blue Threadlocker)

• Primary Function: The all-purpose, standard choice for most industrial and automotive applications (fasteners up to M20). Provides high resistance to vibration but allows disassembly with standard hand tools without heating.
• Ideal For: Machine tool access panels, pump mounts, motor covers, and any component requiring reliable serviceability.
• Incure Example: Re-Lok™ B43 (Medium strength, Blue, often formulated to be oil-resistant)

3. High Strength (Red Threadlocker)

• Primary Function: Permanent locking of major fasteners (up to M36). Designed for critical assemblies that must not loosen under severe shock, vibration, and extreme operating conditions.
• Ideal For: Suspension bolts, flywheel bolts, press fit components, and large assemblies in heavy machinery.
• Removal Requirement: Disassembly usually requires localized heat (e.g., 250∘C) to break down the adhesive, followed by specialized tools.
• Incure Example: Re-Lok™ B77 (High strength, Red)

Specialized Threadlocker Types for Unique Challenges

Beyond the standard strength categories, specific applications require advanced formulations based on cure speed, environment, or assembly method.

1. Wicking Grade (Green Threadlocker)

• Primary Function: Locking fasteners after they have been assembled. Wicking grade threadlockers are extremely low viscosity, allowing them to penetrate and cure in the microscopic gaps between mated threads via capillary action.
• Ideal For: Locking pre-torqued set screws, sealing welds, or fixing fasteners that are difficult to access for prior application.
• Incure Example: Re-Lok™ B90 (Medium strength, Green wicking grade)

2. High Temperature Threadlocker

• Primary Function: Maintaining locking torque in assemblies exposed to sustained, high operational temperatures that would degrade standard threadlockers (which typically top out around 150∘C).
• Ideal For: Exhaust manifolds, cylinder head bolts, heat exchangers, and any component near combustion chambers.
• Incure Example: Re-Lok™ B72 (High strength, rated up to 230∘C)

3. Oil-Tolerant Threadlocker

• Primary Function: Many industrial assembly environments involve light oil, cutting fluids, or preservative coatings. Oil-tolerant CAs are engineered to cure quickly and reliably even on oily or inert metal surfaces.
• Ideal For: Repair and maintenance applications where surface cleaning is difficult or impossible.

How Incure Recommends Your Ideal Threadlocker

The correct threadlocker is a product that balances security with serviceability and environmental resistance. Incure‘s technical specialists use a precise methodology to guide your selection from the Re-Lok™ Series:

1. Serviceability First: Do you need to disassemble the part for maintenance? (Low/Purple or Medium/Blue) Or is it a permanent joint? (High/Red)
2. Fastener Size: The required strength is proportional to the fastener size. We match the compound’s strength rating to your M-size (e.g., Re-Lok™ B22 for M6 and smaller).
3. Metal Type & Surface Condition: For passive metals (stainless steel, plated parts) or surfaces with minor oil contamination, we may recommend a specialized oil-tolerant formula (Re-Lok™ B43) or an anaerobic primer to ensure a reliable and fast cure.
4. Temperature Requirement: We ensure the maximum operational temperature of your assembly is well within the product’s thermal range, recommending Re-Lok™ B72 for applications above 150∘C.

By consulting with an Incure expert, you move beyond guesswork and secure a validated threadlocking solution that minimizes potential failure and optimizes your maintenance procedures.

Secure Your Assets Permanently

Don’t let vibration dictate the lifespan of your machinery. Anaerobic threadlockers are the most cost-effective, high-reliability solution for keeping threaded fasteners secured.

Ready to find the perfect strength and temperature-rated threadlocker for your critical assemblies?

Would you like to schedule a technical review with an Incure engineer to confirm the ideal Re-Lok™ product for your specific fastener size and temperature exposure?