LOCTITE 243 Medium-Strength Oil-Tolerant Threadlocker for Stainless Steel, Aluminum and Plated Fasteners
LOCTITE 243 Medium-Strength Oil-Tolerant Threadlocker for Stainless Steel, Aluminum and Plated Fasteners
  1. LOCTITE 243 Medium-Strength Oil-Tolerant Threadlocker for Stainless Steel, Aluminum and Plated Fasteners
  2. LOCTITE 243 Medium-Strength Oil-Tolerant Threadlocker for Stainless Steel, Aluminum and Plated Fasteners

LOCTITE 243 Medium-Strength Oil-Tolerant Threadlocker for Stainless Steel, Aluminum and Plated Fasteners

1. Product Overview

Loctite 243 is a medium-strength threadlocker designed to prevent loosening caused by vibration. It is suitable for use on all metal threaded assemblies, including stainless steel and plated surfaces, and maintains strong locking performance even in slightly contaminated environments (such as those with industrial oils, cutting fluids, and lubricants).

2. Key Features

  • Suitable for All Metal Threads
    Loctite 243 can be used on steel, stainless steel, and galvanized threads, preventing loosening caused by vibration.
  • Oil Tolerance
    Maintains stable locking performance even in slightly oily environments, without the need for complete thread cleaning.
  • Medium-Strength, Removable
    Provides medium-strength locking while allowing for disassembly, ideal for threaded connections requiring periodic maintenance.
  • High Temperature and Chemical Resistance
    Withstands temperatures up to 150°C and resists various chemicals, making it suitable for harsh industrial environments.
  • Sealing and Anti-Loosening
    Not only prevents thread loosening but also fills gaps, preventing oil and gas leaks.

3. Product Specifications

  • Chemical Type: Methacrylate
  • Color: Blue
  • Viscosity: 900 – 1,500 mPa·s (cP)
  • Cure Time: 24 hours for full cure
  • Maximum Thread Size: M36
  • Operating Temperature Range: -55°C to +150°C
  • Shear Strength: 9.5 N/mm²
  • Breakaway Torque: 19 Nm (M10 bolts)
  • Prevail Torque: 7 Nm (M10 bolts)
  • Chemical Resistance: Excellent resistance to oils, lubricants, and industrial fluids

4. Applications

  • Machinery Assembly and Maintenance
    Loctite 243 ensures the stability of threaded connections in machinery under high vibration and shock conditions.
  • Automotive Manufacturing and Repair
    Widely used in automotive component assembly, especially in engines and transmission systems.
  • Heavy Industry and Manufacturing
    Performs excellently in industrial equipment and pipeline connections, suitable for harsh working conditions.
  • Oil and Gas, Chemical Industry
    Resists oil and chemical contamination in petroleum, natural gas, and chemical production, ensuring equipment safety.

5. How to Use

  1. Clean the Threads (skip if slightly oily): Ensure the thread surfaces are clean and dry.
  2. Apply the Adhesive: Evenly apply Loctite 243 to the thread surfaces.
  3. Assemble the Threads: Tighten the threads to ensure the adhesive covers evenly.
  4. Cure Time: Allow 24 hours at room temperature for full curing.
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LOCTITE 243 Threadlocker is a blue, one-component anaerobic adhesive developed for medium-strength locking and sealing of threaded metal fasteners. Its oil-tolerant, primerless formulation works on active and passive metals, including steel, stainless steel, aluminum and plated surfaces. When confined between close-fitting threads without air, it cures into a durable thermoset polymer that helps prevent loosening, leakage and corrosion caused by shock, vibration and repeated mechanical loading.

LOCTITE 243 Threadlocker Benefits

LOCTITE 243 Threadlocker provides reliable fastener locking while allowing normal maintenance disassembly with standard hand tools. This makes it suitable for pumps, gearboxes, presses, motors and other industrial equipment that requires vibration resistance together with future servicing or component replacement.

Unlike many conventional threadlockers, the product cures effectively on passive metals without requiring a primer under normal conditions. It can also cure through light coatings of corrosion-prevention oil and cutting fluid commonly found on as-received fasteners. Heavily contaminated components should still be cleaned to achieve the most consistent performance.

The thixotropic formulation reduces dripping and migration after application, helping operators place the adhesive accurately within the required thread-engagement area. Positive fluorescence under ultraviolet light also allows production teams to inspect application presence and coverage with suitable UV equipment.

Applications for LOCTITE 243 Threadlocker

LOCTITE 243 Threadlocker is recommended for metal bolts, nuts and studs used in industrial manufacturing, automotive assembly, equipment maintenance and general mechanical fastening. Typical applications include gearbox housing bolts, pump fasteners, motor mounting bolts, bearing-cover screws, machine frames, compressors, conveyors and hydraulic equipment.

The medium-strength cured bond prevents unwanted fastener movement while remaining removable without localized heat in most standard assemblies. By filling the microscopic spaces between male and female threads, the adhesive also seals potential leakage paths and limits the entry of moisture and corrosive contaminants.

Henkel identifies the product for use on all metals, including passive materials such as stainless steel, aluminum and plated components. Regional versions may also carry NSF/ANSI 61 certification for selected potable-water applications. Buyers should confirm that the required approval applies to the exact regional product and package supplied.

LOCTITE 243 Threadlocker Technical Properties

LOCTITE 243 Threadlocker is a blue anaerobic acrylate liquid with a typical specific gravity of approximately 1.08 at 23°C. Henkel lists a viscosity of approximately 2,150 mPa·s at 20 rpm, giving the product a controlled medium-viscosity application profile.

Typical fixture time is approximately ten minutes under representative conditions. Published performance on M10 steel nuts and bolts includes breakaway torque of approximately 26 N·m and prevailing torque of about 5 N·m. The listed service-temperature range is approximately -55°C to 180°C.

These figures are typical reference values rather than guaranteed purchasing specifications. Actual curing and final strength depend on metal activity, thread size, clearance, surface condition, application quantity, tightening torque and ambient temperature.

How to Apply LOCTITE 243 Threadlocker

Remove heavy oil, grease, dust, moisture and loose contamination from the internal and external threads. Light corrosion-prevention oil may normally remain, but heavily contaminated fasteners should be cleaned with a compatible LOCTITE degreaser and allowed to dry.

For through-hole assemblies, insert the bolt and apply the adhesive to the exposed thread-engagement area before installing the nut. For blind holes, dispense several drops down the sides of the hole into the lower thread section and apply additional material to the bolt when necessary.

Assemble and tighten the fastener to the specified torque before fixture strength develops. When passive metals or temperatures below approximately 5°C cause an unacceptable cure time, LOCTITE SF 7649 Activator may be evaluated. Allow the joint to cure fully before exposure to significant loads, heat or chemicals.

Why Choose LOCTITE 243 Threadlocker?

LOCTITE 243 Threadlocker combines medium-strength locking, oil tolerance, primerless curing, high-temperature capability and convenient maintenance removal. It is a dependable general-purpose solution for manufacturers and maintenance teams working with steel, stainless steel, aluminum and plated threaded fasteners.

Review the official Henkel LOCTITE 243 Technical Data Sheet and current Safety Data Sheet before qualification or production use. Explore our medium-strength threadlockers for additional removable fastener-locking solutions.

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