The latest news about anaerobic adhesive technology.
Early anaerobic threadlockers were effective at maximum
continuous operating temperatures of 300°F and were unreliable in
high-temperature applications. Current anaerobic adhesives have been formulated
to withstand temperatures up to 650°F without degrading.
New high-temperature/high-strength anaerobics thrive in demanding applications
and environments, including industrial ovens and boiler rooms, as well as
heat-treating operations in refineries, paper mills, metal-fabrication plants,
and glass-manufacturing facilities. Despite their high heat resistance, these
new threadlockers can be removed with standard hand tools after the fastener is
heated to 700-750°F for about five minutes.
Recent advances in the stability and reactivity of anaerobic
chemistry have resulted in gel and stick formulations that work as well as
traditional liquids but offer unlimited vertical and overhead application
potential. Both gels and semi-solid sticks can be used in applications where
liquids could be too messy or could migrate into problem areas.
Regardless of their physical form, all anaerobic adhesives facilitate fastener
assembly by providing lubrication as the fastener is tightened. This
lubrication allows applied torque to be converted into high clamp load instead
of dissipating as friction or heat. On bolts that are 7/8-inch in diameter or
larger, friction between the threads reduces potential clamp load. Recently
developed high-lubricity threadlockers more effectively control friction and
reliably convert torque energy into clamp load.
The odor of traditional anaerobic adhesives can be a concern when the materials
are used in confined space applications. New anaerobic products are available
with greatly reduced odor, allowing users to work in close proximity to the
liquid with less exposure to chemical fumes.
For more information, contact Henkel Corp., One Henkel Way, Rocky
Hill, CT 06067, or visit www.henkelna.com/loctite.
SIDEBAR: Anaerobic GlossaryThreadlocking adhesives.
adhesives fill the grooves of threads and cure to a hard thermoset plastic that
locks threads together, preventing unwanted movement or loosening and leakage
or corrosion. These adhesives offer high shear strength, good temperature
resistance, rapid cure, easy dispensing and excellent vibration resistance.
They can reliably and inexpensively ensure that a threaded assembly will remain
locked and leakproof for its entire service life.
These easy-to-apply products
block the naturally occurring leak path located where the crest and the root of
a pipe thread meet. Once cured, these materials seal and lock threads. During
assembly, they act as a lubricant to promote tightening while ensuring
consistent assembly torque.
These materials provide instant low-pressure (500 psi) seals, and many
formulations will seal to pressures of 10,000 psi after cure. Thread sealants
can seal pipe unions and compression fittings, and provide exceptional fluid
compatibility and sealing ability.
Anaerobic retaining compounds
are applied to the inside and outside diameter of parts and enable rigid
cylindrical assemblies to be bonded with adhesives rather than by mechanical
means, such as press fits or shrink fits. Once cured, retaining compounds offer
high adhesion to metal surfaces through mechanical interlocking and chemical
bonding. Retaining compounds are used to assemble clearance, slip and
interference fits. They also fill imperfections and augment fits on worn shafts
and slip fits.
Formed-in-place anaerobic gaskets and flange sealants.
These materials produce leakproof seals between mating flanges, preventing the
release of moisture, gasses, fluids, or contaminants. Formed-in-place gaskets
and sealants fill the surface roughness between mating metal parts and add
structural strength to an assembly. In their uncured state, anaerobic gaskets
and flange sealants flow into the microscopic surface irregularities on metal
substrates and fill the voids between flange faces. When cured, they unitize
the assembly, withstand thermal expansion of the mated parts, and resist a
range of chemicals. These materials can be applied to any size flange,
minimizing cut gasket inventories.