What is a threadlocker, and how does anaerobic adhesive cure?

What is a threadlocker?

The MightyLoc Taftlock datasheets describe each grade as an anaerobic thread locking compound for bonding and sealing threads and for retaining cylindrical parts. In use, that means locking nuts, screws and studs against vibration, sealing the threads they lock and retaining close-fitting cylindrical parts such as studs and bushes. For retaining cylindrical parts, Taftlock 43 is the only grade with a published retaining strength: over 8 N/mm² (8 MPa) compressive shear on steel pins and collars to ISO 10123. A threadlocker fills the small gaps between close-fitting metal parts; it is made for assembly, not for bonding two flat panels together. Taftlock 22 and 43 are dimethacrylate esters and Taftlock 71 is a methacrylate ester.

How does an anaerobic adhesive work?

“Anaerobic” means “without air”. The liquid cures in the absence of air and in the presence of metal ions. On an open surface, air keeps it liquid; once it is confined between close-fitting metal threads, air is shut out, the metal surface starts the cure and the liquid hardens into a solid that fills the thread. That is why it goes on threads and shafts rather than open surfaces, and why adhesive left outside the joint stays wet.

The metal matters. Active metals such as plain steel supply the metal ions that start the cure; less active surfaces such as stainless steel and plated or passivated fasteners supply fewer, so they cure more slowly. For these metals MightyLoc specifies Taftlock 43, which its datasheet rates ideal for less active materials such as stainless steel and plated parts; the datasheet names no activator. MightyLoc publishes no cure times on these metals, so allow longer before loading and trial the actual fastener. For Taftlock 22 or 71 on these metals, ask MightyLoc.

Purple, blue or red: which threadlocker strength?

On MightyLoc Taftlock, the colour gives the strength, following a convention common across the industry: purple for low strength on small fasteners that come apart with hand tools, blue for medium strength that is still removable and red for high strength where removal needs heat. Choose by thread size and by whether the joint will be taken apart again; a high-strength grade on a small fastener can need more torque to break loose than the screw can take, so it may shear or strip unless the joint is heated first.

Breakaway torque is the torque that starts a cured nut turning on a bolt that was not tightened before the cure; prevail torque is the torque that keeps it turning once the bond has broken. Both are measured on steel nuts and bolts to ISO 10964, so they compare grades with each other rather than describe a tightened joint in service. MightyLoc’s brochure notes they come from a controlled test and suggests users test their own joint. On M10 steel nuts and bolts to ISO 10964, breakaway torque is 6 N·m for Taftlock 22, 20 N·m for Taftlock 43 and 31 N·m for Taftlock 71. On an M10 joint pre-tightened to 5 N·m, Taftlock 43 needed 24 N·m to break loose. Thread sizes and each grade’s torques are in the torque table on the anaerobic adhesives page.

What does threadlocker work on, and what does it not?

MightyLoc Taftlock works between close-fitting metal threads, and each grade performs best in thin bond gaps. It is the wrong choice for:

• plastic or other non-metal threads, where it does not cure and where uncured adhesive can stress-crack some plastics such as polycarbonate;
• joints where both mating surfaces are painted, because paint prevents cure;
• flat surfaces, wide gaps, or joints where the adhesive itself would have to flex or carry the load (the fastener carries the load; the threadlocker only stops it working loose);
• mixed materials such as plastic or rubber to metal, where an instant surface bond from a cyanoacrylate such as MightyLoc Ninja 108 is the starting point.

Cyanoacrylate is no substitute for a threadlocker either. MightyLoc Ninja 108 fixtures in 3 to 20 seconds at 21 °C and fills gaps only up to 0.1 mm. It is rated to 80 °C continuous and cures rigid, so it does not suit fasteners that vibrate or run hot. The cyanoacrylate or anaerobic comparison sets the two side by side.

MightyLoc rates each Taftlock grade by thread size rather than by gap: Taftlock 22 up to 6 mm, Taftlock 43 from 6 to 20 mm, Taftlock 71 up to 25 mm. MightyLoc publishes no maximum gap for Taftlock: each datasheet says only that the grade performs best in thin bond gaps, so for loose or damaged threads ask MightyLoc before relying on the lock.

Where are threadlockers used?

MightyLoc’s brochure lists Taftlock for automotive engine bolts and nuts, electric motor fasteners, gear pump fasteners and engine and motor compressor screws and bolts. MightyLoc’s pages add these examples:

• set screws, adjusters and instrument screws that are checked often, with MightyLoc Taftlock 22;
• electric motor bolts and machine assembly bolts from 6 to 20 mm, with MightyLoc Taftlock 43 (small guard screws under 6 mm take Taftlock 22);
• stainless steel and plated fasteners from 6 to 20 mm, with MightyLoc Taftlock 43, which its datasheet rates for less active materials (for immersed or below-waterline fasteners, ask MightyLoc first: the datasheets give no sea-water data);
• engine bolts and nuts on vehicles, with the MightyLoc Taftlock grade chosen by fastener size and whether the joint is opened for service; rail bogie fasteners and other safety-critical fixings such as steering, suspension and brake fasteners follow the vehicle builder’s specification;
• transmission and engine-block studs, and studs and bushes that must stay put, with MightyLoc Taftlock 71 (fasteners up to 25 mm).

More in automotive, bus and truck bodies, marine work, metal fabrication, rail and transit vehicles and adhesives for bonding metal.

How long does threadlocker take to cure?

MightyLoc Taftlock reaches handling strength in 10 to 20 minutes, depending on the grade, functional strength in 1 to 3 hours and full cure in 24 hours, all on clean steel at room temperature. The handling time for each grade is in the table on the anaerobic adhesives page.

Leave the joint undisturbed until it reaches functional strength before returning it to service, and allow the full 24 hours before applying maximum load. Cure depends on the metal, the gap and the temperature: less active metals cure more slowly, and so does a cold joint. MightyLoc publishes no cure times below room temperature, so in cold conditions allow longer than the times above before loading the joint. The cure-time guide sets these times beside MightyLoc’s other chemistries.

What temperature range can threadlocker take?

All three MightyLoc Taftlock grades are rated from -55 °C to 150 °C. MightyLoc publishes no strength-at-temperature or heat-ageing data, so for a joint that runs near 150 °C for long periods, ask MightyLoc before relying on the range.

Heat is not the only test a locked thread faces. After 1,000 hours, MightyLoc’s datasheets give the three Taftlock grades 95 to 100 % of their initial strength in motor oil at 125 °C, 80 to 90 % in water and glycol at 87 °C, 80 to 90 % in acetone at 22 °C and 100 % in gasoline, brake fluid and ethanol at 22 °C. The datasheets do not state how the joints were cured or tested, so read these figures as a comparison between grades. Water and glycol is the engine coolant mixture; MightyLoc’s brochure lists good resistance to engine oils, coolants and brake fluids. The full chemical-resistance table is on each grade’s datasheet, and the service-temperature guide ranks every MightyLoc product by its upper limit.

Threadlocker or thread sealant: what is the difference?

A threadlocker is made first to stop a fastener working loose under vibration; because it fills the thread, it also seals the thread it locks. A thread sealant is made first to seal pipe threads and fittings against leaks of liquid or gas, usually on tapered threads and with a pressure rating for the job. MightyLoc’s datasheets describe all three Taftlock grades as for bonding and sealing threads, and the Taftlock 71 datasheet says it prevents corrosion and leakage. MightyLoc publishes no pressure rating or pipe-thread approval for Taftlock, so do not use it to seal pressurised pipework, gas or potable water lines without MightyLoc’s written confirmation.

How do you apply a threadlocker?

1. Make sure the threads are dry, clean and free of oil, grease and any other contamination.
2. Run a small bead onto the clean thread of the bolt before you fit it, enough to fill the threads. In a blind hole, put a few drops into the tapped hole as well, because trapped air can push adhesive off the bolt. Keep the bottle tip off the metal so the remaining adhesive is not contaminated.
3. Assemble and tighten to the specified torque straight away, well inside the handling time (about 10 minutes for MightyLoc Taftlock 71, 10 to 12 minutes for Taftlock 43, about 20 minutes for Taftlock 22). Do not re-tighten once the adhesive has started to cure. MightyLoc Taftlock is formulated to give controlled friction and torque/tension ratio during assembly; MightyLoc publishes no nut factor, so where clamp load is critical, confirm the tightening torque with the equipment maker.
4. Leave the joint undisturbed until functional strength, and allow 24 hours before full load.
5. Wipe the bottle tip clean after use, and never pour unused adhesive back into the bottle.

How do you remove threadlocker?

• MightyLoc Taftlock 22 (purple). Undo it with standard hand tools; it releases without heat or special tools.
• MightyLoc Taftlock 43 (blue). Undo it with hand tools.
• MightyLoc Taftlock 71 (red). The bond is near-permanent. Heat the joint locally, on the nut or bolt head, to soften the cured adhesive, then undo the fastener with hand tools while it is still hot; if it cools, heat it again. Keep the heat away from seals, wiring, plastics and fuel or brake lines. MightyLoc does not publish a removal temperature, but since Taftlock 71 is rated to 150 °C, expect to need more heat than that. For a high-strength bolt, check with the equipment maker whether it may be reused after heating.
• Reusing the thread. Brush the old cured adhesive out of both threads and clean them before applying fresh Taftlock: the datasheets ask for surfaces that are dry, clean and free of any contamination.

Why do storage and handling matter?

Never pour unused adhesive back into the bottle, because it can contaminate the rest and affect cure. Wipe the bottle tip clean after use. Keep unopened MightyLoc Taftlock bottles in a cool, dry place between 8 and 25 °C, which in Singapore means an air-conditioned store; stored this way, each grade has a 2-year shelf life. All three grades come in 50 mL bottles.

Samples, datasheets and where to buy

• Request a sample. The sample form lists MightyLoc Taftlock 22, 43 and 71. You can ask for several at once; say what you are fastening, the thread size and the metal in the notes.
• Read the datasheet for your grade. Datasheets for Taftlock 22, Taftlock 43 and Taftlock 71 are open to read and download, with no login.
• Talk to the team. Tell MightyLoc your fastener sizes, metals and service conditions through the contact form (choose “Technical support”), or call +65 6766 7191.
• Where to buy. Singapore: MightyLoc, 1 Bukit Batok Crescent, #05-40 WCEGA Plaza, Singapore 658064. Elsewhere: MightyLoc is supplied from Singapore, with export reach across South East Asia, the India sub-continent and the Middle East; ask the Singapore team.
• Read on. The anaerobic adhesives page compares the three grades; adhesives for bonding metal sets Taftlock beside MightyLoc’s structural and surface adhesives; the cyanoacrylate or anaerobic comparison helps when the job is not a thread.