Thread securing with anaerobic adhesive

Many threaded units are unable to maintain their strength over time. For example, nuts, bolts, or pipe joints will often loosen over time when exposed to shocks or vibrations. Heat can also have an impact in this context. This problem can be solved by using anaerobic adhesive. By bonding the threads, their lifespan is increased because all gaps are filled, preventing the parts from loosening. Therefore, thread securing with anaerobic adhesive is a widely used method in industry.

About anaerobic adhesives
Anaerobic adhesives are one-component adhesives especially suitable for thread securing. They cure at room temperature when in contact with metal ions and cut off from oxygen. They are resistant to a wide range of chemicals and easy to apply both automatically and manually. Anaerobic adhesives come in many colors, viscosities, and strengths. They are used to prevent nuts and bolts from loosening over time or falling off completely, or as pipe seals to hold the assembly in place with a sealing effect. They have good impact resistance and heat resistance between 150 and 200ºC.

Strengths
When discussing adhesive strength, there are actually two factors to consider: the adhesive’s break torque and the adhesive’s prevailing torque. The break torque is where the adhesive ‘breaks’ when trying to separate parts by hand or tools. Even when the adhesive breaks, the parts may not necessarily separate immediately. Breakage of the adhesive is only the first step in the separation process. The prevailing torque indicates the force required to continue turning the part after the adhesive has broken. Imagine a nut on a bolt secured with anaerobic adhesive — the prevailing torque shows how much force is needed to keep turning the nut after breakage. Both torques are measured in Newton meters (Nm). For example, anaerobic adhesives can have break torques ranging from 6 to 60 Nm.
Some anaerobic adhesives have such high strength that parts cannot be separated after bonding. If separation is necessary, heating the adhesive/part can weaken the bond, typically requiring temperatures around 250ºC.

Approvals
Depending on the industry and application, it’s wise to check if the adhesive is approved for food, drinking water, or gas environments. Look for certifications such as British WRAS, German DVGW, or the international NSF. This is relevant in industries like meat processing or faucet production.

Passive and active metals
It is important to note the type of metal being bonded. Passive and active metals have significantly different chemical properties, resulting in much slower curing on passive metals. Fixing time can differ by hours depending on whether you bond on active metals like brass or passive metals like stainless steel. When bonding passive metals, it is advisable to use an activator containing metal ions to reduce curing time, which is beneficial in production.

Viscosities
Anaerobic adhesives come in many viscosities, allowing you to select the best one for the task. For threads, generally, the larger the tolerance, the more beneficial it is to use a higher viscosity adhesive. For pre-assembled parts, a low viscosity adhesive can penetrate more easily where needed.

Find the right adhesive for thread or screw locking
Visit our product overview for adhesives suitable for thread and screw locking.

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