Most thread locking adhesives tend to display a thread friction coefficient which is higher than what is normally present in the threads, also, a slight prevailing torque characteristic will be present. By the correct specification of tightening torque both these effects can be accounted for accurately. Full cure of the adhesive is normally achieved within 24 hours but is dependent upon the finish applied to the fastener, the bond gap and ambient temperature. With the liquid applied adhesive an activator can be used to improve curing time. Measuring the assembly torque, dynamically, at the assembly stage does not present any problem when using adhesive to lock the threads together.
Problems are present however when the assembly torque is required to be checked after assembly.
The use of any of the three methods for torque auditing of threads which have been bonded by adhesive does present problems. If the cured bond is broken to check the torque, the vibration resistance of the fastener assembly may be impaired. Secondly, the hardened adhesive in the threads increases the threads friction characteristics so that on re-tightening less torque goes into achieving preload and more in overcoming friction. Due to these reasons any of the three methods for post assembly torque auditing are unsuitable for threads which have been bonded together by adhesive. A common method of checking that the specified assembly has been achieved is to re-tighten the joint up to the specified torque whilst checking that the male relative to the female member does not move.