Thread locking

Activation by a metal surface also takes place in the commercially important anaerobic adhesives. These one-part adhesives are stable in the package, but cure quickly in an oxygen-free environment such as a tightly controlled bond line. Important applications include thread-locking, sealing, retaining, and some structural bonding [111]. A representative model formulation has recently been described [112] (Fig. 3). 

Second, having high assembly torque to prevent vibrational loosening is frequently ineffective, since creep in the plastic will reduce the effective assembly torque even if the fastener does not rotate. Using vibra-tionproof screws, lockwashers, locknuts, and thread-locking adhesives are usually a better alternative when loosening is considered a problem. 

Polyester resins and anaerobic adhesives and sealants have also exhibited high radiation resistance. Anaerobic adhesives have several years of long-term exposure in radiation environments due to their use as thread locking sealants in nuclear reactors and accessory equipment. 

Thread locking grades of anaerobic adhesives have sustained 2 x 107 rads without molecular change or loss of locking torque.77... 

Sealing, Lubricating and Wicking Compounds Thread Locking... 

Anaerobic adhesives for surface sealings and thread-locking devices, furthermore,... 

Self Locker. [Hemon Mfg.] Preapplied anaerobic thread locking adhesives. 

Thread locking. The first applications for anaerobic adhesives were for locking threaded fasteners. Filling the inner space between a nut and bolt with a hard, dense material prevents self-loosening. 

In the absence of oxygen and in the presence of metals, anaerobic acrylic sealants, e.g., Loctite, Tree-bond and Sta-Lok, polymerize rapidly. Dimethacrylates are their principal components (Dempsey 1962 Ranch-off and Taylor 1985 Conde-Salazar et al. 1988 Kanerva et al. 1989). Diethylene glycol dimethacrylate oligomer is most commonly used for screw-thread locking, whereas urethane dimethacrylate is used for retaining and locking flat metal surfaces (Bjorkner 1995)-... 

Remember that the only satisfactory way of ranking anaerobic thread-locking media is to measure their prevailing torque by Method D of MoD, DTD 5628, which does not assess their actual anti-vibration capacity (see Section 2.3.2.1 and Table 2.3). 

Occasionally, it is convenient to apply the thread locking medium after assembly. Low-viscosity anaerobic compositions (10-15 mm- s ), ideal for these situations, will generally be readily drawn into the thread by capillary action. If the joint is to be sealed as well as locked, then appropriate techniques should be developed (see Figure 2.26). 

Figure 2.26 Postassembly thread locking. A high-strength, low viscosity anaerobic adhesive has been used to lock an M8 nut and bolt assembly. The adhesive was applied after the nut was tightened. Actual results obtained from a material to DTD 5633/Gl with a performance characteristic similar to pattern B in Figure 2.21.

The use of epoxy adhesives as thread-locking adhesives is somewhat limited by poor adhesive tolerance of oily surfaces. The use of a variety of... 

One of the most important applications for anaerobics is the thread-locking of mechanical fasteners which might loosen with vibration. A range of strengths are available to allow disassembly and use on a wide range of thread diameters. 

Typical Use Fixing and locking of components. Typical Use Thread locking of items that require dtemantling. ... 

Typical Use Fixing of close fitting items, not requiring dismantling. Typical Use Thread locking and sealing of threads and cylindrical ... 

Thread-locking/sealing. Sealing porous weld seams. ... 

Notes Other versions NR603 - medium strength, thread-locking and sealing, Notes Thread < M10. Optimum clearance (D-d) 0.01 mm. x DIN 54 452. ... 

Typical Use Thread locking mechanical fasteners. Typical Use Mounting rotational symmetrical joints (bearings, bushes) ... 

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