Loctite - Advances in Anaerobics

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By Sam Chase, Application Engineering Systems Manager, and Shabbir Attarwala, Senior Scientist Loctite Corporation

The major appliance industry is intensely competitive, with manufacturers moving aggressively to strengthen their competitive positions worldwide. To reduce costs and improve profitability, appliance engineers continually strive to develop innovative product designs and manufacturing efficiencies using new technologies, including adhesives.

The use of anaerobic adhesives has become increasingly popular in appliance assembly applications, as they provide a number of manufacturing benefits. Typically used to augment the seal or holding force of a mechanically joined appliance assembly, anaerobic adhesives serve as threadlockers, thread sealants, retaining materials, and flange sealants. When designed into an appliance assembly, these adhesives are used to reduce component inventories (thereby decreasing total manufacturing costs), enhance equipment reliability, and minimize aftermarket breakdown and associated warrantee problems.

By definition, anaerobic adhesives remain liquid until isolated from oxygen in the presence of metal ions, such as iron or copper. For example, when an anaerobic adhesive is sealed between a nut and a bolt on a threaded assembly, it rapidly "cures" or hardens to form a tough cross-linked plastic with tenacious adhesion to many metals. Though anaerobic applications differ widely, in most cases the adhesive provides high shear strength.

  • When anaerobic adhesive products are used to lock threaded assemblies together, they prevent loosening and corrosion of the fastener, maintain proper clamping force, and offer controlled torque for removal of the assembly. Threadlocking adhesives can be found in almost any appliance where threaded fasteners are used; thread sealants are used in appliances with pipe fittings, such as dishwashers and washing machines.
  • For rigid cylindrical assemblies, such as joining a bushing into a shaft housing, anaerobic adhesives known as retaining compounds enable manufacturers to bond parts that, at one time, could only be assembled using press fits or shrink fits. In appliance applications, retaining compounds are most commonly found in motor and pump assemblies.
  • Anaerobic gasketing materials are widely used as formed-in-place gaskets that produce leakproof seals between mating flanges, preventing leakage of liquids or gasses. These materials can be found in motor and pump applications, as well as vacuum cleaners, stoves, ranges, microwave ovens, refrigerators, and other appliances where a seal must be created to block out moisture, gasses, fluids, or contaminants.

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