Anaerobic adhesives are often known as ‘locking compounds’, being used to secure, seal and retain turned, threaded, or similarly close fitting parts. They are also used to bond coaxial assemblies and seal flange-faces.
A member of the acrylic family of adhesives, they are essentially low viscosiy liquids, although they can be formulated into pastes or thixotropic liquids. They are single-part adhesives which cure when air is excluded, hence the name anaerobic.
Solely under the influence of anaerobic conditions the cure rate is quite slow; in the presence of metal the cure rate is much faster and this, in practice, is how they are used – confined between closely fitting metal parts. The close fit excludes air and the metal surface speeds the rate of cure to a commercially useful degree.
Since hardening only takes place in the absence of air, these adhesives have the advantage that material outside the joint does not normally cure and hence can be wiped off after the assembly has reached handling strength. They are unique among adhesives in that they are made with different strength characteristics ranging from relatively weak materials, which allow the easy dismantling of large parts, to very strong materials for permanent fixing. Within each strength-band there will usually be several products of different viscosities, allowing different gaps to be filled at the same level of controlled strength. They can also be toughened (see toughened adhesives section) to provide greatly improved peel and impact values.
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Post time: May-11-2017