Combined chemical and mechanical screw thread locking - uses grains of carborundum embedded in synthetic resin coated under bolt head

摘要

The method of locking screw threads uses a combined chemical and mechanical fixing. The metal surfaces which lie under the nut or the head of the bolt are coated with a synthetic resin which is mixed with grains of carborundum. The bolt or nut is tightened and the resin allowed to harden. The grains of carborundum are forced in the mating surfaces and so offer a very high resistance to any slackening of the nut of bolt. Tests show that the torque required to undo a nut or bolt, which has been locked in this way, is increased by 50%. If the resin is allowed to harden fully over 24 hours the increase in torque is 75%.