The chemical locking adhesive called threadlocker
Threadlocker is a chemical locking adhesive that is used to fill gaps between the male and female threads to bolt them together. One of the examples is Loctite threadlocker that completely fills all voids between interfacing threads to make an assembly a unified component that will prevent any movement between threads and will ultimately prevent any form of loosening. Locktite has seal threads that are extremely important for assembling through-bolts in an oil reservoir or cooling jacket in order to ensure that fluids are sealed in and corrosion cannot penetrate. The main criteria in the choice for threadlocker are the materials whether metal or plastic, diameter and thread length of the screws and bolts that will be used and their strength class. However, there are threadlockers that are universally applicable to a wide range of thread sizes.
Liquid threadlocking adhesives
Liquid threadlocking adhesives are some of the most reliable and cost effective ways to ensure that a threaded assembly will remain locked and leak proof during its entire service life. Proactive maintenance on threaded fasteners has been proven to increase equipment up-time. Maintenance activities that can counteract self loosening are achieved through the use of mechanical devices such as spring washers, wire retainers and locking bolts that are quite expensive and lack the reliability of a threadlocker. Mechanical devices can be compromised by corrosion. Threadlocker liquid adhesives can be applied in drops to fill the grooves of the thread and cure to hard thermoset plastic when exposed to metal ions in the absence of air. The threaded parts will lock together to form one conjoined part that will resist failure and deliver a high level of reliability. If the assemblies that are held together by threaded fasteners need to be disassembled for repairs, adjustments or maintenance, there are threadlockers available in low strength formulations that can be easy to remove using common hand tools.
Contrary to the belief of the majority, even the threadlocker of the highest strength can be removed with simple hand tools or direct exposure to 450-500oF for about 5 minutes. In addition, the strength and viscosity of the threadlocker which is required by an application is directly related to the size of the fastener that will be used so that a low strength threadlocker can be applied on screws up to ¼”in diameter. Medium strength adhesives are ideal for ¾” in diameter machine tools and mounting bolts. High strength adhesives work best for one inch or more diameters like assembly applications.