The use of an engineering adhesive to secure bearings into housings or onto shafts has many merits, says Henkel
Henkel Loctite states that retaining compounds provide an effective and economical method of eliminating loosening, backlash, fretting corrosion and wear by unitising the assembly and ensuring uniform stress distribution. Applied as a liquid, LOCTITE retaining compound fills all the voids between mating metal surfaces and creates 100 percent contact, with load and stress distributed evenly over the joint. The method eliminates the need for expensive replacements parts, time-consuming machining or the use of mechanical methods such as pins, key/keyway assemblies, splines and serrations, clamp rings and press-, shrink- and taper fits says Loctite.
The company also states that using a retaining compound in conjunction with shrink fit or press fits has benefits too in that it allows higher load transmission and performance with existing design and geometry solutions: or equal performance through lower interference and lighter weight constructions. For most maintenance professionals the decision to use a retaining compound in preference to measures such as machining and sleeving is based on time and efficiency and it was the reason why a cement manufacturer chose this method over mechanical alternatives in a recent application. A loose, spinning bearing had damaged a large fan shaft and although hard facing and machining was considered by the company, it would have resulted in five days of production downtime as well as concerns over the increased likelihood of future weakening from distortion and fretting corrosion.
The preferred solution in this case was the use of the retaining compound LOCTITE 638. Maintenance personnel removed and cleaned the main bearing, applied the adhesive to the shaft and slipped the bearing into position to restore the fan to full working order. This took just eight hours, a small fraction of the time required for hard facing and machining according to Loctite. WRAS approved LOCTITE 638 is a high strength retaining compound which the company recommends for applications requiring high resistance to dynamic, axial and radial loads. It is said to be well suited to the industrial environment as it tolerates minor surface contaminants and cures on inactive metals without an activator.