Strengthens Assembly, Prevents Moisture Ingress

Train bogie wheels are assembled utilising a heavy interference fit of 0.001” per inch of axle diameter, (typically 0.009” for a 9” diameter shaft). In addition, press-on tonnage of between 65-110 tonnes must be achieved and documented to ensure optimal assembly strength.
This can be an extremely difficult task, and the consequences of poor assembly can be expensive or even catastrophic. Therefore if metal pick-up occurs during assembly, the components will be scrapped, and if the tonnage is not achieved within specification, the wheel and axle must be separated and re-matched.

Eliminates Need for Expensive Machining or Brazing

A leading tool manufacturer in Australia was launching new model of pliers for electronic components. Customer considered press fits or brazing the pliers hands to the jaw. They found that all these methods were undesirable. Press fit involved expensive machining to maintain very tight tolerances. Brazing needed expensive brazing machines, was very much dependant of operator skills and was expensive too.

Replaces Expensive Shrink Fit, Reduces Assembly Time and Costs

Interference fit methods of press fit or shrink fit are commonly used for joining cylindrical parts. The bonding is provided by the friction between mating surfaces. In shrink fit mating parts have a high degree of interference and fit together either by heating or cooling the components. Shrink fit needs requires heating equipment and creates bottleneck in mass production. Further there are risks that during the assembly elastic limits of parts might be exceeded or parts may be deformed.

Augments Strength and Adds Reliability

Mehala Machines is a manufacturer of garment sewing machines in India. Mehala’s High-speed Integral Clutch Motors used in Sewing Machines had their rotors (silicone steel) fixed to shaft (En8) with interference press fits. The interference press fits hold the assembled parts together with friction and are expected to have high load bearing capability, however Mehala was receiving field complaints of rotor spin offs. When parts are assembled with the contact area is still limited to the high ‘peaks’ and ‘valleys’ on the mating surfaces and is typically less than 30 – 40% - due the load on mated parts and micro-movements these peaks and valleys are grinded off and the gaps increases resulting the spin-offs.

Eliminates Need for Expensive Machining

The drive bearing of a new model of portable cleaning machines needed to be mounted in the cast iron gear housing. As the Gear housing is cast, it is very difficult to maintain the tolerances. Machining the bearing seat area involved high machining cost and time. Henkel’s Loctite products were recommended for this application: Loctite 660 Quick Metal Retaining compound was used along with 7649 Primer to retain bearing to housing and Loctite 242 used to lock the screws of gear to housing which creates 100% metal-to-metal contact between the mating parts increasing the load carrying capability as well as preventing the area from fretting corrosion.