Theoretically, a bearing’s life can exceed that of the machine in which it’s installed. But in reality, about 1/6th of premature bearing failures occur on account of poor fitting due to – Forceful Installation – Not using the correct fitting tools – Unawareness of the importance of correctly mounting bearings
IDEAL MOUNTING TECHNIQUES:
1. Mechanical mounting: Using a fitting tool, an impact ring and a sleeve against the bearing’s mountable ring to install the bearing ensures that the bearing fits firmly onto the shaft. The right mix of the impact ring and sleeve effectively distributes the mounting force across the ring of the bearing, reducing the risk of damage to the bearing’s raceways and rolling elements.
Rule of Thumb: – The bearings should ideally be positioned perpendicularly to the shaft, which should be slightly lubricated with a thin oil film.
2. Heat mounting: Using a bearing heater, which uniformly distributes heat across the bearing, a slight expansion in girth can be achieved to smoothly install the bearing. The bearing manufacturer specifies the heating limits, as they largely vary with the absence or presence of metal shields, lubricants and other design differences, which may react differently upon being subjected to heat as compared to the bearing. Typically, a temperature difference of 83ºC (150ºF) is sufficient to achieve the necessary expansion for smooth mounting, without causing irreversible changes in the metallurgy, brittleness and dimensions of the bearing and its accessories.
Rules of Thumb: -Don’t heat bearings to more than 125ºC (257ºF) unless otherwise stated. – Induction heaters for bearings are most effective and less hazardous than other lesser-recommended methods such as exposure to flames, hot oil baths and hot plates.
Words of Caution: The electric current of induction heaters magnetise the bearing, requiring immediate demagnetization to avoid metal particles getting attracted towards the bearing resulting in possible contamination, hence premature failure. It is recommended to opt for induction heaters which automatically demagnetize the bearings after the heating process.
3. Hydraulic Mounting:
This is the recommended method for mounting of large bearings (with interference fits).
Perfect mounting can be achieved through oil injection, usage of specialised hydraulic nut to develop the sufficient hydraulic pressure for smooth mounting along with a hydraulic pump and a pressure gauge.
You could save your machine and money simply by educating your users about proper mounting!