Power Transmission


Fig. 1. The right method of lubrication must be selected to match the application conditions and purpose required.


4 Malcolm Watson and Tony Synnott discuss the grease versus oil debate for bearings, and how to achieve best practice in lubricant replenishment and replacement.


4 Malcolm Watson et Tony Synnott parlent du débat « graisse contre huile » pour les roulements, et comment appliquer les meilleures pratiques pour réapprovisionner et remplacer les lubrifiants.


4 Malcolm Watson und Tony Synnott diskutieren darüber, ob sich Fett oder Öl besser für die Lagerschmierung eignet und wie man bei der Nachfüllung und beim Ersatz von Schmiermitteln eine optimale Vorgehensweise erreichen kann.


Best practice in bearing lubrication


L


ubrication of industrial bearings is an essential tool for minimising friction and reducing wear


that could cause premature failure, by preventing direct metallic contact between the bearing’s rings, rolling elements and cage. An appropriate lubrication regime will also prevent foreign material from entering the bearing while guarding against corrosion or rusting. Any discussion of lubrication


Table 1. Examples of applications and grease consistency.


Consistency number


#0 #1 #2 #3


inevitably leads to a comparison between oil and grease lubricants, and a discussion of the pros and cons of each type. The right method of lubrication must be selected to match the application conditions and purpose to gain the best performance from the bearing, so selection of either will depend on the temperature of the operating conditions, and the speed of the process. There are several different types of oil


#4


lubrication methods – oil bath, drip feed, splash, circulating, jet, oil mist and oil air. Oil lubrication is generally suited to higher


Consistency (1/10mm)


355 to 385 310 to 340 265 to 295 220 to 250


175 to 205 Application


Central grease supply


Central grease supply, Low temperature


General grease General


grease, High temperature


High temperature


Where fretting occurs easily


Where fretting occurs easily


Sealed ball bearings


Sealed ball bearings


Where grease is used as a seal


speed and higher temperature applications and has a number of benefits. Its fluidity is good, lubricant replacement is easy, and removal of foreign material is also an easier process than with grease lubrication. It has a high limiting speed, and heat transfer is easily possible using the process of forced oil circulation. However, oil can be prone to leaking unless


measures are taken to effectively prevent it. Careful storage and sealing are also required. It is essential to use a lubricating oil which has suitable viscosity at the bearing operating


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