Lubricants and grease are used in almost every type of moving equipment. Many people get it wrong on when to use oil and when to use grease. They may appear as though they have similar uses. However, lubricants are very different from greases. There are places you are supposed to use a lubricant and other places a grease. You might find it wrong if you interchange their uses and wouldn’t like the results. So when do you use grease and when do you use other lubricants?
When Do You Use Lubricants?
Lubricants are best used to minimize friction between moving parts of a machine and to reduce the passive resistance of fixed parts of metal. All types of lubricants are manufactured from crude oil after a certain refining phase. They come in different types; solid lubricants like Teflon and graphite, semi-solid lubricants like silicon gels, and fluid or liquid like oils.
All lubricants vary depending on their characteristics and performance. However, all of them have one common component, base oil. Lubricants mostly contain approximately 80% base oil of mineral or synthetic origin.
Lubricants are mainly used in high temperature and high-speed applications that don’t require heat transfer on bearing surfaces. They help in cooling the circulation units. Also, most lubricants are used in fluid film bearings that aren’t sticky. Using grease in these parts could attract dirt and unappealing accumulation of the grease. Excess use of grease in these areas could also lead to blockage. Thus lubricants are preferred over grease.
Fluid film bearings, however, tend to reuse oil over an extended period. These can cause contamination from humidity. To prevent the bearings from contamination, you should use a lubricant that;
- Resist foaming
- Easily separates from water
- Protects against corrosion and rust
- Demonstrates chemical stability to resist deposit formation and oxidation
When do you use grease?
Grease is generally designed to be applied on stems, threads, seat posts, cables, cantilever bosses and bearing surfaces. It can also be used where there is a barrier between two parts. Generally, grease is preferred to lubricants in bearing application where heat is relatively low and operate at moderate speeds. Grease is preferred in these areas specifically because of its good adhesion to the lubricated surfaces. They are also insoluble in water hence they resist being soaked making it last longer. In general, grease is preferred as it helps in energy loses and reduction of mechanical fatigue as a result of friction.
Aside from its lubrication purposes, grease acts as a barrier against external elements like heat, solvents, water, and dust. It is important to note that oil and grease are not interchangeable. You only use grease when it is inconvenient or impractical to use oil. Choosing either grease or oil depends on operating conditions and machinery design. You may use grease on:
- Wind turbines, where using oil could wear off the turbines
- Conveyors, where shock loading usually occur
- Applications where cohesion and adhesion are essential.
- Machines that run recurrently or are in store for a longer period. Grease doesn’t come off easily and helps protect machine parts from rust, and dust.
- Machines cannot be easily accessed for regular lubrication. A good quality grease can lubricate inaccessible or isolated parts for long periods without the need to replenish frequently.
- Machines operating under extreme conditions like slow speed under heavy load, shock loads and extreme cold or high temperatures.
- Damaged machine parts. Grease fills up holes enlarged by wear and can extend the life of damaged parts.
Lubricants and grease are essential in virtually every aspect of machinery. They help in lubricating moving parts hence making them last longer while also protecting them from rust and dust. Their uses vary depending on the areas to be lubricated. Lubricants, as seen, are mainly used to lubricate faster moving parts like pedals of a bicycle and machine parts using bearings. They could also be used in areas that are difficult to use grease like door hinges.
Grease, on the other hand, is used primarily on slower moving parts like conveyor belts or machines that are not occasionally used since it lasts longer. Grease is also preferred on these parts because it is insoluble in water hence helps protect the parts from dust and unwanted properties.