What lubricants are?
Lubricants are high expertise products which are considered integral parts of any operating machinery. The proper selection and use of lubricants is crucial for the proper, smooth and effective operation of every machine.
“Lubricants are base oil mixtures (lubricant derivatives of crude oil refining) and chemical additives which are primarily used to reduce friction between moving surfaces in contact, and which are capable of reducing the heat generated due to the produced friction during the surface movement. The property they have to reduce the friction is known as lubricity”.
Additionally, lubricants may be used as a means of power transmission, surface cooling (and heating) and/or circuit flushing.
FUNCTIONS OF A LUBRICANT
The main functions of the lubricant are:
- Friction minimization. The lubricant film developed between moving metal surfaces in contact simply does not allow this contact.
- Reduction of the growing heat. The more viscous the lubricant, the higher the internal friction and heat developed. Proper selection of the lubricant provides the necessary balance between what is necessary to protect the machine without creating excessive internal friction of the lubricant in use.
- Reduction of wear is the basic function of the lubricant. Generally, the more viscous the oil, the greater the protection against wear, with the additive also playing an important role. Modern additives allow the use of a low-viscosity lubricant to offer the same protection against wear.
- Removal of pollutants (maintenance in the suspended mass of the lubricant and dispersion of pollutants).
Protection against corrosion and rust. As lubricants “age”, they create corrosive by-products. The protection of the metal parts is undertaken by specific anti-corrosion/anti-rust additives.
MAIN CHARACTERISTICS OF A LUBRICANT
Lubricants are characterised by:
- High flash point and low pour point (in order to flow and lubricate in a temperature range)
- High viscosity index (in order to remain stable and to lubricate in a range of temperatures and temperature changes)
- Thermal stability
- Weaning (Water separation capability)
- Prevention of corrosion
- High acidity resistance
- Miscibility with other lubricants
- Effective function in high pressures and loads