What are Additives?
What are the roles of Additives in lubricating oils?
Additives are substances formulated for improvement of the anti-friction, chemical and physical properties of base oils (mineral, synthetic, vegetable or animal), which results in enhancing the lubricant performance and extending the equipment life.
Combination of different additives and their quantities are determined by the lubricant type (Engine oils, Gear oils, Hydraulic oils, cutting fluids, Way lubricants, compressor oils etc.) and the specific operating conditions (temperature, loads, machine parts materials, environment).Amount of additives may reach 30%.
Different types of Additives are ,
1-Friction modifiers-Friction modifiers reduce coefficient of friction, resulting in less fuel consumption.
2-Anti-wear additives-Anti-wear additives prevent direct metal-to-metal contact between the machine parts when the oil film is broken down. Use of anti-wear additives results in longer machine life due to higher wear and score resistance of the components.
3-Extreme pressure (EP) additives-Extreme pressure (EP) additives prevent seizure conditions caused by direct metal-to-metal contact between the parts under high loads.
4-Rust and corrosion inhibitors-Rust and Corrosion inhibitors, which form a barrier film on the substrate surface reducing the corrosion rate.
5-Anti-oxidants-Mineral oils react with oxygen of air forming organic acids. The oxidation reaction products cause increase of the oil viscosity, formation of sludge and varnish, corrosion of metallic parts and foaming.
6-Detergents-Detergents neutralize strong acids present in the lubricant (for example sulfuric and nitric acid produced in internal combustion engines as a result of combustion process) and remove the neutralization products from the metal surface. Detergents also form a film on the part surface preventing high temperature deposition of sludge and varnish.
7-Dispersants-Pour point is the lowest temperature, at which the oil may flow. Wax crystals formed in mineral oils at low temperatures reduce their fluidity.
8-Pour point depressants-Viscosity of oils sharply decreases at high temperatures. Low viscosity causes decrease of the oil lubrication ability.
9-Viscosity index improvers-Viscosity index improvers keep the viscosity at acceptable levels, which provide stable oil film even at increased temperatures.
10-Anti-foaming agents-Agitation and aeration of a lubricating oil occurring at certain applications (Engine oils, Gear oils, Compressor oils) may result in formation of air bubbles in the oil – foaming. Foaming not only enhances oil oxidation but also decreases lubrication effect causing oil starvation.