Modern lubricants for demanding applications
Ensuring proper lubrication of the cooperating elements is one of the most important issues in the machinery’s construction and operational phases. The main reason for loss of production capacity of machines and equipment is friction-induced wear. Friction is estimated to be the root cause in close to 90% of failure cases.
Trends in the quality of lubricants, associated with the rapid development of various industries, indicate the need for high-quality products. Ever more restricted environmental requirements enforce the use of lubricants with reduced toxicity. The response to such excessive demands posed by the current state of the art are lubricants and greases based on complex, modified calcium sulfonate.
Greases and lubricants concentrated with complex, modified calcium sulphonate; due to its excellent properties such as high thermal resistance, high shear resistance, water and corrosion resistance, oxidation (ageing) resistance; meet the market needs for lubricants for special applications. Their worldwide production increases every year with the largest production volume recognized in North America. Although sulphonate lubricants are relatively expensive, their use brings great economic benefits: significantly decreased maintenance downtime and reduced risk of equipment malfunction providing desired quality of manufactured goods or increased safety due to reduced risk of leakage.
Moreover, the usage of calcium sulfonate lubricants can provide a reduction in the total consumption of grease by up to 50%.
Operational temperature range:
One of the most important parameters characterising these lubricants is the very high dropping point (above 300 °C), which provides performance at high temperature of grease operation. On the other hand, in low temperatures (down to -60 deg C), these lubricants are characterized by good pumping features thanks to their ability to maintain viscosity.
Resistance to water and washout:
The dynamic water washout test, carried out in accordance with ASTM D 1264, shows that Calcium Sulphonate-based lubricants are characterized by high water and washout resistance. This allows to use them in a damp environment or for applications where the lubricant is in contact with water.
Protection against corrosion:
The requirements of the modern market also entail the need for increased corrosion protection. Greases that are thickened with calcium sulphonate base meet these requirements, even without the use of additives (corrosion inhibitors). This is confirmed by tests under static conditions, carried out in accordance with ASTM D 1743, in both de-ionised water and synthetic seawater environments.
Resistance to oxidation - ageing
Premature oxidation can lead to the degradation of the base oil, resulting in premature hardening of the lubricant, which significantly aggravates its performance. Studies conducted in accordance with ASTM D 942 confirm the excellent oxidative stability of greases based on complex, modified calcium sulphonate.
The multifunctional grease must maintain the appropriate parameters in both hydrodynamic and boundary lubrication conditions.
The tests carried out on a four-ball apparatus, according to ASTM D 2596, prove calcium sulphonate based greases to provide a very high welding point load - ca. 500 [kg], confirming their excellent anti-friction properties.
Moreover, the results obtained from four-ball apparatus test, according to ASTM D 2266, show the diameter of the blemish to be, on average, 0.39 [mm] under a load of 40 [kg], which constitutes an outstanding performance at boundary conditions.
Due to the performance of Calcium Sulfonate-based greases, which already ensure high load capacity, it is not necessary to use the EP (extreme pressure) additives, making them more environmentally friendly.