Lubricating greases can be categorized into: calcium-based grease, composite calcium-based grease, barium-based grease, sodium-based grease, general lithium-based grease, extreme pressure composite lithium-based grease, aluminum-based grease, urea-based grease, bentonite grease, and sulfonated polymer grease, among others.
The advantages and disadvantages of various lubricants are as follows:
Calcium-based Grease: Also known as "Butter," calcium-based grease boasts excellent water resistance, a wide range of raw material sources, and affordability. It is suitable for lubricating various mechanical components exposed to damp environments or water contact.
The drawbacks include: low drop point, limited operating temperature not exceeding service life; poor heat resistance, prone to hardening in steam; and low shear resistance under high-speed conditions, unsuitable for high-speed applications. Composite calcium-based grease has a high drop point, water-resistant, with good mechanical stability, extreme pressure resistance, colloidal stability, and heat resistance; suitable for lubricating mechanical components subjected to heavy loads under high temperatures and humid conditions, with operating temperatures reaching those of barium-based grease, which is water-resistant and has good mechanical stability, is not soluble in gasoline and alcohol; commonly used in oil pumps, water pumps, ship propellers, and chemical pumps. Sodium-based grease has good heat resistance, with operating temperatures up to 120°C, and exhibits good extreme pressure and wear reduction properties; however, it has poor water resistance, emulsifying and thinning upon contact with water; suitable for bearings with significant vibration and high temperatures, particularly for lubricating low-speed, high-load mechanical components, and should not be used in damp environments or areas exposed to water.
Lithium Grease: Lithium grease boasts a high drop point, with a temperature range of -20 to 120°C, and exhibits excellent water resistance, mechanical stability, rust prevention, and oxidation stability. However, potassium grease has the drawback of poor anti-wear performance over time and is not suitable for mixing with other types of grease. It tends to leak oil easily during storage, and compared to non-metallic soap-based greases, it has a narrower temperature range and poorer water resistance, failing to meet the increasingly stringent requirements of modern industry. Extreme pressure composite lithium grease has a high drop point and good water resistance, with excellent extreme pressure anti-wear properties, making it suitable for lubricating gears, turbines, vane shafts, and bearings of high-load machinery operating at temperatures ranging from -20 to 120°C. Aluminum grease has good adhesion, water resistance, and a low drop point, usually around 70°C. As temperature rises, the adhesion of aluminum grease to metal decreases, and it is generally used only as a protective grease for optical instruments, not for lubricating equipment. The production process of composite aluminum grease is complex, requiring high energy consumption, and compared to sulfonated grease and composite lithium grease, it has a shorter bearing service life. Urea grease has a high drop point, hydrophobic properties, high-temperature resistance, and good oxidation stability; however, it is expensive and has poor shear resistance, with significant changes in consistency under high and low-speed shear conditions, making it prone to becoming thin and leaking. Therefore, strict protection requirements are necessary during production and use, and storage and transportation are difficult, with limited usage.
