Technical Information

When selecting industrial oils and greases, viscosity, operating temperature, load, speed, and equipment manufacturer requirements are all considered together. This guide explains the basic lubrication terms used in technical data sheets.

Viscosity and oil selection

Viscosity is the resistance of a fluid to flow. Kinematic viscosity is expressed in mm²/s or cSt; 1 cSt = 1 mm²/s. The measurement temperature should be the same when comparing values. In the selection of hydraulic oil, gear oil, and compressor oil, viscosity class, performance requirements, and material compatibility are checked together.

Viscosity index (VI)

The viscosity index (VI) describes how the viscosity of an oil changes with temperature. A high VI indicates that the viscosity changes relatively less when the temperature changes. It alone does not guarantee wear protection or pumpability at low temperatures.

Yield point

The pour point is the lowest temperature at which oil can flow under defined test conditions. It is not the same as the equipment's safe operating temperature limit. Viscosity and pumpability should also be evaluated for cold start-up.

Total number of acids (TAN) and total number of bases (TBN)

TAN is a measure of the acidic components in the oil, while TBN is a measure of the basic reserve that can neutralize acids; results are expressed in mg KOH/g. TBN is not the name of an additive. In used oil analysis, the new oil value, the change over time, the test method, and the manufacturer's limits are interpreted together.

Components of grease

Lubricating grease consists of a base oil, thickener, and additives. The base oil forms the lubricating film; the thickener supports the structure and retention of the oil. Additives improve performance characteristics such as wear, corrosion, and oxidation resistance. The color of the grease alone does not indicate quality or suitability.

NLGI grade and grease consistency.

The NLGI rating describes the relative softness or hardness of the grease. The classification ranges from 000 to 6. NLGI rating and base oil viscosity are distinct characteristics. Both should be considered when selecting bearing grease and central lubrication system grease.

Dropping point and operating temperature

The dropping point is the temperature at which the first drop of grease separates under defined experimental conditions; it is not the continuous operating temperature of the grease. In selecting high-temperature greases, base oil, oxidation resistance, speed, load, and relubrication interval are evaluated. Temperature specifications for assembly pastes cannot be directly applied to bearing greases.

Mechanical Stability and Grease Compatibility.

Mechanical stability is the ability of grease to maintain its consistency during operation. Excessive softening can lead to leakage, while hardening can cause dispensing problems. Different greases should not be considered compatible, even if they have the same color or NLGI class. Manufacturer's recommendations should be followed when changing products.

Base Oils and Additives

Mineral and synthetic base oils are used for different application requirements. The performance of the lubricant depends on the properties created by the combination of the base oil and the additive package. The term "synthetic" alone does not imply suitability for all equipment; miscibility and seal compatibility must be checked.

Technical Data Sheet and Product Selection

The technical data sheet (TDS) provides typical product characteristics and applications; the safety data sheet (SDS/GBF) provides information on safe handling and storage. For product selection, please share the equipment model, available oil or grease, temperature, speed, load, and ambient conditions.

For technical information and documentation requests regarding industrial oils, specialty greases, metalworking fluids, chain oils, and hydraulic oils, please contact: info@gatamerk.com

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