The performance of lubricants (lubricating grease) is a comprehensive reflection of the composition and preparation process of lubricants (lubricating grease). The testing of lubricant (lubricating grease) performance is not only of decisive significance in production and research work, but also essential in the selection and inspection of lubricants (lubricating grease) in the production and user departments. Practice has proven that physical and chemical performance tests, simulation tests, and bench tests are essential steps for developing new lubricants (lubricating greases):

(1) Evaluate the physicochemical properties of lubricating oils in the laboratory. The test method must be representative, simple, and fast.

(2) Simulation test. Test specific mechanical components lubricated with lubricating grease under standardized test conditions (such as temperature, speed, load, etc.). The selected experimental conditions should be able to simulate actual usage as much as possible.

(3) Bench test. Evaluate the performance of internal combustion engine oil after operating under standardized conditions for a certain period of time on the selected engine. The results of engine bench tests are the basis for determining the quality level of internal combustion engine oil, and are particularly important for internal combustion engine oil.

In production and sales, physical and chemical tests are used as the main measure of product performance. The performance of lubricants (lubricating grease) and the content of the three testing steps are described below.

一、 Performance of lubricating oil

The essential basic performance of modern lubricating oil is to ensure the minimum viscosity of mechanical lubrication; High viscosity index with small temperature variation in viscosity; Excellent antioxidant and heat resistance; Good liquidity under convenient conditions; Excellent wear resistance and lubricity; Strong ability to dissolve oxidation products; No corrosion or rust on machinery; Low volatility in the usage environment; Good anti emulsification and anti foaming properties.

二、 Physical and chemical performance test

The physical and chemical performance test is simple, fast, and representative. The commonly used physical and chemical performance test items are:

(1) Viscosity: It is a measure of the frictional resistance within the flow of a liquid, the most basic indicator for evaluating the flowability of oil products, and an important indicator for the classification, quality identification, and determination of various lubricating oils. Lubricants with the same fraction but different chemical composition have different viscosities.

Dynamic viscosity: Dynamic viscosity is a measure of the internal friction force of a liquid when flowing under a certain shear stress, and its value is the ratio of the shear stress applied to the flowing liquid to the shear rate. In the International System of Units, it is expressed in pascals per second. The dynamic viscosity measured at low temperature can characterize the low-temperature starting performance of oil products.

Kinematic viscosity: It is a measure of the internal friction force of a liquid flowing under the action of gravity. Its value is the ratio of the dynamic viscosity of the liquid to its density at the same temperature, expressed in meters per second in international units.

(2) Viscosity index: It is a widely used quality indicator internationally to control the viscosity temperature performance of lubricating oil. The higher the viscosity index, the smaller the viscosity of the oil changes with temperature.

(3) Pouring point and freezing point: Pouring point is the lowest temperature at which a sample that has been cooled under specified conditions can flow, in ℃; The solidification point is the highest temperature, in ℃, at which the sample is cooled to a stop under specified conditions. The lower the pour point and pour point, the better the low-temperature performance of the oil.

(4) Acid value: The number of milligrams of potassium hydroxide required to neutralize acidic substances in 1 gram of oil is called acid value, in milligrams of KOH per gram. The acid value reflects the total amount of organic acid contained in the oil product. The more severe the oxidation of the oil product, the greater the increase in its acid value. It is an important indicator of the quality and deterioration of the oil product.

(5) Chromaticity: refers to the result obtained when the color of an oil product is closest to the color of a certain standard color plate under specified conditions. Chromaticity is a marker used to preliminarily identify the depth of oil refining and the degree of oxidation and deterioration during use.

(6) Flash point: The open flash point is the flash point measured using a specified open cup flash point tester, expressed in ℃. Oil products are heated under specified test conditions, and their oil vapor forms a mixture with surrounding air, which comes into contact with flames
The minimum temperature at which a flash fire occurs. Usually, the higher the flash point, the higher the operating temperature of the oil. But the flash point is by no means the limit of high temperature use.

(7) Kang's residual carbon: refers to the residual carbon measured using a Kang's residual carbon analyzer. Under specified conditions, the oil evaporates under heat, and the residual carbon residue after combustion is called residual carbon. The size of residual carbon value is related to the depth of oil refining and the degree of deterioration during use.

(8) Ash content: Inorganic matter obtained by calcining the residue of carbonized oil under specified conditions, expressed in%. The ash content in the oil will increase the accumulation of carbon in the engine and increase the wear of the components.

(9) Mechanical impurities: refers to all impurities that are insoluble in solvents in oil products, with a unit of%.

(10) Moisture: refers to the water content in the oil product, expressed in%. Water content is generally not allowed in oil products.

(11) Sulfate ash: refers to the burning constant weight of the carbonized residue of an oil product, which is converted into sulfate under specified conditions by sulfuric acid treatment, with a unit of%.

(12) Insoluble substance: The impurities remaining on the filter paper after filtering the oil dissolved in organic solvents are called insoluble substances, with a unit of%. Used for determining n-pentane and toluene insoluble substances in used lubricating oils.

(13) Foam property: under specified conditions, the foam propensity and foam stability of oil products are determined, in milliliters. Used to determine the separation ability of oil and gas after air is mixed in the oil.

(14) Anti emulsification (water separability): refers to the ability of an emulsion formed by oil and water to be divided into two layers, expressed in fractions.

(15) Aniline point: The lowest temperature at which an oil product is completely miscible with an equal volume of aniline under specified conditions, called the aniline point, measured in ℃. The lower the aniline point, the higher the aromatic content in the oil.

(16) Neutralization value: It is a measure of the acidity and alkalinity of oil products, and is also a common term for the acidity or alkalinity of oil products. It is a quantity value expressed as the equivalent amount of alkali or acid required to neutralize 1 gram of oil products, in milligrams of KOH per gram.

(17) Corrosion test: It is a test conducted under specified conditions to test the corrosion effect of oil on metals, in order to qualitatively determine the amount of acidic substances in the oil, in grams per square meter; Another corrosion test is conducted on copper sheets, with the unit being level.

(18) Rust resistance: refers to the ability of an oil product to prevent rusting of metals in contact with it, observed qualitatively.

(19) Sulfur content: refers to the content of sulfur and its derivatives, such as hydrogen sulfide, mercaptan, etc., present in oil products, in%. Mainly characterizing the refining depth of oil products and the composition of the processed crude oil.

(20) Oxidation stability: The ability of an oil product to resist the action of air or oxygen and maintain its properties without permanent changes, measured in hours.

(21) Total Base Number: The amount of acid required to neutralize all reactive components present in 1 gram of oil under specified conditions, in milligrams of KOH/gram. It is an indicator used to determine the effective additive composition in oil products, indicating the neutralization ability of lubricating oil.

(22) Saponification value: The amount of potassium hydroxide consumed to neutralize and saponify 1 gram of substance under specified conditions, in milligrams of KOH per gram.

(23) Evaporation loss: The mass fraction of the loss of an oil product after evaporation under specified conditions.

To learn more about lubrication, friction, wear, and other mechanical related knowledge, you can visit the Jinan Yihua Tribology website, which has a technical support module that provides more comprehensive content.

三、 Common simulation tests:

(1) Four ball testing machine simulation test: The four ball testing machine simulation test can determine the friction reduction, wear resistance, and extreme pressure properties of lubricating grease. The friction reduction is represented by the coefficient of friction "f"; The wear resistance is represented by the diameter of the wear mark "d"; Extreme pressure is represented by the maximum bite load "PB" and sintering load "PD".

The standard test methods in China include GB/T 12583 Lubricant Bearing Capacity Measurement Method, SH/T 0189 Lubricating Oil Wear Performance Measurement Method, SH/T 0202 Lubricating Grease Four Ball Machine Extreme Pressure Measurement Method, and SH/T 0204 Lubricating Grease Four Ball Machine Wear Performance Measurement Method.

Foreign standard test methods include the American ASTM D 2783 extreme pressure test method for lubricating oil, ASTM D4172 extreme wear test method for lubricating oil, ASTM D2596 extreme pressure test method for lubricating grease, and ASTM D2266 extreme wear test method for lubricating grease.

If the simulation test is conducted according to the SH/T 0189 standard for measuring the wear performance of lubricating oils, the MMW-1A microcomputer controlled universal friction and wear testing machine or the four ball series (MRS-10A, MRS-10P, MRS-10G) can be used. If other standards are referenced, the four ball series testing machine should be selected, which is MRS-10A, MRS-10P, or MRS-10G.

(2) Timken testing machine simulation test: The Timken testing machine simulation test evaluates the anti scratch ability of lubricating grease, using the OK value as the evaluation index.

The standard test methods in China include GB/T 11144 Measurement of Extreme Pressure of Lubricating Oils.

The foreign standard test methods include the American ASTM D2782 method for determining the extreme pressure of lubricating oil and the ASTM D2509 method for determining the extreme pressure of lubricating grease.

This simulation test can be completed using the MRH-5A ring block wear testing machine (Timken testing machine).

(3) Falex testing machine simulation test

The simulation test of the Falex testing machine can evaluate the extreme pressure and wear resistance of lubricants, with the load at the time of test failure (seizure) as the evaluation index.

The standard test methods in China include the SH/T 0187 extreme pressure test method for lubricating oil and the SH/T 0188 method for measuring the wear resistance of lubricating oil.

Foreign standard test methods include the American ASTM D 4007 Standard Method for Determining the Extreme Pressure Property of Liquid Lubricants (Type O), ASTM D2670 and 2714 Standard Methods for Determining the Wear Characteristics of Liquid Lubricants (Type I).

(4) Coking plate test

The coking plate test evaluates the thermal stability of lubricating oil by using the tendency of heated lubricating oil to coking in brief contact with high-temperature (310~320 ℃) aluminum plates. This method has a certain correlation with Caterpillar 1H2 and 1G2 engine testing.

The standard test methods in China include the SH/T 0300 crankcase simulation test method.

The foreign standard test method includes the American FTM 3462 coking plate test (QZX method).

(5) Low temperature viscosity determination method

The low-temperature viscosity measurement method is used to measure the low-temperature viscosity of engine oil at high shear rates between -50 and -30 ℃. The obtained results are related to the engine's starting ability.

The standard test method in China is the GB/T 6538 Determination of Apparent Viscosity of Engine Oil (Cold Start Simulator Method).

The standard test method abroad includes the American ASTM D 2602 method for determining the apparent viscosity of engine lubricating oil at low temperature (CCS).

(6) Determination of low-temperature pumping performance

The low-temperature pumping test method is used to predict the boundary pumping temperature of engine oil in the range of -40~0 ℃ at low shear rates.

The standard test method in China includes the GB/T 9171 method for predicting the boundary pumping temperature of engine oil.

The standard test method abroad includes the American ASTM D3830 method for predicting the boundary pumping temperature of engine lubricating oil (MRV).

(7) Determination of shear stability (ultrasonic method)

The shear stability determination method evaluates the shear stability of oil products based on their viscosity decrease rate.

The standard test methods in China include SH/T 0505 Determination of Shear Stability of Polymer Containing Lubricants (Ultrasonic Method) and SH/T 0200 Determination of Shear Stability of Polymer Containing Lubricants (Gear Machine Method).

The foreign standard test method includes the American ASTM D 2603 ultrasonic shear stability test method for polymer containing lubricating oils.

(8) FZG gear test

The FZG gear test is used to determine the relative load-bearing capacity of steel against lubricants used in steel spur gears, expressed in load levels.

The standard test method in China is the SH/T 0306 Method for Determining the Bearing Capacity of Lubricants.

Foreign standard test methods include European CEC L-07-A-71, British IP 334, and German DIN 51354.

This test can be completed using the MRC-1 FZG gear wear testing machine.

(9) Wheel bearing grease leakage test

The leakage test of wheel bearing lubricating grease is used to measure the leakage of bearings and simulate the working performance of lubricating grease in automotive wheel bearings.

The standard test method in China includes SH/T 0326 Test Method for Leakage of Lubricating Grease Bearings.

The foreign standard test method includes the American ASTM D1263 method for measuring the leakage of automotive wheel bearing grease.

(10) Simulation test of lubricating grease drum testing machine

The simulation test of the lubricating grease drum testing machine is used to determine the mechanical stability of the lubricating grease in the drum testing machine.

The standard test method in China is the SH/T 0122 method for determining the stability of lubricating grease drums.

The foreign standard test method includes the American ASTM D 1831 method for determining the stability of lubricating grease drums.

(11) High temperature bearing test

The high-temperature bearing test is suitable for evaluating the working performance of lubricating grease in light load anti wear bearings under high temperature and high speed conditions. The maximum applicable temperature is 180 ℃.

The standard test method in China is the SH/T 0428 method for measuring the working performance of lubricating grease in anti wear bearings at high temperatures.

The foreign standard test method includes the American FS 791B331.2 method for measuring the working performance of lubricating grease in anti wear bearings at high temperatures.

(12) Lubricating grease gear test

The lubricating grease gear test is suitable for measuring the gear wear value of lubricating grease, which is used to represent the relative lubrication performance of lubricating grease.

The standard test method in China is the SH/T 0427 method for measuring the wear of lubricating grease gears.

The foreign standard test method includes the American FS 791 B335.2 gear wear measurement method.
四、 Bench test face

Due to general physical and chemical tests, the increasingly demanding performance of lubricating oils cannot be well characterized. Therefore, full-scale bench tests are further used. After operating the internal combustion engine oil on the selected engine under standardized conditions for a certain period of time, evaluate its performance. The results of engine bench tests are the basis for determining the quality level of internal combustion engine oil, and are particularly important for internal combustion engine oil. Common bench tests include:

1. Gasoline engine bench test

Mainly including MS IID engine test, MS IIID engine test, MS IIIE engine test, MS V D engine test, MS V E engine test, MS VI engine test, CRCL-38 engine test, Caterpillar 1H2 engine test, Caterpillar 1G2 engine test, etc. 

2. Diesel engine bench test

The main content includes: CRCL-38 engine test, Caterpillar 1H2 engine test, Caterpillar 1G2 engine test, Caterpillar 1K testing machine, Caterpillar 1N engine test, Caterpillar 1M PC engine test, NTC400 test, MackT-6 test, MackT-7 test, MackT-8 test, GM6.2L test, Cumrains L10.