SH/T 0202-1992 Determination of Extreme Pressure Properties of Lubricating Greases (Four-Ball Machine Method)

Transcription review: The load-wear division formula has been checked against the stored scan; independent review remains pending. The percentage wording for maximum non-seizure load is ambiguous and must not be used as a confirmed operating threshold. Full load and corrected-load tables and figures are not reproduced here; other source warnings remain. Another method-card entry for this same edition.

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full title / English name / replacement relationship

• Standard number: SH/T 0202-92
• Chinese title: Determination of Extreme Pressure Properties of Lubricating Greases (Four-Ball Machine Method)
• English title: not provided in the available source
• Replacement relationship: replaces ZB E36 019-89
• Reference adoption: American Society for Testing and Materials standard ASTM D2596-82 (Determination of Extreme Pressure Properties of Lubricating Greases (Four-Ball Method)) (the source writes “ASTM D25% [unreadable separator]82”, requires confirmation against the source standard (source-text extraction))
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Scope of application: This standard specifies a method for determining the extreme pressure properties of lubricating greases on an extreme pressure four-ball testing machine; it is applicable to evaluating the load-carrying capacity of lubricating greases, and the evaluation indicators include the composite wear value ZMZ and the weld load P_D.
• Not applicable: not applicable to lubricating greases based on silicone, halosiloxane, or mixtures of silicone and mineral oil.

3. Method principle

Under the specified load, the upper steel ball rotates against the three stationary lower steel balls, with a rotation count of 1770 r/min±60 r/min, and the lubricating grease temperature is 27℃±8℃; then the load is increased step by step to carry out a series of 10s tests. After each test, the wear scar diameter of any one or all three steel balls in the ball box is measured until seizure occurs.

4. Reagents and materials (purity / preparation)

• Solvent naphtha: meets the requirements of No. 190 in GB 1922.
• Petroleum ether: 60～90℃, analytical grade; or solvent naphtha, meeting the requirements of No. 90 in GB 1922.
• Steel balls: test steel balls specially used for the four-ball machine, made of high-quality chrome alloy bearing steel GCr15, with a diameter of 12.7 mm, and Rockwell hardness HRC 64～66.
• Note: Carbon tetrachloride solvent or other solvents with load-carrying capacity must not be used for cleaning, because they will affect the test results.

5. Instruments and equipment

• Extreme pressure four-ball machine: the spindle rotation count of the four-ball machine shall be not less than 1800 r/min, and the load shall be not less than 4901 N (500 kgf). After the spring chuck loaded with steel balls is installed in the spindle taper hole of the testing machine, the radial circular runout of the steel balls shall not be greater than 0.02 mm. The schematic diagram of the testing machine principle is shown in Figure 2.
• Microscope: equipped with a calibrated micrometer, with a division value of 0.01 mm.
• Timer or stopwatch: accurate to 0.1 s.
• Friction force recorder.
• Note: It is important to distinguish an extreme pressure four-ball machine from a wear four-ball machine. It is best not to perform both extreme pressure and wear tests on the same four-ball machine, so as not to affect the sensitivity of the wear test.

6. Recommended operating conditions

• Spindle rotation count: 1770 r/min±60 r/min.
• Lubricating grease temperature: 27℃±8℃.
• Test time: 10 s±0.2 s.
• Load levels: load step by step according to Table 1; the load levels are 59(6), 78(8), 98(10), 127(13), 157(16), 196(20), 235(24), 314(32), 392(40), 490(50), 618(63), 785(80), 981(100), 1236(126), 1569(160), 1961(200), 2452(250), 3089(315), 3923(400), 4904(500), 6080(620), 7846(800) N(kg).

7. Sampling and specimen preparation

• Fill the ball box with test lubricating grease at temperature 27℃±8℃, avoiding the introduction of air bubbles. Embed three clean steel balls in the ball box, carefully press the retaining ring onto the three balls, tighten the fixing nut, and scrape off excess lubricating grease squeezed out from the fixing nut.
• Clean the steel balls, ball box, chuck, and other parts that contact the specimen during the test with solvent naphtha, then wash twice with petroleum ether, and blow dry for later use. The cleaned steel balls shall be smooth and free of rust spots.

8. Analytical procedure

• 7.1 Start the motor, adjust the spindle rotation count to 1770 r/min±60 r/min, and run idle for 2～3 min.
• 7.2 Clean the steel balls, ball box, chuck, and other parts that contact the specimen during the test with solvent naphtha, then wash twice with petroleum ether, and blow dry for later use. The cleaned steel balls shall be smooth and free of rust spots.
• 8.1 Fill the ball box with test lubricating grease at temperature 27℃±8℃, avoiding the introduction of air bubbles. Embed three clean steel balls in the ball box, carefully press the retaining ring onto the three balls, tighten the fixing nut, and scrape off excess lubricating grease squeezed out from the fixing nut.
• 8.2 Install one clean steel ball into the chuck, and install the chuck on the spindle of the testing machine. Note: Because the chuck is continuously subjected to wear and seizure, the chuck should be carefully inspected before each test. If it is found that the test ball cannot fit tightly with the chuck or the chuck has seizure marks, the chuck should be replaced promptly.
• 8.3 Place the assembled ball box on the ball seat of the testing machine, then bring the upper ball into contact with the three balls in the ball box, and slowly apply the specified load.
• 8.4 Start the motor and run for 10 s±0.2 s.
• 8.5 After each test, measure the wear scar diameter of the test balls according to the following method.
  • 8.5.1 A method: remove the nut, take out the test balls, wipe off the lubricating grease, place the test balls on a suitable ball seat, and use a microscope to measure the wear scar diameter of any one of the three test balls (in two directions, perpendicular to and horizontal to the rotation direction), accurate to 0.01 mm.
  • 8.5.2 B method: leave the test balls in the ball box, wipe off excess lubricating grease from the test balls and the ball box with a soft cloth or paper, and measure and report the wear scar diameter according to the procedure specified in method A (mm).
  • Note: Before using method A and method B, the operator should first visually inspect the test balls to determine whether there is an obvious difference in wear scar diameter among the test balls; if there is an obvious difference, the wear scar diameters of all three balls must be measured, and the testing machine must be adjusted if necessary.
• 8.6 Record the average wear scar diameter measured in each test in Table 1.
• 8.7 Determination of the maximum non-seizure load P_B: when determining P_B, the wear scar diameter is required to be not greater than 5% of the wear scar diameter on the corresponding compensation line (i.e., the compensation diameter). If the wear scar diameter measured under a certain load is greater than the wear scar diameter on the corresponding compensation line by more than 5%, then the next test shall be carried out at the next lower load level (see Table 2), and the wear scar diameters shall be compared again; continue this process until the maximum non-seizure load is determined. To simplify the test procedure, this method provides a P—D compensation (1+5%) table (Table 2) for judging the P_B point. The D compensation (1+5%) in Table 2 represents the compensation diameter corresponding to load P. For example, if a grease has a measured wear scar diameter of 0.47 mm under a load of 785 N(80 kgf), and Table 2 shows that the D compensation (1+5%) under this load is 0.44 mm, then it can be judged that the P_B point of this grease is less than 785 N(80 kgf), and the next test shall be carried out at the next lower load level. If the measured wear scar diameter is less than the D compensation (1+5%), then this load is the P_B point of the grease. Note: When a friction measuring instrument is used, the maximum non-seizure load can be seen from the gradual lateral movement of the indicator pen.
• 8.8 Determination of the weld load P_D: carry out a series of tests by loading step by step according to the load levels in Table 1, record the measured wear scar diameters, and replace the test balls and lubricating grease until seizure occurs. Carry out one repeat test at the load at which seizure occurs. If seizure does not occur, carry out the test at the next higher load level until seizure is verified. Note: When seizure occurs, the motor should be shut down immediately, otherwise the machine will be damaged. During the test, attention should be paid to observation to avoid excessive wear or seizure of the test balls and chuck. Whether seizure occurs can be judged by one or all of the following phenomena: sharp lateral movement of the friction recording pen, increased motor noise, smoke from the ball box, sudden drop of the loading lever arm.

9. Qualitative and quantitative determination and calculation formulas

• 3.1 Composite wear value ZMZ: an index of the extreme pressure resistance of lubricating grease under the applied load. During the test, the load is applied step by step to three stationary steel balls at intervals of 0.1 logarithmic units. Take the results of the ten tests before the weld load, and calculate ZMZ according to formula (4) in clause 10.2.
• 3.2 Weld load P_D: under the conditions of this test, the minimum load that causes seizure between the rotating ball and the three stationary balls, indicating that the extreme pressure capacity of the lubricating grease has been exceeded. Note: Some lubricating greases do not truly seize, but instead the three stationary steel balls show severe scratching. In this case, the load at which the maximum wear scar diameter is 4 mm is taken as the weld load.
• 3.3 Corrected load: the corrected load for each test is the applied load multiplied by the ratio of the Hertz diameter under that load to the measured wear scar diameter.
• 3.4 Hertz diameter: under static load, the indentation diameter caused by deformation of the steel balls can be calculated according to formula (1) or formula (2):
  • D_h = 4.08 × 10^(-2) (P_N)^(1/3) ………………(1)
  • D_h = 8.73 × 10^(-2) (P)^(1/3) ………………(2)
  • Where: D_h— Hertz diameter of the contact surface, mm; P_N— static load, N; P— static load, kgf.
• 3.5 Compensation wear scar diameter: under load conditions where lubricating grease is present but does not cause seizure or welding, the average wear scar diameter produced on the lower stationary steel balls by the upper rotating steel ball.
• 3.6 Hertz line: a straight line drawn on log-log coordinate paper with the Hertz diameter (mm) as ordinate against the applied load N(kgf), as shown in Figure 1.
• 3.7 Compensation line: a straight line drawn on log-log coordinate paper with the wear scar diameter (mm) as ordinate against the applied load N(kgf), as shown in Figure 1.
• 3.8 Maximum non-seizure load: the maximum load at which no seizure occurs under the test conditions, and the average wear scar diameter measured under this load does not exceed 5% of the value on the compensation line for the corresponding load.
• 3.9 Initial seizure region: the load region that causes instantaneous destruction of the lubricating grease film. Destruction of the lubricating grease oil film can be seen from a sudden increase in wear scar diameter and a sudden deflection of the friction measuring instrument pointer, as shown in Figure 1.
• 10.1 Corrected load P_S [N(kgf)] Use the formula (3) to calculate and record (Table 1) the corrected load for each load applied between the maximum non-seizure load and the weld load:
  • P_S = L × D_h / X ………………(3)
  • Where: L— applied load, kgf; D_h— Hertzian diameter, mm; X— average wear scar diameter, mm; if a lever-type four-ball machine is used, then L is the total applied weight (pan and weights) multiplied by the lever arm ratio.
• 10.2 Comprehensive wear value ZMZ [N(kgf)], use the formula (4) to calculate and record according to Table 1:
  • ZMZ = A / 10 ………………(4) (the original formula layout is suspected to be erroneous, requires confirmation against the source standard (source-text extraction))
  • Where: A— the sum of corrected loads for the 10 loads applied before the weld load.
  • Note: ① If the tested lubricating grease conforms to the compensation line, then A is the sum of the corrected loads on the compensation line before the weld point (see Table 3) and the corrected loads of the non-compensation line portion (calculated according to clause 10.1), totaling 10 load levels. ② If the test results of certain lubricating greases do not conform to the compensation line, Table 3 cannot be used; tests must be conducted at 10 load levels before the weld point, and then the comprehensive wear value is calculated according to the formula in clause 10.2.
• 10.3 Weld load P_D [N(kgf)] Verify the weld load according to the method in clause 8.8.
• Table 3 gives the compensation line corrected load for any segment. This value can be found from the intersection of the maximum non-seizure load and the weld load columns in Table 3. For example, if the maximum non-seizure load of a certain lubricating grease is 490 N(50 kgf), then tests are conducted at 618, 784, 981, 1236 and 1569 N(63, 80, 100, 126 and 160 kgf), and the weld load is 1961 N(200 kgf). From Table 3, the value at the intersection of 490 and 1961 N(50 and 200 kgf) is found to be 1457.3 N(148.6 kgf); this value is the compensation line corrected load, which is obtained by summing the corrected loads for the levels 490, 392, 314, 235 and 196 N(50, 40, 32, 24, 20 kgf) calculated separately using the compensation diameter; the corrected load for the non-compensation line portion shall be obtained according to the calculation method in clause 10.1.

10. Precision

Judge the reliability of test results according to the following provisions (95% confidence level).

• 9.1 Repeatability: The difference between the results of two repeated tests on the same sample by the same operator using the same equipment under specified conditions shall not exceed the following values.
  • Comprehensive wear value ZMZ: 127 N(13 kgf)
  • Weld load P_D: one load level increment
• 9.2 Reproducibility: The difference between the results of tests on the same sample by different operators in different laboratories shall not exceed the following values.
  • Comprehensive wear value ZMZ: 157 N(16 kgf)
  • Weld load P_D: one load level increment

11. Report

• The average wear scar diameter measured in each test is recorded in Table 1.
• Test result records: P_B = ___ N(kgf); P_D = ___ N(kgf); ZMZ = ___ N(kgf).
• Table 1 Four-ball machine test record table includes: test number, test conditions, test oil name, test material, test oil formulation, test date, load level, load N(kg), wear scar diameter, compensation wear scar diameter, coefficient, corrected load, remarks, etc.
• 8.5.2 B method: Measure and report the wear scar diameter (mm) with a microscope according to the procedure specified in method A.

12. Referenced documents

• GB 1922 solvent naphtha

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference Q&A