SH/T 0532-1992 Determination of anti-scuffing ability of lubricating oils (Timken method)

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Card type: Test method

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

• Standard number: SH/T 0532-92
• Chinese name: Determination of anti-scuffing ability of lubricating oils (Timken method)
• English name: not provided in the available source
• Replacement relationship: replaces SY 2685-82
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Applicable to distinguishing low, medium, and high anti-scuffing ability of lubricating oils.
• Applicable to lubricating oils with viscosity at 40℃ not exceeding 4500 mm²/s (the source text reads “4500mm’/s”, the unit is suspected to be mm²/s, requires confirmation against the source standard (source-text extraction)).
• Not applicable: no explicit non-applicability clause is provided in the available source; clause 6.6 states that for oils whose viscosity is so high that circulation is difficult, the oil temperature may be appropriately increased, but the precision of the results does not conform to the provisions of this standard.

3. Method principle

At 38℃±2℃, the sample flows from the oil reservoir onto the test ring; the test machine spindle drives the test ring to rotate on the stationary test block; the spindle speed is 800 r/min±5 r/min, and the test time is 10 min±15 s. Pressure is borne between the test ring and the test block; by observing the wear scar on the surface of the test block, the maximum load OK value at which no scuffing occurs is obtained.

4. Reagents and materials (purity / preparation)

• Wash gasoline: meets the requirements of SH 0114.
• Solvent naphtha: meets the requirements of No. 260 in GB 1922.
• Petroleum ether: 60~90℃, analytical reagent.
• Anhydrous ethanol: chemical reagent.
• Petroleum ether-anhydrous ethanol (1:1) mixture: used for scrubbing the surfaces of the test ring and test block (6.4, 6.5).
• Test ring: a steel test ring with Rockwell hardness HRC 58–62 or Vickers hardness HV 653–746; width 13.06 mm±0.05 mm (0.514 in±0.002 in), effective width 12.7 mm±0.025 mm (0.5 in±0.001 in); diameter 49.22 mm (the source text reads “49.22#8: parts mm (1.938=8.88in)”, the value requires confirmation against the source standard (source-text extraction)); maximum radial eccentricity 0.013 mm (0.0005 in); surface roughness between 0.51–0.76 μm (20–30 μin) root-mean-square values; the fit between the test ring and the spindle must be suitable to avoid relative movement during the test.
• Test block: test surface width 12.32 mm±0.05 mm (0.485 in±0.002 in), length 19.05 mm±0.41 mm (0.750 in±0.016 in); a steel block with hardness HRC 58–62 or HV 653–746; each test block can provide four test surfaces; surface roughness between 0.51–0.76 μm (20–30 μin) root-mean-square values; the wear scar direction should be transverse; the perpendicularity and parallelism between test surfaces are not greater than 0.005 mm.

5. Apparatus and equipment

• Timken wear and lubrication testing machine: mainly composed of a measurement system, a spindle drive system, a sample circulation system, and an automatic loading system; the measurement system mainly consists of a test ring, a test block, a test block holder, and a double lever; during measurement, the test ring rotates and the test block is fixed.
• The testing machine should be adjusted to level, and the friction lever should also be adjusted to the horizontal position; the spindle radial runout is not greater than 0.013 mm (0.0005 in); the spindle speed should be 800 r/min±5 r/min; the radial runout between the test ring and spindle assembly should be less than 0.025 mm (0.001 in); if it is greater than this value, the test results may be affected, and the wear condition of the spindle and main bearing and the quality of the test ring should be checked, and adjustment or repair should be carried out.
• Automatic loader: should apply load to the load lever at a rate of 8.9–13.3 N/s (2–3 lb/s), and should be able to load or unload smoothly without impact.
• Microscope: used to measure the wear scar width of the test block; the magnification is not limited, the main requirement being to ensure that the measurement result is accurate to 0.05 mm (±0.002 in).
• Thermometer: 0~100℃, with a division value of 0.1℃.
• Stopwatch: scale (the source text reads “scale within min and so”, requires confirmation against the source standard (source-text extraction)).
• Magnifying glass: about four times, used to observe the wear scar of the test block (7.2).

6. Recommended operating conditions

• Sample temperature: 38℃±2℃ (100℉±4℉).
• Spindle speed: 800 r/min±5 r/min.
• Test time: 10 min±15 s.
• Loading rate: 8.9–13.3 N/s (2–3 lb/s).
• Sample amount: about 2800 mL loaded into the oil tank (the oil level is about 76 mm from the top).
• Sample circulation: the assembled test block and test block holder are placed in the oil bath, and the sample is circulated for 15 min to ensure that the sample temperature meets the requirements.
• The sample outlet pipe orifice is about 1.6 mm from the ring.
• Starting load: may be determined empirically; if it cannot be determined, a load of 133.4 N (30 lb) may be used.
• Spindle cooling: before each test, the spindle should be cooled to below 65℃ (150℉).

7. Sampling and sample preparation

• Select several new rings and new test blocks; before use, clean them with wash gasoline and petroleum ether for 1 h, then soak them in petroleum ether; when used, take out the test pieces and wipe them dry with a clean silk cloth.
• Install the test ring on the spindle (avoid touching the surface of the test ring with fingers); the test ring should be pressed close to the spindle and fixed firmly, neither too tight so that the test ring deforms, nor too loose so that the test ring slides relative to the spindle; then scrub the surface of the test ring with a cotton ball moistened with petroleum ether-anhydrous ethanol (1:1).
• Place the test block on the test block holder, then scrub the surface of the test block with a cotton ball moistened with petroleum ether-anhydrous ethanol (1:1); the test block must be fastened in a suitable position.
• A new test ring should be installed and the test block should be turned to provide a new test surface for each test; if relatively severe scuffing occurs on the test block, the entire test block should be discarded; if the scuffing is not severe, another surface should be used, and testing should not be carried out on the original surface.
• Before the test, first clean the parts of the testing machine that contact the sample with wash gasoline, then with a smaller amount of petroleum ether, and finally with 1000 mL sample; note that solvent, waste sample, and abrasive particles should not remain in the oil circuit; for this purpose, the pump should be started for low-speed circulating cleaning.

8. Analysis procedure

• Fully open the sample valve (the sample outlet pipe orifice is about 1.6 mm from the ring); when there is an appropriate amount of sample in the oil bath, start the motor, bring the spindle speed to 800 r/min±5 r/min within 15 s, then start the loader, and loading should just begin at 15 s; at this time start timing; if it is estimated that no scuffing will occur under this test load, run for 10 min±15 s; if obvious scuffing has occurred during the test, immediately stop the test under this load.
• At the end of the period of 10 min±15 s, immediately shut off the main motor, then close the sample valve, turn the speed regulator back to zero, remove the load, then take out the test block, observe the wear scar of the test block under a magnifying glass of about four times to judge whether scuffing has occurred, then measure the average width of the wear scar with a microscope; if the wear scar is irregular, the cut-and-fill method should be used for measurement (accurate to 0.05 mm).
• When no scuffing occurs above 133.4 N (30 lb), tests should be continued upward in increments of 44.5 N (10 lb) until scuffing occurs, then reduce by 22.2 N (5 lb) for the final judgment; if there is no scuffing, this load is the OK value; if scuffing occurs, reduce this load by 22.2 N (5 lb) as the OK value.
• When scuffing occurs below 133.4 N (30 lb), tests should be continued downward in decrements of 26.7 N (6 lb) until no scuffing occurs, then increase the load by 13.3 N (3 lb) for the final judgment; if there is no scuffing, this load is the OK value; if scuffing occurs, reduce this load by 13.3 N (3 lb) as the OK value.
• Handling of doubtful situations (7.5): when the judgment of scuffing is doubtful, the test should be repeated under that load; if the second test is determined to be scuffing, it is judged as scuffing; if the second test is determined to pass, it is judged as passing; if the second test is still doubtful, then test according to the following two situations:
  • When a doubtful situation repeated twice occurs above 133.4 N (30 lb), an additional test with a load increased by 22.2 N (5 lb) should be carried out; if no scuffing occurs, the doubtful situation is also judged as passing; if scuffing occurs, the doubtful situation is also judged as scuffing; then, based on the load of the doubtful situation, test according to the provisions of clause 7.3.
  • When a doubtful situation repeated twice occurs below 133.4 N (30 lb), an additional test with a load increased by 13.3 N (3 lb) should be carried out; if no scuffing occurs, the doubtful situation is also judged as passing; if scuffing occurs, the doubtful situation is also judged as scuffing; if, when the load is increased by one step, it is still a doubtful situation, the test should be repeated under that load; if it is still doubtful, then the load should continue to be increased, and by the same reasoning, until it is clear; then test according to the provisions of clause 7.4.
• Criteria for judging scuffing (3.5.1): During the test, when scuffing occurs on the specimen, it is mainly manifested as abnormal noise and vibration; a decrease in spindle speed; obvious scratches on the surface of the test ring; after the test, whether scuffing has occurred is judged by the wear scar on the test block. The most severe scuffing feature is the formation of wrinkled, deep and wide wear scars on the test block; the most common scuffing feature is local damage on a relatively smooth wear scar, which extends unidirectionally beyond the wear scar (commonly known as protrusion), and its protruding position must be on the lubricant outflow side, and the protruding point generally has fusion characteristics; OK a wear scar is a relatively smooth wear scar without scuffing under the critical load, that is, without this protruding damage.
• Cases not belonging to scuffing (3.5.2): local damage inside the wear scar (that is, no protrusion); scratches caused by abrasive wear, generally manifested as slender and bright, whose length often extends beyond both sides of the wear scar; discoloration on the lubricant outflow side of the test block wear scar caused by high temperature or chemical reaction.
• End of test: At the end of the entire test, the equipment should be cleaned promptly with washing gasoline or solvent naphtha and petroleum ether, the lever system should be properly placed, and the results should be calculated and reported in accordance with the provisions of Chapter 8.

9. Qualitative and Quantitative and Calculation Formulas

• The anti-scuffing ability is expressed by the OK value.
• Definition of OK value: the maximum load on the weight pan of the load lever when no scuffing occurs on the pure sliding friction surface of the steel specimen on the testing machine of this standard.
• Related definitions:
  • Anti-scuffing ability of lubricating oil: the highest load at which the lubricating oil prevents scuffing of steel/steel moving friction surfaces.
  • Seizure: local fusion of metal on the friction surface of the specimen.
  • Wear: the phenomenon of metal loss from the body due to mechanical or chemical action, or the combined action of mechanical and chemical effects.
  • Scuffing: damage to the metal friction surface caused by seizure; the state of scuffing depends on the degree of seizure.
• MCP: average contact pressure of the wear scar under OK load N/mm²; this indicator is for reference only.
• Calculation formula (the source gives symbol explanations; the formula body requires confirmation against the source standard (source-text extraction)):
  • Where: A— weight mass, N; C— load lever constant, N; L—OK wear scar length, mm; b'—OK average wear scar width, mm.
• Explanation of symbols in the record table: A— mass of weights on the load lever loading pan, N; T initial—initial temperature of the specimen, ℃ or ℉; T final—final temperature of the specimen, ℃ or ℉; b— wear scar width, mm; HRC— Rockwell hardness; OK value, N (lb).

10. Precision

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

• Repeatability: the difference between repeated measurement results obtained by the same operator on the same test equipment in continuous time on the same sample shall not be greater than two load increments.
• Reproducibility: the difference between the measurement results of the same oil sample by two laboratories shall not be greater than four load increments.
• If the test result exceeds the provisions of 9.1 or 9.2, then the result should be regarded with suspicion, the cause should be analyzed, and corresponding measures should be taken in order to reach a clear conclusion.

11. Report

• For test records and reports, see the table in 8.1 clause, "Timken Method Test Record and Report Form".
• The table items include: serial number, sample submitting unit, sample composition, test conditions (test ring material/HRC, test block material/HRC, rotation speed r/min, time min, sample flow rate mL/min, room temperature ℃ (℉), T initial ℃ (℉), T final ℃ (℉), b mm, wear scar condition, remarks), test result report (OK: N (lb), MCP: N/mm²), explanation, test personnel, inspector, year month day.
• 8.2 clause: average contact pressure of the wear scar under MCP—OK load N/mm²; this indicator is for reference only.

12. Referenced Documents

• GB 1922 solvent naphtha
• SH 0114 aviation washing gasoline

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 for Questions and Answers