SH/T 0072-1991 Determination of Friction Coefficient of Liquid Lubricants (Oscillator Method)

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 name / English name / Replacement relationship

• Method number: SH/T 0072-91
• Full name: Determination of Friction Coefficient of Liquid Lubricants (Oscillator Method)
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Approval date: 1991-06-28; Implementation date: 1992-07-01 (visible in the source)
• Technical committee: Technical committee of the Research Institute of Petroleum Processing
• Drafting organization: Refining Research Institute of Luoyang Petrochemical Engineering Company
• Main drafters: Sun Qitai, Fan Chuifan

2. Scope of application and non-applicability

• This standard specifies a method for determining the friction coefficient of liquid lubricants using an oscillator-type oiliness friction testing machine.
• This standard is applicable to evaluating the lubricating performance of various liquid lubricants.
• Non-applicable scope: not provided in the available source.

3. Method principle

This method uses an oscillator-type oiliness friction testing machine. The needle rollers supporting the oscillator pendulum rod press on four steel balls immersed in the test lubricant. After the oscillator pendulum rod is deflected by a certain arc, the oscillator pendulum rod swings back and forth under the action of potential energy and inertial force, and the needle rollers also undergo sliding friction on the steel balls. By measuring the different arc values after the damped oscillation of the oscillator pendulum rod, the friction coefficient of the tested lubricant is calculated.

4. Reagents and materials (purity / preparation)

• 5.1 Solvent naphtha: meets the requirements of NY-190 in GB 1922.
• 5.2 Petroleum ether: analytical grade, 60～90℃; or solvent naphtha meeting the requirements of NY-90 in GB 1922.
• 4.2 Steel balls: the diameter of the test steel balls is 4.76mm, the material is GCr15, the hardness is HRC60-66 (the source source-text extraction is “HRC6 0-6”, requires confirmation against the source standard (source-text extraction)), and other technical requirements meet GB 308 Grade I steel balls.
• 4.3 Needle rollers: the diameter of the test needle rollers is 2.0 -0.012 (the source source-text extraction is “20 -o.oiz”, requires confirmation against the source standard (source-text extraction)), the length is 30mm, the material is GCr15, the hardness is HRC60-66 (the source source-text extraction is “HRC60[unreadable separator]660”, requires confirmation against the source standard (source-text extraction)).
• 4.4 Weights: there are 14 test weights in total, one each of 0.15N and 0.20N, and two each of 0.30N, 0.40N, 0.60N, 0.80N, 1.20N, and 1.60N.

5. Apparatus and equipment

• 4.1 Oscillator-type oiliness friction testing machine: mainly composed of a frame, oscillator pendulum rod, oil box, connecting rod, handle, circular arc scale, and heater. The oil box is fixed on the frame by a support plate. The steel ball support plate and pressure plate in the oil box can fix the steel balls immovably. The oscillator pendulum rod is supported on the steel balls by needle rollers. The handle can deflect the oscillator pendulum rod through the connecting rod. The circular arc scale can measure the arc value of each swing of the oscillator pendulum rod. The heater can heat the lubricant in the oil box from room temperature to 300℃ through a temperature control system. The schematic diagram of the testing machine is shown in Figure 1, and the specimen assembly diagram is shown in Figure 2. Note: Domestic needle-ball friction testing machines are suitable for this method.
• 4.5 Temperature control coefficient (source wording): a temperature control device with power 0.15kW (the source source-text extraction is “0.15kV,”, requires confirmation against the source standard (source-text extraction)).
• 4.6 Temperature detector: detection range from room temperature to 300℃.
• 4.7 Electric hair dryer.

6. Recommended operating conditions

• Test temperature: 25℃±10℃ (6.10).
• Standard test load: 3.00N (8.2).
• Standard test load weight configuration (6.7): install one 0.80N weight at each end of the horizontal rod of the oscillator pendulum rod, at a distance of 340mm from the center of the oscillator pendulum rod; install one 0.40N weight on the vertical rod of the oscillator pendulum rod, at a distance of 100mm from the center of the oscillator pendulum rod; fix the three weights as the standard test load.
• Sample amount: pour about 4mL into the oil box, and the liquid level is best when it just submerges the steel balls (6.6).
• Initial arc: press down the handle so that the pointer on the vertical rod of the oscillator pendulum rod points to the 0.5 arc position on the circular arc scale (7.1).

7. Sampling and sample preparation

• 6.1 Install the testing machine in a test frame free from vibration and air convection influence, and adjust the bolts under the testing machine base plate so that the bubble in the level gauge is in the middle position.
• 6.2 First wash the test steel balls and needle rollers clean with solvent naphtha, then clean them twice with petroleum ether, air-dry them naturally, and place them in a covered glass vessel for later use.
• 6.3 Loosen the screws fixing the needle roller seat, remove the needle roller seat, unscrew the screws fixing the oil box and steel ball pressure plate, and remove the oil box, steel ball pressure plate, and support plate.
• 6.4 First clean the needle roller seat, oil box, steel ball support plate, and steel ball pressure plate with solvent naphtha, then clean with petroleum ether, and then dry with an electric hair dryer.
• 6.5 Fix the oil box on the testing machine, place the steel ball support plate, use tweezers to place the steel balls in pairs symmetrically front and back on the support plate, and fix them with the steel ball pressure plate.
• 6.6 Pour about 4mL of the sample into the oil box (the liquid level is best when it just submerges the steel balls).
• 6.7 Install the weights according to the recommended operating conditions in Section 6.
• 6.8 Use tweezers to insert the needle roller into the needle roller seat so that the lengths of its two ends extending from the center of the needle roller seat are the same. Use a nut to tighten the needle roller in the V-shaped groove of the needle roller seat, install the needle roller seat with the needle roller on the oscillator pendulum rod, and fix it with screws.
• 6.9 Gently place the oscillator pendulum rod into the oil box so that the needle roller presses on the steel balls, and make the gaps between the needle roller and the two inner walls of the oil box equal. Gently swing the oscillator pendulum rod, and after the pendulum rod stops, the pointer should point to the 0 position on the circular arc scale.
• 6.10 Control the test temperature at 25℃±10℃.

8. Analysis procedure

• 7.1 Press down the handle, and through the connecting rod make the pointer on the vertical rod of the oscillator pendulum rod point to the 0.5 arc position on the circular arc scale.
• 7.2 After the pointer stabilizes, gently release the handle, and the oscillator pendulum rod will swing back and forth regularly until it stops. Observe the left circular arc scale and record the arc value of each swing above 0.1 arc. The record table is shown in Appendix A.
• 7.3 Repeat continuously twice according to clauses 7.1 and 7.2 for running-in.
• 7.4 Carry out two formal parallel determinations according to clauses 7.1 and 7.2.
• 7.5 After the test is completed, remove the oscillator pendulum rod, clean the parts that need cleaning again as required, replace the steel balls and needle rollers, and carry out parallel tests.

9. Qualitative and quantitative determination and calculation formula

• 8.1 The friction coefficient of the lubricant is calculated according to the following formula:

  f = C × [A₀·n − (A₁+A₂+A₃+…+Aₙ)] / (1+2+3+…+n)

  Where:

  • f — friction coefficient;
  • n — number of swings of the oscillator pendulum rod (one back-and-forth swing counts as one);
  • A₀ — initial arc;
  • Aₙ — arc value at the nth swing;
  • C — proportionality constant.

  (The symbols in the source source-text extraction formula contain noise; the above is organized according to the source semantics, requires confirmation against the source standard (source-text extraction))

• 8.2 When the test load is different, the proportionality constant is shown in the table below. This method uses standard test conditions, the test load is 3.00N, so the proportionality constant C is 3.200.

  Proportionality constant table:

  Weight M₁, N	0	0.15	0.20	0.30	0.40	0.60	0.80
  Weight M₂, N	0	0.30	0.40	0.60	0.80	1.20	1.60
  Test load, N	1.00	1.75	2.00	2.50	3.00	4.00	5.00
  Proportionality constant C	2.20	2.90	3.00	3.10	3.20	3.50	3.55

  (Some values in the table source-text extraction contain noise, such as “0.[unreadable character]”, “0.[unreadable character]”, “1.[unreadable character]”; they have been organized according to the contextual correspondence, requires confirmation against the source standard (source-text extraction))

• 8.3 Calculate the average of two parallel tests, and take two significant figures.

10. Precision

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

• 9.1 Repeatability: the difference between two results obtained by the same operator on the same testing machine within a continuous time period for the same sample shall not exceed 8% of their arithmetic mean.
• 9.2 Reproducibility: the difference between two results obtained by different operators in different laboratories using the same type of testing machine for the same sample shall not exceed 10% of their arithmetic mean (the source source-text extraction is “10%0”, requires confirmation against the source standard (source-text extraction)).

11. Report

Report the friction coefficient value of the tested sample.

12. Referenced documents

• GB 1922 Solvent naphtha
• GB 308 Steel balls (editor's note: current standard number GB/T 308, current standard name “Rolling bearings — Steel balls”)

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