SH/T 0428-2008 Standard test method for life of lubricating greases in ball bearings at elevated temperatures

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

• Standard number: SH/T 0428-2008
• Chinese name: Standard test method for life of lubricating greases in ball bearings at elevated temperatures
• English name: Standard test method for life of lubricating greases in ball bearings at elevated temperatures
• Replacement relationship: replaces SH/T 0428-1992 "Standard test method for performance of lubricating greases in anti-friction bearings at elevated temperatures"
• Adoption relationship: modified adoption of ASTM D3336-05
• Publication/implementation: published on 2008-04-23, implemented on 2008-10-01
• Issuing body: National Development and Reform Commission of the People's Republic of China

2. Scope of application and non-applicability

• 1.1 This standard specifies a test method for evaluating the performance of lubricating greases in ball bearings operating at elevated temperature, high speed and light load.
• 1.2 This standard uses International System of Units (SI) units.
• 1.3 This standard does not purport to address all of the safety problems associated with its use. Therefore, users should establish appropriate safety and protective measures and determine applicable management systems before using this standard.
• Non-applicable scope: not provided in the available source.

3. Method principle

A SAE No. 6204 ball bearing filled with a grease sample is mounted on the spindle in the oven of a grease bearing test machine, radial and axial loads are applied to the bearing outer ring, and the bearing inner ring is driven to rotate at 10000 r/min speed at the specified elevated temperature until lubrication fails or the specified running time is completed. The running time (h) is used to evaluate the life of the sample in the ball bearing.

4. Reagents and materials (purity / preparation)

• 6.1 Test bearing: model SAE No. 6204, suitable for 371 ℃ elevated temperature. The bearing shall be manufactured in accordance with ABEC technical requirements, with radial internal tolerance of 0.____ mm (original numerical value missing, requires confirmation against the source standard (source-text extraction)). Appendix A describes in detail the American Bearing Manufacturers Association standard method for determining radial internal tolerance of ball bearings. The bearing is equipped internally with a ball retainer made of a suitable material resistant to 371 ℃ elevated temperature. The support bearing of the CRC type spindle shall be the same as the test bearing. Bearings made of 1-4-1 high-speed steel or M-50 (specification A600) tool steel and retainers made of heat-treated silver-plated copper alloy meet the requirements. In addition, for tests conducted at 149 ℃ or below, ASTM No. 6204 bearings (P0N12-43360-12) may be used, in which the bearing rings and rolling elements are made of ANSI 52100 steel and the retainer is made of SEC1D10. The precision requirement of the bearing is ABEC-3, and the internal tolerance range is between 0.____ ~ 0.028 mm (original numerical value missing, requires confirmation against the source standard (source-text extraction)).
• 6.2 Petroleum ether: meets the requirements specified in GB/T 15894, analytical reagent grade, boiling range 109~292 ℃ (original numerical value requires confirmation against the source standard (source-text extraction)), volatile, harmful if inhaled.
• 6.3 Solvent naphtha: meets the requirements of No. 3 in GB 1922, flammable, vapor harmful.
• The n-heptane used for cleaning bearings is changed to petroleum ether (see the difference explanation in the foreword).

5. Apparatus and equipment

• 5.1 Test spindle (see Figure 1, Figure 2 and Figure 3): capable of operating at temperatures up to 371 ℃ and a speed of 10000 r/min. The test bearing housing dimensions shall be 19.99 mm–20.00 mm. If the test bearing and the support bearing are in the same bearing housing (CRC type, Figure 1 and Figure 3), the internal structure of the spindle shall be such that either the external support bearing or both bearings can float freely axially. In the design in which both bearings can float freely, the shaft shall have a free axial clearance of 0.508 mm–0.762 mm in length. The external bearing housing dimensions shall be 19.99 mm~20.00 mm.
• 5.1.1 Test unit (Figure 1 and Figure 2): a finger-type spring washer that generates an axial force of 22 N~67 N applied to the external floating support bearing.
• 5.2 Bearing housing
  • 5.2.1 For CRC type spindle: the bearing housing dimensions shall be 47.005 mm–47.021 mm so that the bearing can be installed properly. The test bearing shall be provided with a splash guard or baffle so that the grease can be retained in the bearing. The guard or baffle shall have a clearance of 0.127 mm–0.178 mm from the inner ring and the shaft, respectively.
  • 5.2.2 For Navy type spindle (test bearing mounted outside the bearing housing): the bearing housing is made of a material similar to that of the test bearing and shall maintain its external dimensions unchanged at elevated temperatures up to 371 ℃. The inner diameter is 47.005 mm~47.021 mm. The bearing housing cover shall be fastened to prevent sample splashing and to allow the grease to be retained on the bearing. Insert one or two small thermocouples into the bearing housing so that the thermocouples lightly press against the outer raceway of the bearing and maintain continuous contact. The bearing housing shall be equipped with a stem connected to a frame for adding weights so that a radial load can be applied to the test bearing. An axial load of 22 N±2 N is applied to the outer ring of the bearing through a helical spring calibrated at room temperature.
• 5.3 Motor drive: a movable shaft support and a motor drive device with constant belt tension, through belt transmission, capable of bringing the spindle speed to 10000 r/min. When installing the motor, the belt tension on the test spindle pulley shall be maintained at about 67 N.
• 5.4 Oven: capable of reaching a test temperature of 371 ℃ within 5 h.
• 5.5 Control devices
  • 5.5.1 The outer ring temperature of the test bearing shall be controlled within 3 ℃ of the specified test temperature. The temperature control device shall be capable of maintaining the test bearing outer raceway temperature within the specified range by controlling the oven temperature. Place one thermocouple in the middle of the oven to control the oven temperature.
  • 5.5.2 Suitable devices shall be provided, such as an adjustable center restart relay and equipment to shut off oven heating and drive motor upon overload, as well as other auxiliary devices (clock, recorder, etc.). Record the oven temperature and bearing temperature.

6. Recommended operating conditions

• 7.1 Temperature: up to 371 ℃ as required.
• 7.2 Speed: 10000 r/min ± 200 r/min.
• 7.3 Start-stop settings:
  • 7.3.1 When not higher than 149 ℃, run for 21.5 h, stop for 2.5 h, and no heating during the stop time.
  • 7.3.2 When above 149 ℃, run for 20 h, stop for 4 h, and no heating during the stop time.
• Radial load: 22 N (see 5.1.1, 5.2.2).
• Axial load: 22 N±2 N (see 5.2.2).

7. Sampling and sample preparation

• 8.1 Before coating with grease, place the test bearing in warm (about 50 ℃) solvent naphtha and rotate to clean it, then continuously clean it twice with petroleum ether, dry it at 71 ℃, and cool to room temperature.
• 8.2 Use a narrow spatula to fill the bearing with sample so that the mass of the sample loaded is equivalent to the mass of a volume of 3.2 cm³ ± 0.1 cm³. The sample may also be measured by volume, using a syringe to add the sample to the bearing. The sample should be injected from both sides of the bearing, and a narrow spatula should be used to ensure that the sample does not overflow the edge of the raceway. For CRC type spindle, the bearing shall be filled with sample.
• 8.3 Install the test bearing, support bearing and finger-type spring washer on the spindle (see Figure 1 and Figure 3), and fix the thermocouple in a position such that it contacts the outer ring of the test bearing (CRC type spindle). For tests conducted at test temperatures of 232 ℃ and above, the finger-type spring washer shall be replaced for each test. For Navy type spindle, install the test bearing into the housing and apply a gentle thrust to the inner raceway of the bearing to press the bearing onto the spindle. Cover the cover plate, insert the thermocouple, and apply radial and axial loads.

8. Analytical procedure

• 9.1 Rotate the bearing by hand, about 100 revolutions in each direction, at a speed not exceeding 200 r/min. At the same time, start the drive motor and heating device, and adjust the temperature controller so that the bearing temperature rises to the test temperature within 1.5 h. After operating at the test speed and test temperature for 2 h, measure the temperature of the test bearing outer raceway. Adjust the controller so that the test bearing outer raceway temperature is the sample test temperature. Record the test running time (h), control temperature and bearing outer raceway temperature at least once every 24 h. Unless an automatic controller is used, the machine should be stopped for 72 h (without heating) on weekends; for Navy type spindle, the oven door should remain closed during the shutdown period.
  • Note: Once the temperature stability of the test bearing meets the requirements, manual adjustment is not necessary. However, fine adjustment may be made according to changes in voltage, ambient temperature, etc.
• 9.2 Continue the test until the sample fails or the specified running time is completed.

9. Qualitative and quantitative determination and calculation formula

• 10.1 The sample is considered to have failed when any of the following conditions occurs:
  • 10.1.1 At the test temperature, the spindle input power increases to more than 300% of the steady-state power.
  • 10.1.2 During the running cycle, the test bearing temperature rise exceeds the test temperature by 15 ℃. Ignore any temperature rise occurring within 30 min after reaching the test temperature at daily startup.
  • 10.1.3 During startup or during the test run, the load on the test bearing increases or the belt slips.
• The running time (h) is used to evaluate the life of the sample in the ball bearing (see Chapter 3).
• Calculation formula: not provided in the available source.

10. Precision

• 11.1 The precision of this standard has not yet been established in accordance with currently prevailing guidelines (see the research report of committee ASTM D02 RR:D02-1007).
• 11.2 The grease life data obtained from two independent cooperative test programs show considerable dispersion; these data do not follow a normal distribution but follow a Weibull distribution. Therefore, it is inappropriate to use statistical parameters such as repeatability and reproducibility. Weibull parameters such as slope, L₁₀, L₅₀ and L₆₃.₂ can better describe the distribution of the test data.
• 11.2.1 Precision can be inferred from the Weibull curves of the test data (see Figure 4, Figure 5) and the calculated Weibull parameters, summarized in Table 1 (the results at the 90% confidence level are shown in parentheses). Precision can also be inferred from the average values reported in Table 1 and the range of the median 50% of the test results.
• Table 1 Grease life (running failure time/h):
  • Grease G- dish-54, test temperature 232 ℃, number of cooperating laboratories 13, number of test results 48, Weibull parameters: slope 1.89 (1.56–2.27), L₁₀ 210 (151–269), L₅₀ 571 (487–657), L₆₃.₂ 693 (601–792), average 615, range of the median 50% of the test results 336~779.
  • Grease G- dish-60, test temperature 177 ℃, number of cooperating laboratories 8, number of test results 31, Weibull parameters: slope 1.53 (1.19–1.92), L₁₀ 115 (67–171), L₅₀ 394 (310–494), L₆₃.₂ 502 (405–616), average 446, range of the median 50% of the test results 183~608.
• 11.3 When this standard is used, it is necessary to conduct repeated tests because the results of grease life tests are considerably dispersed. If a grease is subjected to Weibull analysis, at least five repeated tests are required to obtain sufficient test data to obtain meaningful results.
• 11.4 Bias: There is no bias in the procedure for determining the life of grease in ball bearings at high temperature, because the life value in ball bearings at high temperature is determined solely according to this test method.

11. Report

not provided in the available source.

12. Normative references

• GB 1922 Solvent oil for paints and cleaning
• GB/T 15894 Chemical reagent petroleum ether (GB/T 15894-1995, neq ISO 6353-3:1987)
• ASTM D3336-05 (modified adoption)
• ASTM D02 Committee research report RR:D02-1007 (precision reference)
• Annex A (normative annex) Method for determining the internal tolerance of bearings, according to the American Bearing Manufacturers Association standard 4 (Method 1, clause 3.6)

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 Q&A