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D1743-22 – Standard Test Method Technical Guide
📐 Scope, Apparatus, and Specimens
ASTM D1743-22 (Standard Test Method for Determining Corrosion Preventive Properties of Lubricating Greases) differentiates the corrosion-preventive capabilities of lubricating greases. Based on CRC Technique L 412, this method correlates laboratory results with the performance of greases in aircraft wheel bearings stored under wet conditions. All values in the standard are stated in SI units.
The test apparatus consists of a standardized Timken bearing set (LM11949 cone and roller assembly with an LM11910 cup). The mechanical assembly includes a motor operating at 1750 r/min ± 50 r/min (1/15 hp minimum) and a bearing holder with a precisely calibrated 1 kg ± 0.010 kg thrust load weight, along with specified plastic collars (Parts A, B, and C).
| 🔧 Apparatus Component | 📏 Designation / Specification |
|---|---|
| Bearing Cone and Roller Assembly | Timken® LM11949 |
| Bearing Cup | Timken® LM11910 |
| Motor Speed | 1750 r/min ± 50 r/min |
| Thrust Load Weight | 1 kg ± 0.010 kg |
✅ Key Correlation: This test method is directly correlated with service performance for grease-lubricated aircraft wheel bearings. It remains the primary qualification test in many grease specifications for applications where water contact during storage or idle periods is a concern.
⚙️ Test Procedure and Evaluation Criteria
The procedure requires a new, cleaned bearing to be lubricated with the test grease and run under a light thrust load for exactly 60 s ± 3 s to distribute the grease. Following distribution, the bearing assembly is exposed to reagent water (conforming to Specification D1193) and stored for 48 h ± 0.5 h at 52 °C ± 1 °C (125 °F ± 2 °F) in an environment of 100 % relative humidity.
After storage, the bearing cups are cleaned and examined. The standard provides a critical, specific definition of corrosion: “corrosion is manifested by red rust or black stains on the bearing race.”
⚠️ Critical Distinction for Evaluation: Stains through which the underlying metal surface is still visible are not considered corrosion in Test Method D1743 and must be ignored during the pass/fail determination. Only actual deterioration of the metal surface qualifies as corrosion.
📊 Summary of Critical Test Conditions
| 📐 Condition Parameter | 📏 Specified Value |
|---|---|
| Lubricant Distribution Run Time | 60 s ± 3 s |
| Storage Duration | 48 h ± 0.5 h |
| Storage Temperature | 52 °C ± 1 °C (125 °F ± 2 °F) |
| Storage Relative Humidity | 100 % |
| Corrosion Indicators | Red rust or black stains obscuring metal |
The standard is under the jurisdiction of ASTM Subcommittee D02.G0.06 on Functional Tests – Contamination. A related standard, D5969, tests corrosion-preventive properties in the presence of dilute synthetic sea water environments, providing an alternative or complementary evaluation method for different service conditions.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D1743-22?
Its purpose is to differentiate the relative corrosion-preventive capabilities of lubricating greases. It specifically evaluates performance under conditions of high humidity and direct water exposure, simulating the wet storage of grease-lubricated bearings.