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D1367-96 – Standard Test Method Technical Guide
📐 Apparatus and Material Specifications
ASTM D1367-96 (Reapproved 2001) specifies a rigorous procedure for evaluating the abrasive properties of graphites intended for lubricating applications. The test method relies on a Graphite Lubricant Tester (ASTM Adjunct ADJD1367) which incorporates a bearing holder assembly with an impeller-driven circulation duct, a rigid vertical stand, and a standardized container. The test bearing is a critical wear element with strict dimensional tolerances, and the specific carrier fluid is strictly defined.
| 🟦 Component | 📏 Specification |
|---|---|
| Test Bearing Type | Double-row ball bearing, without closure (seal) |
| Bearing Bore (Inner Diameter) | 12.00 mm (0.4724 in) |
| Bearing Outer Diameter | 32.0 mm (1.2598 in) |
| Bearing Width | 15.875 mm (0.6250 in) |
| Ball Count / Diameter | 7 balls / 5.97 mm (0.235 in) |
| Carrier Fluid | Paraffin Oil (viscosity of 20) |
| Test Container | Griffin beaker, 400 mL, 75 mm diameter |
⚙️ Test Procedure and Operating Conditions
The procedure begins by creating a suspension of the graphite sample in the paraffin oil at a concentration of 15 % by weight. This mixture is placed in the test container, and the tester impeller continuously circulates the suspension through the rotating bearing assembly. The system operates under tightly controlled parameters to guarantee that results are comparable across different graphite samples.
| 🟦 Parameter | 🎯 Specification |
|---|---|
| Graphite Concentration in Oil | 15 % by weight |
| Shaft Rotational Speed | 1750 ± 50 rpm |
| Total Test Duration | 2 hours |
| Container Capacity / Diameter | 400 mL / 75 mm |
| Primary Measured Parameter | Bearing weight loss (wear) |
⚠️ Critical Operating Note: The motor must drive the test bearing shaft at precisely 1750 ± 50 rpm. Deviations from this speed will alter the abrasive dynamics of the graphite particles, invalidating the relative ranking of different samples. The bearing must be thoroughly cleaned and weighed before and after the test to determine the weight loss accurately.
📊 Significance and Interpretation of Results
This test method strictly measures the relative abrasiveness of graphites under the specific, highly controlled laboratory conditions defined. The result is the loss in weight of the standardized bearing, which directly indicates the wear caused by the graphite sample. It is critical for users to understand the specific context of these laboratory results.
📌 No Field Service Correlation: The standard explicitly states that no correlation has been established between this test method and field service. If the test conditions are changed, the relative ratings of the graphites might differ. This test is strictly a comparative laboratory benchmark, not a predictor of real-world performance.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D1367?
It is designed to evaluate the abrasive properties of graphites used for lubricating purposes, providing a comparative wear metric based on the weight loss of a standard ball bearing.
💡 Why is a specific seal-less bearing required?
Removing the seal ensures the graphite-oil suspension can freely circulate through the bearing races, guaranteeing direct contact between the abrasive graphite particles and the bearing surfaces during the 2-hour test.
⚡ How is the graphite sample prepared for testing?
A representative sample of graphite is mixed with paraffin oil to create a suspension containing exactly 15 % graphite by weight. This mixture is constantly circulated by the impeller to maintain uniformity throughout the procedure.
📌 Are these laboratory results representative of real-world performance?
No. The standard explicitly notes that “no correlation has been established between this test method and field service.” The results are strictly valid for relative comparison under these specific laboratory conditions.