ASTM D1404 Test Method Estimation of Deleterious Particles in Lubricating Grease
4. Summary of Test Method
4.1 A small portion of the lubricating grease sample is placed between two clean, highly polished acrylic-plastic plates held rigidly and parallel in metal holders. A pressure of 200 psi [1.38 MPa] pressure is applied, and one plate is rotated 30° relative to the other. Particles harder than the plastic and exceeding in size the distance between the plates will imbed in the plates and cause characteristic, arc-shaped scratches in the plates.
4.2 The relative number of such solid particles can be estimated by counting the total number of arc-shaped scratches on the two plates.
5. Significance and Use
5.1 The significance of the number of scratches as far as correlation with field performance is concerned has not been established. A particle which is abrasive to plastic will not necessarily be abrasive to steel or other bearing materials. Some correlation was obtained in that the contaminant used in Sample 3 (see 10.1.1) had a greater wear rate in a laboratory ball bearing abrasive wear test than the contaminant in Sample 2.
NOTE 1 - The number of scratches obtained cannot be used to draw fine differences between greases, but rather, to group them into two or three general classes. One such possible division could be:
1 ... . less than 10 scratches
2 ... . 10 to 40 scratches
3 ... . more than 40 scratches
5.2 An advantage of this test method is that each test takes only a few minutes to run.
5.3 This test method is used for quality control and specification purpose.
