ASTM D1404 Test Method Estimation of Deleterious Particles in Lubricating Grease
6. Apparatus
6.1 The test apparatus is shown in Figs. 1 and 2. As illustrated in Fig. 2 the plastic test plates, 1, are rigidly held in a parallel position in square recesses in parts 2 and 7. The holder, 7, is part of the cap assembly, 7 to 11, which can be removed as a unit from the body, 3, by removing four cap screws. The lower plate holder, 2, can slide along the axis of the main housing, but it is restricted from turning by keys spaced 180° apart. Pressure is applied to the plastic plates, 13, through the holder, 2, by means of the coil spring, 4, spring follower plate, 5, and loading screw, 6. The large loading screw also serves as a base for the apparatus. The indicator pin, 12, on the spring follower plate, 5, shows the linear amount of spring compression, which in turn, is a measure of the pressure applied to the two plastic plates. The upper holder, 7, is kept from rotating by the threaded pin, 9, which projects through a milled slot in cap, 8, and ends with a locking wing nut, 14. To rotate the upper plate and holder, the wing nut is loosened, and the handle, 11, is turned. A leather washer, 10, between holder, 7, and cap, 8, is used to facilitate turning.
NOTE 2 - Although 6.1 describes an apparatus of specific design, any other device that provides the essential operating conditions can be used. Such device is permitted if it can hold the two plastic test plates parallel to each other; apply and measure a minimum pressure of 200 psi [1.38 MPa] on the plastic plates; and provide for 30° relative rotation of the two plates.
6.2 Plastic Test Plates - acrylic plastic test plates (two per test), 1 more or less 0.050 in. square by 1/8 more or less 0.025 in. [25.4 more or less 1.3 mm square by 3.2 more or less 0.64 mm] uniformly thick, having a Rockwell M hardness of 94 more or less 10 (Test Method D785), and having highly polished surfaces protected on both sides with protective paper.
NOTE 3 - Whether dimensioned in inches or millimetres, the plastic test plates should be fabricated to match the square recesses in holders 2 and 7.
7. Reagents and Materials
7.1 Stoddard solvent conforming to Specification D235. Warning: Flammable. Vapor harmful.
NOTE 4 - Other naphthas or pure paraffinic hydrocarbons, such as n-heptane, can be substituted providing they are suitable volatile and do not soften or otherwise attack acrylic plastic.
