6. Apparatus
6.1 Roll Stability Test Apparatus, capable of rotating a steel cylinder and 5 more or less 0.05kg roller weight at a rolling speed of 165 more or less 15rpm. One such example of a suitable apparatus is shown in Fig.1.
6.2 One-Quarter or One-Half Scale Cone and Shaft with Worker, as described in Test Methods D1403.
7. Procedure
7.1 Determine the worked penetration in accordance with Test Methods D1403.
7.2 Transfer 50 g of the unworked grease to the test cylinder. Distribute the grease uniformly on the inside wall of the cylinder with a spatula. Place the weighted roll in the cylinder and tighten the cap.
7.3 Mount the cylinder in position, start the machine, and record the time and room temperature which should be limited to 20 to 35°C (68 to 95°F). If the cylinder is enclosed within a cabinet, the temperature around the cylinder shall be maintained at 20 to 35°C (68 to 95°F).
7.4 After rolling for 2h more or less 5min, remove the grease from the cylinder promptly and proceed with the requirements of worked penetration in Test Methods D1403. Record the worked penetration. After transferring the greas to the worker, clean the roll stability test apparatus by wiping with clean cloth or tissue.
7.5 Convert the fractional scale penetration values determined by Test Methods D1403 (before and after rolling) into the equivalent full scale cone penetration values using the appropriate equations described in Test Methods D1403.
8. Calculation
8.1 Calculate the change in consistency of the sample as follows:
Penetration change = P2 - P1
where:
P2: final full-scale penetration reading, and
P1: initial full-scale penetration reading.
NOTE 1 - Penetration readings are measured in tenths of a millimetre. A negative penetration change indicates hardening of a grease while a positive penetration change indicates softening.
9. Report
9.1 The value calculated in 8.1 is reported as the change in consistency.
