ASTM D1403 Test Methods for Cone Penetration of Lubricating Grease
ASTM D1403 Standard Test Methods for Cone Penetration of Lubricating Grease Using One-Quarter and One-Half Scale Cone Equipment
7. Procedure for Unworked Penetration
7.1 Sample - Sufficient sample to overfill the cup of the grease worker is required. If the penetration by 1/4 scale is greater than 47 units or by 1/2 scale greater than 97 units, at least three times the amount needed to fill the cup is required as only one result can be obtained from one filling of the grease cup.
7.2 Preparing Sample for Measurement - Place the empty grease worker cup and an appropriate amount of the sample in a container in the temperature bath maintained at 25°C (77°F) for sufficient time to bring the temperature of the sample and the worker cup to 25 ± 0.5°C (77 ± 1°F). Transfer the sample, preferably in one lump, to overfill the cup of the grease worker. Make this transfer in such a manner that the grease will be worked as little as possible. Jar the cup to drive out trapped air and pack the grease with the spatula, with as little manipulation as possible to fill the cup without air pockets. Scrape off the excess grease extending above the rim by moving the blade of the spatula, held inclined toward the direction of motion at an angle of 45°, across the rim of the cup. Do not perform any further leveling or smoothing of the surface throughout the determination of unworked penetration and determine the measurement immediately.
7.3 Cleaning Cone and Shaft - Clean the penetrometer cone carefully before each test. Bending of the cone shaft can be avoided by holding it securely in its raised position while cleaning. Do not permit grease or oil on the penetrometer shaft, as they can cause drag on the shaft assembly. Do not rotate the cone, as this can cause wear on the release mechanism.
7.4 Penetration Measurement - Place the cup on the penetrometer table, making certain that it cannot teeter. Set the mechanism to hold the cone in the zero position of the indicator dial, and adjust the apparatus carefully so that the tip of the cone just touches the surface at the center of the test sample. Watching the shadow of the cone tip is an aid to accurate setting. Release the cone shaft rapidly, and allow it to drop for 5.0 ± 0.1 s. The release mechanism should not drag on the shaft. Gently depress the indicator shaft until stopped by the cone shaft and read the penetration to the nearest full unit (0.1 mm) from the indicator.
NOTE 3 - If the indicator shaft is depressed with force, the penetration measurement may vary considerably.
7.4.1 If the specimen has a penetration over 47 units by 1/4 scale or over 97 units by 1/2 scale, this specimen can then be used for only one test. If the specimen has a penetration of 47 units or less by 1/4 scale or 97 units or less by 1/2 scale, perform three tests in a single cup spacing these tests on three radii 120° apart and midway between the center and side of the cup so that the cone will neither strike the side of the cup nor impinge on the disturbed area made in a previous test. Center the cone carefully in the container and proceed as in 7.4.
7.5 Additional Testing - Make a total of three tests on the specimen (either in three cups or in one, as described in 7.4), and report the average value, to the nearest 0.1 mm, as the 1/4-scale or 1/2-scale unworked penetration of the sample.
8. Procedure for Worked Penetration
8.1 Sample - Sufficient sample to overfill the cup of the appropriate grease worker is required.
8.2 Working - Transfer sufficient specimen to the cup of the clean grease worker to fill it heaping full, mounded up about 7 mm (0.25 in.) at the center, avoiding the inclusion of air by packing with the spatula. Jar the cup from time to time as it is being packed to remove any air inadvertently entrapped. Assemble the worker and, with the vent cock open, depress the plunger to the bottom. Close the vent cock and place the assembled worker in the temperature bath maintained at 25°C (77°F) until the temperature of the worker and contents are at 25 ± 0.5°C (77 ± 1°F). Then remove the worker from the bath and wipe off any water adhering to its surfaces. Subject the grease to 60 full double strokes of the plunger, completed in 1 min ± 5 s, and return the plunger to its top position. Open the vent cock, remove the top and plunger, and return to the cup as much of the grease clinging to the plunger as can readily be removed. As the worked penetration of a lubricating grease can change significantly on standing, proceed in accordance with 8.3, 8.4, and 8.5 immediately.
NOTE 4 - If a water bath is used and if it is desired to immerse the portion of the worker above its closure, take care that the lid is watertight in order to prevent the entrance of water to the worker.
8.3 Preparing Sample for Measurement - Prepare the worked specimen in the cup for testing so that a uniform and reproducible structure of the grease will be obtained. Jar the cup sharply on the bench or floor and pack the grease down with a spatula to fill the holes left by the plunger and to remove any air pockets. Scrape off the excess grease extending above the rim of the cup by moving the blade of the spatula, held inclined toward the direction of motion of an angle of 45°, across the rim of the cup retaining the portion removed.
NOTE 5 - The jarring should be as vigorous as required to remove the entrapped air without splashing the specimen from the cup. In performing these operations, a minimum of manipulation should be used, as any agitation of the grease can have the effect of increasing the working beyond the specified 60 strokes.
NOTE 6 - Retain the grease removed from the cup in scraping for subsequent tests. Keep the outside of the rim of the cup clean so that the grease forced by the penetrometer cone to overflow the cup can be returned to the cup prior to preparing the specimen for the next test.
8.4 Penetration Measurement - Determine the penetration of the specimen as described in 7.3 and 7.4.
8.5 Additional Testing - Immediately make two more tests in succession on the same specimen. Return to the cup the portion previously removed with the spatula, then repeat the operations described in 8.3 and 8.4. Report the average of the three tests, to the nearest 0.1 mm, as the 1/4-scale or 1/2-scale worked penetration of the sample.
9. Calculation
9.1 The penetration values obtained from the 1/4-scale and 1/2-scale cone equipment in 7.5 and 8.5 shall be converted to full-scale penetrations (Test Methods D217) by the following equations:
9.1.1 1/4 Scale:
P = 3.75p + 24
where:
P = cone penetration by Test Methods D217, and
p = cone penetration by 1/4-scale equipment.
9.1.2 1/2 Scale:
P = 2r + 5
where:
P = cone penetration by Test Methods D217, and
r = cone penetration by 1/2-scale equipment.
NOTE 7 - Full-scale penetration values derived from the 1/4-scale or the 1/2-scale may differ from those obtained using Test Methods D217. Parties interested in using full-scale penetration values converted from the 1/4-scale or the 1/2-scale results may use modified conversion equations when mutually agreeable.
