ZZ-R-768B
4.5.6 Hot compression set. Hot compression set shall be determined by ASTM D395, Test Method B, with specimens clamped to 40 percent deflection and aged for 96±½ hour at 194±2 °F (90±1.1 °C).
4.5.7 Volume change after immersion in oil. The volume change shall be determined by Method 6211 of
FED-STD-601 after immersion in medium No. 3 oil of Method 6001 of FED-STD-601 for 96±½ hour at 122±2 °F (50±1.1 °C).
4.5.8 Deformation, resilience, frequency, and absorbed energy. Deformation, resilience, frequency, and absorbed energy shall be determined using a Yerzley oscillograph following the procedure for measurements in compression detailed in ASTM D945. The mechanical properties shall be determined at both 73.4±2.0 °F (23.0±1.1 °C) and
32.0±2.0 °F (0.0±1.1 °C), after conditioning the specimens for 2 days at room temperature plus 4.0±0.1 hour at each test temperature
4.5.8.1 Deformation. Deformation is the percent deflection of the specimen caused by five standard weights, calculated as one inch equals 20 percent.
4.5.8.2 Resilience. The resilience shall be calculated by dividing the vertical distance of the upstroke of the first cycle (rebound) by the vertical distance of the down-stroke of the first cycle from the starting point and multiplying by 100.
4.5.8.3 Frequency. The frequency shall be determined by counting a convenient number of cycles, then measuring in inches the horizontal distance along the center axis of the set of oscillations covered by this number of cycles, and by dividing the number of cycles by the measured distance.
4.5.8.4 Absorbed energy. The absorbed energy shall be calculated by multiplying the vertical distance in inches of the down-stroke of the first cycle by the constant 20. (The constant 20 equals the energy of 5 weights corresponding to one inch vertical distance on the chart per cubic inch of material.)
4.5.9 Cold compression set. Cold compression set shall be determined by ASTM D1229, with specimens clamped to 40 percent deflection and conditioned for 96±½ hour at 32±2 °F (0±1.1 °C), and allowed to recover for 30 minutes at the conditioning temperature before measuring the final thickness.
5. PACKAGING
5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or order (see 6.2). When packaging of materiel is to be performed by DoD or in-house contractor personnel, these personnel need to contact the responsible packaging activity to ascertain packaging requirements. Packaging requirements are maintained by the Inventory Control Point's packaging activities within the Military Service or Defense Agency, or within the military service's system commands. Packaging data retrieval is available from the managing Military Department's or Defense Agency's automated packaging files, CD-ROM products, or by contacting the responsible packaging activity.
6. NOTES
INFORMATION FOR GUIDANCE ONLY. (This section contains information of a general or explanatory nature that is helpful, but is not mandatory.)
6.1 Intended use. This specification describes a synthetic rubber material used as resilient elements of unbonded-spool type and compression type mountings that are used to mount equipment and gages for shock protection and vibration isolation.
6.2 Acquisition requirements. Purchasers should select the preferred options permitted herein and include the following information in procurement documents:
a. Title, number, and date of this specification. b. Form of material required (see 1.1 and 3.2.1).
c. When first article is required (see 3.1 and 3.1.1).
d. Type, dimensions, and tolerances required for resilient components (see 3.3).
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