This standard is issued under the fixed designation D ; the number immediately following rubber O-rings, the following ASTM test methods applicable in. D Standard Test Methods for Rubber O-Rings relative density~ compression set test~ aging test~ mold shrinkage~ Standard + Redline PDF Bundle. RUBBER O-RING. 1. ASTM D Testing Fixture. These test methods provide acceptable procedures for quality control purposes and for the determination of.
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ASTM D - Standard Test Methods for Rubber O-rings. AMS and MIL-R Type 1 Class 1 Typical Values. Hardness, Shore A, ASTM D 90 ±5. Tensile Strength, psi, ASTM D min. download ASTM D TEST METHODS FOR RUBBER O-RINGS from SAI Global.
A xture that accomplishes these requirements is shown in Fig. Any xture or design principle that will accomplish the stipulations of 1 and 2 above may be employed.
If hardness measurements are made with this instrument on O-rings of smaller cross section, the values obtained may be different from those obtained on a standard specimen. Fixtures as shown in For O-rings of less than 3-mm 0.
This is to increase the total thickness to greater than the length of the indentor point. The total depth of the groove must be adjusted to a depth that will reduce within 62 the hardness of a standard specimen of the same material. Immersion Test The detailed procedure for O-rings, outlined in this section however, shall take precedence in case of conict.
For sizes too large in circumference to insert as described, the O-ring shall be cut into segments. The specimen shall be a segment 90 6 2 mm 3. All tests for hardness, tension, elongation, and volume change shall be made in triplicate.
The same three specimens may be used for all tests with hardness and volume determinations made prior to stress-strain tests. In the case of liquids that are volatile at room temperature, the specimen must be quickly placed back into the test liquid after hardness and volume test and prior to tension testing.
For whole O-rings 6 mm 0. For cross-section sizes less than 4 mm 0. Add enough liquid to cover the specimens to a depth of 25 mm 1.
NOTE 4—For liquid mixtures, where the volume percent of the most minor constituent is known, the liquid volume of that constituent shall be This test method is recommended for determining the hardness of O-rings with a cross-sectional thickness of 6 mm 0. NOTE 7—Values obtained with the micro hardness tester may differ from durometer values due to the difference in methods.
The surface effect from aging or curing is more pronounced with the micro tester.
O-Ring Mold Shrinkage Test The specimens are then measured for inside diameter and cross-sectional thickness within 0. Great care must be taken in both the manufacture and maintenance of this mold. Care must be taken not to dent, scratch, or otherwise damage the cavity.
The mold cavities must be kept clean.
The surface nish must be the best commercial practice. This gives the width of the cross section. Check each half for depth. The total of the two halves gives the total depth of the cavity. NOTE 8—Other test sizes varying the cross section and inside diameter may be preferred and are permitted.
This size is recommended merely as the median standard cross section in a diameter easily molded and measured. Some laboratories may prefer a larger size, the important consideration being that the seller and the manufacturer use the same or comparable size for control work.
It has been found important to use a test mold cross-section size as close as possible to the cross-section size of the production mold being considered. Milling time should be the minimum required to obtain a smooth sheet.
The sheet shall be allowed to rest for 30 to 60 min after which preforms shall be cut out with a suitable die. D Other types of preforming, such as a spliced extrusion or slice from a tube may give slightly different results. If an alternative method is used it must be noted in the report.
The mold shall be closed quickly and brought to a pressure equal to a minimum of 3. This curing time and temperature shall be noted in the report. Curing time and especially temperature are very critical in shrinkage consideration. Flash removal shall be done individually and carefully so as not to disturb the basic dimensions of the specimen. An abrasive paper or sand-stick of ne grade is usually employed for the operation.
Excess ash on the inside diameter must be avoided since this will alter the inside diameter measurement. Care must be exercised to ensure proper closing of the mold to prevent erroneous cross-section shrinkage results. Determine actual shrinking by subtracting the average or mean cross section of the specimen from the actual mold cavity size.
Measurement of the cross section in inside diameter, outside diameter, and side-to-side axes is desirable. This provides a check on the accuracy of the mold cavity radius and true roundness of cross section. Some materials, such as silicones, may create an imbalance on the two cross-section axes due to inherent shrinkage characteristics, thus producing an out-ofround cross section.
One or more gages may be necessary to cover a wide range of shrinkage.
Take care not to force the specimen on the step gage. Use only enough pressure to be certain the inside diameter is in intimate contact with the gage. Determine actual linear shrinkage of the inside diameter by subtracting the average or mean inside diameter value of the specimens from the actual mold cavity inside diameter.
The resultant value divided by the mold inside diameter and multiplied by is the percent shrinkage. An alternative method of expression is in units such as millimetres per millimetre or inches per inch. This instrument is very accurate, but if the O-ring is unsupported the diameter must be taken in two directions and averaged. To prevent any out-of-roundness, a special cone can be used in conjunction with the comparator.
The comparator is also used to determine roundness of cross section by measuring thin slices of the cross-sectional area. Corrosion Test NOTE 9—A laboratory desiccator jar is commonly used. The panels shall be made in accordance with the drawings in Fig. If the sample O-ring is smaller than 38 mm in circumference, two whole O-rings may be used.
If supercial rust or adhering particles from the specimen are still present, a light buffing with crocus cloth, steel, or brass wool is permitted.
The rating shall be nil, moderate, or severe. Precision and Bias Refer to these practices for terminology and other statistical details. D FIG. Both repeatability and reproducibility are short term. Six laboratories participated and ve materials were used. A test result is the value obtained from two determinations, each test result being separated by a period of a few days. Therefore, p 5 6, q 5 5, and n 5 2.
The appropriate value is that value of r or R associated with a mean level in Tables closest to the mean level under consideration at any given time, for any given material in routine testing operations.
Two single test results, obtained under normal test method procedures, that differ by more than this tabulated r must be considered as suspect, that is, having been derived from different or nonidentical sample populations. If this is the case, appropriate corrective action should be taken. Two single test results, obtained under normal test method procedures, that differ by more than this tabulated R must be considered as suspect, that is, having been derived from different or nonidentical sample populations.
If this is the case, appropriated corrective action should be taken.
Cracking, flaking, general brittleness, and other characteristics can appear in the rubber O-rings when they are exposed to temperature cycles and solar radiation. Top top grip has a counterweight to allow for even loading. The Rubber O-Ring test standard uses a special motorized fixture that rotates at fixed speed throughout the test. The rotation keeps localized stress moments on the sample to a minimum.
These materials tend to elongate extensively so attention must be made to the total stroke of the tensile tester. There is also another test that does not require the motorized fixture. If your O-ring specimens fall within the allowed criteria, they can be tested with a static fixture.
In some cases, a special type of oil may be used to alleviate friction between the ID of the O-ring and the grip surface. The fixture ships complete with a power adapter for both US and International power outlets.
The fixture can use interchangeable rollers at different sizes. The standard sizes that Universal Grip carries are 3.