1、FORD LABORATORY TEST METHOD BP 116-01 Date 2001 O924 1990 02 23 PERMANENT TENSILE SET OF CIRCULAR RUBBER COMPONENTS Action Revisions Revised Editorial - no technical change A. Cockman Application This method determines the amount of permanent “set“ of circular rubber components such as wings, seals,
2、 and cross sections of tubes and hoses where ASTM D 395, SAE J120, ASTM D 412, and ASTM D 1414 are not applicable due to equipment limitations, small inside diameter, or unusual geometry typical of lip-type oil seals mounted on rigid material castings. Scope This method provides a procedure for dete
3、rmining the percent change in inside diameter or percent tensile set of rubber wings, seals, and cross sections of tubes and hoses after experiencing a specific elongation for defined periods of time at various temperatures and exposure media. It is useful for determining environmental effects resul
4、ting from exposure to heat, ozone, and fluids where dimensional stability and heat or ozone crack resistance are investigated. In cases of 25 percent elongation, this test may or may not give direct correlation to ASTM D 395 (Compression Set), but will yield comparative data to base judgments as to
5、expected compression set performance between materials in the absence of uniform sheet material. This method may or may not meet the stated requirements for particular components when exposed to ozone atmosphere. Refer to FLTM BP 1 O1 -01 and the appropriate Engineering Materials Specification for a
6、pplicability. This method may be employed for obtaining comparative data on lip-seal performance with and without “garter springs“, at actual engineering elongations, or more severe elongations either with casing intact or removed. In cases of desired elastomeric elongations greater than that allowe
7、d by rigid casing or housings typically encountered in various dynamic oil seals, special removal techniques with a lathe and cutter will be required to remove the elastomer from the seal housing prior to elongating the elastomer. Materials and Apparatus Required Profile Projector (Shadowgraph or Op
8、tical Comparator) Nikon V-16, XL-14, or equivalent Source: Optical Gaging Products 850 Hudson Avenue Rochester, New York 14621 U.S.A. Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BP 116-01 Mandrel Of suitable size to enlarge the wings or seals to a predetermined inside di
9、ameter. Aluminum or steel that can be tooled to a precise diameter and polished to a 0.125 micrometre surface or better has been found satisfactory. Forced Air Oven - in accordance with ASTM D 573. Lathe A rotational lathe capable of firmly gripping the outside diameter of the rigid seal housing, an
10、d fitted with a preciseedged, firmly mounted but adjustable stationary knife or blade to accommodate varying seal diameters. It should provide a nick-free, uniform, circumferential removal of the elastomeric seal material while under rotation. Spiral springs (“garter“) or other metal reinforcements
11、are to be removed. If necessary, lubricate the knife or blade edge with liquid soap and water while cutting to avoid “chatter“ or “stepping“. Ozone Cabinet Cabinet as specified in ASTM D 1149 or FLTM BP 101-01 Fluid Aging Properly vented containers, preferably laboratory grade glass, appropriate to
12、safely performing an immersion at a controlled temperature below the flash point of the fluid are required. In cases of elevated temperature, it is recommended that vapors from volatile materials (.e. fuels) be condensed (see ASTM D 471). Caution should be exercised as to the hazards of file, explos
13、ion and toxic vapors. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 OC and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified
14、 Procedure Unless otherwise specified, condition all materials according to ASTM D 1349. 1. Sample five rings or seals from each lot. 2. Inspect the rings or seals for molding imperfections (.e. excess flash, cracks, pits, etc.). necessary substitute substandard ones and note imperfections. If 3. M
15、easure the rings or seals individually on the Shadowgraph and record the inside diameter to the nearest 0.02 mm at right angles for a total of two measurements. Average the two initial inside diameters and record as Di. Page 2 of 3 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST ME
16、THOD BP 116-01 4. 5. 6. 7. 1. 2. Calculate the required increase in diameter to achieve the desired elongation and select or fabricate a mandrel of appropriate diameter. In cases of oil seals contained in rigid structures, determine maximum elongation expected in service or a more extreme elongation
17、 as geometry permits. If the desired elongation is greater than that permitted by the rigid housing, employ procedures for removing the elastomer from its reinforced housing by using rotational lathe techniques. Rinse away residual soap with running water if soap was used in the lathe operation, and
18、 air-dry. Record the mandrel diameter as (D,). Carefully slide the ring or seal on the mandrel, taking care not to nick or invert the cross section or fold under the sealing lip or dust lip of the seal. Use a graphite lubricant if necessary. Place the assembly into the required aging environment. At
19、 the end of the exposure period, unless otherwise specified, remove the assembly and immediately remove the rings or seals from the mandrel and allow to cool on an electrically thermally non-conductive surface for 30 minutes at 23 +/- 2 “C. In the case of fluid aging, cool the rings or seals in a co
20、ntainer of the same unaged fluid for 30 minutes (see ASTM D 471). The ring or seal is then remeasured on the Shadowgraph as in Step 3 and an average final inside diameter (Df) obtained. Eva I u at io n Calculate the percent inside diameter change as follows: percent change = M - D, x 100 Di Calculat
21、e percent tensile set at predetermined elongation as follows: percent set = D, - D, x 100 Dm- Di Where: Di = initial inside diameter Df = final inside diameter after aging D, = mandrel diameter or diameter of elongated ring or seal is subjected to The report should include the method of specimen pre
22、paration (entire part, cross section, or lathe), percent diameter change or percent permanent set based on percent elongation derived from an enlarged inside diameter. Report individual results, median, or average per set of five specimens as appropriate. Report time, temperature, and exposure media, observations on quality, etc. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly Each party is responsible for determining proper use and handling in its facilities. Page 3 of 3 Copynght02001, Ford Global Technologies, Inc
