- Page of 8 Test Documentation This document is a translation of Freudenberg Sealing Technologies (FST) internal test procedure FB 7 008. In case both documents contradict each other, the iginal German version is valid.. Introduction When selecting a suitable material f a sealing solution, in addition to the temperature range consideration of chemical and physical resistance of the elastomeric material is often decisive. The knowledge about all media that come into contact with the elastomeric material, is decisive f reliability. Depending on the application, FLENDER gear units from Siemens are using NBR- FKMcompounds to seal. These are influenced by different ageing- and wearing-effects, which are essential f the lifetime of the Simmerring. A lot of material properties, like hardness, volume, tensile strth and elongation at break, are changed by temperature- and media-influence. To release lubricants f the use in FLENDER gear units, they have to pass static and dynamic compatibility tests with NBR- and FKM-compounds of Freudenberg. The oil sample to be tested must be clearly marked with the ISO VG viscosity class at 40 C the SAE-class if necessary and the type of the base oil (mineral oil, poly-α-olefin, poly-glycol synthetic ester) and the API- classification. 2. Static test 2. Immersion test accding to DIN ISO 87 (08/2008) The volume of the oil to be tested is about 80 times the combined volume of the samples. The free hanging samples have to be fully immersed in and surrounded from all sides by the oil. Accding to DIN ISO 87 the volume of air above the oil shall be minimal. F immersion, test vessels are used closed with glass lids using silicone grease (e. g. Baysilone) to prevent influence of air. The samples have to be prepared in accdance to DIN ISO 2529 (0/2007). 2.2 Test procedure F the static immersion test in media, test samples type S2 (DIN 5504) and discs (Ø 6.6 mm) are cut out of elastomeric sheets with thickness (2±0,2) mm. The cutting die has to be in perfect condition to avoid micro fractures in the samples. Properties f tensile strth and elongation at break are measured at five S2-samples. F clear identification, three discs are marked and used f determination of volume and hardness. In deviation to DIN ISO 87, hardness is measured accding to She A-method DIN ISO 769- (02/202), tensile test is measured accding to DIN 5504 (0/2009). Test samples and test setup without oil are shown in picture and 2.
- Page 2 of 8 Picture : Samples Picture 2: Immersion of samples in test vessel Source: Freudenberg New Technologies Test temperatures to be used f the different oil types and sealing materials are defined in table. Immersion duration is 008 h (± 2 h). Table : Test temperatures Elastomeric material NBRcompounds FKMcompounds Mineral Oil ( API & API 2) & Synth. Ester (API 5) Temperature / C Mineral Oil (AP) &PAO- oils (API 4) Polyglycole (API 5) 95 95 95 0 20 0 The test procedure is set in the Freudenberg-internal instruction document "Durchführung von statischen Tests zur Freigabe für den Einsatz in Flender-Getrieben. 2. Evaluation of test results After the immersion in the test oil, the samples are measured and evaluated concerning changes in hardness, values of tensile strth and elongation at break and volume accding to DIN ISO 87 (08/2008). Test results are signed calculated using the following equation: Value after the test minus value befe the test. Percentages are based on the value befe the test. Limits f maximum acceptable changes, depending on the compounds are listed in the tables 2A and 2B.
- Page of 8 Table 2A: Acceptable change of function values (valid f Simmerring Compounds 72NBR902;75FKM585 and 75 FKM 260466 ); (median values) hardness She A in hardness degrees volume in % tensile strth in % elongation at break in % Points -5 x 5-2 x 5-50 x 20-60 x 20 5 < x 7 5 < x 6 x > 20-0 x < -5 7 < x 0 x < -0 x > 0-5 < x < -2 6 < x 9-5 > x x > 9-65 x < -60 x > 20 2 *) -70 x < -50-75 x < -65 **) < -70 < -75 0 *) only if the deviation to bold written limits exceeds one of the four test criteria limits. If me than one test criteria is exceeded: maximum point. **) only if the deviation to bold written limits exceeds one of the four test criteria limits. If me than one test criteria is exceeded: no point. Table 2B: Acceptable change of function values (valid f O- ring Compounds 80 FKM 60 ; 72 NBR872); (median values) hardness She A in hardness degrees volume in % tensile strth in % elongation at break in % Points -0 x 0-0 x 0-25 x 0-25 x 0 2-5 x < -0 0 < x 5 x < -5 x > 5-5 x < -0 0 < x 5 x < -5 x > 5-50 x < -25 0 < x 50-50 x < -25 0 < x 50 **) < -50 < -50 0 **) only if the deviation to bold written limits exceeds one of the four test criteria limits. If me than one test criteria is exceeded: no point.
- Page 4 of 8 2.4 Necessary amounts of oil / test cost It is mandaty the oil containers are marked with oil designation, base oil type, the API- Group, ISOviscosity, and cresponding purchase der number / test conditions. In addition an actual material safety data sheet in German English must be attached. In der to achieve an oil release of a homologous series with various viscosities by Siemens, the highest and lowest viscosity has to be statically tested. F one test with one elastomer compound and one oil, one liter oil is needed. A static test costs 570.- EUR
- Page 5 of 8.. Dynamic test. Dynamic Oil resistance test in accdance to DIN 76 Next to static tests the compatibility has to be tested on iginal components as closely as possible to real application conditions. F that reason the companies Siemens and Freudenberg developed a test program which represents the influence of lubricants on radial shaft seals during run time. The dynamic sealing test is carried out on specifically built test rigs (picture ). The counter surfaces are plunge ground test shafts out of 8CrNiMo7 hardened to 56+6 HRC. The roughness of the shaft surface is in accdance with SIMRIT catalogue recommendations. The oil level in the test chamber is at the shaft centerline. The test program is run with two Simmerrings, model BAUX2, dimension 5-52-7 on separate test rigs. If synthetic oils are combined with elastomer type 75 FKM 585, the number of tested Simmerrings is increased to three. Picture : Principle of test rig accding to DIN 76
- Page 6 of 8.2 Test method The test procedure is defined as follows: Table 4. Test program - NBR material Test program Test time / min ( h ) Rpm / /min Step 200 (20) 2000 Step 2 240 (4) 0 Eccentricity / Coaxiality G I A 0. mm / 0. mm Test procedure: 2 repetitions of step and 2 = total run time 2 days (768 h) Table 4.2 Test program - FKM material Test program Test time / min ( h ) Rpm / /min Step 200 (20) 000 Step 2 240 (4) 0 Eccentricity / Coaxiality G I A 0. mm / 0. mm Test procedure: 42 repetitions of step and 2 = total run time 42 days (008 h) The test temperature depends on the type of lubricant and elastomer material. The test is carried out with two Simmerrings. If synthetic oils mineral oils Group are combined with elastomer type 75 FKM 585, the number of tested Simmerrings is increased to three. Table 5 Test temperature Elastomer material NBRmaterial FKMmaterial Mineral Oil (API & API 2) & synth Ester (API 5) Oil sump temperature / C Mineral Oil (AP) & PAO- Oil (API 4) Polyglycole (API 5) 80 80 80 90 00 0
- Page 7 of 8. Test evaluation The tested seals are evaluated as follows: Visual Inspection Measuring the functional values with a tapered mandrel and radial fce measuring device The decisive fact f approval is the change in functional values compared to initial values. The tolerance limits relate to the average value of all tested parts. The max/min values are documented f each seal. The shaft run in is measured with a surface measuring devise accding to DIN ISO 4287. The visual inspection of the sealing lip is done with a microscope (6 to 25 x magnification). The evaluation criteria f the visual inspection are based on experience documented in internal picture characteristic catalog of FST. Table 6 Tolerance limits f dynamic test Test parameter Unit Tolerance limits 72 NBR 902 75 FKM Leakage ml 0 0 Sealing time h 768 008 Running track width at 2) mm 0.5 0.4 sealing edge Depth of shaft run in 2) µm 5 0 Radial fce with spring,2) % +0 to -45 +0 to -5 Interference with ) 2) spring mm -0.6-0.5 Interference without ) 2) spring mm -0.7-0.6 Visual inspection of sealing lip 2) Col change at running track 4 Oil carbon fmation Hardening 2 Crack fmation Blistering Wear of sealing edge / running marks Chemical attack Deposit on shaft ) value befe test subtract value after test 2) average value of 2 radial shaft seals Notes Legend f visual inspection: none little 2 significant strong 4 very strong 5 Results within all tolerance limits gets 2 points Slightly exceeding one tolerance limit gets point Significantly exceeding one me tolerance limits gets 0 points The resulting number of points will be given by internal FST-evaluation plan.
- Page 8 of 8.4 Necessary amounts of oil / test cost It is mandaty the oil containers are marked with oil designation, base oil type, viscosity, and cresponding purchase der number / test conditions. In addition an actual material safety data sheet in German English. Table 7 Oil amount and test cost Suitability f elastomer radial shaft seals - dynamic test - Oil amount Price (without tax) [liter] [ ] a) Test with 2 RSS 2 740.- b) Test with RSS 560.- 4. Evaluation and rept The results of the static and dynamic tests are listed on a separate fm and sent to the customer. Next to the evaluated characteristic data, a photo documentation is done in case of extradinary optical conspicuities and attached to the rept. The results of the static and dynamic tests are evaluated with 0 up to maximum points accding to the criteria listed above. The reached number of points can be seen on the individual rept. The overall evaluation of static and dynamic results is made by Siemens after submitting the application f release f an oil. F a release by Siemens, all tests have to reach one point at minimum. This test method was developed in cooperation of Freudenberg Sealing Technologies, Freudenberg Fschungsdienste and Siemens AG MD. Contact persons: Siemens AG Freudenberg Sealing Technologies Freudenberg New Technologies Mr. Dr. Gajewski Mr. Sattler Mr. Daub