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1、WORLDWIDE ENGINEERING STANDARDS Test Procedure Laboratory GMW3155 Thermal Cycling Test for Life Assessment of Powertrain Sealing Systems Copyright June 2002 General Motors Corporation All Rights Reserved June 2002Originating Department: North American Engineering Standards, Records and Documentation
2、Page 1 of 20 1 Scope Note: Nothing in this test method supersedes ap- plicable laws and regulations unless a specific exemption has been obtained. Note: In the event of a conflict between the Eng- lish and domestic language, the English language shall take precedence. 1.1 Purpose. 1.1.1 This test is
3、 used to predict the life of powertrain sealing as it applies to the intended system design. The system includes the gasket, fasteners, structural interfaces and circulating media. Test fixtures are cycled through hot and cold temperature extremes over a period of up to 25 weeks. Time to failure (de
4、fined by media leakage) is the performance measure. See 1.4.3. 1.1.2 This test is used on components and assemblies (up to entire powertrains) to identify and eliminate poor seal designs and/or materials. Design has a significant influence on test results. 1.1.3 The test establishes a no leakage per
5、formance requirement as it relates to customer miles and powertrain objectives (h). See leak definition, 1.4.3. 1.1.4 It serves as a development or validation test. See 1.2.1 and 1.2.2. 1.1.5 See applicability 1.3, for further information. 1.2 Foreward. This document describes two methods for evalua
6、ting sealing systems in their intended subsystem assembly. 1.2.1 Method D (development) evaluates parts that are not final production release. See definitions, item 1.4.1. 1.2.2 Method V (validation) predicts the life of final production released gaskets and seals in their released subsystem assembl
7、y. 1.2.3 References to this test must include the appropriate method using the letter (D or V) designated in parenthesis after the test number, e.g. GMW3155 (V). 1.2.4 Before initially running this test procedure, the operator shall run 1.2.4.2 to verify sufficient initial sealing of the joint. Air
8、leak integrity (1.2.4.1) of the fixture is specified by the requester. Additional checks on late component changes are at the requesters or operators discretion. 1.2.4.1 Air leak test to ensure that the assemblies have sufficient sealing integrity (GMW3149). This may be conducted before, during, and
9、 after the thermal cycling test. 1.2.4.2 Qualitative measurement of the sealing force distribution. For static force distribution measurements, use GMW3152. For dynamic force distribution measurement (pressure mapping) use GMW3137. 1.2.5 The values stated in either SI units or English units are to b
10、e regarded separately as standard. The values stated in each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the test procedure. 1.3 Applicability. 1.3.1 This test is suited to the evaluation of all static powertrain gaskets an
11、d seals that experience thermal cycling during service in European and NAO passenger vehicle and light duty truck applications. Other regional or vehicle applications, e.g. H.D. trucks, may not experience the thermal cycle described in this document. 1.3.2 This test can evaluate internal seals in an
12、 assembly that contain actuators that cyclic load the seal (e.g. transmission bonded pistons). 1.3.3 This test permits the optional use of mechanical devices to impart motion or load on any test fixture(s). 1.3.4 Use GMW3157 for rotating sealing elements such as lip seals on shafts. 1.3.5 This test
13、procedure is not the most efficient for replicating gasket surface fatigue alone; for that purpose use GMW3146. GMW3155GM WORLDWIDE ENGINEERING STANDARDS Copyright June 2002 General Motors Corporation All Rights Reserved Page 2 of 20June 2002 1.3.6 High temperature applications, (head, ex- haust or
14、EGR gaskets) are beyond the limits of this test. 1.3.7 Test Oils. To achieve satisfactory engine or transmission oil test results, the test fluid circulatory system (3.2.2) of each test unit shall permit steady and progressive oxidative degradation (3.3.1.7) of the test oil to the end of test. Fluid
15、 degradation is measured using the appropriate fluid industry tests (3.3.1.7 and 3.3.1.8). 1.3.8 Fluid Leak Requirements. If a component or part statement of work or requirement, print specification, test request, etc. doesnt identify verifiable fluid sealing criteria when referencing GMW3155, then
16、the leak definition (1.4.3) and test default requirements (3.5.3) shall remain in effect. Other criteria stated (in these documents) for evaluation during or after GMW3155 must be defined and/or have measurable values. If not, they are not required for PPAP. 1.4 Definitions. 1.4.1 Development. Test
17、parts or components that are not final production release. Less than 100 % of the parts are final production release. 1.4.2 Validation. All parts or components meet the final production release requirements as deter- mined by the release responsible engineer(s). 1.4.3 Leak Failure. Do not use a GMUT
18、S scale for leak evaluation. 1.4.3.1 Fluids. The accumulation of a 25 mm wide pool of concentrated test fluid on the fixture collection tray. 1.4.3.2 Air/Gas. The leak detection rate (LDR) is part/component specific and is designated by the requester or detail drawing. Measure flow rate (cc/minute)
19、using GMW3149 at 23 C at the designated initial pressure (kPa/Barr). Use the appropriate pressure gauges and flow meters in the designated locations. 2 References Note: Only the latest approved standards are ap- plicable unless otherwise specified. 2.1 Normative. ASTM D445ASTM D664 ASTM D2896ASTM D5
20、483 2.2 GM. GM123MGM6277M GM9064PGM9084P GME L0004GMW3137 GMW3146GMW3149 GMW3152GMW3157 99855229985541 99858099985912 99861669986176 3 Resources 3.1 Facilities. 3.1.1 A suitable area or room for conducting testing with a stable and known environment. See item 4.2. 3.2 Equipment. 3.2.1 Basic. 3.2.1.1
21、 Thermal Test Chamber with Temperature Controller. Chamber internal volume sufficient (greater than or equal to 226 L or (8 ft3) to house the components scheduled for test,1 and can cycle from -40 to 150 ( 3) C. Test chamber must have plumbing and wiring access hole(s). Temperature controller with p
22、rogramming feature2 must maintain 3 C of set temperature. Unit (with temperature indicator) must have multiple thermocouple channels to monitor chamber and part temperature. Sensor input must accept designated temperature measuring device. 3.2.1.2 Fume Hood or Vent. Appropriate industry approved con
23、struction and performance to prevent vapors. 3.2.1.3 Brackets and Mounting Plates. T-slot tables or bed plates for mounting test components in chamber. Fixtures should accommodate vehicle orientation effects. 3.2.1.4 Temperature Monitor. Computer controlled data analyzer capable of measuring in -40
24、to 150 C range to 3 C accuracy. Accepts designated temperature measuring devices. 1 Some chambers should be of sufficient size to hold two transmission or engine (block, head, and covers) assemblies. If assemblies are in-line, a second rear chamber door to facilitate leak checks is highly recommende
25、d. Interior space must accommodate assembly orientation to simulate underhood positioning (3.2.1.3). 2 When a program is interrupted by shutdowns, it must permit the operator to reset the test cycle at ambient (23 C) and resume the cycle toward the last direction the temperature cycle was headed. GM
26、 WORLDWIDE ENGINEERING STANDARDSGMW3155 Copyright June 2002 General Motors Corporation All Rights Reserved June 2002Page 3 of 20 3.2.1.5 Part Temperature Control (PTC) Device. 3 Capable of measuring in -40 to 150 C range to 2 C accuracy. These two devices meet these requirements: A resistive tempera
27、ture differential (RTD) sensor, American National Standards Institute (ANSI) Types E, K or T thermocouple, solid bare wire diameter (gauge) with wire insulation. 3.2.1.5.1 Fluid Temperature Monitoring, Measuring and Control Probe Device. 4 Capable of measuring in -30 to 150 C range to 2 C accuracy.
28、Figure 3 lists the weekday test fluid operating temperatures. See 3.2.2.4 and 3.3.4.8.4 for device location. 3.2.1.6 Fluid Pressure Monitoring and Measuring Pressure Gauge 0 to 100 kPa (15 psi). Accuracy, mid-scale, (ASME B40.1 grade B or equivalent). Mount to fixture(s) supply manifold. Gauge must
29、operate at the required temperatures and test fluids. Gauge must not corrode in this test environment. See 3.3.4.13 and Figure 2. 3.2.1.7 Calibrated Torque Wrench. 3.2.1.8 Shut-off Devices. Provides shutdown of the equipment in the event test assembly exceeds specified fluid, temperature and pressur
30、e conditions (under or over). Automatic shutdown at low end pressure limit and pressure release at the high end. Made from non-corrosive material(s) that withstand the fluid, temperature and pressure environment of this test. See 4.1.3. 3.2.2 Fluid Circulatory System. 3.2.2.1 Reservoir. External to
31、thermal chamber with sufficient volume capacity to accommodate fluid expansion. A typical capacity is 12 to 20 L (3 to 5 gal. U.S.) depending on the number and size of components tested 5 . Reservoir is fabricated from non-reactive material to fit the requirements. Attach a sight glass to monitor fl
32、uid level. 3 Attached to the test fixture, this controls the chamber temperature during the test cycle (see Figure 3). 4 This controls the fluid heater during the 8 to 10 h of test fluid circulation. It also monitors and measures the 30 minute heat response (C) of the test fluid (3.2.2.4) when leavi
33、ng the cold cycle (Figure 3). A recorder must be wired to this device to maintain temperature vs. time data during use. 5 Use the minimum amount of oil needed to maintain the proper fixture fluid feed rates. This promotes reservoir oil degradation by oxidation and heat. Maintain Table 1 test conditi
34、ons. The total test fluid weight between labs for audit or initial qualification shall be within 500 g. 3.2.2.2 Internal Component Tubing (Spray Bar). 6.35 mm (0.25 inches) or 7.94 mm (0.31 inches) ID, aluminum, stainless steel or GM123M plated steel without copper to avoid corrosion by-products wit
35、h mating parts. Tube inside tested component is conduit for delivering hydraulic test fluid to designated joint location. 3.2.2.3 Tube Compression and Flare Fittings. Use brass or other non-corrosive materials to fit diameter of designated tubing. 3.2.2.4 Pump and Heater Oil, and circulating. 6 A ty
36、pical capacity is 24 Lpm (6 U.S. gal/minute), 35 to 500 kPa (5 to 80 psi) pressure range. Heater output must be capable of reaching specified fluid operating temperature in 15 to 30 minutes from cold end of test cycle. See Table 2. Note: Use a separate probe to monitor, maintain and record fluid med
37、ia inlet temperature to achieve Table 1 fixture temps. See 3.3.4.9. 3.2.2.5 Pump and Heater Coolant, circulating. 6 A typical capacity is 300 Lpm (80 U.S. gal/minute at 30 psi), in 35 to 500 kPa pressure range. Heater output must be capable of reaching specified fluid operating temperature in 15 to
38、30 minutes from cold end of cycle. See 3.2.2.4 note. 3.2.2.6 Delivery Lines Supply and Return. Supply lines, 12 mm (0.5 inches) ID minimum, Braided Steel with Polyetrafluoroethylene Liner. Return line and fixture drain fitting, AN12 (0.75 inches) ID minimum. Rated above maximum system test pressures
39、 and pulses. For lower pressure media systems, non-corrosive, rigid stainless steel lines with quick connect end fittings are possible. See spray bar tube, 3.2.2.2. 3.2.2.7 Coolant Expansion Tank. External to thermal chamber with sufficient volume capacity to accommodate fluid expansion. A typical c
40、apacity is 8 to 11 L (2 to 3 gal. U.S.) depending on the number and size of components tested 7 . Tank is fabricated from non-reactive material to fit the requirements. Attach a sight glass or use a translucent material to monitor fluid level. 3.2.3 Optional. 6 Chromalox (Emerson Electric) or Mohawk
41、 units allow a thermocouple for controlling/monitoring fluid temperature leaving fluid pump. See Figure 3. 7 Use the minimum amount of oil needed to maintain the proper fixture fluid feed rates. This promotes reservoir oil degradation by oxidation and heat. Maintain Table 1 test conditions. The tota
42、l test fluid weight between labs for audit or initial qualification shall be within 500 g. -,-,- GMW3155GM WORLDWIDE ENGINEERING STANDARDS Copyright June 2002 General Motors Corporation All Rights Reserved Page 4 of 20June 2002 3.2.3.1 Data Acquisition System - MS-DOS Compatible PC Computer System t
43、o Gather and Store Data From the Measurement System. The computer shall be of sufficient capability to meet or exceed the needs of the data acquisition system. 3.2.3.2 Optical Densitometer for Measurement of Color Intensity on Pressure Sensitive Paper. See GMW3152. Scanning (pixel imaging) the color
44、 density film and image analysis with math based software is also available. 3.2.3.3 Real Time Pressure Mapping - Sensors and Instrument for Quantitative Measurement of Sealing Force. See GMW3137. 3.2.3.4 Bolt Load Measuring Device (Ultrasonic, Strain Gages,.). Calibrated fasteners for assembling th
45、e components. 3.2.3.5. Vibration Table or Shaker. Use a single or three-axis unit to requester requirements. 3.2.3.6 Air Supply. Either shop air or bottled gas, to perform the air leak test. In line oil and water filters recommended. See GMW3149. 3.2.3.7 Calibrated and Correlated Air Flow Meters to
46、Measure Air or Gas Leak Detection Rate (LDR). One (1) rated from 0 to 5000 cc/minute at 0 to 1400 kPa (0 to 200 psi) pressure range for large leaks. A second rated from 0 to 1000 cc/minute at 0 to 10 500 kPa (0 to 1500 psi) range for small leaks. See GMW3149. 3.2.3.8 Refractometer, Industrial Fluid
47、Tester. One (1), hand held, zero to thirty scale, in half degree divisions for monitoring coolant concentration. Units shall have temperature compensation. Digital units are also available through scientific supply catalogs. 3.3 Test Vehicle/Test Piece. 3.3.1 Test Media. 3.3.1.1 Unless otherwise spe
48、cified8, use the known most aggressive factory-fill fluid for the tested component or part. If unknown, use current production factory-fill fluid. Use the appropriate part test conditions in Table 1. 3.3.1.2 Add appropriate dye to test fluid for UV inspection. Commercial dyes may vary in concentrati
49、on, so adjust the amount used to achieve the desired response to UV light. Typically, 2 ml in 4.5 L is sufficient to fluoresce. Some fluids fluoresce in UV light without the benefit of UV sensitive dyes. Check out the material in a test tube before adding dye. 8 Currently, aerated Mobil 1 5W30 synthetic engine oil is known to be more aggressive than mineral based engine oil on silicone seal materials. -,-,- GM WORLDWIDE ENGINEERING STANDARDSGMW3155 Copyright June 2002
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