1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14127 Impact Cold Crack Copyright 2012 General Motors Company All Rights Reserved March 2012 Originating Department: North American Engineering Standards Page 1 of 9 1 Scope Note: Nothing in this standard supercedes applicable laws and regulations.
2、Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. Determine the resistance of topcoat cracking (leather) and topcoat/topskin cracking (plastic roll goods) due to impact at -30 C. 1.2 Foreword. Not applicable. 1.3 Applic
3、ability. Passenger vehicle interior part components. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM D3574 2.2 GM Standards/Specifications. GMW3221 2.3 Additional References. None. 3 Resources 3.1 Facilities
4、. Not applicable. 3.2 Equipment. 3.2.1 Drop Impact Tester. 3.2.1.1 Part A. A Drop Impact Tester capable of producing 4 J on impact. The impact head must be of the dimensions specified in Figure A1. 3.2.1.2 Part B: A Drop Impact Tester capable of producing 1.5 J or 2.5 J on impact. The impact head mu
5、st be as specified in Figure A1. 3.2.2 Cold Chamber. 3.2.2.1 Parts A and B. Cold chamber with port holes capable of maintaining -30 2 C. The impact tester shall be inside of the cold chamber for all impact tests (Part A and Part B). Test may also be performed in a cold room capable of maintaining -3
6、0 2 C. 3.2.3 Hardwood Block. 3.2.3.1 Part A. Two hardwood blocks with dimensions of 100 3 (length) X 100 3 (width) X 25 3 (thick) mm. At the geometric center of each of the four narrow sides of the hardwood block, an 8 to 15 round head wood screw shall be driven to such a depth that the top of the h
7、ead remains approximately 3 mm above the surface of the block. The hardwood block shall be adhesively bonded to a foam block 100 3 (length) X 100 3 (width) X 50 3 (thick) mm. Any suitable adhesive is acceptable. See Figure A2. The foam block shall be made from high resilient polyurethane foam, polye
8、ther type. Upon receipt, the foam must be certified to have a density of 32 to 42 kg/m3. Upon receipt, the load value at 25% deflection shall be 1.24 to 1.72 Pa. The load value shall be determined in accordance with ASTM D3574, Test C. The foam may be used until there is a visual sign of physical di
9、stortion (permanent indentation, crumbling, etc.) 3.2.3.2 Part B. Three specimen holders as specified in Figures A5 and A6. 3.2.4 Cutting Dies. 3.2.4.1 Part A Use Figure A3, and Part B Use Figure A4. Cutting dies can be purchased from: Ontario Die International 2735 20th Street Port Huron, MI 48060
10、Phone: (810) 987-5060, Extension 305 Fax: (810) 987-3688 Email: Contact: Jim Paonessa 3.2.4.2 The Foam May be Purchased From: FXI Corporation 2211 South Wayne Auburn, IN 46706 Phone: (260) 249-0479 Contact: Dan Fritz 3.3 Test Vehicle/Test Piece. 3.3.1 Standard Foundation Board No. 21929X. The fiber
11、board can be purchased from: Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reser
12、ved March 2012 Page 2 of 9 Fibre Converters 15514 South Telegraph Monroe, MI 48161 (734) 240-0833 Contact: Bob Bumoulin 3.4 Test Time. Calendar time: 3 days Test hours: 4.5 hours Coordination hours: 24 hours 3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills. Not applicable. 4 Proce
13、dure Part A. Specimens are mounted on a fixture over a foam block. A drop impact tester and the mounted specimens are placed in a cold chamber for a minimum of 4 h at -30 C. The specimens are impacted at 4 J and evaluated for cracks in the topcoat/topskin. Part B. Specimens are mounted in a fixture
14、over fiberboard. The drop impact tester and the mounted specimens are placed in a cold chamber for a minimum of 4 h at -30 C. The specimens are impacted at the required impact level (see the applicable material specification) and evaluated for cracks in the topcoat/topskin. 4.1 Preparation. 4.1.1 Pa
15、rt A. Cut all specimens following the guidelines in the material specification. The specimen dimensions are included in Figure A3. 4.1.2 Part B. Cut all specimens following the guidelines in the material specification. The dimensions are included in Figure A4. Follow all conditioning and aging requi
16、rements in the material specification prior to testing. 4.2 Conditions. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates,
17、 reports, etc. 4.3 Instructions. 4.3.1 Part A. 4.3.1.1 Install one of the test specimens (appearance side up) over the foam block. Secure the specimen to the block by putting each of the four holes over the heads of the screws in the wooden block. 4.3.1.2 Make all required adjustments so that the im
18、pact tester will produce 4 J on impact before placing it in the cold chamber. Note: To determine the required height, measure from the tip of the indenter (Figure A1) to the surface of the specimen. (Kg)(9.80665)(M) = J. Note: The design of some drop impact testers is such that frost may compromise
19、their function. If frost is known to be a problem, the chamber should be started at room temperature and be cooled with the impact tester inside during the cooling process. Once the chamber has started cooling, do not open the cold chamber door before all testing has been completed. All tests should
20、 be conducted through the port holes. 4.3.1.3 Periodically check the temperature of the cold chamber until the temperature remains stable at -30 C. Start timing the exposure so that the drop impact tester and all specimens remain at -30 C for a minimum of 4 h prior to testing. Note: When handling te
21、st specimens in the cold chamber, always wear gloves to protect your skin from the cold. It is also important to wear gloves to prevent heat transfer from your hands to the test specimens during handling. 4.3.1.4 After a minimum of 4 h, reach through a port hole and install the specimen under the im
22、pact head. 4.3.1.5 Raise the impact head to the correct height and allow it to drop. 4.3.1.6 Lift the impact head and remove the specimen (while still in the specimen holder). Install the next specimen and continue until all specimens have been tested. Examine each tested specimen for cracks that ma
23、y be immediately visible in the topcoat/topskin. Allow the tested specimen to remain for a minimum of 24 h in a room conditioned to the requirements of GMW3221, Code A. Examine the topcoat/topskin again to ensure that no cracks in the topcoat/topskin are visible that may have been hidden by moisture
24、 and condensation. 4.3.1.7 After 24 h of conditioning, remove the tested specimen from the foam block. While holding the specimen with both hands at opposite edges and pulling gently, place one finger under the impacted area from the non-appearance side to stretch it gently. Examine the impacted are
25、a for cracks in the topcoat/topskin. 4.3.2 Part B. 4.3.2.1 Cut one piece of fiberboard to the dimensions shown in Figure A4. Place one fiberboard piece on the bottom retaining ring of the specimen mounting fixture. See Figures A5 and A6 Copyright General Motors Company Provided by IHS under license
26、with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reserved March 2012 Page 3 of 9 for retaining ring dimensions. Install one test specimen (appeara
27、nce side up) over the fiberboard on the bottom retaining ring. Align the holes on the top retaining ring to fit over the four threaded bolts on the bottom retaining ring. Secure the top retaining ring to the bottom one using four winged nuts (finger tight). 4.3.2.2 Make all required adjustments so t
28、hat the impact tester will produce either 1.5 J or 2.5 J. See the material specification for the correct impact level. Note: To determine the required height, measure from the tip of the indenter to the surface of the specimen. (Kg)(9.80665)(M) = J. Note: The design of some drop impact testers is su
29、ch that frost may compromise their function. If frost is known to be a problem, the chamber should be started at room temperature and be cooled with the impact tester inside during the cooling process. Once the chamber has started cooling, do not open the cold chamber door before all testing has bee
30、n completed. All tests should be conducted through the port holes. 4.3.2.3 Periodically check the temperature of the cold chamber until the temperature remains stable at -30 C. Start timing the exposure so that the drop impact tester and all specimens remain at -30 C for a minimum of 4 h prior to te
31、sting. Note: When handling test specimens in the cold chamber, always wear gloves to protect your skin from the cold. It is also important to wear gloves to prevent heat transfer from your hands to the test specimens. 4.3.2.4 Reach through the port holes and install the specimen holder (with the spe
32、cimen) in the impact tester. Raise the impact head to the required height to produce the required impact energy. 4.3.2.5 Release the impact head. 4.3.2.6 Raise the impact head and remove the specimen after it has been impacted. Examine the specimen for cracks in the topcoat/topskin. Allow the specim
33、en to remain for a minimum of 24 h in a room conditioned to the requirements of GMW3221, Code A. Examine the topcoat/topskin again to ensure that no cracks in the topcoat/topskin are visible that may have been hidden by moisture and condensation. Examine the specimen while holding it with both hands
34、 at opposite sides while pulling gently. Place one finger under the impacted area from the non-appearance side to stretch it gently. 5 Data 5.1 Calculations. 5.1.1 Part A. Evaluate and rate cracks in the topcoat/topskin in accordance with the material specification. 5.1.2 Part B. Evaluate and rate a
35、ny cracks in the topcoat/topskin in accordance with the material specification. 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. Document in accordance with the material specification. 6 Safety This standard may involve hazardous materials, operations, and equipment. This stand
36、ard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.
37、2 Acronyms, Abbreviations, and Symbols. Not applicable. 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW14127 9 Release and Revisions This standard was originated in May 2005. It was first approved by the Global Textile Committee in May 20
38、05. It was first published in February 2006. Issue Publication Date Description (Organization) 1 FEB 2006 Initial publication. 2 MAR 2012 5 Year Refresh, no content changes. (Global Textile GSSLT) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for Resal
39、eNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reserved March 2012 Page 4 of 9 Appendix A Note: All dimensions in millimeters Figure A1: Impact Head Dimension 6.2 x 12.5 50 77 1.8 k i
40、l og r am s We i g ht 45deg r ee s 9.5 R adi us I m pa c t H ea d Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 Ge
41、neral Motors Company All Rights Reserved March 2012 Page 5 of 9 Note: All dimensions in millimeters Figure A2: Hardwood Block Dimensions 3 1 0 0 1 0 0 Wo o d Bl o ck F o a m 50 25 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction
42、or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reserved March 2012 Page 6 of 9 Figure A3: Specimen Type for Part A Copyright General Motors Company Provided by IHS under license with General Motors Com
43、panyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reserved March 2012 Page 7 of 9 Note: All dimensions in millimeters (inches) Figure A4: Specimen Type for Part B Copyrig
44、ht General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012 General Motors Company All Rights Reserved March 2012 Page 8 of 9 Note: All
45、 dimensions in millimeters (inches) Figure A5: Fiberboard Dimensions Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14127 Copyright 2012
46、 General Motors Company All Rights Reserved March 2012 Page 9 of 9 Note: All dimensions in millimeters (inches) Figure A6: Retaining Ring Dimensions Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
