1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW16971 Crowbar Test Procedure for Structurally Bonded Plastics Featured on Exterior Lighting Devices Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 1 of 8 1 Scope Note: Nothing in this standard supercedes applicable laws a
2、nd regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. This document defines the mechanical performance requirements, testing conditions, and procedures used to determine the integrity of structurally bonded
3、plastics, featured on exterior lighting devices. 1.2 Foreword. Not applicable. 1.3 Applicability. This procedure applies to all exterior lighting assemblies that feature structurally bonded plastics and will appear on passenger cars, Multi-purpose Passenger Vehicles (MPV), and trucks. 2 References N
4、ote: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 10365 ISO/IEC 17025 2.2 GM Standards/Specifications. GMW3221 3 Resources 3.1 Facilities. The test facilities shall be accredited to ISO/IEC 17025 or by the International Labo
5、ratory Accreditation Cooperation. 3.1.1 Calibration. The test facilities and equipment shall be in good working order and shall have a valid calibration label. 3.1.2 Alternatives. Alternative test facilities and equipment may also be used. However, all measuring variables as specified in this standa
6、rd shall be determined correctly with respect to their physical definition. 3.2 Equipment. 3.2.1 Temperature and humidity controlled chamber. 3.2.2 Water soak chamber. 3.2.3 Crowbars. 3.2.4 Band saw. 3.2.5 Vise grips. 3.2.6 A camera. 3.3 Test Vehicle/Test Piece. Exterior lighting samples of producti
7、on quality (examples include head lamps, tail lamps, fog lamps, reflectors, center high mounted stop lamps (CHMSL), etc.) 3.4 Test Time. Calendar time: 8 days Test hours: 168 hours + pulls Coordination hours: 24 hours Copyright General Motors Company Provided by IHS under license with General Motors
8、 CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16971 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 2 of 8 3.5 Test Required Information. Not required. 3.6 Personnel/Skills. Not required. 4
9、Procedure 4.1 Test Sample Preparation. Test at least six sample parts which includes both left hand (LH) and right hand (RH) samples that shall be obtained off of the intended production line equipment and set production process. Unless otherwise specified, four samples shall be tested in the as-rec
10、eived condition and two samples shall be tested without being exposed to the in-process leak check. If available, additional samples conditioned per GMW3221, Code A, for 72 h after end of line should be submitted for performance comparison. During production of the test samples, three samples of eac
11、h substrate should be tested on line for surface energy levels at six locations within the bond joint prior to applying the adhesive and within five minutes of the completion of the surface treatment. The minimum value shall be reported and any variations 5 dyne/cm (0.005 Nm) shall be mapped on a la
12、mp picture formatted within the report. 4.1.1 Sectioned Sample Preparation. Unless otherwise specified, assembly samples shall be subjected to sample preparation and the testing after the adhesive suppliers recommended time to full cure of the specific adhesive (typically a minimum aging period of 7
13、 to 14 days). A shorter aging period may be used, provided it is recognized that it represents a more severe condition of test and that results obtained at different aging times are not a good basis for comparing the relative performance characteristics of the joint. Cut the samples into smaller sec
14、tions using a band saw or equivalent tool. Each sample section should be random across all samples and possess approximately between 50 mm and 100 mm of continuous bond line. Do not cut through any uncommon features or large structural variations along the samples bond line (example: steep angles, s
15、harp points, quick curves, etc.) Instead, cut around these areas so that the feature or shape is captured in a single section or as few as possible. Leave sufficient substrate length (suggested minimum width 40 mm) beyond the bond line of each section to provide adequate gripping area. To ensure tes
16、ting of the adhesive exclusively, remove any screws/bolts and cut any clips that further secure the bonded substrates. 4.1.1.1 Cutting Precautions. Ensure cutting the sample introduces no cracks, fractures, or other faults within the adhesive or substrate. (For example, sections may need to be cut s
17、lowly to avoid melting the adhesive or excessive vibration to the joint.) 4.1.1.2 Section Labeling. Each test section must be labeled to indicate its original position in the uncut part (part sample mapping). Labeling should also identify which sections belong to which of the six uncut parts. (For e
18、xample: three sample parts are each cut into four sections. Sections for sample “A” could be labeled “A1,” “A2,” “A3,” and “A4.” The corresponding sections of sample “B” would then be labeled “B1,” “B2,” “B3,” and “B4.” The sections of test sample “C” would follow the same pattern.) 4.2 Conditions.
19、Place sample sections in the following environmental conditions for the specified duration. Do not put all the sections from one assembly sample in the same environmental condition. In each environmental condition, each assembly needs to be present and, in combination, represent an entire assembled
20、sample (i.e., one lamp assembly goes through all conditions listed in 4.2.1). 4.2.1 Environmental Conditions. a. Ambient conditions for 48 h at 23 C and 50% relative humidity. b. Water soak for 168 h at 55 C. Test wet at 23 C. c. Water soak for 168 h at 55 C. Test dry at 23 C. d. Hot climate at 82 C
21、 for 48 h (hot pull shall occur within three minutes of removal from environment). Note: Test wet indicates samples are still wet but tested at room temperature (within 15 minutes of removal from water). Test dry means after a 24 h ambient recovery. 4.2.2 Test Conditions. Deviations from the require
22、ments of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.2.2.1 Agreement and approval to deviations required by the applicable GM Engineers (approval shall include both Design Engineering and Validation Enginee
23、ring). 4.3 Instructions. 4.3.1 Force the assembly apart using a crowbar, screwdriver, or other pry tool. As failure propagates, ensure that the tips of any prying tools do not cut into the adhesive and/or substrates. Force the failure across the Copyright General Motors Company Provided by IHS under
24、 license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16971 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 3 of 8 width of the bond joint, as opposed to parallel to the
25、length. This concentrates the cleaving load on one small area at a time. Alternatively, clamp vise grips to both substrates and pull until failure. 4.3.2 Instron Pulling. If the sections cannot be separated by crowbar or hand, an Instron testing machine may be used to force failure. The closest edge
26、 of each gripping hand must be within 40 mm of the adhesive bond. Smaller part sections are recommended for Instron method, approximately between 40 mm and 60 mm of continuous bond line. Photos are required, which show front view, side view, and any additional descriptive angles, to provide proof th
27、at the adhesive joint was under load, which is visually demonstrated with the tongue of joint parallel to the pull direction. 4.4 Performance Criteria. After all test environments, all samples shall yield a minimum of 75% cohesive failure of the adhesive at the bonded joint area, substrate failure,
28、or mixed failures covering across 100% of the bond joint. Mixed failures may including thin film cohesive failure and light fiber tear as defined in ISO 10365. 5 Data 5.1 Calculations. Calculate the percentage of each failure mode for each section and each substrate (lens and housing separately) by
29、comparing the estimated failure area to the bonded area (bonded area/design footprint) x 100). Then, as reference, calculate the overall percentage for each original lamp sample (Sample “A” overall percentage from A1, A2, A3, A4 as described in 4.1.1.2 Section Labeling. 5.2 Interpretation of Results
30、. Expected failure modes are detailed in ISO 10365. If stock breaks (SB) comprise more than half of all failures, the crowbar test must be repeated, ensuring that all loading is focused on the adhesive joint. 5.3 Test Documentation. 5.3.1 Identify and report the test parts (by program, part number a
31、nd description) and the parts materials (both substrate grade specifics and color, adhesive grade and color, and coatings present, and surface treatment method and surface energy report out). 5.3.2. Document the sectioning process with text and photographs. Identify where each section is located on
32、the full lighting fixture by text and photograph. 5.3.3. Document the crowbar test method with text and supporting photographs, Figures A1, A2, A3, A4, and A5. 5.3.4 Tabulate each part with its sections, environmental exposure, labeling, force of failure (if tested with an Instron machine). See Tabl
33、e A1. Also note the actual environmental conditions under which each part was pulled and any delay time, if applicable. 5.3.5. Describe each failure in as much detail as possible. Calculate percentage of each failure mode based on estimate of actual bond area. Identifying which substrate was affecte
34、d if thin film cohesive failure or adhesive failure was observed, and where one failure mode transitions to another. Also describe where on the lamp the sample failure occurred. 5.3.6. If reporting for root cause analysis, include detail visual comparisons of leaked area versus known good areas. 5.3
35、.7. Note any observed patterns and/or any anomalies. 5.4 Sample Review. Samples shall be reviewed by the responsible GM Design Engineer and GM Validation Engineer. 5.5 Sample Retention. Samples shall be retained by the supplier for any future reviews by GM Engineering until start of regular producti
36、on (SORP) +90 days, or until any root cause investigation has final approval and closure in the GM systems, whichever may apply (i.e., Part Report Tracking System (PRTS), or Quality Review Document (QRD) meeting minutes). 6 Safety This standard may involve hazardous materials, operations, and equipm
37、ent. This standard 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. Copyright General Motors
38、Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16971 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 4 of 8 7 Notes 7.1 Glossary. Subs
39、trate: Structural plastics that are bonded together by an adhesive. 7.2 Acronyms, Abbreviations, and Symbols. ADH Adhesive Failure CHMSL Center High Mounted Stop Lamp COH Cohesive Failure LH Left Hand MPV Multi-purpose Passenger Vehicles PP Polypropylene PRTS Part Report Tracking System QRD Quality
40、Review Document RH Right Hand SB Stock Break Failure SORP Start of Regular Production 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW16971 9 Release and Revisions This standard was originated in May 2013. It was first approved by the Adhe
41、sives Global Subsystem Leadership Team in August 2013. It was first published in August 2013. Issue Publication Date Description (Organization) 1 AUG 2013 Initial publication. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or n
42、etworking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16971 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 5 of 8 Appendix A Table A1: Example Test Results Sample A: GMX351 Headlamp Environmental Conditioning: 48 h at 23 C and 50% relative
43、 humidity Section Bond Length (mm) Details Section Failure A1 90 Outboard lens leg/glue track: 100% ADH / 0% ADH Unusually strong bond in vicinity of clip Inboard lens leg and glue track: 100% COH 50% ADH 50% COH A2 50 Outboard lens leg/glue track: 100% ADH / 0% ADH Inboard lens leg/glue track: 0% A
44、DH / 100% ADH 100% ADH A3 45 Outboard lens leg/glue track: 100% ADH / 0% ADH Evident prior to prying Inboard lens leg/glue track: 0% ADH / 100% ADH 100% ADH A4 60 Outboard lens leg/glue track: 100% ADH / 0% ADH Inboard lens leg/glue track: 100% ADH / 0% ADH 100% ADH failure to PP A5 100 Outboard len
45、s leg/glue track: 100% COH Unusually strong bond in vicinity of clip Inboard lens leg/glue track: 0% ADH / 30% ADH Cohesive for 70 mm 80% COH 15% ADH A6 100 Outboard lens leg/glue track: 100% COH Inboard lens leg/glue track: 70% ADH / 0% ADH Cohesive for 30 mm 65% ADH 35% COH A7 110 Outboard lens le
46、g and glue track: 75% COH Glue track pulled off completely for 30 mm at one end Inboard lens leg/glue track: 100% ADH / 0% ADH 70% ADH 30% COH A8 50 Outboard lens leg/glue track: 100% ADH / 0% ADH Inboard lens leg/glue track: 100% ADH / 0% ADH 100% ADH A9 60 Outboard lens leg/glue track: 0% ADH / 10
47、0% ADH Inboard lens leg/glue track: 0% ADH / 75% ADH Glue separated from both lens leg and glue track for 18 mm 100% ADH A10 115 Outboard lens leg/glue track: 0% ADH / 60% ADH Cohesion for 25 mm Inboard lens leg/glue track: 100% COH 30% ADH 70% COH A11 100 Outboard lens leg/glue track: 0% ADH / 20%
48、ADH Cohesion for 80 mm Inboard lens leg/glue track: 100% COH Difficult to pry due to large glue reservoir in corner. 90% COH 10% ADH A1 to A11 Total: 67% ADH, 33% COH Key: ADH = Adhesive Failure COH = Cohesive Failure PP = Polypropylene Copyright General Motors Company Provided by IHS under license
49、with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16971 Copyright 2013 General Motors Company All Rights Reserved August 2013 Page 6 of 8 Figure A1: Example of Photographs Required in Test Report - Illustrates the Crowbar Test for Section 8 and Shows 100% Adhesion to the Glue Track Figure A2: Example of P
