1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW16537 Metal Bonding Structural Adhesive Acceptance Criteria and Repair Procedures - Welded Bonded, Rivet Bonded, and Bonded Structures Copyright 2012 General Motors Company All Rights Reserved February 2012 Originating Department: North Amer
2、ican Engineering Standards Page 1 of 12 1 Scope Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. This standard provides the acceptance criteria
3、 and repair procedures for structural adhesives in automotive products for which GM is responsible for establishing or approving product design. This standard does not apply to hem flange or anti-flutter (semi-structural) adhesives. 1.2 Applicability. This standard applies to any applications where
4、a structural adhesive is used to bond metallic automotive substrates. The criteria established in this standard become mandatory when referenced in product release information. Deviations from any adhesive criteria provided in this standard must be identified in product release information or an app
5、roved Product Quality Standard (PQS) document. 1.3 Usage. Structural bonds are considered satisfactory when they meet the performance requirements, defined in the material specification GMW15200 Metal Bonding Structural Adhesive Performance Requirements. Service loads on structures containing adhesi
6、ve in a vehicle are varied in both type and magnitude and cannot be addressed by this standard. Therefore, while the adhesive quality criteria of this standard are consistent with service loading requirements, they have been established specifically for use in process and product monitoring. Any att
7、empted application of this document to other uses, such as post-crash quality assessment, may lead to an erroneous result or conclusion. Discrepant adhesive applications may still contribute to the integrity of the assembly by retaining a portion of their engineering properties. 1.4 Clarification. F
8、or clarification of this standard or editorial comments, email the GM Global Weld Council at: . Proposed changes to this standard must be presented to the Global Weld Council. To suggest a change to this standard, reference the “Procedure for Weld Standard Changes” on the Global Weld Councils web pa
9、ge. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. None 2.2 GM Standards/Specifications. GMW14057 GMW15200 GMW14058 GMW15563 2.3 Additional References. GMS Operating Guidelines and Global Launch Manual, Section
10、B4 GQR120-18 Global Quality Requirements Procedure for Weld Standard Changes 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 GMW16537 Copyri
11、ght 2012 General Motors Company All Rights Reserved February 2012 Page 2 of 12 3 Requirements 3.1 General Acceptance Criteria. 3.1.1 Correct Material. The structural adhesive applied shall be the material specified in the design release documentation and/or the Process Data Sheet (see Figures A1 and
12、 A2). The product is non-conforming if incorrect material is being applied. 3.1.2 Material Open Time, Closed Time and Shelf-Life. The “open time”, “closed time” and “shelf-life” of the material shall not exceed the requirements in the material specifications. Material with “open time”, “closed time”
13、, or “shelf life” exceeding the specifications shall be replaced and the system shall be purged. The material shall not be exposed to temperatures during storage which exceed the requirements in the material specifications. 3.1.3 Substrate Gap. Substrate gap refers to the amount of separation betwee
14、n the faying surfaces of a joint. The maximum allowable gap is 0.5 mm (1.4 mm for full spectrum impact resistant (IR) adhesive). Joints that exceed the desired gap should have the product and/or process adjusted to reduce the gap to the desired range. 3.1.4 Substrate Condition. Cleaning of the fayin
15、g surfaces is not required unless visibly contaminated by dirt, dust, corrosion, or other foreign matter. Preparation of the faying surfaces is not required unless specified in the material specifications. 3.2 Visual Acceptance Criteria. 3.2.1 Bead Location. The bead position on the flange, includin
16、g the start and stop location, is properly located when installed within 6 mm from the location indicated in the design release documentation and/or the Process Data Sheet (see Figures A3 and A1). Beads not properly located require the process to be adjusted to the specified start and stop locations
17、 as well as bead position along the flange (see Figure A3). Bead position across the flange may be adjusted to achieve wet out and to minimize or eliminate excess material squeezed out of the joint (see Figures A3 and A4). Dissimilar metal joints (e.g., aluminum to steel) bonded flanges or adhesive
18、bead applications identified as the “primary seal” require visible adhesive squeeze out on both sides of the flange. Squeeze-out of adhesive is not allowed in locating holes, fixing holes and tooling holes. For other types of holes, e.g., clearance holes, drain holes, etc., small amounts of squeeze-
19、out can be accepted as long as functionality is not degraded and work environment and wash-off problems do not occur. Local squeeze-out towards the paint shop side of the flange shall be used to prevent pockets or undercuts where there is a risk of moisture intrusion between a paint shop seal and a
20、weld through adhesive. Missing beads cause the product to be nonconforming. 3.2.2 Wet Out. Wet out is defined as the “footprint” of adhesive surface area on each of the flanges in a joint that the adhesive covers. It is required that both flange surfaces exhibit evidence of adhesive contact (flatten
21、ing of the dispensed bead) after separation. Actual transfer of adhesive during this separation may, or may not occur (see Figure A4). On flange surfaces that do not exhibit some evidence of adhesive “footprint” on both flanges the process is to be adjusted to eliminate the condition. 3.2.3 Wet Out
22、Width. The wet out width is to be a minimum 7 mm wide to a maximum of 100% of the flange width (see Figures A4 and A5). It is to be measured on the bead application flange surface at the narrowest place. If the wet out width is less than 7 mm at the narrowest place, then the bead is to be adjusted t
23、o eliminate the condition. 3.2.4 Voids, Skips or Interruptions. Adhesive voids, skips or interruptions are discontinuities and cannot be counted in the effective bond line length. Any voids, skips or interruptions in adhesive bead applications identified as “primary seal”, cause the product to be no
24、nconforming. 3.3 Measurable Acceptance Criteria. 3.3.1 Effective Bond Line Length (Le). Adhesive bond lines that have an effective length greater than or equal to the minimum required length (as described in Table 1) are acceptable provided that the maximum allowable discontinuity value listed in Ta
25、ble 1 is not exceeded. Adhesive bond lines that do not have an effective bond line length greater than or equal to the minimum required length (as described in Table 1) are nonconforming and the process is to be adjusted to eliminate the condition. Refer to Appendix C, Figure C1 for Bond Line Length
26、 Acceptability Flow Chart used with Table 1. 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 GMW16537 Copyright 2012 General Motors Company
27、All Rights Reserved February 2012 Page 3 of 12 Table 1: Bond Line Length Requirements Note 1 Specified Bond Length (mm) Lw Maximum Allowable Length (mm) for any Single Discontinuity (post wet out) Length Tolerance (mm) Lt Minimum Required Length (mm) Lr 150 30 Note 1: Effective Bond Length is define
28、d as Le = La Ld. Where: Le = Effective Bond Length La = Actual Bond Length Ld = Combined discontinuity lengths Note 2: A single discontinuity may not exceed 30 mm for any bead. 3.3.2 Bond Cross Section(s). The required number and location of the representative cross section sample(s) are determined
29、by the specified bond line length (Lw) as shown in Table 2. Table 2: Cross Section Quantity and Location Requirements Note 1 Specified Bond Line Length (Lw) Quantity of Cross Section(s) Approximate Location of Cross-Sections Lw 30 mm 1 Midpoint of bond 30 mm 100 mm 3 Equally spaced from each other a
30、nd the start and end of the bond Note 1: Shift cross section if approximate location falls on a weld or mechanical fastener if present. 3.3.2.1 Post-cure Bond Line Height. Bond line height refers to the thickness of the cured “ribbon” of adhesive between the faying surfaces of a joint after the full
31、 paint bake. Post-cure bond line heights greater than 0.5 mm (1.4 mm for full spectrum impact resistant (IR) adhesive) shall adjust the process -or- correct the mating parts to reduce the height to the desired range. 3.3.2.2 Post-cure Bond Line Width. Bond line width refers to the wideness of the cu
32、red “ribbon” of adhesive across the faying surfaces of a joint after the full paint bake. Post-cure bond line widths less than 7.0 mm shall adjust the process wet out to bring the width to within desired range. 3.4 Disposition/Repair Procedure. 3.4.1 Disposition. All known and suspect product with n
33、onconforming adhesive bonds must be repaired. See Appendix B, Table B1 to determine when an adhesive bond is discrepant. 3.4.2 Repair Procedures. When required, adhesive bonds shall be repaired according to the procedures specifically authorized by the appropriate Product Engineer. In the absence of
34、 an engineering approved repair procedure, the following repair methods shall be used in the following order of preference. 3.4.2.1 Open Adhesive Beads. Open adhesive beads that are nonconforming with the standard can be repaired with suitable methods, e.g., placement of a new adhesive bead conformi
35、ng to this standard. 3.4.2.2 Resistance Spot Weld Repair. Spot weld with a weld gun that is qualified for the metal types and thicknesses to be welded. Repair spot welds must meet the requirements of GMW14057. The quantity and Copyright General Motors Company Provided by IHS under license with Gener
36、al Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16537 Copyright 2012 General Motors Company All Rights Reserved February 2012 Page 4 of 12 location of repair spot welds shall be such so that the spacing between
37、 any combination of spots and repairs does not exceed 30 mm in length. 3.4.2.3 Arc Spot or Plug Weld Repair. Weld using Gas Metal Arc Welding (GMAW) plug or GMAW spot with filler wire. The GMAW spot or GMAW plug weld shall conform to the applicable arc spot and plug weld acceptance criteria standard
38、. All repair personnel using this method of repair must be periodically qualified and approved following local procedures. The quantity and location of repair spot welds shall be such so that the spacing between any combination of spots and repairs does not exceed 30 mm in length. 3.4.2.4 Arc Fillet
39、 Weld Repair. A GMAW fillet weld may be used for two metal thickness joints. The GMAW repair weld must be located so the spacing between any combination of spots and repairs does not exceed 30 mm in length and the repair fillet must be a minimum of 20 mm in length. The repair welds must conform to G
40、MW14058. All repair personnel using this method of repair must be periodically qualified and approved following local procedures. 3.4.2.5 Dissimilar Metal Substrates. For repair of two mixed material sheets: If the adhesive is missed completely, a suitable mechanical fastener shall be selected and i
41、nstall using the manufacturers approved tool. The quantity and location of repair fasteners shall be such so that the spacing between any combination of existing mechanical fasteners and repairs does not exceed 30 mm in length. 3.4.2.6 “Seal Enabled” Beads. Voids, skips or interruptions in adhesive
42、bead applications identified as requiring “primary seal” can be repaired with paint shop sealer. 3.4.3 Repair Exceptions. An exception to specified product repair requirements may be permitted provided there is documented review and approval by the responsible Product Engineer allowing the suspect p
43、roduct to deviate from specification and/or conformance criteria. 4 Manufacturing Process 4.1 Process Control. The welding source is responsible for establishing practices and test methods to assure that the criteria of this standard are met and are consistent with the GM Joining and Dispense Proces
44、s Control Procedure, GMW15563. 4.2 Adhesive Cure Control. The painting source is responsible for establishing practices and test methods to assure that the cure and/or post-cure cycle criteria are met and are consistent with the applicable material specifications. 5 Notes 5.1 Glossary. Bond Line: In
45、termediate layer of adhesive used to connect substrates of similar or different materials. Closed Time: The period of time between mating of the parts to be bonded (after application of the adhesive) and the time when it is cured. Faying Surfaces: Pre-bonded pair of close fitting surfaces that are t
46、o be connected. Open Time: The period between application of the adhesive and the mating of the parts to be bonded. Primary Seal: A body shop sealing operation that is not resealed in paint shop. Primary seal operations are to be noted in the design release documentation. Product Quality Standard (P
47、QS): Measurable requirements for product characteristics, which, when satisfied, ensure the product meets internal and external customer requirements. (Refer to GMS Operating Guidelines and Global Launch Manual Section B4.) Shelf Life: The length of time the adhesive can be stored at the manufacturi
48、ng facility (providing it is stored according to the required storage procedures). The shelf life is specified by the Material Specification, and commences upon receipt from the Manufacturer. 5.2 Acronyms, Abbreviations, and Symbols. IR Impact Resistant La Actual Bond Length Ld Combined Discontinuit
49、y Lengths Le Effective Bond Length Lr Minimum Required Length 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 GMW16537 Copyright 2012 General Motors Company All Rights Reserved February 2012 Page 5 of 12 Lt Length Tolerance Lw Specified Bond Length PQS Product Quality S
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