1、WORLDWIDEENGINEERINGSTANDARDSMaterial Specification GMW14057Weld Acceptance Criteria and Repair ProceduresResistance Spot Welds - Steel Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Originating Department: North American Engineering Standards Page 1 of 111 ScopeNote: Nothing
2、in this standard supercedes applicable laws and regulations.Note: In the event of conflict between the English and domestic language, the English language shall takeprecedence.This standard applies to steels approved by GM for Resistance Spot Welding (RSW).1.1 Purpose. This standard provides the acc
3、eptance criteria and repair procedures for resistance spot weldsin automotive products for which GM is responsible for establishing or approving product design.1.2 Applicability. The criteria established in this standard become mandatory when referenced on a welddesign document. Deviations from any
4、weld criteria provided in this standard must be identified on a welddesign document or other product design document.1.3 Usage. Welded structures are considered satisfactory when they carry the intended service loads for arequired period. Service loads on weldments in a vehicle are varied in both ty
5、pe and magnitude and cannot beaddressed by this standard. Therefore, while the weld quality criteria of this standard are consistent withservice loading requirements, they have been established specifically for use in process and productmonitoring. Any attempted application of this document to other
6、 uses, such as post-crash weld qualityassessment, may lead to an erroneous result or conclusion. Discrepant welds by retaining a portion of theirengineering properties may still contribute to the integrity of the assembly.1.4 Clarification. For clarification of this standard or editorial comments, e
7、mail the GM Global Weld Council .Proposed changes to this standard must be presented to the Global Weld Council. To suggest a change to thisstandard, reference the “Procedure for Weld Standard Changes” on the Global Weld Councils web page.2 ReferencesNote: Only the latest approved standards are appl
8、icable unless otherwise specified.2.1 External Standards/Specifications.None2.2 GM Standards/Specifications.GMW14058GMW155632.3 Additional References.x Body Opening Appearance Perceptual Quality Best Practices Weld Appearance Zone Diagrams (Thesupplier shall work with the GM responsible engineer to
9、comprehend this requirement.)x Global Weld Council web page: https:/ Global Manufacturing System (GMS) Operating Guidelines and Global Launch Manual3 Requirements3.1 General Acceptance Criteria.3.1.1 Individual Spot Weld Criteria. There are multiple visual and measurable attributes that are used toe
10、valuate spot weld quality. These attributes are divided into two categories: attributes that make the weldCopyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEER
11、ING STANDARDS GMW14057 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 2 of 11discrepant; and attributes that do not make the weld discrepant, but the attribute is undesirable for appearanceor processing.3.1.2 Categories of Spot Welds. There are two categories of spot weld
12、s: structural and process.3.1.2.1 Structural Spot Welds. Structural spot welds are installed for performance of the welded product. Allspot welds are structural unless specifically noted as process welds on the weld design document.3.1.2.2 Process Spot Welds. Process spot welds are installed to faci
13、litate in-process assembly, but are notrequired for structural performance of the product. Process spot welds must be approved by Product andManufacturing Engineering and shown on the weld design document.3.1.3 Adjacent, Missing or Cold Welds. Product detected with two or more adjacent structural sp
14、ot weldsthat are not installed (missing welds), or judged to be cold welds must be repaired regardless of the patterntolerance.3.2 Visual Acceptance Criteria.3.2.1 Visual AttributesDiscrepant Welds. Welds that exhibit any of the following attributes are discrepantwelds.3.2.1.1 Cracks. Spot welds wit
15、h crack(s) around the circumference that are visible without the aid ofmagnification, are discrepant welds. Spot welds with surface cracks confined within the impression left by theelectrodes are not discrepant welds. See Figure A1.3.2.1.2 Holes. Spot welds that contain holes extending through the w
16、eld are discrepant welds and cause theproduct to be nonconforming, regardless of the quantity tolerance. See Figure A2.3.2.1.3 Edge Welds. Welds in which the spot weld imprint, as defined by the impression left by the electrodes,is not contained within all edges of the sheet metal being welded are d
17、iscrepant. See Figure A3, welds Eand F.3.2.1.4 Missing Welds. When fewer welds exist than are specified on the weld design document, the omittedwelds are discrepant.3.2.2 Visual AttributesAppearance and Processing Considerations. Welds that exhibit the followingattributes are undesirable either from
18、 an appearance or processing viewpoint. However, these attributes do notmake the weld discrepant and should not be used in determining weld pattern conformance.3.2.2.1 Extra Welds. The number of spot welds installed shall not exceed the number specified on the welddesign document, except as required
19、 by the repair procedures described in 3.4 of this standard. The weldingprocess shall be adjusted to eliminate extra welds.3.2.2.2 Whiskers. Welds exhibiting whiskers should have the welding process adjusted to eliminate thecondition. See Figure A4.Note: Welds shall be free of whiskers when using ul
20、trasonic inspection equipment to avoid damage to thetransducer.3.2.2.3 Distortion. Spot welds in which the sheet surfaces are distorted more than 25 degrees from the normalplane shall have the welding process adjusted to the original qualified setup in order to reduce the distortion toless than 25 d
21、egrees. See Figure A5.3.2.2.4 Thinning. Spot welds exhibiting thinning greater than 30% of the total metal stackup should have thewelding process adjusted to the original qualified setup in order to reduce the thinning below 30%. See FigureA6.3.2.2.5 Trim Edge Deformation. Welds in which the origina
22、l edge of the weld flange is deformed by theelectrodes but whose spot weld imprint is contained within all edges of the sheet metal being welded are notdiscrepant. The process shall be adjusted to the original qualified setup to eliminate the condition. See FigureA3, welds C and D.3.2.2.6 Indentatio
23、n. Indentation is a depression on the sheet surface. See Figure A6. The appearance criteriafor indentation are listed in Appendix A.3.2.2.7 Surface Eruption. Surface eruption is an upsurge of the sheet surface adjacent to the electrode capimprint. See Figure A7. The appearance criteria for surface e
24、ruption are listed in Appendix A.3.2.2.8 Spatter. Spatter is weld metal expulsion that remains attached to surface(s) adjacent to the weld. SeeFigure A4. The appearance criteria for spatter are listed in Appendix A.Copyright General Motors Company Provided by IHS under license with General Motors Co
25、mpanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14057 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 3 of 113.2.3 Perceptual Quality Requirements. Spot welds visible to the customer in strategic
26、 areas of the body areto be considered Perceptual Quality (PQ) spot welds (reference the “Body Opening Appearance PerceptualQuality Best Practices Weld Appearance Zone Diagrams”). Product Quality Standards are to be utilized todocument the appearance acceptance standards addressing the desired weld
27、spot precision (alignment,spacing, concentricity) and prominence (indentation, distortion, whiskers). Spot welds not meeting appearancestandards should have the process adjusted to the original qualified setup to eliminate the undesirablecondition.3.3 Measurable Acceptance Criteria.3.3.1 Weld Locati
28、on. Spot welds must be properly located relative to design location as indicated on the weldtemplate and to each other as follows.x In a pattern consisting of a single in-line row of welds in which a distinct product feature provides visualreference to the end weld, an end weld installed greater tha
29、n 10 mm in radial distance from the designlocation is a discrepant weld. A distinct product feature must be a visible trim edge or other recognizablepart feature that is perpendicular or nearly perpendicular to the row of welds and within 30 mm of the endweld.x For all other welds, a spot weld insta
30、lled greater than 20 mm in a radial distance from the design locationis a discrepant weld.x For visible secondary surface welds, Appendix A specifies the weld location tolerance. Refer to the WeldAppearance Zone diagrams in the Best Practices file for classification of visible weld.x If the spacing
31、between two adjacent welds in a pattern consisting of a single in-line row of welds exceedsthe design spacing by greater than 20 mm, the weld furthest from the design location is a discrepant.3.3.2 Weld Size. The weld size may be measured by either using the weld button (Figure A8), the weld nugget(
32、Figure A9), or the fusion zone. A spot weld is discrepant when the measured weld size is less than theminimum acceptable weld size specified in Table 1.How to identify the Determining Thickness for a 2 or 3 loose sheet stack up is shown in Appendix B.Table 1: Minimum Acceptable Weld SizeDetermining
33、Thickness(DT) Minimum Acceptable Weld Size0.65 to 1.29 mm 4.0 mm1.30 to 1.89 mm 5.0 mm1.90 to 2.59 mm 6.0 mm2.60 to 3.25 mm 7.0 mm3.3.2.1 Interfacial Fracture. With certain steels or types of loading, a weld button may not always result fromdestructive testing. In these cases of interfacial fracture
34、, examination of the fusion zone must be used todetermine weld size. Criteria for evaluation of the fusion zone must be in accord with an approved ProductQuality Standard.3.3.2.2 Cold Welds. Weld locations that do not produce a weld button after a destruct test and are notinterfacial fractures are c
35、old welds. Cold welds are discrepant welds.3.3.2.3 Laminated Vibration Damping Steel. The minimum weld size specified in Table 1 is required only atthe faying surface for laminated steel. There are no minimum weld size requirements for the interface betweenthe layers of the laminated steel.For purpo
36、ses of determining the minimum weld size, the laminated steel shall be treated as one sheet whosethickness is equal to the sum of the two outer sheets and the inner visco-elastic layer as shown in Figure A10.3.4 Disposition/Repair Procedure.Copyright General Motors Company Provided by IHS under lice
37、nse with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14057 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 4 of 113.4.1 Spot Weld Pattern Conformance Criteria. A pattern is a
38、 collection of spot welds to which a tolerance isapplied to meet structural requirements and for determining manufacturing acceptance of the product. Spotweld patterns must include all structural welds and be shown on the weld design document. Process weldsshall not be included in any weld patterns.
39、The spot weld pattern is conforming when the number of acceptable spot welds (not discrepant per therequirements of this standard) within a pattern meets or exceeds the pattern tolerance as stated on the welddesign document. Manufacturing acceptance of product is based on all patterns conforming. Kn
40、own andsuspect product with nonconforming patterns must be repaired.Note: Two or more adjacent missing or breaking welds cause pattern nonconformance regardless of thequantity tolerance. Structural spot welds with holes cause the pattern to be nonconforming regardless of thequantity tolerance.3.4.2
41、Repair Exceptions. An exception to specified product repair requirements may be permitted providedthere is documented review and approval by the responsible Product Engineer allowing the suspect product todeviate from specification and pattern conformance criteria.3.4.4 Surface Appearance. Spot weld
42、 surface appearance criteria are not used in determining weld patternconformance.3.4.5 Process Spot Welds. Process spot welds are not to be used in determining weld pattern conformance.Process welds containing holes require product repair.3.4.6 Repair Procedures. When required spot welds shall be re
43、paired according to the procedures specificallyauthorized by the appropriate Product Engineer. In the absence of an engineering approved repair procedure,the following repair methods shall be used in the following order of preference.3.4.6.1 Resistance Spot Weld Repair. Spot weld with a weld gun tha
44、t is qualified for the metal types andthicknesses to be welded. One repair spot weld shall be added for each spot weld being repaired. Repair spotwelds must meet the requirements of this standard. Locate repair spot welds as close as possible to theoriginal designated weld location without overlappi
45、ng the existing spot weld.3.4.6.2 Arc Weld Repair. Arc weld repair of laminated steels is not permitted.3.4.6.3 Arc Spot or Plug Weld Repair. For each spot being repaired, weld using Gas Metal Arc Welding(GMAW) plug or GMAW spot with steel filler wire. The GMAW spot or GMAW plug weld shall conform t
46、o theapplicable arc spot and plug weld acceptance criteria standard. All repair personnel using this method of repairmust be periodically qualified and approved following local procedures.3.4.6.4 Arc Fillet Weld Repair. A GMAW fillet weld may be used for two metal thickness joints. The GMAWrepair we
47、ld must be located as close as possible to the original designated weld location and must be aminimum of 20 mm in length. The repair welds must conform to GMW14058. All repair personnel using thismethod of repair must be periodically qualified and approved following local procedures.4 Manufacturing
48、Process4.1 Process Control. The welding source is responsible for establishing practices and test methods to assurethat the criteria of this standard are met, and are consistent with the GM Joining and Dispense ProcessControl Procedure (GMW15563).5 Notes5.1 Glossary.Cold Weld: A weld that does not p
49、roduce a weld button after a destruct test. At the faying surface of a coldweld, there is no indication of fusion. Cold welds do not indicate a nugget when the weld is cross-sectioned.Crack: A fracture type discontinuity characterized by a sharp tip and high ratio of length to width of openingdisplacement on the exterior surface. See Figure A1.Distortion: Angle of displacement that the sheet surfaces are distorte
