1、WORLDWIDEENGINEERINGSTANDARDSMaterial Specification GMW15774Chromium Plated Aluminum Wheels andAluminum Wheel Metal Trim Copyright 2013 General Motors Company All Rights ReservedMay 2013 Page 1 of 81 ScopeThis standard covers the materials and processing required to chromium plate aluminum wheels an
2、d trim.Plating durability requirements are also included.While not all surfaces of a three dimensional part can be exposed at the prescribed test angles, all exposedsurfaces must be evaluated for compliance to the requirements. In order to evaluate a wheel to thisspecification, a part drawing is req
3、uired so that the analyst can select the appropriate tests for the variousplated, partially plated, and painted surfaces.1.1 Material Description. Chromium Plated Aluminum Wheels and Aluminum Wheel Metal Trim.1.2 Symbols. Not applicable.1.3 Typical Applications. This specification applies for all ca
4、st and forged wheels and could also be used forsome metallic trim on wheels.2 ReferencesNote: Only the latest approved standards are applicable unless otherwise specified.2.1 External Standards/Specifications.ASTM B456 ISO 2177ASTM B764 ISO 3497ISO 14632.2 GM Standards/Specifications.GMW3059 GMW1470
5、0 GMW15891GMW3286 GMW14829 GMW15919GMW14458 GMW152822.3 Additional References.TMC003 Material Safety Data Sheet guidance documents (available at ).3 RequirementsNote: Online systems using more than one chemical supplier are not recommended for purposes of problemresolution and continuous improvement
6、.3.1 Chemical Requirements.3.1.1 Pretreatment for Chromium Plating. Adequate pre-plating surface preparation requires cleaning andmetrology related procedures. The choice of these procedures should be based upon knowledge of theincoming surface to be prepared, including the soils, surface topography
7、 and alloy chemistry. It isrecommended that only one chemical supplier be used throughout the preparation stages, for purposes ofproblem resolution and continuous improvement.3.1.2 Physical Requirements.3.1.2.1 Plating Thickness. Plating thickness measurements shall include a mapping of the areas of
8、 the wheelas identified on the part drawing.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 GMW15774 Copyright 2013 General Motors Company A
9、ll Rights ReservedMay 2013 Page 2 of 83.1.2.1.1 Plating Thickness Requirements.x Chrome (0.25 to 0.4) mx Micro porous nickel (No minimum but must meet STEP requirements)x Bright nickel 16 m minimumx High sulfur nickel (No minimum but must meet STEP requirements)x Semi-bright nickel 24 m minimumx Sem
10、i-bright/(semi-bright + bright) 60 % minimumx Copper thickness 10 m minimumx Total nickel thickness 40 m minimumx Total plate thickness 50 m minimum3.1.2.1.2 Plating thickness requirements apply on all surfaces designated on the Engineering Part Drawing.3.1.2.1.3 Plating thickness shall be determine
11、d by the microscopic method, ISO 1463, the electrochemicalmethod, ISO 2177 or the x-ray method, ISO 3497. The x-ray method is applicable to measuring only thechrome thickness.3.1.2.1.4 Exceptions to the minimum plating thickness are generally shown as a detail on the part drawing byeither designatin
12、g plating checkpoint(s) or by indicating in an appropriate view the area(s) with deviatedthickness(es) allowed. These exceptions must still meet the specified number of corrosion test hours.3.2 Plated Part Performance for Primary Surfaces. The engineering part drawing shall designate all of thesurfa
13、ces that must meet these requirements. These surfaces should all be plated with near optimum currentdensities as recommended in the control plans and technical data sheets for the process and chemicals,respectively, either by system anodes or auxiliary anodes. In addition, these surfaces shall be pr
14、otected fromcreepback, peeling or other forms of degradation that could initiate from other areas of the part. The table inAppendix B could be used to organize the plating data for PPAP submissions.The test parts shall be positioned in the environment such that at least one of the primary surfaces i
15、s exposedat the specified Copper Accelerated Acetic Acid Salt Spray (CASS) test (GMW14458) angle, but all exposedsurfaces must be evaluated for compliance to the requirements. Since all other surfaces would therefore beexposed to a less severe environment than the chosen primary surface, they should
16、 be evaluated and held tothe full requirements of the specification.3.2.1 Plated parts must pass 120 h of CASS testing per GMW14458, with no significant corrosion on theexposed surfaces. Parts should be evaluated at 66 h to determine if the finish is in conformance at that stageof the test. The only
17、 visual change that could be considered acceptable is the expected opening of the micropores because this is designed into the system as a mode of degradation. The micro pore change must beuniform, and must be considered acceptable to the buyer of the parts. Analysts are encouraged to developvisual
18、standards and review them with GM for a conformance/non-conformance agreement.3.2.2 All surfaces with some plating must pass the Reverse Saw Cut Test, Appendix A. In the Reverse SawCut Test, position the part in a vise or fixture so that the exterior plated surface is perpendicular to the sawblade a
19、nd the cutting motion of the blade is in a direction which tends to pull the plating away from the basemetal with no loss of adhesion at any interface. Without exception, all surfaces with any plating must pass thistest with no loss of adhesion.3.2.3 Plated parts shall be evaluated using the followi
20、ng Thermal Shock Test after CASS exposure:Parts or wheel sections shall be heated to (+150 10) C for 1 h 15 minutes and then direct immersed towater at room temperature (+23 3) C). The requirement is no blistering or flaking of the coating afterimmersion.3.2.4 Nickel Electrode Potential. Determine p
21、otential difference following ASTM B764.3.2.4.1 The bright nickel layer shall exhibit an anodic electrode potential difference of 100 mV minimum and170 mV maximum to semi-bright nickel.3.2.4.2 The bright nickel layer shall exhibit an anodic electrode potential difference of 10 mV minimum and a40 mV
22、maximum to the micro porous nickel layer.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 GMW15774 Copyright 2013 General Motors Company All
23、Rights ReservedMay 2013 Page 3 of 83.2.4.3 The bright nickel layer shall exhibit a cathodic electrode potential difference of -40 mV minimum and a-5 mV maximum to the high sulfur nickel.3.2.5 Discontinuous Chromium. This shall be evaluated by either the copper deposition (Dubpernell) methodor by the
24、 determination of active corrosion sites after corrosion testing. Both are described in the Appendix ofASTM B456.3.2.5.1 The micro discontinuous chromium surface shall exhibit a minimum of 10 000 pores/cm2 as determinedby copper deposition or 2000 pores/cm2 as determined by active sites. Stripping o
25、f chrome after 120 h CASStesting and prior to active site determination is acceptable.3.3 Secondary Surfaces. The brake side and tire side of the rim are secondary surfaces that could requirecosmetic protection beyond that which is provided by the less than optimum current densities plated withinthe
26、se areas. The cosmetic performance of these surfaces must meet the consumers expectations and is theresponsibility of the wheel manufacturer.The engineering part drawing must document the specific areas for which the minimum requirements of theprimary and secondary surfaces apply. In addition, the w
27、heel supplier is responsible for implementingadequate cosmetic protection to avoid peeling of the plating layers and thus, avoid cosmetic or handling issuesfor all wheel surfaces.Production parts must meet the requirements of this section when tested 72 h minimum after the coatingprocess is complete
28、d. A shorter aging time may be used provided it is recognized that it represents a moresevere condition of test.Rim sections of the test parts shall be positioned in the environment such that each type of secondary surfacesof interest is tested at the prescribed test angle. The part drawing is requi
29、red so the analyst can determine howmany surfaces should be evaluated, e.g., brake side rim, tire side rim, back of the spokes, etc.3.3.1 All rim areas where a coating is applied over the plating must meet the following requirements:3.3.1.1 There shall be no creepback, peeling, or flaking more than
30、1 mm from a straight scribe, and no blistersafter being exposed to 66 h in CASS per GMW14458, and followed by air blow-off of the scribe perGMW15282.3.3.1.2 After exposure to 500 h according to GMW3286, the un-scribed surface shall not exhibit any evidenceof blistering or other appearance changes. T
31、he exposure will be continued to 1000 h, the surface will beexamined for changes, and any changes will be addressed in the suppliers continuous improvement plans.3.3.1.3 Coatings shall exhibit 99 % adhesion along a scribe as shown in GMW14829, after exposure to theThermal Shock Test according to GMW
32、15919.3.3.1.4 Chip resistance according to GMW14700 with a Rating 6 between the plating and the coating. Nochipping is allowed between plating layers.3.3.1.5 Paint cure test according to GMW15891.3.3.2 Coating thickness shall be identified on the drawing with minimum film builds at designated T poin
33、ts foreach surface of the wheel. Since the quality of each low current density surface is unique and depends on thewheel design, and the process pretreatment and plating, the amount of added protection that is required of acoating must be determined by the wheel manufacturer. The wheel manufacturer
34、shall document the coatingand coating thickness for each surface on the part drawing.4 Manufacturing ProcessNot applicable.5 Rules and Regulations5.1 Legal Regulations. All materials must satisfy applicable laws, rules, regulations and recommendationsvalid in the country of usage.5.2 Language. In th
35、e event of conflict between the English and domestic language, the English language shalltake precedence.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 ENGINEERI
36、NG STANDARDS GMW15774 Copyright 2013 General Motors Company All Rights ReservedMay 2013 Page 4 of 85.3 Inspection and Rejection. Samples of components or materials released to a GM material specificationshall be tested for conformity with the requirements of this material specification and approved
37、by theresponsible Engineering department prior to commencement of delivery of bulk supplies.A new approval must be received for any changes, e.g., properties, manufacturing process, location ofmanufacture, etc. If not otherwise agreed, all testing and documentation normally required for initial rele
38、asemust be completed.It is the responsibility of the supplier to inform the customer in a timely manner, without solicitation, and toinclude documentation of all modifications of materials and/or processes and to apply for a new release.If not otherwise agreed, all release tests shall be repeated an
39、d documented by the supplier prior tocommencement of delivery of non-conforming bulk supplies. In individual cases, a shorter test can be agreedto between the responsible Engineering department and the supplier.5.4 Material Safety Data Sheets/Safety Data Sheets (MSDS/SDS). For new product submission
40、s, or when achange in chemical composition of an existing product has occurred, a complete copy of the Material SafetyData Sheet/Safety Data Sheet must be submitted in compliance with the Globally Harmonized System ofClassification and Labeling of Chemicals (GHS) requirements or other country-specif
41、ic MSDS/SDSrequirements. In addition, product MSDS/SDS submissions must be in compliance with specific countryGeneral Motors TMC003 Material Safety Data Sheet/Safety Data Sheet guidance documents where available.5.5 All materials supplied to this standard must comply with the requirements of GMW3059
42、, Restricted andReportable Substances for Parts.6 Approved SourcesMaterials supplied to this specification must be approved by General Motors.Engineering qualifications of an approved source are required for this standard. Only sources listed in the GMMaterials File (GM Supply Power) under this stan
43、dard number have been qualified by Engineering as meetingthe requirements of this standard.For other GM locations, the responsible Engineering group should be contacted to obtain the approved sourcein that individual country.7 Notes7.1 Glossary. Not applicable.7.2 Acronyms, Abbreviations, and Symbol
44、s.ASTM ASTM, InternationalCASS Copper Accelerated Acetic Acid Salt SprayGHS Globally Harmonized System of Classification and Labeling of ChemicalsMSDS Material Safety Data SheetSDS Safety Data SheetSTEP Simultaneous Thickness and Electrochemical Potential8 Coding SystemThis standard shall be referen
45、ced in other documents, drawings, etc., as follows:Material per GMW15774Copyright 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 GMW15774 Copyright 2
46、013 General Motors Company All Rights ReservedMay 2013 Page 5 of 89 Release and RevisionsThis standard was originated in December 2007. It was first approved by the Global Finishes and CoatingsTeam in June 2008. It was first published in June 2008.Issue Publication Date Description (Organization)1 J
47、UN 2008 Initial publication.2 MAY 2013 5 year refresh updateCopyright 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 GMW15774 Copyright 2013 General
48、Motors Company All Rights ReservedMay 2013 Page 6 of 8Appendix AA1 Reverse Saw Cut TestA1.1 Scope. This guideline describes equipment and a procedure that could be used for the reverse saw cuttest. This test is used to evaluate the adhesion of a plated material to a substrate. This procedure should
49、beused to evaluate if there is a significant non-conformance in the plating system due to a lack of adhesionbetween the layers. This test alone is not an indication that the plating system will have acceptable fieldperformance.A1.2 Procedure.A1.2.1 Equipment. Lack of adhesion can be identified with metal cutting band saws with the followingvariables: Regular-toothed blades having (3 to 10) teeth/
