GMW 14670-2006 Organic coat finish for steel wheels.doc

GM WORLDWIDE ENGINEERING STANDARDSGMW146701 Introduction1.1 Scope. Organic coat finishes which ensure adequate protection against corrosion on surfaces of road wheels.Note: Some sections reference both, GMW test methods and local test methods. As soon as the GMW is available, it supersedes the local test method.1.2 Mission/Theme. This specification describes the properties of organic coat finishes which ensure adequate protection against corrosion on surfaces of painted steel wheels.Suitable systems may include the following: 1.2.1 Single Coat System.Electropaint (epoxy or acrylic ELPO). Spare wheels and wheels that are fully covered (more than 90 %) can be painted by epoxy elpo. Acrylic elpo should be for wheels that are not fully covered and for this reason need higher UV-resistance.1.2.2 Multi-coat Systems. Double or multi coat systems (e.g. elpo and top coat or elpo, base coat and clear coat).The clear coat (powder or wet coat) shall be resistant against light fastness, weathering and chemicals.Acrylic paint for example is suitable.Note: The colored paint coat and the top coat (clear coat) of any multi-coat system when required need only be applied to significant and/or visible surfaces as shown on the relevant engineering drawing e. g. the disc outer, spoke recess and rim flange.Note: The specific composition of the organic coatfinish is not a part of the specification, however pretreatment, specific composition and minimum film thickness of the organic coat finish shall be confirmed by the supplier in writing and are part of the initial sample approval.The relevant suppliers as well as their material designations of the used pretreatments and materials shall be communicated.1.3 Classification / Wheel types.1.3.1 Type A. Single Coat System cathodic elpo black (only wheels which are fully covered or spare wheels).1.3.2 Type B. Single Coat System acrylic elpo.1.3.3 Type C. Double Coat System (elpo, topcoat)1.3.4 Type D. Multi Coat System (e.g. elpo, base coat, clear coat)Note: Nothing in the specification, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.2 ReferencesNote: Only the latest approved standards are applicable unless otherwise specified.2.1 External Standards/Specifications.ASTM G152-05SAE J2020ASTM G153-04J20202.2 GM Standards/Specifications.GME 60203GM 9511PGME 60410 GMW 3059GME 60400GMW 3286GME 60402GMW 14333GME 60403GMW 14334GME 60407GMW 14700GMI 60266GMW 14829GM9163PGMW 148732.3 Additional References. None.3 Test Preparation and Evaluation3.1 Resources.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 specification shall be determined correctly with respect to its physical definition.3.1.3 Facilities. Apparatus as required by the appropriate test method.3.1.4 Equipment. Equipment suitable for measuring coating thicknesses based on eddy current or ferromagnetic principles having an accuracy of 2.0 m.3.1.5 Test Vehicle/Test Piece. Test pieces, shape, dimensions and number of test pieces as specified in the appropriate test method.3.2 Preparation./ Conditioning. Tests according to paragraph 4.4.7 to 4.4.11 are only applicable for the disc outer.If test pieces cannot be prepared due to wheel dimensions for the relevant tests, the supplier shalldeliver special test samples with the original substrate (material) in dependence of the test but the original coat in any case.3.3 Safety. This procedure may involve hazardous materials, operations, and equipment. This method does not propose to address all the safety problems associated with its use. It is the responsibility of the user of the method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.3.4 Documentation. Samples of components or material released to this specification shall be tested for conformity with the requirements of this specification and approved by the responsible GM Department prior to the start of delivery of production level components or materials.Any change to the component or material, e.g., design, function, properties, manufacturing process and/or location of manufacture requires a new release of the product. It is the sole responsibility of the supplier to provide the customer, unsolicited, with documentation of any change or modification to the product/process, and to apply for a new release.If not otherwise agreed to the entire verification test shall be repeated and documented by the supplier prior to start of delivery of the modified or changed product. In some cases a shorter test can be agreed to between the responsible GM Department and the supplier.3.4.1 Test Results. With reference to this specification the results shall be represented in a test report.3.4.2 Deviations from Test Procedure. Deviations from the requirements of the test procedures shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc.4 Requirements and Procedure4.1 General. 4.1.1 Pre-treatment. In order to meet the requirements of this specification it is necessary that road wheels shall undergo suitable cleaning followed by appropriate pre-treatment (e. g. multi-cation-phosphating with sufficient coating weight) before organic coat application.4.1.2 Composition and Surface Condition.Wheels shall show no surface characteristics which impair corrosion resistance, e.g. burrs and/or welding deposits. Single coat systems of steel wheels (see paragraph 1.2.2.1.) shall only be used in addition with wheel covers. Multi-coat systems shall be triple-layer at least. Clear coat shall be used for top coating. Double-layer types are only permissible for inflatable spare tires.4.3 Organic Coat Requirements. 4.3.1 The stoved coating shall be smooth and free from any surface blemishes prejudicial to serviceability,appearance, or subsequent processing.4.3.2 Coating Thickness. The coating thickness shall be determined using an apparatus based on eddy current or ferromagnetic principles to within 2 m.Type AType BType CType D Disk inner 18 m18-30 m 18 m 18 mTread 18 m 18 m 18 m 18 mDisk outer 18 m18-30 m40-80 m 60 mVisible areas rim flange 18 m18-30 m40-80 m 60 m 4.4 Tests.4.4.1 Scratch Resistance. According to GME 60402-Rating 1. In the as received condition only.4.4.2 Cross Hatch Test. According to GMW 14829, Rating 0 or 1, in delivery conditions, after salt spray fog testing (4.4.3) and after delamination test (4.4.12).4.4.3 Salt Spray Fog Testing. 336 h according to GMW 3286.No corrosion, except along the scribe line, blisters or any change of surface are allowed. Total corrosion creepback according to GM9102P shall be 3 mm max. The evaluation of the creepback can be realized by blowing with compressed air or by using adhesive tape. Slight rust is permitted but shall not exceed 20 % of the length of the exposed edges.4.4.4 Scab-test. Scab test according to GM 9511P (4 weeks). Corrosion creepback per GM9102P shall be less than 6 mm in total.4.4.5 Salt Spray Fog-Climate Testing. Type C and D: GME 60203-F-Grade 7, allowable total corrosion creepback according to GM9102P should be 3 mm max.The test is not applicable for Type A and B.4.4.6 Impact Resistance. Impact resistance according o GME 60407 - 40 000 / Total coat system.Note: This test is applicable only to the surface of the disk outer. Sections from other areas are permissible only if the coat system is identical them of the disk outer.4.4.7 Resistance to Stone Impact. Resistance to stone impact according to GMW 14700.4.4.7.1 Type A, B and C: None4.4.7.2 Type D: Method A or B : Rating 8 ( GM 8)Method C: Rating 8 ( GM 8).4.4.8 Abrasion Resistance. According to GME 60400 - 1.4 l/m min.4.4.9 Resistance to Cleaning Agents. Resistance to cleaning agents according to GMW14334 / GMI 60266 - Rating 2.4.4.10 Resistance to Fuel. Fuel Resistance according to GMW14333 - Rating 2.4.4.11 Resistance to Color Change. According to GME 60403.4.4.11.1 Type A and B: None4.4.11.2 Type C and D: No change on the surface permissible. 4.4.12 Resistance to Hot Water Immersion.Delamination test according to GME 60410.4.4.13 Weather Resistance. The test shall be performed optionally in following test equipments paragraph 4.4.13.1, 4.4.13.2. or 4.4.13.3. This test is not applicable for type A.Requirements: The surface finish shall show no significant deterioration such as change in surface appearance, change in gloss, color change or other defects detrimental to serviceability, which cannot be removed by polishing.4.4.13.1 Method. Test as performed with apparatus of Atlas SFTS, B.V. company: (CI-65A, CI 4000 or CI 5000 Xenon-Arc-Weather-Ometer) or apparatus of ASTM G152-05 or ASTM G153-04 (Carbon-Arc-Apparatus). Inner- and external filter: Borosilikat Radiation exposure: 0.27 W/m2 (for Xenon-Arc) or 0,55 W/m2 (for Carbon-Arc) at calibration point 340 nm. Radiation energy: 1944 kJ/m2 continuous test cycle of 17 min light only, 3 min light and spray).The relevant surface of the test piece shall face the light source during test. Black panel temperature (during light only period) of (+63 3) C. Tested after cooling down (+23 5) C.4.4.13.2 Method. Test to J2020 using QUV Cabinet (or equivalent) and UVB313 lamps. Cycle: 4 h condensing humidity at (+40 + 1)C and 8 h UV at (+80 + 1) C. Test duration shall be 1000 h.4.4.13.3 Alternative Method. Similar types of commercial apparatus meeting the requirements described above may also be used.Note: If a supplier shall be able to prove a positive result of two years outdoor exposure the accelerated weathering test is not necessary. Accepted outdoor exposure locations are listed below:GME and GMNA: Exposure in Florida, 5 from horizontal, facing south, black box, without heating (according to GNW14873 / GM9163P).GM Holden: Test location Allunga, Queensland, Australia. 180 K Langleys, exposed due north5 from horizontal (southern hemisphere). LAAM: Cruz Alta Proving Ground Exposure, 5 from horizontal, facing north, black box, without heating (according to GNW14873 / GM9163P).4.5 Additional Requirements 4.5.1 Other additional requirements may be specified on the relevant engineering drawings, material specifications etc.4.5.2 Environmental Protection. Restricted and reportable