GMW GMW14700-2012 Stone Impact Resistance of Coatings Issue 3 English.pdf

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1、WORLDWIDEENGINEERINGSTANDARDSTest Procedure GMW14700Stone Impact Resistance of Coatings Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Originating Department: North American Engineering Standards Page 1 of 61 ScopeNote: Nothing in this standard supercedes applicable laws and r

2、egulations.Note: In the event of conflict between the English and domestic language, the English language shall takeprecedence.1.1 Purpose. This standard describes the test procedures to evaluate the stone impact resistance of coatings.It is applicable to both coated metallic and coated composite pa

3、nels. Method A is a contained method wherethe gravelometer is contained in a constant temperature freezer and Method B is the transfer method wheretest panels are transferred from a freezer to the gravelometer at room temperature. Method C is a containedmethod where the gravelometer is contained in

4、a constant temperature room. If this standard is used onuncoated panels (e.g., molded-in-color (MIC) plastic), alternate evaluation and rating procedures will berequired.Method A: A cold room or freezer of sufficient size in which the gravelometer and the test samples can bemaintained at -18 C 2 C.M

5、ethod B: A freezer in which the test samples can be cooled to the test temperature of -18 C 2 C. Pre-conditioning that causes frost on the surface of the test specimens must be avoided.Method C: A room in which the gravelometer and the test samples can be maintained at 22 C 5 C.1.2 Foreword. Not app

6、licable.1.3 Applicability. Not applicable.2 ReferencesNote: Only the latest approved standards are applicable unless otherwise specified.2.1 External Standards/Specifications.SAE J4002.2 GM Standards/Specifications.None3 Resources3.1 Facilities. Not applicable.3.2 Equipment.3.2.1 Gravelometer. A gra

7、vel projecting machine constructed according to design specification shown inSAE J400. Similar type of commercial apparatus meeting these specifications can be obtained from: T. J. Bell,1340 E. Home Avenue, Akron, OH 44310. Q-Panel Col. 800 Canterbury Rd., Cleveland, OH 44145 (NorthAmerica distribut

8、ors); Erichsen GmbH Q-Panel China, RM1809/1810,Liangyou Building, 618 Shabgcheng Road, Pudong District, Shanghai, 200120 China (China distributor).3.2.2 Gravel-water-eroded alluvial road gravel 8 mm to 16 mm in size.It is important to remove the small pieces before reusing the gravel. Gravel meeting

9、 these specifications canbe obtained from any of the suppliers identified in 3.2.1. An additional source in Europe is available: Q-LabDeutschland GmbH, In den Hallen 30, 66115 Saarbrcken, Germany.3.2.3 Tape. The use of a filament strapping tape such as 3M 898 or 3M 8981 is recommended. Other tapesca

10、n be used as agreed upon by both the lab and the test requestor.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 GMW14700 Copyright 2012 Gene

11、ral Motors Company All Rights ReservedOctober 2012 Page 2 of 63.3 Test Vehicle/Test Piece. Not applicable.3.4 Test Time. Not applicable.3.5 Test Required Information. Not applicable.3.6 Personnel/Skills. Not applicable.4 Procedure4.1 Preparation.4.1.1 Test samples shall be cut from parts that are be

12、ing evaluated when size and geometry of the part permit.When this is not possible, special test plaques (test panels of 100 mm x 300 mm are most suitable) shall beprepared using the same substrate material, substrate thickness, surface preparation (such as phosphatizingor anodizing), coating materia

13、l processing that duplicates that used on the part.For initial sample approval and in arbitration purposes, at least three test pieces shall be tested for each testtemperature.Note: Test samples that are small (not meeting size requirements) or have a complex geometry must haveperformance requiremen

14、ts defined on the engineering drawing.4.1.2 When test panels are used to evaluate a new substrate material or coating system, the panel preparationshall be defined by the engineer requesting the evaluation.4.2 Conditions.4.2.1 Environmental Conditions. Not applicable.4.2.2 Test Conditions. Deviation

15、s from the requirements of this standard shall have been agreed upon. Suchrequirements shall be specified on component drawings, test certificates, reports, etc.4.3 Instructions.4.3.1 Test Procedure. All test specimens must be positioned at approximately 90 degrees to the trajectory ofthe stones unl

16、ess otherwise specified by the responsible engineer.x Method A: Condition at -18 C 2 C.x Method B: Condition such that the samples are tested at -18 C 2 C.x Method C: Condition at +22 C 5 C.Note: Temperatures defined above are at start of gravel exposure. Actual sample temperature will increasedurin

17、g test because of warm air flow. Maximum sample temperature is -18 C 2 C for Method A andMethod B, and 22 C 5 C for Method C, unless otherwise specified in the material specification.4.3.2 Adjust the air pressure on the gravel apparatus to approximately 480 kPa (70 psi) with the air valve open.Keep

18、the lid to the gravel chamber on the apparatus closed during this operation as a safety precaution.4.3.3 After adjusting the air pressure, shut off the air valve, open the lid to the gravel chamber, and collectapproximately 473 mL (1 pt) of graded gravel in suitable container, unless otherwise speci

19、fied by theresponsible engineer.4.3.4 Place one test sample at the desired test temperature in the panel holder with the coated side facing thefront of the apparatus and close the lid to the gravel chamber.Note: The actual exposure zone of a 101 mm x 304 mm (4 in x 12 in) is 101 mm x 152 mm (4 in x

20、6 in).4.3.5 Gravel Feed. Feed gravel manually or automatically to the air stream within approximately 8 s. Do notturn on fan prior to gravel feed.4.3.6 Shut off the air valve, open the lid to the gravel chamber and remove the tested panel. Allow the panel toreturn to room temperature and remove any

21、condensed moisture, dust and other contaminants by wiping drywith a cloth.4.3.7 Cover the exposure zone of the test panel with approximately a 100 mm (4 in) wide strip(s) of maskingtape. Press the tape down firmly by rubbing and then pull off to remove any loose chips or paints.4.3.8 Highlight chips

22、 to substrate on metallic test panels using a Copper Sulfate or Copper Chloride solution.Use a 20% weight/volume solution of CuSO4 or CuCl2 in water. Wet the surface of the test panel with thesolution. The surface will rapidly turn orange-brown if there is no paint film. If there is paint film, ther

23、e will be nochange in color.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 GMW14700 Copyright 2012 General Motors Company All Rights Reserv

24、edOctober 2012 Page 3 of 65 Data5.1 Calculations.5.1.1 Evaluation and Rating.5.1.1.1 Unrepresentative Chips. Unrepresentative chip(s) can be eliminated from the evaluation according tothe following guidelines. In making this determination, all like test samples (minimum three per test conditionper 4

25、.1.1) shall be taken into account.x No more than one chip per panel can be eliminated from the evaluation.x No more than two chips per three panel set can be eliminated from the evaluation.Unrepresentative chips are defined as chips which are different than those typically found on the panels in the

26、panel set, for example, double hits.5.1.1.2 Test Sample Rating. Samples can be rated using the following procedure. Note that this process doesnot apply to uncoated panels (e.g., MIC plastic).5.1.1.2.1 For each layer, as applicable in the coating system, starting with chips to substrate, record poin

27、t offailure (based on Table 1).Table 1: Point of Failure NotationNotation LayerS SubstrateE ELPOP/S Primer SurfacerB BasecoatC ClearcoatM Monocoat5.1.1.2.2 Chip Frequency. For each panel, record chip frequency per Table 2.Table 2: Chip FrequencyNumber of Chips Chip Frequency25 High0 01 12 23 34 45 5

28、6 to 10 Low11 to 25 Moderate25 High5.1.1.2.3 Panel Rating. For each panel, record panel rating based on maximum stone impact diameter(millimeters) per Table 3.Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitt

29、ed without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14700 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 4 of 6Table 3: Panel Rating Based on Maximum Stone Impact Diameter (millimeters)Failure Mode 10 9+ 9 8 7 6 PoorTo SubstrateNoChipsandNoSurfaceMarksNo

30、Chips:SurfaceMarksOnlywithintopcoatinglayer1.0 - 1.5 2.0 2.0To ELPO 1.0 1.5 2.0 - 2.0To Primer 1.0 1.5 2.0 - 2.0To Basecoat 2.0 - - - 2.0To Clearcoat 2.0 - - - 2.0Within Monocoat 2.0 - - - 2.05.1.1.2.3.1 Calculation of the Stone Impact Diameter. The stone impact diameter of any particular chiprefers

31、 to the average stone impact diameter of that chip which shall be calculated as shown in Figure 1.Figure 1: Stone Impact DiameterWhere:D1 = horizontal diameterD2 = vertical diameterAverage Diameter = DD1 225.1.1.2.4 Single chips can sometimes have multiple points of failure, as shown in Figure 2, wh

32、ere a larger chipto the electro-deposition primer (ELPO) layer has within it a smaller area of exposed substrate. When ratingthis chip per 5.1.1.2.3, each point of failure is counted individually. However, it is considered a single chipwhen determining overall panel chip frequency.Copyright General

33、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 GMW14700 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 5 of 6Figure 2: Single Chi

34、p with Multiple Points of Failure5.1.1.2.5. It is recommended to use a data sheet similar to that shown in Table 4.Table 4: Data Collection Example FormPanel IDPoint of Failure Maximum ChipDiameter Chip Frequency RatingSubstrateELPOPrimerBasecoatClearcoatMonocoatOverall Panel RatingOverall Panel Chi

35、pFrequency5.2 Interpretation of Results. Not applicable.5.3 Test Documentation.5.3.1 Report. Report the test temperature, test method used (Method A, B, or C) and evaluation results.Return the tested panels to the test requestor. If requested, photograph all panels (clearly marked sets areacceptable

36、) and return to requestor.6 SafetyThis standard may involve hazardous materials, operations, and equipment. This standard does not propose toaddress all the safety problems associated with its use. It is the responsibility of the user of this standard toestablish appropriate safety and health practi

37、ces and determine the applicability of regulatory limitations priorto use.7 Notes7.1 Glossary. Not applicable.7.2 Acronyms, Abbreviations, and Symbols.ELPO Electro-deposition PrimerMIC Molded-in-colorCopyright General Motors Company Provided by IHS under license with General Motors CompanyNot for Re

38、saleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14700 Copyright 2012 General Motors Company All Rights ReservedOctober 2012 Page 6 of 68 Coding SystemThis standard shall be referenced in other documents, drawings, etc., as follows:Test t

39、o GMW147009 Release and RevisionsThis standard was originated in October 2005. It was first approved by the Global Paint Committee in January2007. It was first published in February 2007.Issue Publication Date Description (Organization)1 FEB 2007 Initial publication.2 DEC 2009 Clarification to ratin

40、g and test methods (Global Paint and Polymers Center).1 Scope added applicable to both coated metallic and coated compositepanels and uncoated panel information. 3.1 added Gravelometer Q-LabDeutschland source information, 3.2 Added German supplier, 4.3.3473 mL 10 mL info updated, 4.3.5 Gravity Feed

41、Time updated to 2 s, 4.3.8and 5.1.1.1 thru 5.1.1.2.1 added 5.1.1.2.4 revised text. Document placed inTest Procedure template replacing Test Method template. (Global PaintCommittee)3 OCT 2012 Corrosion Global Subsystem Leadership Team updated sections with minorrevisions to 4.3.1, 4.3.2, 4.3.3, 4.3.5, 4.3.7 and 4.3.8. Rearranged 5.1.1.2 andminor revisions to 5.3.1. (Corrosion Global Subsystem Leadership Team)Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-