1、WORLDWIDEENGINEERINGSTANDARDSTest Procedure GMW14688Scratch and Mar Resistance Copyright 2012 General Motors Company All Rights ReservedSeptember 2012 Originating Department: GME Specification Center Page 1 of 61 ScopeNote: Nothing in this standard supercedes applicable laws and regulations.Note: In
2、 the event of conflict between the English and domestic language, the English language shall takeprecedence.1.1 Purpose. Determination of the scratch resistance of plastics (Method A) and the determination of the marresistance on plastics (Method B). For this purpose the surface is scratched.Note: M
3、ethod A is the standard method. Method A may be used for molded parts and for sample plates.Method B is a development method. Method B may only be used for sample plates with correct color andgrain.Method A is based on ISO 7724.Method B is based on ISO 2813.1.2 Foreword. Not applicable.1.3 Applicabi
4、lity. Uncoated interior and exterior plastic parts.2 ReferencesNote: Only the latest approved standards are applicable unless otherwise specified.2.1 External Standards/Specifications.ISO 2813 ISO 77242.2 GM Standards/Specifications.None3 Resources3.1 Facilities. Not applicable.3.2 Equipment.3.2.1 M
5、ethod A.3.2.1.1 Tool. Cylindrical hard metal pen with ball-shaped end (radius (0.5 0.01) mm, polished) according toFigure 1. Prior to the measurement the pen shall be checked by microscope. The surface shall be free of anydeterioration. In case of any surface change or damage to the pen, a new pen s
6、hall be used to preventincorrect measurements caused by a damaged tool.3.2.1.2 Measuring Equipment. Spectrophotometer that fulfills the requirements to ISO 7724.For determination of the scratch resistance shall be used the principle of spectro-photometrically measuring ofthe luminance L* with help o
7、f the “Ulbrichtsche Kugel” (see Figure 2).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 GMW14688 Copyright 2012 General Motors Company All
8、 Rights ReservedSeptember 2012 Page 2 of 6Figure 1: Cylindrical Hard Metal PenFigure 2: “Ulbrichtsche Kugel”1 Brilliancy opening2 Brilliancy of a perfect mirror3 Observation opening4 Source of light5 Measurement with gloss excluded6 Test piece (medium brilliancy)x Type of light: D 65 diffusedx Measu
9、rement geometry: d/8x Restrictor: 27 mm diameterx Gloss trap: yes (SEX = Specular EXcluded)3.2.2 Method B.3.2.2.1 Tool. Stainless steel disc (diameter (16 0.3) mm, (1 0.02) mm thick) with rounded and polishedborder (radius (0.5 0.01) mm) according to Figure 3.Copyright General Motors Company Provide
10、d by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14688 Copyright 2012 General Motors Company All Rights ReservedSeptember 2012 Page 3 of 6Prior to the measurement the disc shall
11、be checked by microscope or magnifying glass. The surface shall befree of any deterioration. In case of any surface change or damage to the disc, the disc shall be turned suchthat a non-damaged area is used for test. If this is not possible a new disc shall be used to prevent incorrectmeasurements c
12、aused by a damaged tool.Figure 3: DiscA Scratch direction3.2.2.2 Measuring Equipment. Gloss measuring apparatus with 60 measurement geometry to ISO 2813,elliptic measurement area according to apparatus supplier information.3.2.3 Scratching Device. Motor driven cross cutting tool, e.g., Erichson Mode
13、l 430, with the ability to scratchthe specified grid pattern at specified test speed and possibility to place the specified loads on the scratchingtool.3.3 Test Vehicle/Test Piece. Test pieces shall be obtained from finished parts. Shape shall be plane and sizeshall be such that an even contact betw
14、een the test piece, its support and the measurement equipment isobtained, and a stroke on the test piece surface of 40 mm is available.For initial sample approval and arbitration purposes, at least three test pieces shall be examined; for routinequality control purposes, at least 1 test piece shall
15、be examined.3.4 Test Time. Not applicable.3.5 Test Required Information. Not applicable.3.6 Personnel/Skills. Not applicable.4 Procedure4.1 Preparation. For initial sample approval and arbitration purposes, the minimum period betweenmanufacturing of the component and testing shall be seven days. For
16、 routine quality control tests, 72 h will besufficient.Note: The tested surface shall not be touched and shall be free of any contamination.4.2 Conditions.4.2.1 Environmental Conditions.4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Suchrequirem
17、ents shall be specified on component drawings, test certificates, reports, etc.4.3 Instructions.4.3.1 The test shall be performed at a temperature of (+23 5) C.The measurement of luminance (Method A) respectively brilliance (Method B) shall be conducted immediatelyafter bringing up the scratching sc
18、reen.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 GMW14688 Copyright 2012 General Motors Company All Rights ReservedSeptember 2012 Page 4
19、 of 64.3.2 Method A. For the test the tool is clamped in a suitable apparatus with lever arm. Subsequent the leverarm is balanced out. The tool is loaded with the first required load (coding per Table 1) and is pulled over thetest piece surface 40 mm with a speed of (1000 50) mm/minute. At least 20
20、scratches parallel to eachother are brought up with a distance of 2 mm. The application of the scratches is repeated perpendicular toeach other, so that the result is a scratching screen (see Figure 4). The scratching direction shall beunidirectional. The test is repeated for each additional require
21、d load, until for each load a separate scratchingscreen (see Figure 4) has been scratched. Each scratching screen shall be marked by the related code of theload per Table 1.Note: If no definition is given in the material specification or on the engineering drawing, all codes (1 to 3) shallbe execute
22、d.Figure 4: Scratching Screen (Method A)Analysis: Every specimen is measured with 5 single measurements, one in the center and 4 in the corners(see figure 5). The result represents the average of these 5 values.Figure 5: Location of the Measuring Points (Method A)Copyright General Motors Company Pro
23、vided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14688 Copyright 2012 General Motors Company All Rights ReservedSeptember 2012 Page 5 of 6Table 1: Defined Loads for Scratch T
24、estCode Load in N1 5 0.052 10 0.13 15 0.154 As specified4.3.3 Method B. For the test the tool is clamped in a suitable apparatus with lever arm. Subsequent the leverarm is balanced out. The tool is loaded with (7 0.07) N and is pulled over the test piece surface 40 mm witha speed of (1000 50) mm/min
25、ute. The alignment of the tool shall be transversal (see Figure 3) to the traveldirection. Minimum 80 mar lines parallel to each other are brought up with a distance of 0.5 mm. Theapplication of the mar lines is repeated perpendicular to each other, so that the result is a mar screen (seeFigure 6).
26、The mar direction shall be unidirectional.Figure 6: Mar Screen (Method B)Analysis: Every specimen is measured with 5 single measurements, one in the center and 4 in the corners(see Figure 7). The result represents the average of these 5 values.Figure 7: Location of the Measuring Points (Method B)5 D
27、ata5.1 Calculations. Not applicable.85 85 85 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 GMW14688 Copyright 2012 General Motors Company
28、All Rights ReservedSeptember 2012 Page 6 of 65.2 Interpretation of Results.5.2.1 Method A. To ISO 7724.5.2.2 Method B. To ISO 2813.5.3 Test Documentation.5.3.1 Method A. The scratch resistance of plastics is reported with reference to this standard as the differenceof the luminance L* of the unscrat
29、ched from the scratched areas.5.3.2 Method B. The mar resistance is reported with reference to this standard as the difference of thebrilliance grade of the polished from the unpolished areas.6 SafetyThis standard may involve hazardous materials, operations, and equipment. This standard does not pro
30、pose toaddress all the safety problems associated with its use. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and determine the applicability of regulatory limitations priorto use.7 Notes7.1 Glossary.Mar: Change of gloss grade caused by pla
31、ne flattening of the surface structure.Scratch: Change of luminance caused by linear damage of the surface structure.7.2 Acronyms, Abbreviations, and Symbols.SEX Specular EXcluded8 Coding SystemThis standard shall be referenced in other documents, drawings, etc., as follows:8.1 Example for Method A:
32、“Scratch Resistance to GMW14688 Code 2 - 1.0 max”Scratch Resistance = DesignationGMW14688 = Test ProcedureCode 2 Code per Table 1 (= (10 0.1) N load)1.0 max = Requirement8.2 Example for Method B:“Mar Resistance to GMW14688 - B - 1.0 max”Mar Resistance= DesignationGMW14688 = Test ProcedureB = Method
33、B1.0 max = Requirement9 Release and RevisionsThis standard was originated in October 2005. It was first approved by the Global Material Engineering PlasticsTeam in April 2007. It was first published in April 2007.Issue Publication Date Description (Organization)1 APR 2007 Initial publication.2 SEP 2012 5 year refresh update.Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
