1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW3005 Topcoat, Generic Qualification Copyright 2013 General Motors Company All Rights Reserved November 2013 Page 1 of 24 1 Scope This specification details the minimum performance, compatibility, and processing requirements for international
2、 approval of all exterior topcoats. 1.1 Material Description. Materials qualified to this standard shall meet the performance requirements shown in Appendix A for the specific topcoat type. Appendix A summarizes all requirements for material technology approval. Additional testing or any exceptions
3、to the requirements may be directed by the GM approving engineer. Suppliers must demonstrate that the material technology is production capable via successful trial completion in an agreed upon paint facility prior to use for GM production parts or vehicles. Any material development performance issu
4、es or values that fall outside specified ranges must be discussed with the responsible topcoat materials engineer for resolution. Note: Line trials may begin after two years of Florida exposure. 1.2 Symbols. Not applicable. 1.3 Typical Applications. This specification applies to all exterior topcoat
5、s for use on vehicles or parts supplied to GM. Topcoats and their performance levels are defined by classes and types. 1.4 Remarks. The topcoat type defines the requirements for test panel preparation, basic testing, compatibility testing, and processability for use in a specific application. Table
6、1 defines the general topcoat types. Table 1: Topcoat Type Type Usage A Rigid Body: Metallic Substrates, i.e., Steel or Rigid Composites with Flex Modulus of 800 MPa B Rigid Parts: Composites with Flex Modulus of 800 MPa, or Metallic Substrates C Flexible Parts: Composites with Flex Modulus of 80 C)
7、 GMW15581 or ST1405 (US: ACT panels) C Thermoplastic Olefin (TPO) GMW15187 ABS = Acrylonitrile Butadiene Styrene PC = Polycarbonate Note 1: Other substrates may be selected per engineering agreement. 3.3.1.3 Composite substrates power washing per 9984801 or appropriate cleaning agent must be used fo
8、r cleaning all composite substrates. 3.3.1.4 Pretreatment Coating for Metallic Substrates. All metallic substrates must be phosphated per a GMW3011 approved phosphate system and E-coated (electrocoated) with an approved GMW3008 electrodeposition primer. Generic test panels such as ACT panels may be
9、used where appropriate, per agreement with the responsible engineer. 3.3.1.5 Topcoat Paint Application. All test materials must be sprayed at the target application viscosity. Target spray non-volatiles, density (weight per liter or weight per gallon), viscosity, and reduction solvent will be establ
10、ished by agreement with the responsible engineer before testing begins. Control samples must be sprayed at production viscosity and with production reducers. 3.3.1.5.1 Topcoat Test Colors Families. New topcoats shall be qualified with four colors: White Light Metallic Medium Red Metallic Black Copyr
11、ight 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 GMW3005 Copyright 2013 General Motors Company All Rights Reserved November 2013 Page 7 of 24 The
12、specific WAXXXX numbers, as defined by the responsible engineer, must be reported. The supplier must demonstrate color match capability to the four test colors as well as any defined premium colors. The color match will be reviewed and approved by the responsible color engineer prior to the start of
13、 any testing. 3.3.1.5.2 Film Thickness (ISO 2808). Specific film builds are established by initial screening and agreement with the responsible engineer and are to meet all appearance and performance criteria of this specification. Film build is characterized by the following: T = Target L = Low fil
14、m build H = High film build The T, L, and H will vary by technology. When preparing test panels, use Appendix A to determine the film build requirements for each test. 3.3.1.5.3 Bake. Bake is defined as the time the substrate is at the target temperature. Document oven type used (for testing perform
15、ed in North America, gas-fired ovens shall be utilized). Panel temperature must be monitored with thermocouples or thermisters using a Datapaq or agreed upon equivalent to ensure that test panels are processed at specified times and temperatures. Note: Oven loading and panel position may affect actu
16、al cure. 3.3.1.5.4 Target Bake Definition. A target bake must be identified by the supplier such that the topcoat meets all appearance and performance criteria over a minimum range of film build, time, and temperature (basic box). The size of the box and the upper/lower limit temperature variance fr
17、om target will be dictated by the type of technology. The requirements to define the lower limit (LL) and upper limit (UL) temperatures are defined in Table 7. All deviations from this minimum performance window must be discussed with the responsible engineer prior to test initiation. Table 7: Table
18、 Definitions Symbol Description Time (Minutes) Note 1 Temperature (C) Temperature (F) T Target t T T LL Lower Limit t - 5 T - 5 T - 10 UL Upper Limit t x 4 T + 15 T + 25 Note 1: Bake time (t) must be compliant per GM Bill of Process as defined by the responsible GM engineer. 3.3.2 In-line Reprocess
19、Panel Preparation. All in-line reprocess panels shall be prepared over first coats which have low film and UL bake temperatures unless otherwise specified. Recoats must be applied within 24 h after each topcoat bake. Document the time between bakes. Basic reprocess adhesion should be evaluated witho
20、ut sanding unless otherwise stated. The responsible engineer should be consulted immediately if sanding is required so that long-term weathering tests and process controls can be appropriately established. 3.3.3 Final Line Reprocess Preparation. All final line reprocess panels shall be prepared over
21、 first coats which have low film and UL bake temperatures unless otherwise specified. Recoats must be applied within 24 h after each topcoat bake. Document the time between bakes. Panels must be reprocessed and tested in two ways unless specified by the responsible engineer. 3.3.3.1 Spot Reprocess.
22、See Appendix A for specific testing requirements where P = Panel reprocess and S = Spot reprocess. Use a 10 cm x 30 cm (4 in x 12 in) panel and scuff sand 7.5 cm x 30 cm (3 in x 12 in) down the side of the panel, leaving a 2.5 cm x 30 cm (1 in x 12 in) strip unsanded. Apply a wedge of basecoat/monoc
23、oat from 5 m (0.2 mil) to target film, starting at the bottom of the panel with 5 m (0.2 mil). Apply a wedge of clearcoat from 5 m (0.2 mil) to target film, starting at the bottom of the panel with 5 m (0.2 mil). 3.3.3.2 Panel Reprocess. Divide the panel into two sections horizontally. Sand one-half
24、 of the Original Equipment Manufacturer (OEM) panel with 600 grit paper (or equivalent). Recoat with a uniform film of reprocess BC/CC. Minimum basecoat/monocoat film is the minimum for a specific color based upon workability and ultraviolet transmission. The minimum clearcoat film is 38 m (1.5 mil)
25、 unless otherwise specified. 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 GMW3005 Copyright 2013 General Motors Company All Rights Reserv
26、ed November 2013 Page 8 of 24 3.3.4 Conditioning. All test samples shall be subject to an aging period of at least 72 h at room temperature 23 C 5 C (73 F 9 F) and 50% 5% relative humidity following the bake cycle prior to testing unless defined otherwise by the responsible engineer. 3.3.5 Control M
27、aterials. Control panels are required for all tests as designated by the responsible engineer. Control materials are to be current, approved production materials. The specific material used as the control will be established by the responsible engineer when the test program is initiated. The supplie
28、r is expected to incorporate procedures into all programs to ensure that the right material and processes are used during panel preparation, that testing equipment is properly calibrated and run, and that any unusual defects on outdoor exposure panels can be demonstrated to be an unusual weathering
29、incident. 3.4 Bake Chart Creation. Utilizing an approved statistical software tool, develop a 3 x 3 Design of Experiment (DOE) (9 points) utilizing bake time and bake temperature as variables to provide an estimation of a quadratic response surface model. Checkpoints (2 x 2 DOE, four points) must be
30、 used to verify the quadratic model and augment the 3 x 3 design to allow an estimation of a cubic response surface model (see Figure 1 for an example). The bake time has a total of five levels non-linearly distributed to allow for the non-linearity of reaction kinetics. Suggested levels are 10, 20,
31、 30, 70, and 130 minutes. Confirmation points must be used to verify the response surface model in regions of physical performance concern. The entire bake DOE must be reviewed and approved by the responsible engineer prior to execution. The entire DOE (see Figure 1) must be performed on all OEM lay
32、ering. One in-line reprocess (ILR) must be evaluated over all confirmation points at target film build and target bake. In line reprocess must be evaluated with and without sanding between coats. The following steps must be followed in the bake chart preparation for each product: 3.4.1 Initial Scree
33、ning for Failure Points. The supplier must demonstrate specific time and temperature conditions that show physical property failures. Design Bake Time (Minutes) 3 x 3 2 x 2 Confirmation 3 x 3 10 157 C (315 F) - - 3 x 3 30 157 C (315F) - - 3 x 3 130 157 C (315 F) - - 3 x 3 10 129 C (265 F) - - 3 x 3
34、30 129 C (265 F) - - 3 x 3 130 129 C (265 F) - - 3 x 3 10 101 C (215 F) - - 3 x 3 30 101 C (215 F) - - 3 x 3 130 101 C (215 F) - - Check Point 20 - 143 C (290 F) - Check Point 70 - 143 C (290 F) - Check Point 20 - 116 C (240 F) - Check Point 70 - 116 C (240 F) - Confirmation 70 - - 157 C (315 F) Con
35、firmation 20 - - 129 C (265 F) Confirmation 70 - - 129 C (265 F) Confirmation 20 - - 101 C (215 F) Notes: The 3 x 3 design points provide estimation of a quadratic response surface model. The 2 x 2 check points are used to augment the 3 x 3 design to allow estimation of a cubic response surface mode
36、l. The check points could be used to verify the quadratic model. Confirmation points are used to verify the response surface model in important underbake and overbake regions. These points may or may not be needed depending on a case-by-case basis. Figure 1: Bake Window DOE Design - Generic Example
37、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 GMW3005 Copyright 2013 General Motors Company All Rights Reserved November 2013 Page 9 of 24
38、 3.4.2 Panel Preparation. See Table 8 for required testing and panel requirements. The colors to be used are a White and a Medium Red Metallic. Table 8: DOE Panel Definition Panel Number Tests to be Run 1 Initial adhesion, chip, 240 h humidity and adhesion 2 Appearance, gloss, Buchholz or Tukon hard
39、ness, Xenon and yellowing (white only) 3 Quick knife adhesion (Type A only Note 1) 4 Cycle I for Type A, Cycle A for Type B Note 1: Agreed upon glass bonding system. 3.4.3 Final Bake Chart Creation. Analyze the surface response data, utilizing appropriate statistical software and convert the results
40、 to the approved bake chart format (see Figure 2). Figure 2: Bake Chart - Example C l e a r c o a tBa s e c o a tP r i m e rE c o a t310300290280270260250240230 20 30 40 50 60 70 80 90 100A d h e s i o n : I n i t i a l / H u m i d i t y/ C yc l e A / G l a s s Bo n d A C T U A L D O E C O N D I T I
41、 O NC h i p Re s i s t a n c eC o r r o s i o n Re s i s t a n c eC h e m i c a l Re s i s t a n c e rE t c h Re s i s t a n c eS o l ve n t / F u e l Re s i s t a n c eH a r d n e s sE x p o s u r e - Q U V / X E N O N W e a t h e r o m e t e rE x p o s u r e - F l o r i d aA p p e a r a n c eF i l
42、 m b u i l d Ra n g eG M A p p r o va l D a t e S u p p l i e r A p p r o va l D a t eG M M E P A I N T - I N T E R N A L U S E O N L YTEMPERATURE(0F/C)T I M E ( m i nut e s )R E Q U I R E M E N T S ( s e e A P P E N D I X A f o r d e ta i l )T O P C O A T B A K E W I N DO W( S U PPL IE R N A M E )
43、T E C H N O L O G Y S U B M IS S IO N T Y P E G M S P E CS U P P L I E R C OD EU N D E R B A K E : P O O R A D H E S I O N , H A RD N E S S , C H E M I C A L RE S I S T A N C EO V E R B A K E : P O O R C H I P , E T C H R E SI ST A N C E , M A R G I N A L P E R F O R M A N C EO P T I M U M P E R F O
44、 R M A N C EA L L P RO P E RT I E S M E E T o r E X C E E D RE Q U I RE M E N T ST A R GE T B A KE ( T )Re c o m m e n d e d O p e r a t i i o n a l Ba ke : LL - x x x x xoF / CT - x x x x xoF / CU L - x x x x x oF / CRe c o m m e n d e d C C F i l m b u i l d s :L - x . x x m i l sT - x . x x m i l
45、 sH - x . x x m i l s 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 GMW3005 Copyright 2013 General Motors Company All Rights Reserved Nove
46、mber 2013 Page 10 of 24 3.4.4 Film Build Dependence Panel Preparation. Prepare panels per Figure 4 (OEM) and Figure 5 (ILR) for two colors: White and a Medium Red Metallic, and two bake conditions: UL and L (Figure 3), or as specified by the responsible engineer. 3.4.5 Testing. The panels must be ch
47、ecked for adhesion and 240 h humidity and adhesion at all film build variations (see Figure 3). Report any failures on the chart shown in Figure 3. 3.4.6 Test Methods. See Appendix A for testing and performance requirements for Type A, Type B, and Type C materials. BC = Basecoat H = High L = Low OEM
48、 = Original Equipment Manufacturer UL = Upper Limit CC = Clearcoat ILR = In-line Reprocess LL = Lower Limit T = Target Mode of Failure: A = Between OEM BC and primer E = Between OEM CC and primer B = Between OEM BC and OEM CC F = Between OEM BC and ILR BC C = Between OEM CC and ILR BC G = Between OE
49、M CC and ILR CC D = Between ILR BC and ILR CC Figure 3: Testing Detail and Failure Summary (OEM or ILR) If no adhesion failures occur, report “no failures” as the first line of the table. If adhesion failures occur, report the percent failure and the mode of failure in the initial adhesion and/or humidity adhesion columns. Failure numbers
