1、 FORD LABORATORY TEST METHODBI 162-01Date Action Revisions 2004 02 18 Activated J. Holubka Printed copies are uncontrolled Copyright 2004, Ford Global Technologies, LLC Page 1 of 3 CLEARCOAT CRACKING OVER ROOF- DITCH SEALERS Application This method is used for determining the resistance of an automo
2、tive clearcoat to cracking when applied over a roof-ditch sealer material. The test method can be used in both laboratory evaluations and field evaluations at appropriate outdoor exposure sites (e.g., Florida, Jacksonville). The test method is easily adaptable to evaluate clearcoat cracking over a r
3、ange of roof ditch designs that are dictated by the specific design of the vehicle Required Test Equipment Aluminum Tank - having approximate dimensions of 14“ X 16“ (deep enough to vertically immerse entire sample) and capable of holding about 40 liters of water. Tank is insulated with “ thick Styr
4、ofoam (Safety item) Lid on tank insulated with “ thick Styroform for heating efficiency 12“ x 12“ hot plate or larger that is placed under the aluminum tank, in the case of the smaller hot plates, the corners of tank are stabilized with lab jacks or other non-slip devices (Safety Item) Ice water imm
5、ersion bath that allows for the complete and immediate immersion of all test samples Vented Laboratory Oven capable of heating to achieve paint/sealer cure temperatures of up to 180 C Thermometer capable of measuring in the range of 0 to 100 C Analytical Balance capable of measuring to 0.1 g Immersi
6、on circulating heater Fisher Scientific #13-873-44A or equivalent Sample holders two stainless steel rods “ X20“ with a 90 bend at one end using 1“ of the total rod length Machine shop brake device for preparation of roof-ditch test substrate Timer to measure immersion times Plexiglass stop that is
7、5mm high, 20mm long and the width of the ditch (e.g., 1 ) that taped into one end of the roof-ditch test panel covering the hole in the panel. Paint application equipment/ laboratory - for preparation of painted samples representative of painted vehicle system Humidity Cabinet capable of maintaining
8、 95 F/95% RH Lighted 10x magnifying glass to examine the sealed roof ditch for cracks Permanent Marker for sample labeling FORD LABORATORY TEST METHODBI 162-01Printed copies are uncontrolled Copyright 2004, Ford Global Technologies, LLC Page 2 of 3 Materials and Solutions Required 4“ x 12“ Panels of
9、 the metal substrate used on the specific vehicle application, having a standard “ hole in the middle of the panel and centered ca 3/8“ from the top. Coating system that is expected for the use with the roof-ditch sealer, including the phosphate system ecoat, primer and topcoat paints Heat resistant
10、 tape capable of maintaining properties up to ca 180 C Method A Laboratory Testing This method is used for determining the sensitivity of a clearcoat to cracking, when it is applied as part of an overall paint system over sealer materials that are part of roof-ditch structures on vehicles. The exper
11、iment is conducted, at least in triplicate or to that number that satisfies the applicable Engineering Specification. I. Preparation of Test Specimens 1. Using the 4“ x 12“ panels of a substrate to be used on the vehicle and a machine shop brake device prepare a simulated roof ditch along the long a
12、xis of the panel. Typical dimension for the ditch is “ x 11/8“. Dimensions for the roof ditch representative of a specific vehicle design should be used whenever possible. 2. Coat the simulated roof ditch panel using the phosphate conversion coating and electrocoat specified for use on the vehicle.
13、3. Insert a Plexiglass stop into the “hole end“ of the simulated roof ditch, carefully covering the hole on the steel panel and tape in place with the heat resistant tape. Block the other end of the roof-ditch with heat resistant tape. 4. The roof-ditch sealer material (78 g +/-2 g) is weighed into
14、the ditch. The test specimen is tapped and moved to accomplish a uniform layer of sealer across the entire length of the specimen. The sealer is then gelled or fused in the manner representative of production use. Plexiglass stop is removed. 5. Primer, basecoat and clearcoat are applied and cured at
15、 specified production coating thicknesses and bakes, respectively. 6. The test panels are conditioned at 95 F and 95% RH for 10 days prior to testing. II. Determination of Crack Resistance 1. Fill the temperature bath with water. Bring up and equilibrate the temperature to 90 C (+/- 4 C), using the
16、Fisher Scientific #13-873-44A or equivalent immersion heater. If necessary turn on heating plate to assist in warming process. 2. Fill the immersion bath with ice water and bring down and equilibrate temperature at 0 C (+ 1 C). 3. Inspect the test panels carefully, noting initial appearance and indi
17、cating the presence of initial defects in the paint surface. 4. Hang the panels from the rods. 5. Immerse panels into 90 C water bath for 5 minutes. FORD LABORATORY TEST METHODBI 162-01Printed copies are uncontrolled Copyright 2004, Ford Global Technologies, LLC Page 3 of 3 6. Remove the test panels
18、 from the hot water bath and immediately immerse them into ice water. 7. Repeat. Each hot/cold exposure represents one cycle. 8. After 5 cycles, carefully inspect panels using magnifying glass looking for cracks, and if present the direction of crack propagation. 9. Continue cycles until 100 cycles
19、are performed. III. Evaluation of Results 1. At the end of the test, the surface of the paint within the roof-ditch is carefully examined with a 10X magnifying glass. An unequivocal “Pass“ for this test is one where NO cracks within the roof-ditch are observed. 2. A provisional pass is one where a l
20、inear crack is observed, but is contained entirely within the elbow of the roof-ditch and does not extend more than 6 over the entire 24“ of roof ditch elbow that exists. The provisional pass requires an additional 50 cycles of testing. If the cracking does not extend beyond a total of 6“ or more im
21、portantly does not extend over the center portion of the roof ditch, the test is considered to be a pass. 3. A unequivocal FAILURE is a sample that shows any crack features that extend over or into the center portion of the roof ditch. Characteristic cracks that would define a FAILURE are summarized
22、 in Figure 1 and include sloping cracks (A), spikes (B), stars (C), and scallops (D). Figure 1 A B C D Method B Field Exposure Testing The method used for field testing is largely identical to the method described for laboratory testing except for the replacement of the laboratory cycling experiments with a static environmental exposure at outdoor sites (e.g. Jacksonville, FL). Preparation of test specimens and evaluation of results is conducted in a manner that is identical to the procedures described in Method A of this test procedure.
