Method for determining adherence to a vehicle panel surface

A method for determining the degree of adherence to a non-flat, opaque vehicle panel surface of a component adhered thereto. The method includes providing an integrally cast clear matched surface in the panel so that the contacting surfaces of the component may be directly viewed.

BACKGROUND OF THE INVENTION 
In current manufacture of vehicles, many exterior components are affixed to 
the vehicle exterior body surface by use of adhesive material as opposed 
to mechanical fasteners of the type which were extensively used in the 
past. The components secured to the body exterior surface may be of 
different sorts, and include such things as trim, name plates, and other 
indicia. The use of adhesives for securing such components to vehicles is 
advantageous from a production standpoint as well as the fabrication 
standpoint since openings in mechanical fasteners do not have to be 
provided. Modern adhesive materials are of high enough quality to firmly 
secure such components in place providing that adequate contact is made 
between the adhered surfaces. 
One problem which has been encountered is inadequate surface contact 
between the component and vehicle body surface when such components are 
adhered to curved body panels. It is not possible to inspect the adhesion 
quality after the component has been secured in place with adhesive 
because the adhesive and the contacting surfaces are not available for 
inspection, being hidden by the opaqueness of the component and vehicle 
body panel. This has resulted in some cases in not obtaining the desired 
degree of adherence. 
In accordance with the present invention, a method is provided for visually 
inspecting the degree of adherence of a component to a vehicle body 
surface. Basically, the method involves the provision of a clear plastic 
window which is cast into an opening made in the body panel. The adhesive 
contact of the component with the surface of the clear plastic window may 
be seen through the window to thus determine whether or not the desired 
degree of adherence has been obtained. 
SUMMARY OF THE INVENTION 
A method for determining the degree of adherence to a non-flat opaque 
vehicle panel surface of a component adhered thereto is provided. The 
method comprises the step of first marking a surface area of interest on 
the vehicle body panel exterior curved surface. Then, flowable plastic 
material is applied to the vehicle body panel exterior surface over the 
area of interest and surrounding areas adjacent thereto. The plastic 
material is then cured to a hardened sheet to form a splash. The splash is 
removed from the vehicle body panel. The vehicle body panel is then cut 
along the periphery of the marked area with the cutaway portion being 
removed from the vehicle body panel to leave an opening in the shape of 
the marked area. 
The splash is then fastened back onto the exterior surface of the vehicle 
body panel in its original position thereby covering the opening. A layer 
of flowable clear plastic material is then cast into the opening from the 
interior side of the vehicle body panel. The clear plastic material is 
cured to a hardened state. The splash is then removed from the vehicle 
body panel. The designated component is then adhesively secured to the 
exterior surface of the vehicle body panel over the layer of clear plastic 
material. The adhered component is then visually inspected through the 
layer of clear plastic material from the interior side of the vehicle body 
panel to determine the degree of adhesion. Preferably, the clear plastic 
material is cast over the interior surface area surrounding the opening to 
form a flange for retaining the hardened plastic layer in place.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1, a car door 10 is illustratively shown as the body 
component upon which the method of the present invention is used. The 
method may be used in connection with other body components as desired. 
The door 10 has an exterior vehicle body panel 12 and interior panel 
structure 14. Portions of the interior panel structure 14 are removed as 
necessary in order to gain access to the interior surface of the panel 12. 
The panel 12 is illustratively curved. The method is adapted for use with 
curved panels or with panels having other forms of irregular surfaces. 
Flat surfaces do not normally pose a problem. 
A door 10 is conveniently supported by a table structure 16 with the 
exterior surface of the panel 12 facing upwardly. The area of interest is 
marked or scribed as at 18. This is the area that it is wished to 
determine the degree of adherence of an adhered component such as a trim 
element. 
After the area 18 has been marked, the surface of the panel 12 is cleaned 
to remove any dust, dirt, or other contaminants. A release agent such as a 
paste wax is applied to the surface and the surface is polished as needed. 
The surface is oriented to the horizontal plane as much as possible. A 
releasing film, such as a silicone spray, or other suitable parting agent, 
is applied directly to the exterior surface of the panel 12. If needed, 
sheet wax may be applied, and wood dikes or other suitable dikeing 
materials may be provided on the surface of the panel 12. 
After the surface has been prepared, a casting resin such as an epoxy is 
applied as shown in FIG. 2. This material is a flowable plastic material 
and is applied over the area 18 of interest as well as surrounding area 20 
adjacent thereto. The plastic may be applied manually as with a brush 22 
as illustrated in FIG. 2. The plastic may be reinforced as desired as, for 
example, with a weaved glass cloth. Such reinforcing materials should be 
used as required to assure strength and dimensional stability of the final 
application. When reinforcing materials are used, a thin layer of the 
casting resin should be applied just before application of the reinforcing 
material. The reinforcing material should then be thoroughly impregnated 
with the casting resin. 
In any event, a layer of plastic is applied as illustrated in FIG. 2. The 
plastic used contains a hardener that results in curing of the plastic to 
a hardened sheet to form what is termed a "splash" 24 which mates with the 
surface configuration of the panel 12. In the case of complex surfaces, a 
multiple piece splash may be made. Such a splash may be fabricated in 
stages to allow for the complex configuration. The splash should be 
completely cured between each stage to assure minimal distortion. The 
splash, whether multiple piece or single piece, should be completely cured 
before an attempt to separate it from the panel 12 is made. As required, 
splash edges may be cut to size and deburred. Multiple piece splashes may 
be closed and fitted for mechanical fastening. As necessary, the splash 
surface should be lightly sanded and/or polished to a high gloss level 
using a rubbing compound or polish to provide a smooth surface. 
After the splash 24 has been removed, the panel portion 26 which exists 
within the marked area 18 is cut away from the panel 12 as shown in FIG. 4 
to leave an opening 28. The opening 28 may be made by using conventional 
cutting tools. 
After the opening 28 has been formed, the splash 24 is fastened back onto 
the exterior surface of the vehicle body panel 12 in its original position 
thereby covering the opening 28. The splash 28 is illustratively fixed in 
place by use of clamps 30. Prior to fastening the splash in place, the 
surface area facing the panel 12 should be cleaned as required and a 
releasing agent such as a paste wax should be applied. A releasing film 
such as a silicone spray should also be used over the releasing agent. 
Referring now to FIG. 6, the door 10 with splash 24 in place is supported 
by the table structure 16 in as horizontal a position as possible. The 
interior surface of panel 12 faces upwardly thus exposing a space 32 (FIG. 
5A) into which a layer 34 of flowable plastic material is cast. The 
plastic material may be, for example, an epoxy or equivalent material. The 
key thing is that the plastic should be clear to result in an integrally 
cast clear matched surface after it hardens. The plastic may be applied in 
stages for maximum clarity while at the same time re-orienting the splash 
between stages if necessary. The plastic material is allowed to cure 
completely between each stage. After the plastic material has completely 
cured to a hardened state, the splash 24 is removed. As will be noted in 
FIG. 6A, the plastic material is cast over the surface area surrounding 
the opening 28 to form a flange system 36 which retains the hardened clear 
plastic layer 34 in place. 
In the illustrated embodiment, a door trim element 38 is the designated 
component to be tested for adherence over the opening 28 as shown in FIG. 
7. The trim element 38 has an adhesive applied to its contacting surface. 
The adhesive used may be a conventional pressure sensitive double faced 
tape, an adhesive film or the like. The element 38 illustrated is 
fabricated of plastic. However it should be appreciated that the method is 
applicable to components made of other materials such as forged aluminum 
or zinc die castings. 
Referring to FIG. 8, after the trim element 38 has been adhered in place, 
as shown in FIG. 7, the adhering surface is viewed through the layer 34. 
What is of interest in inspecting the adhered component surface is the 
degree of adhesion. This is done through what is termed the evaluation of 
adhesive wetout which is an indication of intimate contact or bond. FIG. 9 
illustrates the area encircled in FIG. 8. The shaded area 40 is intimately 
bonded. The clear areas 42, 44 do not have the desired bond. The entire 
bond may, of course, be adequate even if all areas are not totally 
adhered. Inspection may be by a practiced eye or instrumentation such as a 
compensating polar planimeter or an electronic digital planimeter may be 
used.