The power of xDNA came to light when troubles arose on the production line of a large European car factory when they suddenly discovered that the metallic silver paint they had painted on body panels did not appear to match the color of the bumper panels supplied by an outside supplier. very ok. While they've had occasional minor issues with some definite root cause before, this time the body panels were a darker color than the bumper panels and the difference in appearance was noticeable.
The process engineers at the car manufacturing plant performed a traditional root cause analysis of the problem, first trying to determine whether the problem was an internal process, whether the automotive coating supplier changed the parts. Production line workers told engineers that part comparisons showed some degree of unexpected variation, while field inspectors using the X-Rite MA68II said inspection instruments indicated differences in part reflectivity. Based on the measured data, the engineers deduced that the root cause of the problem lay in the paint formulation, so they sought help from the paint supplier.
Paint makers have been unable to match the color and appearance of the bumper panels to the body (the latter being a lighter shade) for nearly two months -- even trying to change the paint formulation to no avail. At that time, automotive companies began to believe that the MA68II instrument could not accurately measure the color painted on vehicle parts. To determine whether the root cause of the problem lay with the MA68II instrument itself, the automaker asked X-Rite to perform a repeatability and reproducibility study to assess whether there was a problem with data errors.
When the results of the study showed that the MA68II was functioning properly and that the correct measurement technique was used, X-Rite personnel provided a new MA98 to analyze the paint, not only to confirm the data, but also to see if the MA98 was an effective instrument that could reveal the root cause of the problem. instrument.
The MA68II faithfully reproduces the difference in the L* value (the value indicating how light/dark the color is) of the color - higher values are found on the bumper panel closer to the angle of reflection. But other than the fact that the color of the bumper panels does not match the color of the body panels, no more information can be provided about it.
Because the MA98 measures from 10 angles instead of 5, the instrument can record comparisons of key aspects of the effect paint, such as flake size and particle dispersion. The data showed major changes in +/- 25° out-of-plane angles, which may be due to differences in the positioning of the scales. Simultaneously, the xDNA software interprets measurements of bumper panels and body panels by displaying a 3D map that uniquely depicts their effect paint. The graphics show similar shapes but different positions in 3-D space, which also indicates a change in the process rather than a recipe.
X-Rite further analyzed the data by transforming, calibrating and adjusting the scale of the 3D drawing, and confirmed that a good investigation method is to check the process of spraying paint. The xDNA analysis provided another important clue - the measurement of the difference in the reflection angle curves out of the plane of the 25° angle pointed to the fact that the difference arises in the way the scales are positioned. All indications were that the mismatch or misalignment was due to a process difference between the bumper panel and the body.
The automaker then realized that they had changed key process parameters a few months earlier, turning the bell/air method used for the base coat and final coat applied to the body panels into a full bell/bell method . Due to the high percentage of flakes in the coating, the type of silver paint that is sprayed contains relatively low tinting and relatively high reflectance values. When using the bell/air method, the paint can essentially float in the coating and spread randomly across the body panels in a horizontal fashion. This positioning maximizes the reflective properties of the flakes, giving the paint a lighter appearance.
Before the process change, the color and appearance of the body panels and bumper panels can be coordinated, because the bumper supplier uses the air/air process, the flakes can self-calibrate in a similar way to the painting method of the car factory .
But when automakers implement the bell/bell method, the process produces consistent positioning of the flakes at the edges, reducing their reflective quality and thus giving the paint a darker appearance. Paint engineers were aware of this phenomenon, but did not consider this information during process changes and subsequent root cause analysis until MA98 and xDNA pointed out the difference.
It took only two days for X-Rite personnel to obtain the data measured by the MA98 and interpreted by xDNA, which the automaker used to adjust the paint supply rate in the bell-bell system and coordinate with the bumper supplier , so that the color of the body panel and the bumper panel are consistent. MA98 and the xDNA system are a powerful demonstration of the value that automakers and their suppliers can use to monitor processes more closely, save hundreds of man-hours in root-cause analysis of problems, and test The effect of using a new process in an existing product. That's the power of xDNA - empowering decision makers with more information can save time, reduce waste and duplication of effort, and improve processes.
