The Client’s Critical Issue

One of the Big 3 automakers called Dimensional Engineering because of a serious build issue on their flagship luxury SUV. The condition was an oil canning effect on the hood of the vehicle. The plant had investigated the build issue for several months, and could not determine the root cause using their conventional technology.

The oil canning effect on the SUV’s hood was so noticeable that customers were returning the vehicle to the dealership, demanding that the hood be replaced.

The Dimensional Engineering Solution

The hoods are delivered “just in time” (JIT) from two different sources, which we will call Source “A” and Source “B” for the purposes of this case study. The hoods arrive unhemmed, then are hemmed on the production line. As we began track the hemming process, we established that the oil canning problem was a result of this process, and occurred on hoods from only one of the suppliers.

Our focus now turned to the hood’s inner panels. With the aid of a holding fixture, we completely scanned 15 hood inner panels from each source. The holding fixture located the inner panels using the same datum features as the hemmer die.

We analyzed the collected data against the existing CAD model and to each source individually. We discovered that Source “A” was consistently rearward in the area of the front brow and had a discrepancy of 11.0 mm. This meant the lower brow needed to push forward 11.0 mm when loaded in the hemmer die, and the top of the brow was deflected downward. Once the hemmed hood was released from the hummer, it sprang back causing the oil can effect on the hood outer.

The Value We Provided

Based on the results of this study, the stamping plant recognized the adjustments needed to eliminate the oil canning effect on the SUV hoods received from Source “A” and implemented the changes accordingly. This resolved the quality concerns.