Laser scanning means speedy delivery for Ferrari Racer.

The Austin Group, Quincy, Ill., a consulting design firm for lost foam casting, was contracted to reconstruct a transmission case made of A356 T6 aluminum for a rare 1967 330P4 Ferrari Racer. The original P4 Racers are estimated to be worth $10 million, and a replica can net $200,000. The functioning transmission case consisted of complex shapes that required high levels of accuracy, and the customer wanted the part right away.

CAD geometry did not exist for the transmission case, so the Austin Group needed to reverse-engineer the 18 x 14 x 12-in. (45.72 x 35.56 x 30.48-cm) component. In the past, the design firm used a digitizer arm to measure the position of individual points as it was moved around a part. The resulting points were imported into modeling software for the designer to stitch together to form a solid model of the component. Generally, capturing a few thousand points with the digitizer arm would take 70 hours, but many of the points needed to determine the precise geometry of a component often still are missing. The designer is forced to rely upon intuition and guesswork to create a final model. The interpretation process typically takes 50 hours of work, making the total time spent to re-engineer the part 120 hours. The approximate total cost to reverse-engineer the part would have been more than $10,000.

Instead, the Austin Group opted to use a new reverse engineering method involving laser scanning, in which a line of laser light is projected onto surfaces while cameras continuously triangulate the distance and profile of the laser line as it sweeps along the component. The laser probe computer translates the video image of the line into 3-D coordinates, giving the operator immediate feedback on areas that might have been missed. Far more points are generated with the laser scanner than through the use of a digitizer arm, so the solid models are created more quickly and with better accuracy.

GKS Inspection Service Inc., Minneapolis, provided the Austin Group with laser scanning and consultative engineering services for both the reverse engineering and inspection of the part. In less than a week, GKS provided solid models of the component that matched the original physical part at a cost of $6,000--40% less and two times faster than the previous method.

With the geometry of the Ferrari Racer transmission case fully defined, the Austin Group could proceed with casting it in lost foam. Using the solid model provided by GKS, the firm created a foam pattern and gating system, which was coated with refractory and dried under controlled conditions.

The coated cluster was invested in a flask with loose, unbonded sand, which then was vibrated for compaction. Molten metal was poured onto the top of the gating system, directing the metal throughout the cluster to replace the foam gating and patterns and create the casting.

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