Reverse Engineering For Better Quality

Reverse Engineering For Better Quality

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Reverse Engineering for Better Quality For a leading European automaker, reverse engineering is a major tool in continual engine improvement. The company is using reverse engineering to implement a new computer-aided inspection (CAI) process for a plant that builds nearly 600,000 engines a year. More than 900 specialists oversee quality assurance on the plant’s production lines and operating units. Core engine block components, such as the crankcase, crankshaft, connecting rods, and the cylinder head, are verified by spot checks in the company’s precision measurement laboratory, where engine components must conform to tolerances of hundredths of a millimeter. Faced with these rigorous quality demands, the company wanted to move beyond traditional inspection processes using coordinate measurement machines (CMMs). CMMs collect a sample of discrete points on a part, one at a time. The process is slow and does not adequately address surface-to-surface inspection required to verify the accuracy of sheet metal or free-form surfaces. Results are recorded in a 2-D geometric dimensioning and tolerance (GD&T) report that does not directly correlate with the 3-D CAD model of the part. The CAI process uses noncontact scanners to collect millions of points in seconds. Software based on reverse engineering principles then processes the information automatically to compare an as-built part to its CAD representation. The process creates an interactive loop among the design, manufacturing, and quality control divisions. The first step in the CAI process is to capture accurate geometry and dimensions by placing target points, which are used to align multiple scans, on the surface of the existing engine component. The engine part is then scanned with a noncontact white-light scanner that generates a polygonal model. Jagged edges, holes, and surfaces on the polygonal model are smoothed out, and the model is cleaned to remove extraneous points or noise that might undermine the data. The completed files are then merged, aligned, and saved in STL format. The STL model is imported into CAI software, which automatically allows engineers to align and compare the STL model with the original CAD data to determine exactly where variations in the geometry occur and to analyze how deviations might impact the part’s functionality.

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Even miniscule differences between the physical part and the CAD data can result in performance flaws and inaccurate engineering analysis, so the auto maker imposes a tolerance level of 0.02 to 0.03 millimeters–less than the width of a human hair. If parts differ from the original design by more than that, they are sent back to be reworked. Part discrepancies are communicated through reports with visual images and numerical results that are generated automatically by the CAI software. Reports can be output in many standard formats, including HTML, PDF, Microsoft Word, and Excel, or as customizable graphics. The reports are also leveraged by suppliers, quality engineers, and others in the company’s supply chain. The European automaker is joining its Japanese counterparts in finding that the CAI process based on reverse engineering saves time and increases quality by ensuring dimensional accuracy and engineering performance. According to the manufacturer, design engineers have better information about the quality of parts early in the product life cycle, which saves the company money and produces a better end product for consumers.

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