To be useful as a quality-inspection tool, a 3D scanner must characterize the complete surface geometry of a propeller blade, in a completely automatic fashion, in the time span of only a few minutes. In addition, the scanning system must collect dense, accurate, noise-free data from all types of blades, with surface finishes ranging from brushed aluminum to painted.
After a complete set of data has been collected, an analysis package is typically used to extract measurements from the data. However, companies that are committed to achieving excellence have discovered that conventional inspection/analysis programs often find features by searching for min/max data points. Basing a measurement on a single data point is frequently fooled by outliers and/or poor data collected along the edges of an airfoil.
Unique Blade Analysis Software
That is why Metronic developed proprietary application software to accurately find airfoil features using 3D scan data. The “Metronic Blade Analysis” software is fully integrated with the 3D scanning process so that after scanning is complete, the critical blade geometry characteristics are automatically evaluated and a report is generated without the need for user intervention.
The Metronic software uses high order polynomials to fit the leading and trailing edge data. Fitting the data is important especially along the trailing edge where the radius is tight and full scan coverage is difficult. In addition to accurate leading/trailing edge determination, the Metronic System measures the cord line distance, blade thickness, edge and face alignment, and blade angle at each measurement station.
Automatic geometric inspection of a propeller blade allows rapid feedback to the manufacturing process as well as the ability to select sets of blades with matching geometric shapes.