Novel alignment method for optical 3D gear metrology of spur gears with a plain borehole

In 3D optical metrology, novel approaches to characterise the geometrical quality of gears require a custom gear alignment process to produce reliable results. This study proposes a novel scan alignment method known as subsequent gear alignment (SGA). It emphasises on the proper alignment of the gear hole and follows the alignment of gears in real-world applications. Therefore, the SGA method increases the usability of the previously developed and published methods. The scanned data were first processed with both the commercial global alignment and SGA methods and then evaluated to obtain standard geometrical parameters. These were compared with those obtained by the tactile method, and the SGA method offered improved results over the global alignment method. •A novel scan alignment method SGA for optical gear metrology was developed.•Affected parameters were identified and the effect was evaluated.•Alignment is proven to be a key step in optical gear geometry.•The SGA method provides a significant advantage over the standard global alignment.