Morphological characterization of chip segmentation in Ti-6Al-7Nb machining: A novel method based on digital image processing

Abstract

α + β titanium alloys, namely Ti-6Al-7Nb, have found growing importance in the biomedical industry, in which CNC machining plays a decisive role in the production of high-quality components. Metal chip analysis is a consolidated method for machining optimization, particularly in difficult-to-cut materials that tend to form saw-tooth/segmented chips. A novel automatic method for quantification of classical geometric aspects of Ti-6Al-7Nb alloy saw-tooth chips was developed. Geometric features, including the minimum and maximum chip thickness, as well as the saw-tooth width, were evaluated. These aspects were obtained by association of optical microscopy and digital image processing. The advantage of this methodology is the fully automated analysis of the geometric aspects of the chip, which are generally obtained manually. The robustness of the measurements was ensured by the selection of shape descriptors tested on a range of cutting speeds. This work also delivers a set of valuable experimental results about Ti-6Al-7Nb machining.