Experimental investigations of threads surface integrity manufactured by cutting insert and with internal thread rolling head

The objective of this study was to provide insights for a deeply understanding of the threads surface integrity manufactured by cutting tap, rolling tap, cutting insert and with internal thread rolling head, using the multiscale surface texture and fractal analysis in order to show the performance of the internal rolling head by mechanical tests and also to highlight the advantages of rolling internal threads. A series of eight internal thread samples M80 × 1.5 manufactured by cutting insert and internal thread rolling head were analyzed on their surface texture characteristics and material properties. Surface characteristics of low carbon steel Ç1020 (equivalent to AISI 1020) were quantified by measuring four locations on regions of each sample. The threads made by cutting inserts and internal thread rolling head were subjected to tensile test and it was found that the average tensile load of threads made by internal rolling head is higher with 20% than the threads made by cutting insert. Furthermore, the internal thread sections of samples were analyzed using an optical projector by comparing the appearance of failed threads at low magnification to known failure modes, as well as scanning electron microscopy (SEM) for surface material characterization. It was found that it can be discriminate between the thread surface regions of samples manufactured by cutting insert and with internal thread rolling head, using area-scale analysis and surface texture characteristics. The surface micro-morphology results can be applied in studies about improving the lifetime of similar rolled threads and for mathematical modelling of lubrication processes between tool and workpiece.