PCBN hard turning of ball bearing steel: Influence of PVD coating deposition on tool wear and surface finish / surface integrity of machined surface
2013 (English)Manuscript (preprint) (Other academic)
The wear characteristics of a uncoated and PVD coated low cBN content PCBN cutting tools during hard turning of hardened ball bearing steel have been evaluated. Post-cutting examination of the worn cutting inserts were performed using high resolution field emission gun scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and optical surface profilometry. Also, the machined work material surfaces were characterized in order to evaluate the influence of tool wear on surface finish / surface integrity of machined surface.
The PCBN cutting tools evaluated in the present study all display crater wear, flank wear and edge micro chipping. With respect to the observed scatter in the results the influence of PVD coating on crater and flank wear resistance is very small. Besides a gradual wear mainly caused by adhesive and abrasive wear the PVD coatings show a high tendency to spalling. Flank and crater wear of the PCBN material was found to be controlled by both mechanical and tribochemical mechanisms. SEM and EDS analysis of the crater and flank wear regions showed that the worn PCBN surfaces were covered with patches of adhered work material consisting of mainly iron oxide. AES analysis support these results.
The machined surfaces show a smooth surface with a Ra-value in the range of 100-200 nm and with a superficial plastic deformation limited to the extreme surface. However, with increasing crater and flank wear in combination with edge chipping the machined surface topography becomes more rough showing Ra-values in the range of 300-400 nm.
Place, publisher, year, edition, pages
Hard turning, PCBN, PVD coating, Tool wear, Wear mechanisms
IdentifiersURN: urn:nbn:se:liu:diva-102546OAI: oai:DiVA.org:liu-102546DiVA: diva2:678964