Tool life in stainless steel AISI 304: applicability of Colding's tool life equation for varying tool coatings

The current paper investigates the applicability of Colding's equation for modelling tool life while turning stainless steel AISI 304. The turning inserts used in the study together with the work material displayed an irregular wear behaviour, thus making it impossible to use flank wear as the tool wear criterion. Failure of the tool tip was thus used as an alternative criterion. The obtained tool life model is shown to have some amount of extrapolative power and a potential for modelling tool behaviour outside the experimentally tested cutting parameter range by using the constant K to adjust Colding's model for different tool coatings. Solid carbide (WC-Co) inserts with constant cutting geometry and with five different PVD coatings were used in the machining trials. The results will help minimize the amount of work material and test time as well as tools needed to obtain reliable machining data.