Coldings tool life model applied on tool wear when machining the Maxthal material

Summary, in English

Coldings tool life equation for metal cutting tools has been modified to suit the difficult to machine material Maxthal. The dominant tool wear mechanisms during machining of Maxthal are abrasive and adhesive wear and a strongly temperature dependent chemical deterioration. The combination of these three mechanisms leads to a considerable variation in tool life, even when the cutting speed has been varied in a relatively close range. Metal cutting experiments has been carried out as straight turning, were the wear level of the tool has been monitored by cutting force measurement. Sample tests have been performed with 3 different insert types. The results show that the best cutting conditions are obtained with a cermet insert. The difference in tool life and total cutting capacity between the studied insert types is ca 10%. The experimental data has been adapted to Coldings tool life model. Within the cutting data interval 25<vc<50 m/min, Coldings model can suggest a cutting speed for a total tool life of 7 minutes with an average accuracy better than 10%. For carbide inserts, maximum chip vol-ume flow is obtain for a fixed value of the equivalent chip thickness he, for a given tool life.