Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

Although round tools as carbide drills and mills are dominating by far the application of submicron and ultrafine hardmetals the consumption for PCB microdrills had the strongest growth rate over the last decade. This paper deals with the latest developments of ultrafine hardmetals and their application for PCB microdrills and metal cutting inserts. Based on optimized processing and properties such as hardness, hot hardness, toughness, strength and wear resistance a new generation of microdrills is presented. In particular the failure probability of the microdrills could be considerably reduced and the number of drilling strokes was nearly doubled. Combining improved pressing behaviour with proper doping and optimized processing new applications of submicron and ultrafine hardmetals could be obtained by using complex shaped metal cutting inserts. Apart from these application examples this paper gives some insight into fundamental investigations on sintering and properties of ultrafine hardmetals and shows in particular the influence of milling, doping and sintering on the properties of ultrafine hardmetals. This paper also presents a new ultrafine WC grade showing a 0.1 mum WC intercept of a sintered WC-10 wt%, Co structure and a hardness of HV30 = 2050 for a 1 wt% mixed VC/Cr3C2 doping. (C) 2002 Elsevier Science Ltd. All rights reserved.