Milling of WC-Co-hardmetals
Due to their high modulus of elasticity, the significant higher hardness compared to steels as well as the higher toughness compared to ceramics sintered carbides play an important role in metal forming. Nowadays the components are in many cases produced using time- and cost-intensive abrasive processes and due to the originated edge zone damage they are often finished. As result of the progressing development of highly hard cutting materials milling can be considered an alternative. Research on milling of sintered carbides has until now only been conducted in the field of micro cutting, so that important scientific questions concerning performance and process limitations are currently unsolved. Until now the fundamental studies have been conducted especially for the kinematic simpler process of planing/ slotting, though the preliminary studies indicate that milling of sintered carbides offers a high potential. However further fundamental research on the influence of material, process parameters and processing strategies on cutting force, tool wear and work piece quality is required.The available results of the state of research and the preliminary work done by the applicant show the potential of milling of sintered carbides, though the process has been hardly considered for lack of technological fundaments. The main objective of this research project is a fundamental contribution to the understanding of the processes occurring during milling sintered carbides. This is restricted to the machining of WC-Co carbides. The study focuses on the investigations on the influence of the tool, especially the stabilization of the cutting edge, the process variables, the processing strategies and the carbide alloys on the load-dependant edge zone damage in the work piece. For receiving a more precise understanding of the cutting mechanism and the local edge zone damage slotting experiments, i.e. with linear cutting motion, are additionally conducted at certain parameter combinations.Based on the experimental findings an empirical model to describing the impact on the edge zone of the component as a function of the carbide alloy, i.e. the material hardness, is developed. The objective is to predict the occurring edge zone damage as a function of the material hardness for future machining tasks. Furthermore the model enables the process design in order to milling a carbide component in the required quality.In conclusion, a fundamental evaluation of performance as well as a determination of process limitations in milling of sintered carbides is carried out. The parameter-dependant depth of damage of the produced component is considered as a significant result of the research project. It can be used for deriving future processing strategies in order to minimize the occurring edge zone damage.