Root cause analysis of coining tool failure with proposed solution to extend its service life

•Root causes analysis of the coining tool failure served as a tool for revealing the causes of damage and early decommissioning of the punch.•The cause of crack initiation was plastic deformation during pressing, hardening during martensitic transformation, and improper chroming process.•The cracks appeared outside the relief of the coining die, and also in the core of its working part.•Changes in production allowed for a 148-fold increase in the number of minted coins produced by a single minting tool. The article deals with a root cause analysis of coining tool failure after its untimely discarding and the design to extend its service life by innovating the manufacturing process. The analysis was performed on the coining die which had to be put out of service due to the insufficient quality of minted stainless coins. The purity of steel and the microstructure of the material of the semi-finished goods were evaluated. Furthermore, an analysis of the coining die failure under the surface and in the core was performed as well as the state of the chromium layer failure on the coining die relief. Based on the results of the analysis, a new experimental coining die was designed and produced according to an innovative manufacturing process. The pressing of the relief was carried out in a vacuum furnace and relief was coated with a TiAlN by the PVD method. New processes introduced in the production of coining die prevented the failure of die punches, extended the time of operation, thereby increasing quality of the coin production.