## 4 Conclusions  
The conducted studies on the tribological properties of friction pairs composed of a DMLsed 20 MnCr5 countersample and different types of metal sheets allowed to determine the changes in the character of the friction process depending on the type of these friction pairs. Based on the experimental studies, the following conclusions can be drawn:  
* The most stable friction force variations during wear tests were recorded for friction pairs of the 20 MnCr5 countersample with Inconel 625 and 321 steel sheets. These sheets were characterised by the highest strength among all the analysed sheets. For these sheets, similar COFs were observed during the entire wear test (COF = 0.194\(-\)0.213). The remaining sheets with increased plasticity showed significantly higher values of the coefficient of friction (COF = 1.234 for the 20 MnCr5/ EN AW-6061 T0 friction pair and COF = 0.813 for the 20 MnCr5/pure copper friction pair).
* The largest gain of countersample mass was observed for the 20 MnCr5/EN AW-6061 T0 friction pair. The sample mass loss in this combination was also the largest, amounting to 19.96% of the initial mass. A similar behaviour of friction pair materials was observed for the 20 MnCr5/pure copper friction configuration. On the other hand, for the 20 MnCr5/Inconel 625 friction pair, no significant changes in the mass of friction pair materials were observed.
* During the friction of pure copper and the EN AW-6061 T0 sheet, the main friction mechanism resulting from the high plasticity of these materials was adhesive wear. In contrast, in the 20 MnCr5/Inconel 625 and 20 MnCr5/321 steel friction pairs, abrasive wear dominated.
* Based on the changes in friction force, COFs, and mass changes in friction pair components during wear tests, it can be concluded that potential tools in the form of inserts or working layers manufactured using 3D printing technology, the DMLS method, without additional surface treatment can be successfully used for stamping sheets of 321 steel and Inconel 625. These sheets are characterised by a low mass loss, the lowest COFs, and stability of the friction force during the wear test.  
Three-dimensional printing-aided rapid tooling is expected to have a major industrial impact on the design and production of stamping tools. The implementation of 3D metal printing can enhance the technology in flexible manufacturing systems according to the concept of Industry 5.0. Although the number of metal grades for use in DMLS is still limited, intensive work is underway on the development of new powders and the adaptation of existing technologies along with the expansion of the part design space.  
Conceptualization, K.Z. and M.M.; Methodology, K.Z., M.M., B.L.-M., T.T. and R.S.; Software, K.Z., M.M. and B.L.-M.; Validation, K.Z., M.M. and B.L.-M.; Investigation, K.Z., M.M., B.L.-M., T.T. and R.S.; Data Curation, K.Z., M.M. and B.L.-M.; Writing--Original Draft Preparation, K.Z. and T.T.; Writing--Review and Editing, K.Z., M.M., B.L.-M., T.T. and R.S.; Visualisation, M.M., B.L.-M. and T.T. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.