## 4 Conclusions  
The conducted tests made it possible to analyze the reaction forces as well as the strength characteristics and tightness of the joints produced. Based on empirical research, the following conclusions were drawn:  
* For the generated surfaces characterized by the surface topography parameter \(Std\) in the range of 86-93\({}^{\circ}\), it is possible to make tight joints with lower compressive forces than for surfaces in which the value of the \(Std\) parameter is outside of the indicated range of values.
* For two different surfaces, in which the value difference between the \(Sv\) parameter values did not exceed 5 \(\upmu\)m, the leak test result was lower.
* In the set of samples with different generated sealing surfaces, in which the difference in value between the \(Sv\) parameter values did not exceed 5 \(\upmu\)m, the tightness was obtained with a lower compressive force.
* The selection of pairs of cooperating elements in terms of tightness should be based on surfaces with similar parameters, since it allows for the geometric formation of the surface topography elements during the induced plastic stresses.
* The tightness of the components is achieved by the deformation of two mutually opposing surface topography components, with a given force obtained for a pair of samples (1-2) up to 8 times reduction in leakage when applying a force that is higher than 465%. This phenomenon is made possible by the mutual plastic deformation and filling of free spaces, namely, valleys through the peaks of the second component.
* There is a limiting compressive force of the components, at which a clear increase in the tightness of the parts, can no longer be noticed. This indicates that plastic deformation has already reached a point where all of the free inter-surface spaces have already been closed and a further increase in compression will not change their geometric position relative to each other. For samples from code group A of the first pair, an increase in force of more than 2200 N did not cause a clear increase in tightness.
* Regarding the \(Spc\) parameter for samples with comparable surface roughness profiles (surfaces with \(Spc\) parameter values of 27,565 \(\upmu\)m, 14,779 \(\upmu\)m, 8454 \(\upmu\)m, 2602 \(\upmu\)m, and 584 \(\upmu\)m were analyzed). It was noted that for flat and extensive peaks, it was easier to achieve tightness than for pairs of joints where surfaces with sharp peaks predominated. The larger radius of curvature of the peaks had the effect of increasing the contact area between the compressed parts, which reduced the occurring paths of possible leakage of the testing medium between the two samples. The leakage  
Figure 17: The value of leakage Q as a function of the difference in the value of the surface topography parameter \(Sv\) for a constant compressive force of 2280 N.  
value between the surfaces with extreme values of the tested parameter _Spc_ was 10 times smaller.  
Conceptualization, N.W.; methodology, N.W., G.K., M.S. and J.K.; software, G.K.; validation, N.W., M.R., G.K. and M.K.G.; formal analysis, N.W. and M.R.; investigation, N.W. and M.R.; resources, M.S.; writing--original draft preparation, N.W., M.R. and M.F.; writing--review and editing, N.W., M.R. and M.K.G.; visualization, N.W., M.R. and M.F.; supervision, G.K.; project administration, M.S.; funding acquisition, M.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Regional Operational Programme for the Wielkopolska Voivodeship financed by the Structural Funds of the European Union and the State budget of Poland, under grant no. RPWP.01.02.00-30-0046/16.  
Not applicable.  
The authors declare no conflict of interest.