In this scientific paper it is presented the statistical analysis of the experimental data obtained by the study of the influence of the cutting parameters exerted in end-milling process on the surface roughness. The surface roughness parameter is measured in the cutting feed direction and against it. The parameters of the cutting process, the number of levels and their values were established. Based on these parameters, the research was designed on a complete factorial experiment, randomized with seven blocks. The surface roughness values were measured using a roughness tester. The research method used involved the Romanovski test. The aim of this test was to identify the data affected by aberrant errors, to remove them from the samples and then to repeat the tests for the remaining data strings until all values met the conditions imposed by the test.

From a theoretical point of view, the research carried out in this manuscript was carried out starting from the study of the links between surface roughness and cutting speed, cutting depth and feed per tooth in the end milling process. From an experimental point of view, it started from the organization and development of the physical cutting process, the cutting regimes to be analyzed were established, after which the surface roughness was determined and measured. In this way, the connections between the factors and parameters pursued in the research resulted. The main purpose of this research is to check the random nature of the measured data related to the quality of the end milled surface of the Al7136 aluminum alloy. The main types of statistical processing performed on the sample values from the experimental measurements, the algorithms and the corresponding work modes are according to the method of research that is based on the use of the Young test. The conclusions highlighted the importance of adopting this research method and opened new directions of study.

The research presented in detail in this scientific paper refers to the modelling of process parameters for natural gas transmission in a centralized system. The method of the factorial experiment was used to model some parameters considered to be vital, namely the gas temperature, the air temperature as well as a certain correction factor on the flow delivered to the population. The study was conducted by accessing information provided by a regulation-measurement station that delivers gas to an important locality in a locality in central Romania. Experimental data collected over 24 hours on a summer day but also on a winter day were used. After a previous study with classical experimental research methods, the factorial experiment was used, which allows the delivery of much more detailed information and the graphical representations are much more precise and detailed, in other words, relevant and useful conclusions can be obtained on objective studied in the research approached.

Machining with tool that have cutting edge radius provides components with high fatigue strength, microhardness of a large surface layer and plastic deformation. Finite element simulations of the cutting process give a better knowledge of the chip generation phenomenon, heat generation in the machining area, stress and temperature field results. This study emphasizes the true importance of the mathematical model that underlies the shape of the tool in the pre-processing steps of finite element analysis. The argument is that its achievement and definition depend on the network difficulty. This research purpose is to perform simulations series of orthogonal machining with different radius and depth of cut. In this way, conclusions on the impact of these variations on the whole cutting process were drawn. The finite element application used is Deform 2D, the Lagrange incremental method and the Johnson-Cook material model. The temperature distribution, stress distribution, von Mises stress distribution, effects on specific tool pressure and wear, and fluctuations in the cutting resistance of the tool tip and C45 workpiece were analyzed.