# Modelling Wear Phenomena Specific to Mixer Blades in Concrete Production Plants
[10] highlighted the fact that the erosion rate depends on the following environmental factors: the chemical composition of the mixture, the hardness of solid particles, the density of solid particles, the percentage of solid particles, the shape of solid particles, and the size of the solid particles. The dynamic factors that affect the erosion rate, which are shown in study [10], are the flow regime of the fluid, the impact speed on the blade surface, the impact frequency, and the impact angle. The above statements were also confirmed by the results already mentioned in [9; 10; 11; 12; 13; 14]. Through experiments carried out on a stand that reproduces (1:2 scale) a drum from the composition of a horizontal mixer with a double axis, in the work [15], it was possible to establish the dependence between the type of material and the wear rate of the mixing  
Figure 1: Schematic representation of a mixing arm and blade [8]. blades, as well as the influence exerted by the angle of attack. The stand had the possibility to change the value of the attack angle of the mixing blades, corresponding to the following values: 30\({}^{\circ}\), 45\({}^{\circ}\), and 60\({}^{\circ}\). In the experimental research, samples/specimens made from three types of cast iron alloyed with chromium [15] were used, specific to the construction of mixing blades, as well as three types of steel. The working environment was a mixture of crushed mineral aggregates corresponding to the granulometric class 4-8 mm. The results obtained from the experiments [8; 9; 10; 11; 12; 13; 14] showed that with an increase in the inclination angle of blades, wear through erosion becomes predominant, accelerating the phenomenon of mechanical degradation in the samples; the small angle of inclination of the blades largely restrains the movement of aggregates on the sample surface, reducing the erosive effect. In this situation, impact wear becomes predominant, the speed being directly proportional to the resistance characteristics of the sample material. [PERSON] et al. [16] studied the wear of the mixing blades of a mixer, in accordance with the pressure exerted by the concrete mixture on the blade surface. The results revealed lower wear values for tilt angles between 30\({}^{\circ}\) and 40\({}^{\circ}\). Therefore, it can be stated that theoretical and experimental research into erosive wear processes has been a key interest for many experts in the field of tribology [17; 18; 19; 20; 21; 22; 23; 24]. The development of abrasive erosion models is defined by a technical level of theoretical and experimental investigation resources that are currently being rapidly improved. The results of the erosion research were obtained via the development of mathematical models specific to these tribological processes. In his study, [PERSON] [25] presented and analyzed 28 such models. The empirical models are developed from the experimental data from material erosion in the laboratory test rig. In essence, mathematical models of erosion suggest calculation equations for the intensity of erosive wear, depending on the geometric and dynamic parameters of the studied system and also on the chemical characteristics of the operating environment. Interest in the tribological modeling of erosion phenomena is also shown in [26], where an analysis of variance (ANOVA) was performed to statistically analyze the effect and contributions of specific metal-cutting parameters on the response variables, namely: tool life, surface roughness, volume of material removed, power consumption, and cutting zone temperature. The effect of the surface quality on the functionality of the systems benefits, apart from the approach based on the classic tribological theories, from the development of unconventional models, as it results from [27]. Taking into account these considerations, we can state that the subject addressed in this article complements other studies in the field and confirms the previous results obtained by the authors of this paper and the results published by other authors.