The authors propose in this paper testing of materials used in dental constructions and dental cutters used for their processing on an electric stand, made by the authors. The stand will be equipped with a transmission that ensures variation of the rotation speed of the cutter from 3000 to 30000 rpm, variation of the sample rotation speed of the tested material from 10 to 300 rpm, vertical and horizontal plane and horizontal rotation mechanisms. The operation of the stand is considered to be simple. In order to carry out the tests, it is necessary and obligatory that the sample preparation operation is carried out in accordance with the validation standards, namely, the knowledge of the sample material, the mechanical properties, the dimensions and their weight. After mounting the samples and the cutter on the stand, the pressing force is established by adding additional weights, the rotation speed of the sample is set and the rotation speed of the cutter is also set to the horizontal movement speed to the cutter (measured in microns) by means of a micrometric screw mounted on the table stand acting on the sample holder.It measures the test time, determines the shape, dimensions and the weight of the samples after each period of time. Following the determinations we can observe the proportionality of the friction force with normal reaction, the connection between the coefficient of friction and the rotation speed during the test, the quality of the sample surfaces and the milling cutter subjected to the test.The study was conducted to determine the wear properties of dental cutters used in dental laboratories, where many materials with different mechanical and technological properties are used.
Dental resin composites have a wide applicability in the dental field. They exhibit their own chemical composition that imparts certain physico-mechanical properties. The machining of the pieces of these composites must be sufficiently light, without affecting their strength. For processing these parts, respectively of the dental work, is used or carbide burs, or diamond burs, depending on the mechanical strength of the composite. To determine composite behaviour under action of the conical finishers was simulated their behaviour in specific simulation programs. As a result, stress concentrators may appear from the first processing which may affect the later resistance of the piece or dental work.
The paper presents experimental results regarding the main parameters that give information on the wear of the dental mills. The study of the phenomenon of wear of dental mills by experimental methods aims to highlight a multitude of parameters that influence the interaction between the dental mills and the material to be milled. It presents such a set of parameters that define the process and, based on the results, an eventual hierarchy of the influence of these parameters on the milling process is analyzed. The phenomenon of milling wear has been studied in various working regimes generated by the variation of the milling rotation speed and pressing force, measuring at equal time intervals of one hour the main parameters that can provide quantitative and qualitative information about the milling wear: the angle of sharpening, the angle of placement, the angle of clearance, the area of the circle at the tip of the tooth, the radius of the circle at the tip of the tooth in crosssection, the radius of curvature of the release channel, the mass of material lost by the body of the mill. Also, this paper briefly presents the general framework in which the experiments are performed, the milling cutters and the milled material, the working regime. After selecting the set of parameters in which the phenomenon is to be described, the variation of these parameters in relation to time is analyzed. Discussions and conclusions use graphical representations of the experimental data to configure statistical analysis, to develop a complete experimental plan to record any parameters that were not monitored in these early experiments, and also to suggest future statistical or deterministic models of the phenomenon. The deterministic mathematical modelling, towards which the material in this paper tries to orient the future researches, starts from the observation of a possible asymptotic damping of the aggressiveness of the dental mills towards the material and from the expression in terms of the theory of control systems. The mathematical models that are obtained starting from the structured experimental data and commented in this article will be used to investigate the possibilities of improving or optimizing the working regimes of the dental cutters. Both statistical and deterministic models will be used.
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