Due to its durability, tungsten carbide has long been used as a material to produce dental burs. WC– Co burs are designed for smooth, efficient cutting and extended life. Dental burs are available in different sizes and shapes, for example round burs, pear and cylinder-shaped, egg-shaped, as well as there are various tapered ones, which enable an individual selection of the drill for the right treatment. Carbides can be used for standard crowns and bridges, for extensive surgical procedures and they should minimize damage to the existing teeth. The design of WC–Co dental bur reduces a patient’s discomfort because of the operating time and the fact that its liquidity is preserved. The head of the bur (the cutting edge) delivers optimum concentricity and strength. The shank is made from stainless steel allowing a bur to be autoclaved multiple times without the risk of corrosion. The main purpose of this study was to evaluate the wear of a tungsten carbide dental bur. The results of stereoscopy microscope and SEM/EDS analysis are presented.
Otakar Bokůvka, Michal Jambor, Libor Trško, František Nový and Barbara Lisiecka
In this paper, the authors publish their own experimental results of the examination of the different holes (milled, drilled and drilled + shot peened) on the fatigue lifetime of 20MnV6 steel. The experiments were carried out at low-frequency loading (f = 10 Hz, pulsating tension loading) in the region from N = 2×105 up to N = 2×106 cycles. The best fatigue properties were obtained in the parts with drilled + shot peened holes.
On the paper the influence of modifying micro additives on the refinement of primary silicon crystals in the hypereutectic AlSi21CuNi piston silumin have been examined. As the modifiers there were used micro additives of Phosphorus in the form of AlCu19P1.4 and CuP12 pre-alloys, sulfur in the form of CuS and iron in the powdered form. The modifying micro additives were used separately and together. Micro additions of iron were used together with phosphorus. Sulfur micro addition provided the fragmentation of the primary silicon crystals, but not as effective as the phosphorus micro additive. The best effect of fragmentation of the primary silicon crystals was ensured by the combined addition of phosphorus in the form of AlCu19P1,4 pre alloy with a micro additive of powdered iron which reduced the average size of the primary silicon crystals from 114 μm to 20 μm.
Barbara Lisiecka, Otakar Bokůvka, Tomasz Tański, Łukasz Krzemiński and Michal Jambor
Aim of this paper is to present the properties of carbon preforms for the production of biomorphic composites. Carbon samples were obtained through pyrolysis of paulownia wood, replicating the microstructure of the cellulosic precursor. Many characterization methods such as Raman Spectroscopy, light microscopy, hardness tests and pore size analyzer detection were used to investigate the microstructure of the product as well as the pore size of carbon samples. Obtained results showed that the parts of early or late wood template play an important role in the pore size, specific surface area and pore volume of the product. This review aims to be a comprehensive description of the development of carbon chars: from wood templates and their microstructure to potential applications of biomorphic materials.
Árpád Barsi, Ádám Nyerges, Vivien Potó and Viktor Tihanyi
Driving a road vehicle is a very complex task in terms of controlling it, substituting a human driver with a computer is a real challenge also from the technical side. An important step in vehicle controlling is when the vehicle plans its own trajectory. The input of the trajectory planning are the purpose of the passengers and the environment of the vehicle. The trajectory planning process has several parts, for instance, the geometry of the path-curve or the speed during the way. Furthermore, a traffic situation can also determine many other parameters in the planning process.
This paper presents a basic approach for trajectory design. To reach the aim a map will be given as a binary 2204 x 1294 size matrix where the roads will be defined by ones, the obstacles will be defined by zeros. The aim is to make an algorithm which can find the shortest and a suitable way for vehicles between the start and the target point. The vehicle speed will be slow enough to ignore the dynamical properties of the vehicle. The research is one of the first steps to realize automated parking features in a self-drive car.
During operation, sterilization and disinfection, the surface working part of dental burs deteriorates. In this study a commercial metallic dental bur with extra coarse gradation (177-250 μ of ceramic embankment), made of a stainless steel were covered with a nickel-diamond composite was examined. The working part of the tool is round-end taper shaped and is intended for crown and bridge preparation. Analysis of microstructure was carried out using Jeol JSM-6610 LV scanning electron microscope with EDX analyzer. After 3 months of operation, the bur can be used for further work in the dental surgery.
The objective of the analysis conducted and described in this paper has been to present the practical application of the Six Sigma method based on the DMAIC cycle in improving the quality of the service process. The first part of the article contains the theoretical framework of six sigma and the issue of using its tools in the aspect of services. Afterwards, there has been calculated the initial sigma value which indicated the need for improvement. Measurement phase has been developed by the value stream mapping, process FMEA and customer survey which results have been analyzed in Pareto chart and fishbone diagram. Improve phase includes the Impact&Effort Matrix and target sigma level that can be achieved as a result of failures reducing and service quality improvement.
Paper present impact of human resources issues as well as issues related to provision of medical services on leadership styles in hospitals in Poland. In this study a descriptive research design was used and a quantitative research was conducted, which was based on the so-called BOST methodology. Surveys were conducted among department heads of 10 public hospitals of various referral systems from the Upper-Silesian Agglomeration providing various types of medical services (which shows a large variety of research sample) operating in Poland. The research showed that both improtance of service provision as well as human resources were not as important as they should be.
Amorphous materials based on magnesium are new materials for potential biomedical application, especially for new implants, as they bear resemblance to titanium implants. Mg66Zn30Ca4 alloy has specific properties, especially mechanical and corrosive, therefore, it has biomedical application as its properties are better than that of other materials. The following paper describes amorphous alloy based on magnesium, properties and shows how to produce amorphous samples of Mg66Zn30Ca4.