Abstract The monograph deals with the issue of using Six Sigma systematic thinking, methods and tools to eliminate deficiencies in chosen organization in automobile industry. This work is divided into four main parts. First part explains the overview of the current state and it defines the basic term of quality and what Six Sigma is in the area of ensuring quality and potential lack of quality. Then we clarify the basic pillars of Six Sigma, Six Sigma implementation process and tools used in Six Sigma. Furthermore, definitions of Six Sigma, its history, principles, levels, key components and procedure of realization of Six Sigma itself are mentioned in this work. This moves us to more concrete theme which is implementation of Six Sigma at the occasion of decreasing number of scraps (wasters) in the production of silencers in automobile industry. In the second part, we specify the objective of this work and in the third section we suggest the methodology used to solve implementation of Six Sigma which is necessary to help us to meet the goal of our work. The fourth chapter deals with experimental research and results.

1 Introduction Composite material is not a new material in mankind history, Fig. 1.1. Among the firstly used composites were unburnt clay bricks consist of clay (matrix) and straw, reed or grass stalks (oriented fibres). The ancient composites were generated without computational methods but based on experiences and knowledge obtained during longer periods. Fig. 1.1 Relative importance of the four classes of materials (ceramics, composites, polymers and metals) in mechanical and civil engineering as a function of time [1] Even, the names of individual historical periods are defined according to preferably used material for tools or weapons – stone age, bronze age and iron age. One can see that in historical periods the man is returning to already known things that serve as resource of knowledge. The man makes some “re-discovering” but every time it creates also the new added value [2,3]. Fig.1.2 System Material Application Computational Method Experimental Data Production Technology Introduction 2 Presently, the professionals re-discover the composite materials and the added value is creation of new and superior and more sophisticated materials, computational methods, production technologies and applications (Fig. 1.2). The sophisticated and progressive materials are developed thanks to new computational methods used in designing process of either material or composite component and furthermore thanks to new production technologies of materials. The four mentioned elements: material – computational (calculation) method – production technology – application, create system that is schematically shown in the Fig. 1.2. The outcome of interaction among the first three elements is the final application; it means the sophisticated product based on composite material or composite structure or hybrid structure etc. 1.1. Analogy: Applications of steel and composite materials The analogy can be made with steel (iron) that was not the completely new material in the middle of 19th century. The steel became the re-discovered material regarding to new technologies of steel production in 19th century that allowed the wide industry applications and also the low price of steel. The possibility of usage the steel as engineering material the new production and calculation methods had to be developed. Many scientists contributed to development of mechanics and its calculation methods in 19th century such as L. Navier and his theory of beam bending and computing of suspension bridges, G. Moseley and his first theory of steel bridges calculation, L. Schwedler and his theory of space arched roofs, S. Poisson, B. Saint Venant, G. Lamè, B. Clapeyron, D. Maxwell, L. Cremon, K. Coulman and others who concern to graphical and graphicanalytical methods of structure estimation. We can declare the influence of calculation method and new material to structure by bridges built in New York between 19th and 20th centuries. The firstly built Brooklyn Bridge was the bridge connecting the individual parts of New York. However, Brooklyn Bridge involved new material in form of steel ropes (the first suspension bridge using the steel ropes), it has robust construction (stone bridge towers), and it was being built for 13 years (finished in 1883). The new calculation methods, e.g. Moisseiff's deflection theory, were applied to new steel material and used for other bridges in New York changed bridges to lighter-weight, all-steel and longer constructions that were built in much shorter time. Moisseiff's deflection theory was used to design Manhattan Bridge with steel towers. L. Moisseiff had become a leading suspension bridges engineer in USA in the 1920s and 1930s. He made such saving modifications in construction of Tacoma Bridge (the third longest suspension bridge span in the world in its period) based on his theory that resulting the collapse in four months. The failure confirmed the limitation of his theory. Naturally, the usage of steel definitely changed the arms and weapons of that time armies. Since 1900, the all battle ships as the guns and cannons were made of steel. Many new weapons as the machine guns, submarines and tanks (the first in 1915) could not be made of other material than steel. The similar situation in field of composites is in aircraft and military industry. It was the first that starts to use composite materials and it still moves the usage possibilities of composites. Presently, the composite materials are in use of all industries. However, this field can present the case of engineering work failures. The well-known failure is, except the Tacoma Bridge collapse, the Challenger Space Shuttle accident in 1986. The designers inclined in design of failed component to experimental data without specific theory [4]. The mentioned two cases of engineering fail (Tacoma Bridge and Challenger accident) in 20th century serve as examples of two anti-poles: computational (calculation) method and experimental data. It is needful to realize that there are two sides of the same coin. While in 1970s the share of carbon fibre composites used in Airbus aircraft was only 5%, at the beginning of 1990s it was 10% and at the beginning of 21st century 15%. The share was 22% in Introduction 3 Airbus 380 in 2005 and the new Boeing 787 (the first fly in December 2009) involves 60% of carbon fibre composites. [5] The composite usage increment is evident in Fig. 1.3. Fig. 1.3 Composite ratio in structural aircraft weight [5] Nowadays, we can develop so called the design-material approach in designing process that puts together the component designing and inner material structure that is not homogeneous but anisotropic (orthotropic). Designing of structures regarding composite material structure is connected with components manufacturability. Finding the appropriate production technologies is the work for material engineer technologists. There are other tasks: what would be strength and stiffness of designed composite material of component; what are the material properties of designed composite material; where is the dangerous location of component etc. Finding the answers is impossible without appropriate computational methods that are able to reliably simulate the material structure including the reinforcement or provides some idealisation – homogenisation. Furthermore, the experiments are necessary to do to verify the results of the computational models.

Abstract The submitted monograph is oriented towards application of 3D printing in a structure of a new generation of moulds. As to the content the monograph has been divided into two basic parts, i.e. theoretical and practical. The introductory chapters describe fundamental principles on the basis of which additive manufacturing works, i.e. seven principal types of additive manufacturing. Greater emphasis is laid on the DMLS technology serving as a base for practical part. The second part of theoretical overview deals with inner structure and its optimization. Consequently, the objectives were defined along with theses and methodology of elaboration. The introduction of the practical part offers analysis of the current state of the art as well as of the difficulties emerging in the course of manufacturing of the component parts by means of the DMLS technology. Further on, the monograph shows a case study analysing a shaping intermediate piece designed for plastic injection from the point of view of strength analysis and manufacturing process analysis in case of which the data serve as input information for verification of data after optimization of in-ner typology. The final chapters assess achieved results.

Nowadays, manufacturing companies are forced to adapt to new conditions by flexibly responding to different customers' and their clients' demands. Simulation can be applied to various existing systems, validations, and ana-lyzes, machine and equipment utilization, personnel availability, capacity re-quirements for detection of bottlenecks, design of manufacturing systems, analysis of existing systems, as well as production management concept veri-fication. Today's simulation programs can simulate the entire production pro-cess in a matter of minutes, uncover its deficiencies, or evaluate the produc-tion-associated costs. Simulation is a reliable tool for gathering progress and production process results that provide a wealth of data to help managers make the right decisions quickly and easily. Computer simulation is characterized by the fact that in a few hours, it can run experiments that take several days or months on real systems. The simula-tion answers the questions like "What happens when?", "Where are the main risks?", "Where does the system have its bottlenecks?" This process is associated with the effects of predicting the behavior of the system under assessment, supporting decision-making at different levels, better understanding of the system's function and its gradual improvement, saving money and, ideally, eliminating the potential risks in the human-machine environment. Although a computer-based expertise approach cannot replace a human ele-ment in the management process, or a complex system management, its appli-cation, naturally subject to managing the initial cost of acquiring a simulation system, its installation and successful application is associated with a number of positive benefits, ranging from financial cost savings for the operators of the systems under assessment, to environmental aspects and aspects of tech-nical and humane workplace safety.

FOREWORD The publication is intended for students of Faculty of Mechanical Engineer-ing of Slovak University of Technology in Bratislava, ERASMUS students, for the internationalization of education and science in Slovakia, for academic mobility, within the Central European exchange program for university stud-ies CEEPUS and for general public. The publication complements the theoret-ical knowledge from lectures, deepens and practically shows the knowledge gained in lectures but also by studying the solution of practical tasks that are in line with the focus on the new accreditation program, for students giving comprehensive instructions for solving single-phase circuits. The publication consists of theoretical introduction and solved examples with circuit schemes and the solution of phasor diagrams. The publication presents typical tasks given to students of civil engineering in exams from the former Department of Electrical Engineering, founded in 1962. The publication is, among other things, a tribute to the founder of the Department of Electrical Engineering, Assoc. prof. Eng. Ivan Puzjak, PhD. on the occasion of his undead 92 birth-day. It is our kind duty to thank all those who have helped us with their experi-ence and advice in preparation, an we believe that the publication will help listeners and general public to cope with the issue of single-phase currents and will be a good aid in the study. In Bratislava, July 2021 Authors

INTRODUCTION Dear readers, The development of new cars reflects the strategy of the EU to produce material and energy-efficient vehicles, including the introduction of cutting-edge ultra-low carbon production technologies in vehicles. The requirements for the minimum weight and maximum strength of the structure placed on current vehicles result in the use of new composite materials that are problematic in terms of recycling. Plastics, non-ferrous metal-bearing materials, the significant growth of electronics and the start of the series production of electric vehicles give rise to new challenges also in the area of recycling. Concerning the critical raw material resources, EU policy determines the trend of the increasing share of secondary raw materials with an emphasis on increasing the level of recycling raw materials of a mineral origin and the efficient material or energy recovery of organic waste. The Slovak economy still consumes more resources than its natural capacity and therefore has a negative ecological footprint. However, we have significant potential for improving the use of existing resources in waste management, thus it is necessary to focus on promoting research and the development of modern recycling technologies not only in the area of municipal waste but also for industrial waste, as well as the construction of recycling capacities for those commodities that lack or have insufficient recycling capacities. The generation of waste is logical, although the undesirable consequence of anthropogenic activity related to the flow of energy and materials. Waste is generated in the entire social reproductive process, from the extraction of raw materials and their treatment to technological processing into products and their use. After the value of the product is consumed (after the end of a product’s life cycle), the product itself becomes waste. The issue of reducing the production of waste and methods for safe, ecological and economically viable waste recovery or disposal is currently one of the most important economic and political problems worldwide. In addition to energy decarbonisation, the European Green Deal also determines the achievement of a climate-neutral and clean circular economy. The New EU Industrial Strategy and the New EU Circular Economy Action Plan order the member states to monitor the priority waste observation areas as well as to monitor the progress for municipal waste and for waste containing substances that may replace natural resources by their recycling. The primary objective of this policy is to gradually turn the produced waste into the main source of raw materials and to leave the not-yet-depleted natural resources as a consumption reserve for the future. An important stage in the EU’s progress towards sustainability and a recycling society was the adoption of the programme Towards a Circular Economy: A zero waste programme for Europe. The principal vision defined in the Environmental Policy Strategy of the Slovak Republic until 2030 is to achieve a better quality of the environment and a sustainable circular economy based on the thorough protection of the components of the environment and only the minimal utilisation of non-renewable natural resources and hazardous substances. The issue of waste management belongs among the priority environmental challenges in Slovakia and the preferred areas of the environmental policy until 2030. Dear experts, as well as the technical and non-expert public, In your hands is a publication produced by the “University and Industrial Research and Education Platform of the Recycling Society (hereinafter referred to as ‘UNIVNET’)” – an association focusing its activities on progressive waste recovery technologies in the automotive industry in the Slovak Republic. The UNIVNET association was established upon an agreement between the Ministry of Education, Science, Research and Sport of the Slovak Republic (MESRaS SR) and the leader of the association – the Slovak University of Technology in Bratislava (STU BA). In addition to the STU BA (Faculty of Mechanical Engineering of the Slovak University of Technology in Bratislava), the association includes other universities, in particular: Technical University of Košice (TU KE, Faculty of Mechanical Engineering, and TU KE, Faculty of Materials, Metallurgy and Recycling), University of Economics in Bratislava (EU BA, Faculty of National Economy, and EU BA, Faculty of Economic Informatics), University of Žilina (UNI ZA, Faculty of Mechanical Engineering), Technical University in Zvolen (TU ZVO, Faculty of Technology) and the Automotive Industry Association of the Slovak Republic (AIA SR). The main aim of the association consists of prognostic and research and development activities in the search for new technologies and methods for the maximum efficient recovery of waste, especially in the automotive industry, to minimize negative impacts on the environment and save the primary resources of energy and raw materials. The present monograph is a thematic continuation of monographs issued in 2020 under the title “Stav a vízie zhodnocovania odpadov z automobilového priemyslu SR” (The condition and visions of automotive industry waste recovery in the Slovak Republic) and in 2021 “Progresívne technológie zhodnocovania odpadov v automobilovom priemysle” (Progressive technologies of waste recovery in the automotive industry). We believe that the monograph of the UNIVNET association will capture your attention and even become a certain inspiration for those who deal with the recovery and recycling of cars after the end of their life cycle and others. Editors Dr.h.c. prof. Ing. Ľubomír ŠOOŠ, PhD. Dr.h.c. mult. prof. Ing. Miroslav BADIDA, PhD.

Vorwort Das vorliegende Buch entstammt einer Examensarbeit, verfasst an der Bergischen Universität Wuppertal, die zu betreuen mich die Verfasserin im Jahr 2017 bat. Zu dieser Zeit sah sich Deutschland mit einer bis dahin nie gekannten Flüchtlingswelle konfrontiert. Das herausragende, soziale Engagement der Autorin gebot es ihr, sich der Gruppe der minderjährigen Flüchtlinge anzunehmen. In einer eigens dafür ausgestalteten sozialen Einrichtung betreute Natalie Drewitz diese Gruppe über zwei Jahre sehr intensiv. Ihre besonderen Erfahrungen und Erlebnisse wollte Drewitz wissenschaftlich durchdringen und konzipierte dazu eine empirische Studie, die die Akkulturation und das neue Leben dieser unbegleiteten minderjährigen Flüchtlinge im Aufnahmeland Deutschland analysiert. Im Zeitraum von 2016 bis 2018 arbeitete Drewitz im Rahmen ihrer Tätigkeit als Projektleiterin und darüber hinaus durch Recherchen in Bibliotheken und Datenbanken intensiv – immer mit dem Ziel, mit ihren Erkenntnissen einen positiven Beitrag für eine nachhaltige Integration von minderjährigen Flüchtlingen zu leisten. Eine Online-Befragung von 25 minderjährigen männlichen Flüchtlingen, im Durchschnitt 18 Jahre alt, geben ersten Aufschluss über die Akkulturations-strategien und das Wohlbefinden der jugendlichen Flüchtlinge, die ohne ihre Familien in Deutschland angekommen waren. Natürlich ist es für uns als Aufnahmeland Deutschland überaus interessant zu erfahren, wie sich diese unbegleiteten jungen Männer in ihrer prekären Lebenssituation fühlen, wie sie das Leben in Deutschland wahrnehmen und wie wir sie bestmöglich fördern und integrieren können. Mit dem von ihr geprägten Begriff der kultur-identischen Bürgschaft schafft Drewitz schließlich sehr kongenial zu Bennetts Developmental Model of Intercultural Sensitivity eine Theorie-Praxis-Verknüpfung. Sie schlägt vor, einem jungen Flüchtling einen Bürgen an die Seite zu stellen, der zwischen den Welten der einen und anderen Kultur vermittelt und die Rolle eines Coachs oder Scouts in verschiedensten Lebenslagen einnimmt. Ein, wie ich finde, vielversprechender Ansatz! Und nun wünsche ich Ihnen, liebe Leserinnen und Leser, viel Spaß bei der Lektüre! Prof. Dr. Petra Buchwald Düsseldorf, den 30.7.2021