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Otakar Bokůvka, Michal Jambor, Libor Trško, František Nový and Barbara Lisiecka

,9, 715. M iková , K. et al . 2013. Int. J. of Fatigue, 55, 33. S kočovský , P. et al . 2014. Náuka o materiáli. EDIS ŽU v Žiline. (in Slovak). T rško , L. et al . 2014. Dynamic Stength and Fatigue Lifetime, EDIS ŽU v Žiline. T rško , L. et al . 2014. Materials & Design, 57, 103. T rško , L. et al . 2017. J. of Mat. Eng. and Performance, 26, 6, 2784. U lewicz , R. M azur , M. Production Engineering Archives, No.1, 32.

Open access

J. Jersák and S. Simon

Abstract

The Technical University of Liberec and Brandenburg University of Technology Cottbus-Senftenberg investigated the influence of cooling lubricants on the surface roughness and energy efficiency of cutting machine tools. After summarizing the achieved experimental results, the authors conclude that cooling lubricants extensively influence the cutting temperature, cutting forces and energy consumption. Also, it is recognizable that cooling lubricants affect the cutting tools lifetime and the workpiece surface quality as well. Furthermore, costs of these cooling lubricants and the related environmental burden need to be considered. A current trend is to reduce the amount of lubricants that are used, e.g., when the Minimum Quantity Lubrication (MQL) technique is applied. The lubricant or process liquid is thereby transported by the compressed air in the form of an aerosol to the contact area between the tool and workpiece. The cutting process was monitored during testing by the three following techniques: lubricant-free cutting, cutting with the use of a lubricant with the MQL technique, and only utilizing finish-turning and finish-face milling. The research allowed the authors to monitor the cutting power and mark the achieved surface quality in relation to the electrical power consumption of the cutting machine. In conclusions, the coherence between energy efficiency of the cutting machine and the workpiece surface quality regarding the used cooling lubricant is described.

Open access

B. Srivathsa and D.K. Das

.G. and Hutchinson J.W. (2000): The ratcheting of compressed thermally grown oxide on ductile substrate. – Acta Mat., vol.48, pp.2593-2601. Helminiak M.A. (1998): Factors effecting the lifetime of thermal barrier coatings. – Mech. of Mat., vol.26, pp.91-110. Hsueh C.H. and Fuller E.R. (2000): Analytical modeling of oxide thickness effects on residual stresses in thermal barrier coatings. – Scripta Materialia, vol.42, pp.781–787. Hutchinson J.W. (2001): Delamination of compressed multilayers on curved Substrates. – J. Mech. Phys. Solids, vol.49

Open access

Koudelka Libor

Abstract

In the first quarter of the last century hydraulic power plants were equipped with high-speed Francis turbines even in the situation when a contemporary project manager would suggest Kaplan turbine. The reason is simple. Mr. Kaplan patented his turbine only in 1912 [1], https://en.wikipedia.org/wiki/Viktor_Kaplan . Those high-speed Francis turbines have just reached their lifetime. Mainly runners need repair. Our customers’ respond is that even renowned firms refuse to deliver runners with better parameters. Offer is to replace whole turbine with Kaplan or to make a copy of the existing runner. This paper presents experience and results of such a high-speed runner design. The runner substituted the one of Prokopa & sons from 1939 in powerhouse and mill at Křemže stream. Virtual prototyping technique has been used.

Open access

Peter Šlesar and Roland Jančo

- Strojnícky časopis 2017 (67), No. 2, pp. 77 - 84. [7] F. Trebuňa, F. Šimčák, Elasticity, strength and plasticity in mechanical engineering. Edition of scientific and special publications - Faculty of Mech. Eng. TU in Kosice, Emilena, Košice 2005. ISBN 80-8073-276-0. [8] F. Trebuňa, F. Šimčák, J. Bocko, and M. Pástor, Analysis of the Causes of Casting Pedestal Failures and the Measures for Increasing Their Residual Lifetime, Engineering Failure Analysis 2013 (29), 27 - 37.

Open access

Miroslav Pástor, Peter Frankovský, Martin Hagara and Pavol Lengvarský

REFERENCES [1] F. Trebuňa, F. Šimčák. Stability of the Mechanical System Elements (in Slovak), Košice, 2004 [2] F. Trebuňa, F. Šimčák, J. Bocko, M. Pástor. Analysis of the Causes of Casting Pedestal Failures and the Measures for Increasing Their Residual Lifetime. Engineering Failure Analysis 2013 (29), 27 – 37. [3] F. Trebuňa, et al. Final Report on the Examination of the Anchor Threaded Joints of the ZPO 2 Casting Pedestal (in Slovak). Košice 2014 . [4] Y. Nashwan. Experimental Strain Investigation of Bolt Torque Effect in

Open access

Miroslav Pástor, Peter Čarák and Imrich Gömöry

Causes of Casting Pedestal Failures and the Measures for Increasing Their Residual Lifetime”, Engineering Failure Analysis 29, pp. 27 – 37, 2013 . [12] Trebuňa, F., Šimčák, F., Pástor, M., Šarga, P. “Residual stress analysis in containers for transport of radioactive materials”, Applied Mechanics and Materials 732, pp. 28 – 31, 2015 . DOI: 10.4028/ www.scientific.net/AMM.732.28 [13] Hagara, M., Trebuňa, F., Pástor, M., Huňady, R., Lengvarský, P. “Analysis of the aspects of residual stresses quantification performed by 3D DIC combined with standardized

Open access

Valentin Gornoava, Gheorghe Ion Gheorghe and Liliana-Laura Badita

Abstract

The main objectives of the present project are to study and to improve mechanical properties of different systems from mechatronic and biomedical domains, in order to increase their functionality and life span. This is why nanostructured thin films (e.g. Al, Cr, Ti, Ti/Al multilayers) were deposited on different steel substrates, used in mechatronic and biomedical applications. By the characterization of coated surfaces of the products used in various fields such as medicine, mechatronics, electronics, etc. depends their proper operation, durability and reliability. This is the main reason why, we studied new types of layers and multilayers using Atomic Force Microscopy and scratch tests. The main result of the realized tests is that all studied nanostructured thin films offer the possibility of increasing the lifetime of substrates, being an important factor for proper functional operation, durability and reliability of the final systems in which they are used.

Open access

Liliana-Laura Badita, Gheorghe Gheorghe, Vasile Bratu, Valentin Gornoava, Marian Vocurek, Aurel Zapciu and Iulian Sorin Munteanu

Abstract

Taking into account the importance of mechatronic applications, researches regarding the possibility to improve the lifetime of mechatronic components were made. Nanostructured metallic thin films (Ti, Cr, Al and Ti/Al multilayer) were deposited on different types of steel substrates, because nanomaterials have exceptional properties in relation to the common materials. In this paper a part of the results obtained after mechanical and topographic characterization of the thin films are presented. Cr is the deposited thin film showing the highest hardness on the surface of steel substrate type OSC. After the scratch tests realized, Ti layer presented the best adhesion on all types of steel substrates used in experiments. The results of these researches could be extremely useful for engineers in the mechatronic field.

Open access

Dan-Maniu Duşe and Cătălin Nemeş

References Duşe, C. S., Duşe, D., Nemeş, C., (2010), Leadership in Classical Universities: between an Entrepreneurial and Virtual World, 6th European Conference on Management, Leadership and Governance, Wroclaw, Polonia Maxwell, J. (2008) Leadership Gold. Lessons I`ve learned from a lifetime of leading., Gardners Books Rendell, M. (2007) Managing tomorrow’s people.The future of work to 2020, PricewaterhouseCoopers LLP. Senge, P. (2006) The fifth Discipline, Second edition, Copyrightmaterial