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Recent 45

Vol. 16 (2015), No. 2 (45), July 2015

 

This issue of the RECENT® journal was edited with the support of:


CONTENTS



  • Mirela AGAPIE, Béla VARGA

Structural Non-Homogeneities Analysis of Zn-22 Wt. % Al Alloy by Nano-indentation

» Abstract

In the present paper the structure and properties of different phases/constituent of the eutectoid Zn-Al based alloys obtained by gravitational casting in brick moulds have been investigated. The microstructural analyses were performed by scanning electron microscopy which was followed by energy dispersive X-ray spectroscopy analysis. Nano-indentation testing has been used to determine the phase/constituents mechanical properties like elastic modulus and hardness for a 22 wt. % Al alloy composition. The structural analysis and the nano-indentation results have revealed the intensity of the segregation phenomena during alloy solidification at smaller cooling rates.

» Keywords

Zn-Al, alloys, microstructure, nano-indentation, elastic modulus, hardness indentation

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  • Romeo CIOARĂ

Correlated Determination of Mechanical Press Functional Parameters

» Abstract

Each mechanical press, as any press in general, has a number of characteristics, which are geometrical, kinematical and energy related. The kinematical and energy related ones are functional characteristics, the defining ones including the nominal force, maximum length of the slide stroke, nominal length of the load stroke, frequency of the main motion, maximum available work, maximum power, maximum admitted torque at the main shaft and machine stiffness. The optimum design of any press requires the adequate and correlated determination of its functional parameters. More so, for families of presses of similar types the values of each functional parameter need ordering, thus allowing the conceiving and efficient deployment of machinery of the considered type. The paper specifies for each functional characteristic the modality of determination and ordering, underpinned by the adequate mathematical rationale.

» Keywords

mechanical press, characteristics, parameters, ordering, correlated values, series of values

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  • Radu Francisc COTERLICI, Virgil GEAMĂN

Evaluation of Mechanical Properties of Friendly Cotton / Nestrapol 455-60 Composites after Saline Environmental Condition

» Abstract

In this research paper a comparison between mechanical characteristics of two friendly composites with three and five layers after immersion were evaluated. Five specimens for each composite were immersed in 5% NaCl aqueous solution for 90 days at room temperature. Three point bending test show that the saline environmental conditions concern the mechanical characteristics between composites and with the increasing number of layers increases and properties.

» Keywords

natural fibers, polymers, friendly composites, water absorption, mechanical characteristics

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  • Adela-Eliza DUMITRASCU

Assessment of Environmental Aspects for Manufacturing Processes

» Abstract

In this paper are presented the aspects regarding the implementation of environmental management system in accordance with ISO 14001:2005, and the method of evaluation of environmental aspects. The case study refers to the identification and evaluation of environmental aspects of manufacturing processes. Researches results indicate that after establishing and implementing the corrective and preventive actions, all environmental issues have insignificant environmental impact, demonstrating an improvement of environmental performance.

» Keywords

assessment, environmental aspects, significant impact, manufacturing process, ISO 14001

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  • Stoyna ELKINA, Nikolay KAZAKOV, George CHERVENDINEV

A Ergonomically Research for Forklift

» Abstract

This paper provides analytical research and overviews the forklifting in fulfilling loading tasks for different time load during logistics machine maintenance. The point is to show to collect, process and analyze the results of the questionnaire made. Summary information and analyze results will allow to refine the operating conditions of the forklift drivers to provide a basis for new ergonomic requirements and to monitor the working environment again after the introduction of changes.

» Keywords

logistics, ergonomic, analyze, loading, forklift, logistics equipment

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  • Boriana ILIEVA, Georgi KIUCHUKOV

Procedures and Documents from the Laboratory for Testing of Products to Obtain the Certificate of Participation of the Single European Market

» Abstract

Standardization is a prerequisite for creating an optimal order in the economy and social life of each country. It is an integral part of science, as any science to manufacture certain products is based on standardized terminology, technical safety requirements and test methods for assessing the conformity of the quality characteristics of the products. Without standardization it cannot be achieved advanced technical guidance on the production and marketing of products.

» Keywords

procedures, laboratory for testing, standardization

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  • Alexi NICOLOV

Experimental Evaluation of Competitiveness of Logistics Equipment

» Abstract

This study presents an examination of an experimental evaluation of the competitiveness of a typical representative of logistics equipment – forklifts with internal combustion engines (ICE forklifts), including assessing the competitiveness of a particular brand of forklifts, applying the emotional method.

» Keywords

competitiveness, experimental evaluation, logistics equipment, forklift, emotional method

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  • Alexandru PASCU, Ionuţ Claudiu ROATĂ, Elena Manuela STANCIU

Laser Cladding of Metco 68F-NS-1 Cobalt Based Powder

» Abstract

This paper addresses to the laser cladding of cobalt base powder on AISI 5140 chromium steel. Experimental investigations are made to determine the influence of the scanning speed on the geometrical feature of the laser cladded tracks. An 1kW diode laser made by Coherent and a Precitec YC50 cladding head manipulated by an seven axes CLOOS robot were used for the achievement of coatings. Macroscopic and microscopic analyses of the laser cladded tracks are discussed in the article. Coarse dendrite structure and hard laves phases enclosed in a cobalt matrix characterise the microstructure of the coatings. It was determined that cladding speed has a direct influence on the clad high and melt depth.

» Keywords

laser cladding, cobalt powder, scanning speed

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  • Hristo K. RADEV, Vassil J. BOGEV, Velizar A. VASSILEV

Determination of Errant Run-Out of the Axis of Rotation of Objects, Performing Accurate Rotational Movements

» Abstract

This article discusses problems of the accuracy of the axes position of objects accomplishing rotary motion. Different schemes to estimate the errant run-out of the axes and faces of object tables are proposed, as well as their capabilities are estimated.

» Keywords

rotary motion, radial and axial run-out, errant radial and axial run-out

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  • Ionuţ Claudiu ROATĂ, Elena Manuela STANCIU, Alexandru PASCU

Microstructure Evaluation of Stainless Steel Welds

» Abstract

This study aims to determine the optimal parameters for cold metal transfer MAG welding of stainless steel. Starting from this perspective, the filler material of ER 316LSi full wire type and a MAG CMT - Pulse regime of welding with a low linear energy were used. Welded joints characterization was acquired by performing macro - microscopic analyses, mechanical tests (microhardness) with the purpose of lowering the thermo - mechanically affected zone. The results focus on the significant influence of the welding parameters over the weld bead geometry. The results shows that by using a proper welding speed is possible to reduce the microhardness of the weld bead and to obtain a high quality welded joint.

» Keywords

stainless steel, cold metal transfer, filler material (ER 316LSi), microhardness

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  • Simeon SAVOV, Petko NEDYALKOV

Mathematical Modeling and Research of Purpose Function for Relative Power Consumption per Unit Product in KID-300 Operation

» Abstract

This paper presents the creation of mathematical model of purpose function for relative power consumption per unit product at operation with cone inertial crusher type KID-300. There are presented the choice of governing factors affecting on the purpose function for relative power consumption and formulation of purpose function for relative power consumption. There are experiment and statistical analysis of the experimental results. Results from statistical analysis of relative power consumption purpose function are presented and analyzed with regression models and 3D diagrams for determination of the influence of governing factors. The results will be used for a future work of functional crushing process optimization and multiple factors optimization of the working process in terms of relative power consumption per unit product in cone inertial crushers.

» Keywords

KID-300, mathematical modelling, statistical analysis, purpose function, relative power consumption

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  • Elena Manuela STANCIU, Alexandru PASCU, Ionuț Claudiu ROATĂ

Laser Welding of Austenitic Stainless Steel Thin Sheets

» Abstract

This paper presents investigations regarding the laser welding of austenitic stainless steel. Several laser welding tests were made using AISI 304 stainless steel in a butt joint configurations. An 3.3 kW Rofin laser and a Rofin welding head manipulated by an ABB six axes robot were used for the achievement of the welding tests. Different laser power, welding speed and spot diameter were used to define the influence of the process parameters to the weld bead geometry. Full penetration was obtained on all welded samples. It was determined that penetration depth is directly influenced by the laser power and the weld bead width depends mainly by the welding speed. Macro and microstructure of the welds are discussed in the article. The optimal parameters interval for welding stainless steel thin sheets was defined to be between 230 and 280 kW/cm2.

» Keywords

laser welding, stainless steel, AISI 304, power density

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  • Milka VICHEVA

Integration of Management Systems through the New Framework of ISO

» Abstract

Systems for quality management, environmental management and health and safety at work management are analyzed in order to investigate the process of their integration. The advantages of an integrated management system and the main obstacles to its implementation are determined. The main provisions of the new framework of standards of management systems according to Annex SL are discussed. Elements that are added to the new structure of standards management systems, and the benefits to organizations of their implementation are analyzed. Particular attention is paid to the introduction of risk assessment. Implementation of the new structure standards of management systems will provide greater flexibility in the integration process and will avoid the existing obstacles and difficulties in the development and implementation of integrated management system.

» Keywords

management systems, integrated management systems, ISO annex SL, structure of standards for management systems

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