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Vol. 21 (2020), No. 1 (60), 2020

 

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

CONTENTS



  • Oana PANAZAN, Cătălin GHEORGHE

Aspects of Risk in the Defence Industry from Romania

https://doi.org/10.31926/RECENT.2020.60.004

Abstract

Tensions in the world economy, international migration, the rapid growth of the world's population, competition for natural resources are some of the problems that have led to the growing concern of states regarding national defence. The article proposes an analysis of the risk related to the most important companies in the Romanian defence industry. For this purpose, a process was selected based on quantitative data analysis for estimating the risk of bankruptcy. The model was applied to the Romarm Group companies, as it is the main supplier of military equipment, ammunition and maintenance services in Romania.

Keywords

bankruptcy risk, model, defence industry, Romania

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  • Aurel LUNGULEASA, Cosmin SPIRCHEZ

Experiments about Roughness of Wood Composites

https://doi.org/10.31926/RECENT.2020.60.013

Abstract

The paper presents some values of roughness for the main composite wooden materials. A device Mitutoyo with diamond tip for determining the roughness was used, fixed on a vertical device taken from Kennon Instruments. The values of roughness obtained for the main analyzed wooden composites were compared with massive wood, after that they were correlated with the 14 classes of quality provided by the European standard in the field EN ISO 4287:1997. The obtained results make possible a better knowledge of the wooden composites presently used in the wooden industry, from the point of view of surface smoothness. A general rule for increasing or decreasing the roughness according to the type of composite wooden material was not noticed surely, all roughness depending on the state and surface material (finished or not, veneered or not calibrated or not).

Keywords

roughness, composites, absolute deviations, average square root, average maximum height

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  • Maria STOICANESCU

Study on Holding Time Influence on Heat Treatments Applied to Modified Cast Irons

https://doi.org/10.31926/RECENT.2020.60.019

Abstract

The purpose of this paper is studying the possibility of shortening the time of graphitization by combining two procedures, i.e. modification and malleableizing annealing. Thus, graphitization tests were performed in two stages on hypoeutectic cast iron. A quantity of modifier was introduced in the liquid cast iron at the beginning. After cooling and solidification, a graphitization process start was detected, i.e. small and compact graphite inclusions appeared on the white cast iron. Afterwards, a 900C annealing was applied, with holding times of 1-4 h. Following this treatment, there was detected an increase in the size of primary graphite separations, concomitantly with the partial development of the second stage of graphitization. Through this succession of metallurgical operations, the treatment time was reduced from several tens of hours to about 2 hours.

Keywords

cast iron, heat treatment, metallurgical operations

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  • Ahcne AKNI, Rachid CHAIB, Abdelaziz KAHLOUCHE, Ion VERZEA

Impact of Repair Costs on Company Performance: Technical-Economic Analysis between Two Locomotive Engines DL07 and DM04

https://doi.org/10.31926/RECENT.2020.60.026

Abstract

Today, the company operates in a strong competitive environment where financial concerns are very pronounced and the maintenance function is no exception to this rule of cost reduction. Moreover, it is more ethical than legislative to be satisfied with technical and economic performance without taking into account environmental constraints. As a result, globalization has pushed the Algerian industry towards a direct confrontation in terms of operating safety, profitability and competitiveness, while respecting the protection of the environment in the various branches of industry, particularly in rail transport. An important part of this upgrade is the improvement of the RAMS concept and its application at the level of the different industrial structures. The lack of reliable data and efficient data processing tools, as well as maintenance management methods, has long reduced the maintenance function to troubleshooting tasks, resulting in subsequent high costs such as business performance is not obvious. Thus, the maintenance service must be established as a key player in competitiveness to engage in a quality approach, in particular to determine the performance compatible with the possibilities of the equipment (age, operation, etc.), or even its renewal. Our work is based on a technical-economic analysis between two locomotive engines, the DL07 and the DM04, to determine its operating performance, which is subject to strict reliability, availability and safety objectives while using methods specific to field of reliability. Thus, the estimate of the residual time of operation before the failure of a piece of equipment must make it possible to avoid unnecessary maintenance expenses. This study is based on the evaluation of the number of stops of two engines during five years of operation, an analysis of the different repairs of the two engines with respect to their frequencies and their costs, ended by a comparative study between these two engines in terms of reliability indicator and repair costs.

Keywords

RAMS, maintenance cost, failure, prognosis, rail, quality and operating performance

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  • Marius Valeriu COMICI, Ioan GIACOMELLI, Maria STOICANESCU

Heat Treatments Applied to Martensitic Stainless Steels and the Results Obtained

https://doi.org/10.31926/RECENT.2020.60.034

Abstract

For this paper, various heat treatment operations were performed on 40Cr130 steel with a view to the structures obtained and some mechanical properties. Of these, the hardness and shock resistance were determined under different test conditions. Significant variations in fracture energies were found depending on both the structural state and the test temperature.

Keywords

heat treatment, martensitic stainless steels, mechanical properties

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  • Andrea DEACONESCU

Compliance Adjustment of a Gripper System Designed for the Seizing of Objects of Modifiable Consistency

https://doi.org/10.31926/RECENT.2020.60.038

Abstract

The necessity of seizing objects of unknown forms and/or consistency entails conceiving gripper systems whose design and control strategies are oriented towards the capacity of safe physical handling. The paper presents and discusses such a soft gripper system that includes a pneumatic muscle as its actuation motor. The compliance of the entire system is achieved by modifying air pressure in the pneumatic muscle within a closed loop, thus ensuring the safe gripping of deformable objects.

Keywords

pneumatic muscle, gripper system, compliance

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  • Nicoleta RACHIERU

Prints Lubrication, a Factor Influencing the Quality of the Cast Parts

https://doi.org/10.31926/RECENT.2020.60.045

Abstract

In today's market economy, where customer demand is increasingly diversified and where value for money is a basic consideration, companies are continuously adapting, increasing their performance and focusing on the use of modern and improved technological processes and equipment to increase profits and reduce losses. To be ideal, the parts produced must meet the requirements imposed by their specific use, according to regulations and dimensional tolerances and in accordance with agreements with the customer. This article deals with aspects of aluminium die-casting, its importance for the technological casting process, the lubrication of the casting mould prints, and the problems that can appear, in terms of casting quality, due to improper pulverization. In a case study carried out on a part of a vehicle component, respectively the Oil bath, a constructive improvement of the Nozzle head is proposed. This improvement led to a reduction in the number of damaged pressure casting parts.

Keywords

die-casting, aluminium, mould fingerprint, spray head, lubrication

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