Applied Mechanics and Materials Vol. 657

Abstract: In the practice of organizations, we notice the existence of a problem which influences negatively the operating parameters of a product and it has to be very accurately identified and proposals have to be drawn-up in order to remove it. This paper presents a method for assessing the quality of welding by applying one of the classic instruments of quality management. The clauses that generate welding defects are identified and classified. The causes are also grouped in two large categories: positive causes and negative causes depending on the effect they have on the studied problem. An Ishikawa diagram with a new formula 4M+4RM was proposed, to separate the positive causes from the negative ones. The importance of this method is also mentioned in the analysis of quality products.

Abstract: This paper presents a comparative study on the corrosion behaviour of the Al depositions, obtained by thermal spraying in electric arc - the classic method (ASP) and the Al deposits behaviour, carried out with a thermal spray combined device (CTSD). The use of CTSD allows the thermal field modification of the spraying jet and implicitly the modifying the mechanical, physical and chemical properties of the deposits of aluminium. Evaluation of the corrosion behaviour of the aluminium deposits was achieved by exposure to salt water - sea water (3.5NaCl). The corrosion products, formed on the surface of the coatings, were investigated based on the photographic records, electronic microscopy – SEM and X-ray diffraction. The aluminium oxide, obtained on the depositions, carried out by using CTSD - exposed in saline environment is more adherent then the oxide obtained on the deposits, carried out through ASP - which leads to a loss in thickness.

Abstract: The Paper Presents the Measurement Systems Analysis, System Capability and Optimization of a Laser Cutting System for 3 Mm Alloy Steel. for the Measurement System Analysis and System Capability the Data was Introduced in a Excel Sheet which was Designed According to QS9000 Standard (Measurement System Analysis) to Calculate the Measuring System Repeatability, Reproducibility and Capability. Design of Experiment (DOE) was Used for Process Optimization the Optimization was Conducted in an Operational Manufacturing Environment and was Based on the Design of a 2⁵ Full Factorial Experiment. the Laser Parameters (input) were Feed Rate v, Gas Pressure p, Power P, Frequency F and Efficiency R while the Response was the Roughness R_z. it was Analyzed the Influence of Laser Parameters on Roughness to Obtain a Complex Relationship to Show Roughness R_z Variation According to these Parameters, to Minimize the R_z and Maximize the Feed Rate.

Abstract: The paper aims to determine, through experiments, the necessary force for detaching the deposited layer (SD) from the support layer (SB). The thermal sprayed coating was formed by successive deposition of two sub-layers, one for anchorage and the second for corrosion resistance. Shear adhesion strength tests were performed on a specialized stand, while force (F_ad) and displacement (x) values were recorded with a data acquisition system. The variation curves, F_ad = f (x), outline the evolution of the detachment process of the sprayed layer and the two main components of the deformation process: slip and breakage.

Abstract: The use of laser engraving equipment for marking on certain products the expiry date, the bar code as well as customizing them, represents an efficient and non-polluting method. This method is very challenging from the technological point of view and with a lot of process variables that demand research. The current paper tackles the quality of the laser engraved glass in CO₂ environment, as a function of the following parameters: the lasers power and the lasers pulse length. Based on the experimental results a quality system is being proposed which relies on the visual examination of the craters, of the top area of the crater and the quantity of excess material surrounding them. The research method used in the current paper is the experiment and the comparative analysis of the experimental results.

Abstract: It is known that the unevenness of the cutting depths during the cutting processes, the different physico-mechanical characteristics of the processed materials, values as well as the parameters variation of the working regimes can lead a wear more or less pronounced of the used cutting tools. The lubricant presence in the cutting area may contribute to the friction and thermal field values reduction, affecting the wear processes. It can be said therefore that, the tools durability is influenced by all these factors, which requires decisions and actions to reduce the tools or/and the cutting inserts wear processes. In case of the cutting inserts are known many researches concerning their coverage with material (ions) by vacuum deposition, using methods as: electric arc evaporation, pulverization, ionic plating and chemical vapor deposition. Researches carried out by authors had consisted in making titanium deposition, in thin layer, on the cutting inserts surface in their hardening purpose. The results obtained consisted in a substantial increase of the durability for the used tools in cutting processes in report to those, whose cutting inserts were coated with titanium.

Abstract: The hardness of the coated surfaces by nickel-iron electroplating process is closely linked to the characteristics of deposited layer. These characteristics depend on various process variables, such as current density, temperature, pH and stirring. This work presents the modelling and the optimization of nickel-iron electroplating process variables to maximize the surface hardness. To study the combined effect of current density J (A/dm²), temperature T (°C) and pH were used a 2³ orthogonal central composite experimental design for experiments design and Response Surface Methodology for analysis of experimental results. The modelling was performed using the following intervals for process variables: 1.75 - 3.51 A/dm² for current density, 25-35 °C for temperature and 2.5-3.5 for pH. The empirical model was further used in the optimization process using the Gradient method. The optimum values of these electroplating process variables were found to be J = 2.23 A/dm², T = 30.80°C and pH = 2.81; in this point the surface hardness is 136.89 HV given by empirical model and 137.52 confirmed experimentally.

Abstract: There are various electrical discharge machining techniques and experimental researches could be necessary in order to establish the operating conditions for an optimal machining process. Some theoretical considerations concerning the process of generating the surface asperities as a consequence of the electrical discharge machining process were elaborated. Experimental method was applied in order to evaluate influence exerted by some input factors (pulse on time, pulse off time, average intensity of electric current) on certain surface roughness parameters (Ra, Rz, Ry and Rq). One developed an experimental research by using a copper tool electrode and a workpiece made of high speed steel, in accordance with the requirements specific to a complete factorial experiment with three independent variables at three levels. A ram electrical discharge machine was used as machining equipment. One measured the surface roughness parameters specific to the machined surfaces. Empirical mathematical models of type power functions were established by using the method of least squares.

Abstract: This paper presents an experimental study carried out on the properties of Ti depositions, obtained through thermal spraying in electric arc - thermally activated. The spraying process is a combination between the classical process of thermal spraying and the spraying process in flame. Finite elements analysis of the thermal spraying process in electric arc, allowed the estimated determination of the temperature variations of the jet drive, of the amount of gaseous fuel and also of the optimum spraying distance. The investigations, carried out through the performing electron microscopy analyses (SEM), X-ray diffraction, by determining the porosity and the adhesion of the Ti deposition, allowed the highlight fact that through an optimum choosing of the entrainment jet temperature, are producing dense Ti deposits, characterized by high adhesion (16%). In addition, the deposit porosity -required for integration of the biocompatible materials, can be controlled by the optimal choosing of the spray distance.

Abstract: In the case of the MAG welding of carbon and low-alloyed steels wires or hollow wires with (rutilic or basic) flux with metallic powder or self-protection are used. In indoors weldings huge quantities of smoke, gases, dust and particles in suspension, etc. get accumulated. These noxious substances produced during the welding process may severely affect the welders health. To improve the welders working conditions, on an international scale, the following are used: welding masks with self-obscurazation and air control; noxious substances vacuum cleaners fitted with filters; MAG welding pistols with gase and smoke absorbing devices. For the improvement of the welders working conditions, producers of welding materials invented hollow wires with (rutilic flux or with metallic powder) with a smoke-reduced emission [1,2,3,4,5].