Miroslav Gombár

Statistical Analysis of the Factors Effect on the Zinc Coating Thickness

In order to improve the corrosion resistance of the material EN 355 the thickness of the zinc coating, deposited during the acid zinc plating process at a constant current density 1 A·dm-2, was monitored. The thickness of deposited coating has been investigated as the relationship of physical and chemical factors acting during the galvanic zinc plating, i.e. the electrolyte temperature, electrolyte composition (the amount of zinc, the amount of chloride and boric acid in the electrolyte), the plating time and the size of the voltage. Based on the mathematical-statistical analysis of the obtained data the suitable predicting model was developed for determining the thickness of deposited zinc coating reflecting the technological conditions of the acid zinc plating process.

The Influence of Sodium Chloride on the Resulting AAO Film Thickness

The contribution examines the effects of the electrolyte chemical composition on the resulting AAO layer thickness, which is one of the main indicators of corrosion protection of aluminium parts and which also favourably affects mechanical properties of component surfaces. For comparison purposes, there were selected the electrolytes comprising sulphuric acid, oxalic acid, boric acid and sodium chloride. Anodizing time for all specimens was 210.00 minutes. At the same time, equal electrolyte temperature 22.00°C ± 13.64% as well as equal magnitude of the applied voltage 12.00 V ± 4.17% were determined for all specimens. The results obtained lead to the assumption that it is possible to replace conventional electrolytes by those that are more environmentally friendly, reduce the costs of their disposal and allow obtaining oxide layers of the same thickness. The admixture of sodium chloride plays here the crucial role and its effect on the thickness of the formed oxide layer has not been published yet in any study.

Usage of Neural Network to Predict Aluminium Oxide Layer Thickness

This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A·dm−2 and 3 A·dm−2 for creating aluminium oxide layer.

Experimental Study and Modeling of the Zinc Coating Thickness

The effects of six factors, affecting during the acid zinc plating process as its technological conditions, on the thickness of the resulting zinc coating has been examined. In order to control the quality of the resulting zinc coating deposited on the surface alloy EN 355 at a constant current density of 5 [Adm-2], the mathematical model predicting the thickness of deposited coating was developed using Design of Experiments (DoE) method. The obtained mathematical model describes the resulting deposited layer of zinc coating in dependence on the factor-level changes and combinations with the reliability of 58.75%.

Non-linear modelling and evaluation of pressure and traverse rate influence to acoustic sound pressure level at abrasive waterjet machining

This paper deals with experiments, research and evaluation of the influence of pressure and traverse rate to acoustic sound pressure level at Abrasive Waterjet (AWJ) machining of 15 and 20 mm thick stainless steel. Significance of selected AWJ factors independent variables (traverse rate, pressure) that influence the acoustic sound pressure level was evaluated by analysis of variance. Further, the manufacturing system with AWJ machining and the cutting process was evaluated. The regression equation obtained from analyses of variance gives the level of acoustic sound pressure significance Laeq as a function of the treatment factors. Different factor significance has been found, that was generated under defined conditions by AWJ. Results show the AWJ machining factors significance and their effect to noise environment at AWJ machining of stainless steel.

Effect of the Electrolyte Temperature and the Current Density on a Layer Microhardness Generated by the Anodic Aluminium Oxidation

The paper investigates the influence of the chemical composition and temperature of electrolyte, the oxidation time, voltage, and the current density on Vickers microhardness of aluminium oxide layers, at the same time. The layers were generated in the electrolytes with different concentrations of sulphuric and oxalic acids and surface current densities 1 A·dm−2, 3 A·dm−2, and 5 A·dm−2. The electrolyte temperature varied from −1.78°C to 45.78°C. The results have showed that while increasing the electrolyte temperature at the current density of 1 A·dm−2, the increase in the layer microhardness values is approximately by 66%. While simultaneously increasing the molar concentration of H2SO4 in the electrolyte, the growth rate of the microhardness value decreases. At the current density of 3 A·dm−2, by increasing the electrolyte temperature, a reduction in the microhardness of the generated layer occurs with the anodic oxidation time less than 25 min. The electrolyte temperature is not significant with the changing values of the layer microhardness at voltages less than 10.5 V.

Mathematical Modelling and Optimization of Technological Process Using Design of Experiments Methodology

The paper deals with statistical methods application to the evaluation of the relationships between the investigation range of input factors and response in longitudinal turning process. Our research was aimed at creation of the model of real situations of cutting conditions effects on the machined surface morphology applying longitudinal turning of steel C45 with specific values. Design of experiments (DoE) have increasingly had a wider application when creation mathematical and statistical models of technological processes. So the main part of the paper is to demonstrate the procedure of statistical processing of experimentally obtained data in order to create a prediction model and compare it with the theoretical calculation formulas.

Analysis of abrasive waterjet factors influencing the cast aluminium surface roughness

This paper deals with experimental research and evaluation of abrasive waterjet cutting technology process by evaluation of technology factors, which influence the microgeometry (average roughness) of 10 mm thick aluminium tooled workpiece surface through design of experiments. Significance of six chosen process factors ? independent variables (traverse rate, abrasive mass flow rate, pressure, J/T abbreviation and feeding direction) that influence on the surface quality - has been evaluated by full factorial design with six factors at two levels. The surface quality has been evaluated by static quality characteristic average roughness Ra. The multiple non-linear regression equation obtained from ANOVA gives the level quality Ra as a function of the treatment factors. Different factor significance was found, which generated surface profile under defined conditions by abrasive waterjet.

Monitoring of influence of significant parameters during anodizing of aluminium

The paper deals with the possibilities of control the technological process of aluminium anodic oxidation using the Design of Experiments (DoE) and the higher order neural unit to monitor the influence of the significant parameters on the resulting AAO (anodic aluminium oxide) film thickness. It also compares the relationship between individual inputs factors and their mutual interactions on the AAO thickness at monitored current density of 1.00 A·dm-2 and 6.00 A·dm-2. The developed predicted model describes the influence of input factors on the final AAO thickness by cubic function and its reliability is 99.37 % at current density of 1 A·dm-2 and 99.47% at current density of 6 A·dm-2. The electrolyte temperature and the size of an applied voltage had the most important influence.

Logistics risk identification of new and renovated production machines

The paper deals with logistics risk management safety program of new and renovated machines, which as members of the management of company must deal with. There are accountable consequences of untreated risks that may stop a dangerous event. In this case, damage can be life or health of users or it can create damage to their property i.e. that may end up as damage of the machine. Contribution from own perspective is focused on: defining the basic concepts of base solution, logistics system methodology management of technical risks and logistic system analysis of the machinery.