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  • Author: Renata Dwornicka x
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Abstract

The subject of the presented work was the analysis of the influence of the distance between the electrodes using in the coating process on the tribological properties of oxide coatings. Oxide coatings were prepared on EN AW-5251 aluminum alloy samples. The samples surfaces were subjected to hard anodizing process in a multicomponent electrolyte based on sulfuric acid with an addition of organic acids. Anodizing was carried out with a constant electric charge density of 180 A·min/dm2. The distances between the electrodes for subsequent samples increased every 0.125 m up to 1 m. The tribological partner in a sliding couple with oxide layers was pin of PEEK/BG. Tribological tests were conducted on a T-17 tester in reciprocating motion, in technically dry friction conditions. Before and after tribological test, examination of the geometrical structure of counter-specimens’ surface was carried out using the Form Talysurf contact profilographometer, via a 3D method. The most satisfactory tribological parameters were obtained for the PEEK/BG association with the coating produced at a distance between the electrodes equal to 0.25 m.

Abstract

The design of experiment (DoE) is a methodology originated from early 1920s when Fisher’s papers created the analysis of variance and first known experimental designs: latin squares. It is focused on a construction of empirical models based on measurements obtained from specifically structured and driven experiments. Its development resulted in the constitution of four distinctive branches recognized by the industry: factorials (full or fractional), Taguchi’s robust design, Shainin’s Red-X®and a response surface methodology (RSM). On one hand, the well-known success stories of this methodology implementations promise great benefits, while on other hand, the mathematical complexity of mathematical and statistical assumptions very often lead to improper use and wrong inferences. The possible solution to avoid such mistakes is the expert system supporting the design of experiments and subsequently the analysis of obtained data. The authors propose the outline of such system and provides the general analysis of the ontology and related inference rules.

Abstract

The analysis of product quality is an indispensable action in developing enterprises. In case of mechanical products, the non-destructive tests (NDT) are effective way to make control. Non-destructive tests allow making assessing product quality without destroying it. Due to the dynamically growing requirements of customers and necessary, the improvement actions for demanding organizations important is to make a complex analysis of quality products. Such an action was proposed to a production and service company located in Podkarpacie region of Poland. The aim was to analyze the quality of the mechanical lever and improvement the process of non-destructive tests, in order to identify the source of nonconformity with using quality management techniques. These activities were to demonstrate that the sequence (NDT and selected quality management techniques) would allow the detection of unconformities on the product surface and also identify the source of this unconformity. In the enterprise, the quality research of the product using fluorescent and magnetic-powder methods was made. After identified the unconformity on the product the additional actions which could point the source of unconformity were not practicing. The proposition of improvement in the NTD was use appropriately selected quality management techniques (Ishikawa diagram and 5Why method) after identified the unconformity. The mechanical lever was tested, which its surface using the magnetic-powder method was analyzed. After identified unconformity (scratch) using the Ishikawa diagram, the potential causes were identified and four main causes were selected (i.e.: uncleaned pattern, impurities during production, poor molding mass, poorly carried out product production method). It has been shown that sequence of NDT, Ishikawa diagram and 5Why method allows to identify the unconformity on product surface and source its creation. This sequence could be practicing to analyze other product in production and services enterprises.

Abstract

Shainin's component search procedure uses variability source detection based on specific median test. This approach has only two triple subsets and the certainty of inference can be weak for this reason. This paper checks this approach by series of numerical simulations.

Abstract

Faced with ever-increasing customer demands and global competition, companies are forced to look for production reserves, increase efficiency and productivity. Hence, the need to monitor the use of the machine park has arisen, making it possible to identify waste and production reserves in the implemented technological processes. The aim of the article is to evaluate the effectiveness of the production line of internal frame doors and to analyze the correctness of the use of selected key indicators of the production process effectiveness. This article proposes a response to the problems formulated in manufacturing companies, including practical aspects of the use of specific measures to assess the effectiveness of the use of technical infrastructure. The solutions presented in the article can be used in practice for improvements in production units.

Abstract

The bootstrap method is a well-known method to gather a full probability distribution from the dataset of a small sample. The simple bootstrap i.e. resampling from the raw dataset often leads to a significant irregularities in a shape of resulting empirical distribution due to the discontinuity of a support. The remedy for these irregularities is the smoothed bootstrap: a small random shift of source points before each resampling. This shift is controlled by specifically selected distributions. The key issue is such parameter settings of these distributions to achieve the desired characteristics of the empirical distribution. This paper describes an example of this procedure.

Abstract

The paper considers the use of the bootstrap method to improve the determination of confidence intervals identified by the DOE (design of experiment) procedure. Two different approaches have been used: one that is appropriate for factorial designs and the other one relevant to the methodology of the response surface. Both approaches were tested on the real experiment datasets and compared with the results obtained from the classical statistical expressions based on well-known asymptotic formulas derived from the t distribution.

Abstract

The article summarizes research on a method used to improve tribological properties. The paper presents possibilities of using laser surface modification by means of EDM. The performed research confirmed that the concentrated laser beam stream can effectively modify the state of the ESD coating layer, WC-Cu and improve their usability. The work aims to assess the properties of coatings after laser treatment, based on the observation of the newly created structure of the material, the measurement of adhesion and microhardness measurement.