This paper presents the forecasting of the wear of working elements in an abrasive soil mass using the theoretical wear model. One of the widely used models providing a basis for the relationships describing wear is the Holm-Archard model. This relationship describes abrasive wear because of the contact between two bodies. The model assumes that the wear of an operating part is directly proportional to the sliding force and distance and inversely proportional to the hardness of the material of the part. To date, the model has not been verified in the wear of a soil mass, which is a discrete friction surface. Four grades of steel resistant to abrasive wear, intended for the manufacturing of operating parts exposed to wear within a soil mass, Hardox 500, XAR 600, TBL Plus and B27, were subjected to testing. TBL Plus steel was characterised by the smallest wear irrespective of the soil type. In turn, the highest values of the wear were noted in the light soil for Hardox 500, in the medium soil for XAR 600, while in the heavy soil for B27. Based on the obtained results, a high correlation coefficient was noted, with the highest values obtained for light and heavy soils.

Original scientific paper Today, most contemporary organisations are facing many dilemmas, the essence of which is the determination of the ways of acquisition or maintenance of their position in the competitive environment. Companies have to continuously increase their economy. One of the ways to get competitive prevalence is analysis and optimization of material flow which contributes to the reduction of the company costs. Material flow in a production organization tells us a lot about how well the system is organised. The paper presents an analysis of the current state of material flow in a production company of the automotive branch. A project of the material flow optimization has also been proposed; the project consists of creation of a program of internal transport and optimization of the location of the working stands. The paper describes the current problems of the company internal transport and indicates solutions to those problems. Keywords: automotive industry; company logistics; material flow analysis; optimization; program of internal transport Optimizacija toka materijala -analiza slučaja u industriji motornih vozilaIzvorni znanstveni članak Danas je većina organizacija suočena s mnogim dilemama, bit kojih je određivanje načina postizanja ili održavanja stečenog položaja u konkurentnom okruženju. Poduzeća moraju neprestano povećavati svoju ekonomiju. Jedan od načina stjecanja nadmoći nad konkurencijom je analiza i optimizacija toka materijala, što doprinosi smanjenju troškova. Tok materijala u proizvodnoj organizaciji govori nam mnogo o organizaciji sustava. U radu se daje analiza postojećeg stanja toka materijala u jednoj proizvodnoj organizaciji motornih vozila. Predlaže se i projekt optimizacije toka materijala; projekt se sastoji od novog programa internog prijevoza i optimizacije položaja radnih štandova. U radu se opisuju postojeći problemi u internom prijevozu poduzeća i daju rješenja tih problema.

MikołAjczAk P, NAPiórkowski j. Analysing the reliability of working parts operating in abrasive soil pulp taking into consideration confounding factors. Eksploatacja i Niezawodnosc -Maintenance and reliability 2016; 18 (4): 544-551, http://dx

The paper presents the results of abrasive wear resistance tests on Creusabro 4800 and Creusabro 8000 steel. The results obtained for laboratory samples were referred to the structure of the examined types of steel and to the basic indicators characterising their mechanical properties. As a result of the conducted tests, which used the methods of light and scanning microscopy, it has been concluded that, in its delivered condition Creusabro, steel exhibits a complex type of structure, characteristic for steel with the “TRIP effect.” The identified type of structure indicates a precisely adjusted chemical composition and the use of specialised heat treatment and forming processes in the production process of those materials. The abrasive wear resistance tests conducted by means of the “spinning bowl” method in real soil masses, i.e. light soil (loamy sand), medium soil (light till) and heavy soil (normal till), as well as the conducted measurements of hardness, have proven the strict dependence of the obtained indicators of abrasive wear resistance on the phase structure and on the status of the heat treatment of the tested steel. The results of abrasive wear resistance tests for Creusabro steel were referred to 38GSA steel in a normalised condition for comparison.

The paper presents the structure and the results of abrasive wear resistance tests of XAR®600, TBL PLUS, and B27 steel. As a result of the tests conducted by means of light and scanning microscopy, it has been proven that these types of steel are characterised by subtle differences in their structures, affecting their strength and performance properties. In the delivered condition, all types of steel are characterised by a fine-grained structure with post-martensitic orientation with insets of carbide phases. The structural type of the discussed steel types disclosed in the course of the research, as well as the results of the conducted spectral analyses of the chemical composition, indicate that their properties are shaped in the course of specialist procedures of thermomechanical rolling. According to the above-mentioned test results, it can be concluded that the analysed steel types were designed in compliance with the canons of materials engineering in relation to low-alloy steel resistant to abrasive wear. Due to this, the obtained results of the structural tests of XAR®600, TBL PLUS, and B27 steel were subjected to verification in the course of abrasive wear resistance tests by means of the “spinning bowl” method. The tests, conducted in real soil masses – loamy sand, light clay, and normal clay, compared with the results of hardness measurements, indicated a strict dependence of abrasive wear resistance ratios as a function of structure and the heat treatment condition of the tested types of steel. All the obtained test results were referred to 38GSA steel in a normalised condition.