Proceedings of SerbiaTrib '13

6. SELECTION OF MATERIALS FOR THECONSTRUCTION MECHANIZATIONWORKING PARTSLarge number of parts of the constructionmechanization (hoop's teeth, rippers, mixers' blades,knives for lifting and removing asphalt, knivesbladesfor channels digging, crushers impact beamsetc.) are, during operation, in indirect or directcontact with rock materials, and, depending on therole and function of the part, they are exposed tovarious types of wear [10-12]. Mainly one dealswith abrasive wear or a combination of severaltypes of wear.The main factors in selection of materials exposedto wear are their chemical composition andstructure. Those materials are mainly steels and(white) cast irons. The most resistant to wear arematerials of high hardness. Though that characteristiccan not be the only criterion, it is mainly usedfor quality estimates of materials exposed to wear.Depending on the degree of wear, machines'working parts could be replaced by the new ones,or could be subjected to reparatory hard-facing.When selecting the reparation technology,mechanism of abrasive wear is being analyzed,both theoretically and experimentally, taking intoaccount hardness and microstructure of parts, andrelated wear resistance in laboratory and realoperating conditions. That represents the basis forselection of the optimal procedure, technology andfiller metal for working surfaces regeneration.Investigations, until now conducted by these authors,have shown that the working life of the properlyregenerated parts exceeds several times thenew parts working life. Besides that, the machinedown-time, assortment and quantity of the necessaryspare parts are reduced. All these point tocomplexity of materials selection for the workingparts of construction mechanization, as well as toimportance of knowing the properties of the rockmaterials.7. CONCLUSIONIn this paper are presented investigation resultsof the rock materials physical and mechanical propertiestests, for four types of rock materials mostfrequently applied in construction of driveways.The conclusion was reached that those materials arefirm and homogeneous rocks, of medium to highhardness. It was determined that the compressionstrength values are on average 10-40 times higherthan the shear, bending and tensile strengths, whilethe wear resistance is good in majority of studiedrocks, being especially high for andesite.Obtained results enable estimates of the individualrock material's quality and point to the complexityof the material selection for the workingparts pf construction mechanization. Experimentalresults of rock materials properties and the complexworking conditions of the tribo-system, can serveand must be taken into account in selection of thebase metal and reparation technology of thedamaged parts of the construction mechanization.AcknowledgementThis research was partially financially supportedthrough grants TR35024, TR35021, TR34002 andOI174004 of Ministry of Education and Science ofRepublic of Serbia.REFERENCES[1] M. Janjić: Fundamentals of geology and engineeringgeology, Part I, Faculty of Civil Engineering,Belgrade, 1964.[2] M. Janjić: Engineering geodynamics, Faculty ofMining and geology, Belgrade, 1979.[3] M. Janjić: Engineering geology with geologyfundamentals, Scientific Book, Belgrade, 1982.[4] M. Luković: Engineering geology, Scientific Book,Belgrade, 1950.[5] N. Panjukov: Engineering geology, Civil EngineeringBook, Belgrade, 1963.[6] M. Mutavdžić: Reparatory hard-facing of parts ofmachines and devices in constructionmechanization, MS thesis, Faculty of MechanicalEngineering, Kragujevac, 2007.[7] R. Stojadinović: Soil mechanics – I, Faculty ofCivil Engineering, Belgrade 1978.[8] M. Muravljov: Civil engineering materials, CivilEngineering Book, Belgrade, 2002.[9] Standards: JUS B.B8.001 to JUS B.B8.086.[10] V. Lazić et al.: The working life theoretical andexperimental estimates for machine parts hardfaced using austenite-manganese electrodes,Materials end Technology, Vol. 46, No 5, pp. 547-554, 2012.[11] M. Mutavdžić et al.: Model investigations of thefiller materials for regeneration of the damagedparts of the construction mechanization, Tribologyin Industry, Vol. 30, No. 3&4, pp. 3-9, 2008.[12] V. Lazić et al.: Selection of the most appropriatetechnology of reparatory hard facing of workingparts on universal construction machinery, Tribologyin Industry, Vol. 33, No. 1, pp. 18-27, 2011.280 13 th International Conference on Tribology – Serbiatrib’13