Proceedings of SerbiaTrib '13

In order to calculate the metallic component’swear, we use the method described above. Theequations (8) and (9) take into consideration, for thestudied materials, particular forms obtained byintroducing the interfering parameters numericalvalues, thus obtaining for a mean depth h mu and aworn material volume V u the following relations: Nylonplast AVE polyamide + 30% glass fibres/ steel:25h l 8r 6.94 10N (mm) (10)mum14V u 4.5510Nl m(mm 3 ) (11)The studies concerning the metallic semi-couplewear are generally based on the elastic contacthypothesis. For these plane half-couple the valuesfor the equivalent elasticity module for NylonplastAVE polyamide + 30% glass fibres, E = 20.25MPa. Assuming that the plastic liner does notcrush, we impose the condition p max 0.5H,where H stands for the Brinell hardness. Therequired condition allows us to establish thefollowing values of the maximum loadings (contactpressure) of the couple:p 1 = 16.3 MPa; p 2 = 23.5 MPa; p 3 = 28.2 MPa;p 4 = 32.6 MPa; p 5 = 36.4 Mpa.We perform the experimental tests consideringbroader domains to vary the relative speed andnormal loadings, or contact pressures. We usecouples with liner made from thermoplasticmaterial with linear contact on a steel surface(C120, Rp3, a.s.o.).Table 1. The results of the experimental tests performed inorder to determine the wear rate of metallic component.Frictional couple: Polyamide Nylonplast AVE +30% glassfibres / C120; ν = 18.56 cm/s.N (N)) t (hour)10 110 120 120 130 130 140 140 150 150 1Average wear rateh mu (10 -4 mm/h) V mu (10 -6 cm 3 /h)0.9649 0.13872.4798 0.44044.0336 0.83815.4874 1.30867,1635 1.8667(a)3. RESULTSTable 1 is the representation of the experimentaltests results, testing two friction couples, for one ofthe 8 different relative sliding speeds used. Table 1represents the results of the tribologicalexperimental tests, e.g. the mean values of the wearimprint depth h u (10 −4 mm), and the average valuesof the worn material volume V u (10 −6 cm 3 ). Theaverage width l m represents the arithmetical averagecalculated based upon 3 measured values of thewear trace’s width. By dividing h u and V u to theduration of experimental test, we obtain the valuesof the wear rate in terms of depth h mu (10 −4 mm/h)and volume V mu (10 −6 cm 3 /h).Based upon the methodology described above,we process the results obtaining the variationcurves of the wear with normal loading and relativespeed, presented in Fig. 2 (a) and (b), for two of thetested couples, Nyloplast AVE Polyamide + 30%glass fibres / C120 steel, and respectively NyloplastAVE Polyamide + 30% glass fibres / Rp 3 steel.(b)Figure 2. The results of variation curves of the wearvolume with normal loading and relative speed, fortested couples (a) Nyloplast AVE Polyamide + 30%glass fibres/ C120 steel and (b) Nyloplast AVEPolyamide + 30% glass fibres/ Rp 3 steel. Measurementerrors were ±1.5 %.These curves characterize only the testedfrictional couples (one combination of materials).Furthermore, we can make the comparativeevaluation of different couples only qualitatively.Thus, using relations (8) and (9) we obtain thevariation curves of the "comparative wearcoefficients" (as volume and depth), K (cm 3 / cm)and K * (mm / cm). These master-curves are plottedin Fig. 3 and Fig. 4 representing the two tested and13 th International Conference on Tribology – Serbiatrib’13 61