Proceedings of SerbiaTrib '13

3. EXPERIMENTAL RESULTSTaking into account that PTFE has lowermechanical properties as compared to PBT [10], itwas considered necessary to study the influence ofthe normal force on the surface quality of thispolymeric blend, before and after testing.Figures 3, 4 and 5 present the average values ofthe amplitude and functional parameters, obtainedwith the help of the proposed methodology, for theinitial and tested surfaces generated on the blocksmade of PF10 (material symbol for the polymericblend PBT + 10% PTFE), for the tested conditions:three forces and three sliding speeds and a slidingdistance of L = 7500 m.μm141210m 8µ6420141210m 8µ6420141210m 8µ642014121086420PF10L = 7500 mInitial surfaceSa Sq Sp Sv SzF=1.0NF=2.5NF=5.0NPF10L = 7500 mv = 0.25 m/sSa Sq Sp Sv SzF=1.0NF=2.5NF=5.0NPF10L = 7500 mv = 0.5 m/sSa Sq Sp Sv SzF=1.0NF=2.5NF=5.0NPF10L = 7500mv = 0.75 m/sSa Sq Sp Sv SzFigure 3. The influence of the normal force on theaverage values of the dimensional amplitude parametersfor the blocks made of PF10 (PBT + 10% PTFE)The wear track surfaces are characterized byparametric values 2...3 times lower than those ofthe initial surfaces as they were obtained by themoulding technology.6420-26420-26420-26420-2PF10L = 7500 mInitial surfaceSskPF10L = 7500 mv = 0.25 m/sSskPF10L = 7500 mv = 0.5 m/sSskPF10L = 7500 mv = 0.75 m/sSskSkuSkuSkuSkuFigure 4. The influence of the normal force on theaverage values of the a dimensional amplitudeparameters for the blocks made of PF10The surface quality of this material is onlyslightly dependent on the normal force, at least forthe tested values (F = 1 N, F = 2.5 N and F = 5 N).Sa and Sq have very close values, regardlessthe force values, but Sp and Sz present a slightdecrease when the force increases, for the testdone with the sliding speeds of v = 0.25 m/s and v= 0.5 m/s.Sku (surface Kurtosis) values greater than 3.0indicate narrower height distribution due to the13 th International Conference on Tribology – Serbiatrib’13 121