Proceedings of SerbiaTrib '13

Figure 5. Functional scheme of the test rig for study ofstarting frictionThe experimental arrangement consists of body1 and counterbody 2, which form a contact. Thebody 1 is fixed in the holder 3 and is connectedthrough the nonelastic thread with thedynamometer 6 and micrometric screw 5.Tangential force is loaded on the body 1 near thecontact surface through slow turning of themicrometric screw. The normal load Р is set bymeans of the loading bodies 4.The body 1 is a prismatic sample of size30 х 50 х 8 mm made of duraluminium (Al), andthe counterbody 2 represents a round disk ofdiameter ф 100 mm and thickness 3 mm with thedeposited coating.The procedure of measurement the friction forceis of following sequence:- The specimen 2 with coating is fixed in the bedof the base, and the body 1 is mounted in the holder3, then they are put on the specimen 2.- The normal load is set by the loading bodies 4.- The elastic dynamometer 6 is put in the initialreset to zero.- The micrometric screw 5 is turned very slowlyand the pointer of the dynamometer 6 shifts withease. In the moment of shivering of the pointerbackwards, the indication of the dynamometer isread. The maximum value of the indicationcorresponds to the value of the starting frictionforce То.- The screw keeps on turning and the indicationsof the dynamometer are observed; they match thekinetic friction force Т after the jump of friction.- The dial of the dynamometer is calibrated inforce [N].- During the tests the body 1 is made of the samematerial but for each test with different coatings adifferent specimen of this material is used. Allspecimens of the body have equal size androughness Ra 0, 418 m.Table 3 shows the results of starting and kineticfriction, and the figures give some diagrams.353025201510500‐ 0+ 5‐ 5+ 100‐ 100+ 200‐ 200+ 250‐ 250+Figure 6. Diagram of starting friction force То0,10,090,080,070,060,050,040,030,020,01Figure 7. Diagram of the jump of friction force Δµ30252015105040353025201510500‐ 0+ 5‐ 5+ 100‐ 100+ 200‐ 200+ 250‐ 250+Figure 8. Diagram of the relative change ofstarting friction Ψs0‐ 0+ 5‐ 5+ 100‐ 100+ 200‐ 200+ 250‐ 250+Figure 9. Diagram of the relative change ofkinetic friction Ψр13 th International Conference on Tribology – Serbiatrib’13 35