Reducing the Coefficient of Friction in a Rubber Profile-Metal Tool Friction Pair

<ns3:p>Precise cutting of a rubber element requires periodically moving it within a rigid tool that positions the profile. Currently, to reduce the associated significant friction resistance, the rubber-metal friction pair is lubricated with volatile aliphatic hydrocarbons, which have a harmful effect on the human body.The aim of the project is to develop a method of modifying the surface of a metal tool (the automotive industry does not allow interference with the sealing material) that would reduce friction resistance to a similar level without lubrication.The authors quantified the actual forces involved in the profile assembly in the tool and measured the roughness of the profile’s internal surface. Their analysis revealed that in some areas the surface was smooth, which allowed for the determination where the work related to the tool surface modification should focus. To this end, the authors developed methodology for measuring the coefficient of friction using two tribometers: one with a roller-block friction pair and one working in a pin-disc system. Due to the smaller dispersion of the friction force values under load conditions corresponding to real operating conditions, the metal pin – rubber disc friction pair was selected for further tests. The recorded friction force curves had a stick-slip character, typical for rubber friction. The tribological characteristics recorded for rubber of different hardness were subjected to Fourier transformation from the force domain to the frequency domain. The obtained discretecurves of energy dissipated in rubber during friction were compared for several friction pairs, in the case of which coatings were applied to the metal sample.</ns3:p>