A study of friction and wear of polyoxymethylene-polyoxymethylene and polytetrafluoroethylene-polytetrafluoroethylene pairs with simultaneous registration of the level of heating caused by friction has been carried out. The data obtained were analyzed both by using the energetic wear versus friction power plots and by using the solutions of finite element simulations of the thermal problem in the realistic friction geometry of the thrust bearing type used in the experiments. The solutions provide estimates of heating in vacuum and atmosphere. The calculated heating levels in vacuum suggest that triboinduced scissions of polyoxymethylene macromolecules registered by means of mass-spectrometry in polyoxymethylene-polyoxymethylene pair are initiated at temperatures below the temperatures of the onset of pure thermal decomposition of this polymer and its melting. Correlation between the presence of triboinduced scissions of macromolecules upon friction force transition, the registered exponential growth of wear upon increase of friction power in polyoxymethylene-polyoxymethylene pair and the absence of these phenomena in other pairs studied suggests that triboinduced scissions of macromolecules is governing mechanism controlling overall wear of the polymers studied. The approach was also shown to be informative in comparison of the wear of these polymers against steel and of the wear of pure polyoxymethylene and its composite with C60 fullerene.