The friction in GLYCODUR® bearings mainly depends on the bearing load, the sliding velocity and the operating temperature. The surface roughness of the mating surface and, especially with GLYCODUR® A bearings, the lubrication conditions are also important.
The coefficient of friction for GLYCODUR® F bearings is between 0.03 and 0.25 depending on the operating conditions. The coefficient of friction for GLYCODUR® A bearings is similar, but lubrication has a stronger effect in this case. The lower coefficients of friction are typically obtained under high specific bearing loads and low sliding velocities (see diagram).
Under extremely favorable conditions as well as with low loads the indicated value may even be exceeded. GLYCODUR® bearings show negligible “stick-slip”.
Guidelines for friction coefficients for GLYCODUR® F bearings
During the running-in phase of GLYCODUR® F bearings a part of the polytetrafluoroethylene top layer will be transfered to the mating surface. For this reason, the characteristically low operating values for wear and friction will be obtained with GLYCODUR® F bearings after they have been run in.
GLYCODUR ® A plain bearings can function as electrical insulators due to their sliding layer made out of POM. In order to avoid electrostatic charging, affected components must be appropriately grounded.
The chemical properties of GLYCODUR® sliding bearings are mainly determined by the steel back layer and the tin bronze sinter layer, because the sliding layers are resistant to many chemicals. The top layer of GLYCODUR® F bearings is virtually inert, due to the PTFE material used, it can be attacked by molten alkaline metals or by free fluorides at elevated temperatures. The POM top layer of GLYCODUR® A bearings is resistant to organic substances.
The tin bronze sintered structure is resistant to seawater, water vapor, atmospheric effects, salt solutions and sulfuric acids at room temperature, but is not resistant to oxidizing acids and media containing ammonium hydroxides.
All exposed surfaces on the steel back are tin plated; but in most applications there is only limited protection against corrosion. If the bearings are exposed to corrosive media, or a risk of contact corrosion between the steel back of the bearing and the housing material, the back may be protected by a Ni, Cr, or Zn layer. Further details are available upon request.
Under dry sliding conditions, there is no lubricant to provide protection against corrosion. Special attention must be paid to the corrosion properties of the mating material.