The development of an optimal dust stop system is aim of the national German research project “Reduction of Emission at the Dust Stops of Internal Mixers”. A target of the optimization is to extend the service life of the sealing rings. At the same time the necessary amounts of lubricants and the associated waste materials have to be reduced. One approach for advanced dust stop systems is the use of lubricant free sealing rings. Based on latest field tests the chances and risks of lubricant free dust stops are presented including a brief description of wear mechanisms and their consequences for the use of such systems. A functional analysis is completed by observations and recordings of process procedures.