Clean-Air Technology

Reduction of emissions in the vicinity of plunger kneader dust seals

In principle, an adaptation of the processing and operating parameters, and particularly of the specific plunger force and plunger route, leads to a clear improvement in the sealing properties. Extensive practical texts have resulted in an optimised system for unlubricated dust seals; apart from reducing emissions, this system significantly reduces the amounts of oil consumed and the lateral flow volumes.


The production of caoutchouc mixtures takes place in so-called kneaders. Emissions resulting from this process are suppressed with the aid of dust seals. The development of an optimised sealing system that would make it possible to increase the service life of the bearing rings took place in response to increasing economic and ecological requirements for the mixing plant and more stringent quality demands with regard to the product properties.
An attempted solution was the development of unlubricated dust seal rings. The opportunities and risks of using this type of seal were investigated in extensive practical tests based on wearing analyses and service life studies.


  • The use of unlubricated dust seals resulted in a reduction of the oil consumption by at least 40%, while at the same time the lateral flow volumes decreased by 70-80% in comparison to conventionally lubricated systems.
  • The problem of having friction partners with different hardness levels, which contributes towards wear and tear, may be solved by using suitable materials. In addition to design optimisation, the selection of suitable wearing partners for a production line for technical rubber products resulted in a considerable extension of the service life of unlubricated seals. A service life of 6 years or more is possible for the machine and product range in question, which would be comparable to the service life of corresponding, conventionally lubricated sealing rings.

Project Participants

Implementing Institutions

Veritas Aktiengesellschaft

Böttcher Gelsdorf GmbH & Co. KG

Harburg-Freudenberger Maschinenbau GmbH


Universität Paderborn Institut of Polymer Engineering

More Project Information

Project title: Reduction of emissions in the vicinity of plunger kneader dust seals

Project number: 01RC0154, 01RC0155, 01RC0156, 01RC0157,01RC0158

Project period: 01.09.2001 - 31.08.2004

Project contact:

Herr Prof. Dr.-Ing. Limper

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Source: German National Library of Science and Technology Hannover (TIB)