TRIBO Hartstoff GmbH is manufacturer of cemented carbides on basis of tungsten
carbide and cobalt. Due to their outstanding properties with regard to
compressive and wear resistance these cemented carbides are used as components
in so called hyper compressors where they are of enormous significance for a
stable high-pressure generation. In this area of high pressure products TRIBO is
cussion we will refer to plungers with carbide coating layer, solid cemented
carbide plungers and carbide-tipped high-pressure bushes are to be mentioned.
Today hyper compressors using plungers are critical machines used for the
production of LDPE. In these compressors plungers are operated together with
high pressure packings made of special bronze which guarantee the sealing of
discharge pressures up to 350 MPa. In order to ensure this sealing system will
work efficiently and safely over a long period of time mineral or synthetic
lubricants are used. The outcome is a tribological system consisting of 4
components - ethylene, high pressure packings, plunger and lubricant.
In many years of analysing the issues in the tribological system we have gained
considerable knowledge, and in particular concerning the cemented carbides, its
influence and the system components involved. This knowledge is based upon real
failures in the field and subsequent investigation carried out in rectification.
Conclusions from these investigations have proved of crucial importance to plant
managers in providing the basis for future process improvement.
Picture 1: The 4 components of the tribological system