Special armouring for rubber extruders

In a great number of cases armouring with traditional resurfacing materials, such as stellites, has not proven itself. By rubber processing a very high surface pressure arises between screw hard facing and cylinders wall. This comes about due to unequal force balances during the pulling in of the mostly only slightly tempered rubber strips. The pressure stresses arising from this, also called sigma tension, exceed the boundary values of the stellites by far. Occasionally, an armoured screw with stellite has only the half service life as a normally nitrated screw. From this reason we employ a nitrate adaptable armouring material. This material has already after the welding a basic hardness of approx. 50 HRC and is afterwards also nitrated. The resulting supporting-effect from the high basic hardness with respect to the nitrate layer improves the wear resistance considerably with respect to normally nitrated screws.