Bimetal pipes were developed to meet extreme conditions:
- High mechanical loads > 70 N/mm²
- High speeds up to 30 m/sec
- Wide temperature range -70° C to +250°C
This is made possible by the manufacturing process from which a bronze/steel interface is created by casting, characterised by an intermetallic diffusion zone of 3 to 5 μ without the appearance of a brittle phase. Bronze and steel form a single bimetallic part that combines the advantageous mechanical properties of the two materials: friction and mechanical strength.
The interface does not contain any anchoring elements, metallisations or underlays that weaken the intermetallic bond. The mechanical strength of the interface controlled by ultrasound is higher than that of the bronze itself: There is no risk of detachment, even under extreme loads. The coefficients of expansion of the two materials are similar.
After casting and cooling, the end faces of the tube and the inner diameter are machined to ensure a surface finish and tolerances that allow easy finishing for finishing. The outside diameter is shot peened.
Additional components can be added by welding without changing the bronze layer of the bimetal tube.
By varying the dimensions of the tubes, within the limits of the manufacturing programme, bimetallic tubes can be produced in an infinite range of diameters and wall thicknesses. The standard range available from stock and the wide range of special dimensions that can be produced on request allow savings in materials and machining.
The bronze used favours the formation of a solid lubricant under certain conditions (start-up in mixed operation or breaking up of the oil film).