The typical recovery process of exhaust
valves and seats involves:
- Cleaning and detection of defects; dye-penetrant
testing to detect surface defects and cracks; and cleaning of the deposits
on the water lines indicated on the seats;
- Preliminary mechanical processing, during which the
worn-out metal layer is removed, followed by defectoscopy;
- Welding of sublayers, intermediate machining, welding
of the final hard layer (nimonic or stellite), final processing,
dimensional control, defectoscopy for the presence of cracks.
When the surface being sealed (or
the entire valve) is of the nimonic type, a special heat treatment is performed
on the valve spindle (disperse solidification) in a specialized furnace in
order to obtain a high level of hardness of the sealed surface.
The valve cages of the four-cycle
engines are restored by analog technology.