(1) there are two slender oil passages in the casting of electro-hydraulic valve casting, and it is difficult to form the slender sand core;
(2) the wall thickness of the valve casting is uneven and the material is high-strength nodular cast iron. When casting with green sand, it is easy to have hole casting defects inside;
(3) the inner cavity of the cast iron part of the valve casting is complex, which makes it difficult to clean the oil passage;
(4) due to the high working pressure of the electro-hydraulic valve casting, the local deformation of the valve body occurred during the test after processing and assembly.