has weak property in the progress of casting and produce blowhole easily ，under the long-term vibration and impact, easy to cause stress concentration and result in the casting process crack of the shell. Because of poor weld ability of and plus request the airtightness of hydraulic equipment higher, the traditional welding process cannot repair. And the site general has no such equipment spare parts, buying replacement needs a lot of downtime.
Such problems often use polymer composite materials to repair now , excellent mechanical properties of polymer metal repair material and good stick relay, pressure resistance, make the problem solve effectively. Repairing process: according to the site situation, recommended that the enterprise use electro welding to connect crack top and bottom several points of welding are used to strengthen shell structure，find the end of the casting process crack location, at the end of 4.2 mm to check in to prevent the further extension of casting process crack. Use polishing machine to grind clean along the casting process crack ，on both sides to expand 75 px. After cleaning with anhydrous ethanol mixed polymer metal repair materials,cooperate and strengthen repairing management of the casting process crack.