The pattern is the main tool during the casting process. The replica is the thing to do at the casting process, with some modifications. The main ones are the addition of allowances pattern, and key supply prints. If the casting to be hollow, additional patterns called cores used to create the cavities in the finished product. Depends produced quality solutions on the contents of the pattern, design, and construction. The pattern and the costs related equipment seen in the cost of the solutions. The use of expensive author pattern when the required quantity substantial castings. Double Functions
1. A pattern mold cavity prepares to solutions.
2. pattern projections is called heart prints if the casting core and hollow necessary.
3. Runner, gates and risers used for feeding molten metal into mold cavity to be part of a pattern.
4. Patterns done correctly and be finished and smooth surfaces reduce casting defects.
5. minimizes pattern is built right on the total cost of the castings.
casting process 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 iron casting 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.