Views: 12 Author: Site Editor Publish Time: 2018-04-06 Origin: Site
No matter during die casting process or advanced machining process, there are always some defective parts, how to deal with them?
The casting parts with defects after die casting or advanced machining process is generally scrapped directly. Repairs may only be carried out in the two following cases and if there is a possibility of repair.
1. The die casting parts are very complex in shape, or it is very difficult to be casted or it takes a very long processing cycle.
2. The die casting parts are casted with casting insert which is made of precious material that is not be recovered and reused.
There are two kinds of repairing methods: Complementary Welding and Patching.
The complementary welding is to brazing the welding rod with the same or slightly lower melting point of the casting material, and then the shape and size required to be repaired by the fitter after welding. After welding, the diecast parts should be treated or annealed to eliminate the stress. It is better not to weld the positions that require hydraulic or pneumatic working conditions. Since during repair welding, the compacts of the castings may be reduced, thereby reducing the performance under hydraulic or pneumatic pressure. If the welding is necessary, the internal inspection of X rays or other methods shall be performed 100 percent after the welding.
Patching is to machine the defective position so as to get a pin hole and then insert a pin made of same material with the die castings. Then machine or fit-trim the pin to the desired shape and dimensions of the die casting parts. However, there should be no more than two pins in the same castings, and there should be a certain distance between the pin and the edge of the casting parts. If the pin diameter is less than 4mm, the distance between the pin and the edge of the casting shall be 1.5 times the diameter of the pin. If the pin diameter is greater than 4 mm, and the distance is equal to the diameter of the pin. If the distance is not controlled strictly the strength of the castings will be reduced.
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