How to deal with the problem of precision casting deformation

In the process of manufacturing precision castings, due to some hardware facilities, management, casting cooling and correction problems, the deformation of the castings will occur. How do we deal with the deformation of the castings?

Casting deformation is divided into: micro self-deformation, flaring deformation of the casting and warping deformation.

Trace self-deformation: Among alloy materials, gray cast iron is most prone to micro-deformation. After the falling of the gray cast iron, the residual stress is mainly the residual thermal stress. In addition to the defects such as cold cracking of the casting and deformation of the casting, the residual stress is also the main reason for the occurrence of trace self-deformation. Even if the residual stress does not exceed the yield strength of the material, under the action of the gray cast iron, the micro-plastic deformation will occur slowly with the continuation of time. This deformation is called micro-self-deformation.

Flare deformation: The reason for the formation is that the sand core or sand type at the opening size hinders the shrinkage of the casting and plastically deforms the free structural portion of the casting opening, thereby producing a flaring deformation defect.

Warpage deformation: The castings after sand cleaning have warped deformation at both ends or one end or even the peripheral edge, which causes the middle part of the casting to be concave, which causes the casting to be uneven. This form of deformation is called warping deformation. The reason for the formation is as follows: when the casting is cooled, the thickness of the casting is uneven or the thickness is uneven, and there is a temperature difference, which causes different cooling speeds of various parts of the casting, resulting in uneven plastic deformation, resulting in warping deformation.

For the deformation problem of precision castings, this paper mainly proposes four relevant recommended measures:

1. Before the wax is sprayed, find the mold in the wax chamber preset until the mold temperature is the same as the room temperature of the wax chamber. When the shell is used, the temperature of the wax will not need to be mentioned, because there is no control there. Well, maybe it’s directly listed, and it’s up.

2. After the wax is out, it should first be self-tested. It mainly checks whether there is any deformation or other defects in the die-cutting project. The wax parts should be placed neatly according to the uniform placement method, and try to avoid overlap and dangling; Fixture inspection to improve detection speed and accuracy, and to calibrate the fixture at a certain period.

3. After the furnace is opened, the overlap should be avoided when the module temperature is still high, so that it can be placed regularly so that the deformation direction is consistent and it is easy to shape and correct the fashion clip.

4. Fixtures for the correction of castings should be made of hard materials, and the surface should be wear-resistant. For some parts with large area, the tonnage of the press or punch should be reasonably calculated to avoid waste of equipment or insufficient strength.