How to deal with deformation of castings

In the production process of precision castings, due to problems such as hardware facilities, management, pouring, cooling and correction, casting deformation problems will occur. So how to deal with casting deformation?

Casting deformation is divided into: slight self-deformation, flaring deformation and warping deformation.

Trace self-deformation: Among alloy materials, gray cast iron is prone to trace self-deformation. After the gray cast iron is cleaned, the residual stress is mainly residual thermal stress. Residual stress will not only cause defects such as cold cracking and deformation of castings, but also cause trace self-deformation. The main reason. Even if the residual stress does not exceed the yield strength of the material, gray cast iron will slowly undergo trace plastic deformation over time, which is called trace self-deformation.

Flaring deformation: The reason is that the sand core or sand at the opening size hinders the shrinkage of the casting, causing plastic deformation of the free structural part of the casting opening, resulting in flaring deformation defects.

Warping deformation: Two ends, one end and even the outer end of the sand-cleaning casting are warped and deformed, causing the middle part of the casting to be dented, resulting in uneven castings, which is called warping deformation. The reasons are: due to the cooling of the casting, the thickness or thickness of the casting is uneven, and the temperature difference , the cooling rates of various parts of the casting are different, and the plastic deformation is uneven, resulting in warping deformation.

Regarding the deformation of precision castings, this article puts forward 4 relevant suggestions:

1. Before waxing, preset the mold in the waxing room until the temperature of the mold is the same as the waxing room temperature. As for the temperature of the wax part during the back shell, there is no need to mention it because the control there is not good and it may be directly listed. When it comes out, the shell will swell.

2. After the wax parts come out, self-inspection should be performed first, mainly to check whether there are deformations or other defects in the mold project; the wax parts should be placed neatly in a unified manner to avoid overlapping and hanging; it is recommended to check the finished product shipments as much as possible to improve inspection Speed ​​and accuracy, and calibrated at a certain period.

3. After opening the furnace, when the module temperature is still very high, overlap should be avoided and placed regularly to make the deformation direction consistent, which facilitates correction and clamping during plastic surgery.

4. Tools for correcting castings should be made of hard materials, and the surface should be wear-resistant. For some parts with larger areas, the tonnage of the press or punch should be calculated reasonably to avoid waste of equipment or insufficient power.

Precision castings have a great impact on the performance of mechanical products. Poor quality precision castings will seriously affect the service life of mechanical products. Therefore, once deformation of precision castings is found, it should be corrected in time to prevent precision castings from affecting the performance of mechanical products.