How to deal with the deformation of precision castings


In the production process of precision casting, because […]

In the production process of precision casting, because of some hardware facilities, management, pouring cooling and correction problems, will produce casting deformation, then we encounter casting deformation how to deal with it?

Casting deformation is divided into: micro self deformation, casting flare deformation and warpage deformation.
Trace self-deformation: Among the alloy materials, gray cast iron is most prone to trace self-deformation. The residual stress that exists in gray cast iron after sand cleaning is mainly residual thermal stress. Residual stress is the main cause of trace self-deformation, in addition to the defects such as cold cracking and casting deformation. Even if the residual stress does not exceed the yield strength of the material, but under its action, gray cast iron with the continuation of time, will slowly occur a trace of plastic deformation, this deformation is called trace of self-deformation.
Flare deformation: The reason for the formation is that the sand core or sand pattern at the opening size hinders the shrinkage of the casting, which causes plastic deformation in the free structural part of the casting opening, thus creating a flare deformation defect.
Warpage deformation: after sand clearing of the casting occurs at both ends or one end or even the peripheral side end warpage deformation, so that the middle of the casting concave, resulting in uneven castings, this form of deformation is called warpage deformation. The reason for its formation is: due to the cooling of the casting, the casting thickness or thickness is not uniform, there is a temperature difference, resulting in different cooling rates of various parts of the casting, resulting in uneven plastic deformation, resulting in the formation of warpage deformation.


For the deformation of precision castings, this paper mainly puts forward the relevant four proposed measures.
1. before the injection wax find out the mold in the injection wax room pre-set, until the mold temperature and injection wax room room temperature is the same before starting to shoot wax; as for the back of the shell when the temperature of the wax parts do not need to mention much, because there is no good control perhaps directly listed, up the shell.
2. wax parts out should first self-inspection, mainly to see whether there is deformation in the starting mold project, or other defects; wax parts should be placed neatly according to the uniform placement, and try to avoid overlap, overhang; finished products shipped recommended to try to use jig inspection to improve detection speed and accuracy, and according to a certain cycle calibration jig.
3. After the furnace is opened, the temperature of the die set is still very high when you should avoid overlapping, so that the regular placement, so that the deformation direction is the same to facilitate the plastic correction fashion clamps.
4. Calibration jigs for castings should be made of hard material, the surface should be wear-resistant, and the tonnage of the press or punch should be reasonably calculated for parts with a relatively large area to avoid wasting equipment or insufficient force, etc.
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, so once the precision castings are found to have deformation and other problems, to be corrected in a timely manner, so as to avoid precision castings affect the performance of mechanical products.

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