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How to deal with the deformation of precision casting:
During the production of precision castings, due to some problems of hardware facilities, management, pouring cooling and correction, casting deformation will occur. Then, how should we deal with casting deformation when we encounter it?
Casting deformation is divided into: trace self-deformation, casting flaring deformation and warping deformation.
Trace self - deformation: Among alloy materials, gray cast iron is the most prone to trace self - deformation. The residual stress of grey cast iron after sand removal is mainly residual thermal stress. In addition to cold cracking and casting deformation, residual stress is also the main cause of minor self-deformation. Even if the residual stress does not exceed the yield strength of the material, trace plastic deformation will occur slowly in gray cast iron over time, which is called trace self-deformation.
Flameout deformation: The reason for flameout deformation is that the sand core or sand mold at the size of the opening prevents the shrinkage of the casting, which results in plastic deformation of the free structure of the opening of the casting, thus causing the flameout deformation defect.
Warping deformation: after sand removal, the two ends or one end of the casting or even the outer ends of the casting warp deformation, so that the middle of the casting concave, resulting in the casting not flat, this form of deformation is called warping deformation. The reasons are as follows: due to the uneven thickness or thickness of the casting during cooling, temperature difference exists, resulting in different cooling rates of each part of the casting and uneven plastic deformation, resulting in warping deformation.
For the deformation of precision castings, this paper mainly puts forward four relevant measures:
1. Before the wax shooting, find the mold and set it in the wax shooting chamber, and do not shoot the wax until the mold temperature is the same as the room temperature; As for the back of the shell when the wax piece temperature does not need to mention, because there is no good control may be directly column, opened the shell.
2. The wax parts should be self-checked after coming out, mainly to check whether there is deformation or other defects in the molding lifting project; The wax parts should be neatly placed in a uniform way, and try to avoid overlapping and hanging; It is suggested to adopt fixture inspection as far as possible to improve the detection speed and accuracy, and calibrate fixture according to a certain period.
3. After the furnace is opened, when the module temperature is still very high, overlapping should be avoided and regular placement should be done to make the deformation direction consistent for plastic shaping and correction of fashion clips.
4. The fixture of the corrected casting shall be made of hard material with a wear-resistant surface. For parts with large area, the tonnage of the press or punch shall be reasonably calculated to avoid equipment waste or insufficient strength.
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, timely correction should be carried out once deformation of precision castings is found, so as not to affect the performance of mechanical products.
Casting deformation is divided into: trace self-deformation, casting flaring deformation and warping deformation.
Trace self - deformation: Among alloy materials, gray cast iron is the most prone to trace self - deformation. The residual stress of grey cast iron after sand removal is mainly residual thermal stress. In addition to cold cracking and casting deformation, residual stress is also the main cause of minor self-deformation. Even if the residual stress does not exceed the yield strength of the material, trace plastic deformation will occur slowly in gray cast iron over time, which is called trace self-deformation.
Flameout deformation: The reason for flameout deformation is that the sand core or sand mold at the size of the opening prevents the shrinkage of the casting, which results in plastic deformation of the free structure of the opening of the casting, thus causing the flameout deformation defect.
Warping deformation: after sand removal, the two ends or one end of the casting or even the outer ends of the casting warp deformation, so that the middle of the casting concave, resulting in the casting not flat, this form of deformation is called warping deformation. The reasons are as follows: due to the uneven thickness or thickness of the casting during cooling, temperature difference exists, resulting in different cooling rates of each part of the casting and uneven plastic deformation, resulting in warping deformation.
For the deformation of precision castings, this paper mainly puts forward four relevant measures:
1. Before the wax shooting, find the mold and set it in the wax shooting chamber, and do not shoot the wax until the mold temperature is the same as the room temperature; As for the back of the shell when the wax piece temperature does not need to mention, because there is no good control may be directly column, opened the shell.
2. The wax parts should be self-checked after coming out, mainly to check whether there is deformation or other defects in the molding lifting project; The wax parts should be neatly placed in a uniform way, and try to avoid overlapping and hanging; It is suggested to adopt fixture inspection as far as possible to improve the detection speed and accuracy, and calibrate fixture according to a certain period.
3. After the furnace is opened, when the module temperature is still very high, overlapping should be avoided and regular placement should be done to make the deformation direction consistent for plastic shaping and correction of fashion clips.
4. The fixture of the corrected casting shall be made of hard material with a wear-resistant surface. For parts with large area, the tonnage of the press or punch shall be reasonably calculated to avoid equipment waste or insufficient strength.
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, timely correction should be carried out once deformation of precision castings is found, so as not to affect the performance of mechanical products.
