Review the rationality of casting structure from the aspect of avoiding defects

The casting process of part structure usually refers to that the structure of the part itself should meet the requirements of casting production, which is not only convenient for the whole casting process, but also conducive to ensuring product quality.

There are two functions to analyze the product part drawing: first, to check whether the part structure meets the process requirements of casting production. Because the designers of parts often do not fully understand the casting process. In case of any irrationality found in the structural design, it is necessary to conduct research with relevant parties and improve it without affecting the use requirements. It can simplify the process, guarantee the quality and reduce the cost. Second, under the given structural conditions of the parts, considering the main defects that may appear in the casting process, the corresponding technological measures are taken in the process design to avoid them.

1.Castings should have reasonable wall thickness

Each alloy has its suitable range of wall thickness. Wall thickness is too thin, easy to appear insufficient pouring; too thick, easy to appear grain coarseness, mechanical properties reduced.

2.Casting shrinkage should not be seriously hindered. Pay attention to the transition of wall thickness and casting fillet

Gradual transition and transformation shall be adopted at the joint, bend and joint of thickness and thickness of castings, and larger fillet shall be adopted for connection to avoid sudden transformation, stress concentration, crack and other defects. Special attention should be paid to alloy castings with high grade and large shrinkage to prevent cracks caused by seriously hindering the shrinkage of castings.

3.The thickness of inner wall shall be less than that of outer wall

The internal ribs and walls of the casting have poor heat dissipation conditions, so they should be thinner than the external walls, so that the external walls and internal walls of the whole casting can be evenly cooled to prevent internal stress and cracks.

4.The wall thickness shall be uniform as much as possible, and most of the thickness shall be reduced to prevent the formation of hot spots

If the wall thickness is not uniform, the cooling of the casting is not uniform, and the internal stress, shrinkage cavity and crack are easy to form at the joint.

5.Conducive to feeding and sequential solidification

For thick and large parts, riser shall be set according to the characteristics of parts for feeding.

6.Pay attention to prevent warpage and deformation of castings

For long and thin pieces and large flat pieces, when the casting shrinks, it is easy to cause warpage and deformation due to inconsistent cooling. More stiffeners shall be arranged to prevent such deformation.

7.Avoid large horizontal planes

During pouring, the rising speed of horizontal large plane liquid flow is very slow, baking the top surface of the mold for a long time, which is easy to cause defects such as sand inclusion and insufficient pouring, and is not conducive to the discharge of metal inclusions and gases.

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