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Accurate casting by controlling the shrinkage of the casting:
Casting in the solidification process, its various parts of the size generally to reduce, the casting size reduction percentage, called casting line shrinkage rate or casting shrinkage rate. Manufacturing casting mold (including core box), to determine the casting shrinkage rate, the casting mold to enlarge some, to ensure that the size of the casting after cooling to meet the requirements, xinyuanzhu group according to the actual situation of the foundry, combined with years of casting experience on the shrinkage of castings made the following summary.
The shrinkage of each size when the casting is cooled can be obtained from the following formula.
Shrinkage = casting size × casting shrinkage rate
Many factors affect the shrinkage of castings, the main ones are.
1. the casting material casting material is different, the casting shrinkage rate is also different. For example, the shrinkage rate of cast steel is larger than that of gray cast iron; shrinkage rate increases when there is more sulfur in gray cast iron, and shrinkage rate decreases when there is more silicon.
2. the structure of the casting casting structure complex shrinkage difficulties, the shrinkage rate of the casting reduced. For example, the same composition of cast steel parts, because the structure of the shape is different. Which is the largest shrinkage rate when free shrinkage.
3. castings of the yielding castings of good yielding, the shrinkage of the casting increases. For example, castings cast with wet and water glass sand casting than dry castings shrinkage rate is large. By the same token, as the size of the casting increases, the yielding nature of the casting becomes worse, and the shrinkage of the casting is reduced.
Therefore, the casting shrinkage rate should be selected with the actual situation. Castings with precise dimensional requirements, the casting shrinkage rate should be corrected according to the test castings.
The same casting, due to structural reasons, its axial and radial or length, width and height of the three directions of the shrinkage rate may not be consistent. For castings with more precise dimensional requirements, each direction should be given a different shrinkage rate. In actual production, the general casting, especially the size of the castings, all directions with the same shrinkage rate, although this will cause some errors, but because the error is generally not large, and this greatly facilitates the processing of the casting mold manufacturing.
Xinyuanzhu Group specializes in the production of Ductile iron castings, Pig iron gray iron casting, Steel casting, Brass Casting, Malleable Iron Casting, and undertakes batch casting processing of castings. Welcome guests to cooperate with pictures or samples.
