As we all know, the quality of ductile iron out of the material and the use of materials, and its design of the riser and cold iron also deeply affect the quality of its quality is good or bad. The design of the good can reduce the riser, improve the ductile iron pieces excellent rate, can also directly reduce production costs and promote economic efficiency. Therefore, in order to achieve the above results, we must understand the role of riser and cold iron and the design process need to pay attention to the problem!

The role of the riser: in the casting process to provide the volume changes due to the need to fill the metal liquid to prevent the casting in the type of shrinkage defects.
 
The role of cold iron:
1) to speed up the cooling part of the casting part of the cooling rate, so that casting tends to solidification at the same time, is conducive to prevent the deformation of the casting or cracks, and may reduce segregation.
 
2) with the riser to use, so that the cooling of the local area of the casting to accelerate the strengthening of the casting direction (order) solidification conditions, is conducive to riser and expand the riser range, so that not only help to prevent casting Loose, shrinkage defects, it is possible to reduce the number of risers or volume and the slope of the increase, to improve the production rate of ductile iron pieces.
 
3) to speed up the casting of some special parts of the cooling rate, in order to achieve the casting surface hardness and wear resistance, refine the purpose of matrix structure.

4) In the difficult place to set the riser or riser is not easy to fill the site to prevent cold iron to reduce or prevent the emergence of shrinkage, shrinkage.
5) on the ductile iron, chilled with cold iron can increase the casting surface or the center of the temperature gradient, is conducive to improving the degree of use of graphite expansion and improve the riser effect.
 
The nodular cast iron is solidified in a solidified form, and we are designed to design this solidification, and we need to do solidification simulations to verify that the process we have designed is correct. Of course, consider the whole process as much as possible to consider the riser and cold iron, put them together to consider. So in the design of cold iron and riser, we must pay attention to the following questions:

The riser must be able to transport enough molten iron to compensate for contraction.
 
Liquid shrinkage: higher than TL temperature: 1,5% / 100 ° C.
 
Solid shrinkage: 0 - 2 - 5%, depending on the metallurgical quality of molten iron.
 
The riser must work: the dark riser must have a Williams core and a gas eye, and the riser must have a hot cover.
 
The riser has a certain distance to fill it, depending on the wall thickness and the metallurgical quality of the molten iron. It can be: Horizontal fill distance: 10 to 2 times the section thickness, vertical fill distance: 15 to 4 times the thickness of the section.
 
It is important to realize that ductile iron produces a solid layer in contact with the styling. The layer (2-3mm) is more important for thin-walled parts than for thick-walled parts.
 
Cold iron can not make up the molten iron shrinkage, it will only transfer this loose to other areas.
 
The maximum utility of cold iron is half of its thickness or half of the wall thickness, whichever is the minimum.
 
The cold cross section reduces the distance of the riser. On the riser "around" part can not be cold, closer to the riser, the smaller the cold iron thickness.
 
In the whole design should be clear and out of misunderstanding: cold iron only to reduce the role of casting modulus, can not achieve the purpose of filling. Now a lot of people are very faint to think that cold iron can solve the shrinkage that cold iron can remove the loose loose, in fact, the iron will be iron iron cast iron parts of the modulus reduction, and shrink loose to other parts of the.


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