Shandong Aluminum Alloy Die Casting Factory teaches you how to solve shrinkage porosity of die castings. It is a common phenomenon that shrinkage porosity exists in aluminium alloy die castings. Is there a thorough solution to this problem?
1. Causes of shrinkage and porosity in aluminium alloy die castings: There is only one cause for shrinkage and porosity in die castings, that is, phase transformation shrinkage is inevitable when liquid phase is transformed into solid phase after filling of metal melt. Because the solidification characteristics of die castings are cooling from outside to inside, shrinkage and porosity will inevitably occur inside when the wall thickness of castings is large. Therefore, as far as the die castings are concerned, especially the heavy ones, it is inevitable to have shrinkage and porosity problems, which can not be dealt with.
2. The only way to deal with shrinkage and porosity defects of aluminium alloy die castings: shrinkage and porosity of die castings can not be thoroughly dealt with by the die casting process itself. To deal with this problem thoroughly, we can only go beyond the process, or seek treatment methods from outside the system. What is this method?
In terms of technological principle, the treatment of shrinkage and porosity defects in castings can only be stopped according to the technological idea of feeding. Phase transformation shrinkage in solidification process of castings is a natural physical phenomenon. We can not reverse the law of this natural phenomenon, but only follow its law to deal with this problem.
3. There are two ways of feeding: natural feeding and forced feeding. Many people intuitively think that low pressure casting can deal with shrinkage and porosity defects of castings, but this is not the case. The application of low pressure casting technology does not mean that shrinkage and porosity defects of castings can be dealt with, if low aluminum alloy die casting technology is used. The system has no feeding process measures, so the blank consumed by this low-pressure casting wrist may also have shrinkage defects of 100%.
Because of the characteristics of the die casting process itself, it is difficult and complicated to establish a natural "secondary solidification" process measure. The most basic reason may also be the "secondary solidification" process measure, which always requires the casting to have a comparatively long solidification time, which is somewhat inconsistent with the die casting process itself. The biggest characteristic of forced solidification feeding is that the solidification time is short, which is only one fourth or less of the second solidification. Therefore, the addition of forced feeding technology measures on the basis of the die casting process system is compatible with the characteristics of die casting process, and it can deal with the shrinkage porosity of die castings very well.
4. There are two levels of forced feeding: extrusion feeding and forging feeding. There are two levels when the forced feeding of castings is completed. One is the fundamental level which can eliminate shrinkage and porosity defects in castings, the other is the level which can make the inner of the blank reach the level of broken grain or forged structure. If we want to use different words to express these two different levels, then the former can be expressed by "extrusion feeding" and the latter can be expressed by "forging feeding". One of the concepts to be fully aware of is that feeding is a direct skill that cannot be accomplished indirectly. In technology, we can have a process parameter to express, which is "feeding pressure". In physical principle, the concept of pressure can be presented in two situations. One is in the place of liquid, i.e. Pascal's law. For clarity, we define it as "liquid pressure" and the other is in the place of solid, we define it as "solid pressure". It should be noted that the applicable conditions of the concept of pressure presented in these two different states. If we mix it up, we will have a big problem.
Shandong Aluminum Alloy Die Casting Factory teaches you how to solve shrinkage and porosity of die castings. Jinan Hongjie Mold Co., Ltd. has 20 years experience in die processing and manufacturing. It has always followed the spirit of excellence and innovation, constantly carving its own products, constantly improving its own technology, and enjoying the process of product sublimation in both hands. Welcome to inquire!