The minimum wall thickness of sand casting iron castings is an important parameter of the evaluation of the factory’s ability, a measure of the molding and sand processing technology, and has a great influence on the tensile strength and impact toughness of the ferrous products. Therefore, the minimum wall thickness of sand casting is closely related to the production quality and safety of the factory.
In general, the minimum wall thickness of ferrous castings depends on the size and complexity of the castings, the type and characteristics of ferrous materials and the chemical composition of the metals. For general sand-casting of ferrous castings, the wall thickness should not be less than 4mm.
In most cases, when the casting design requirements are too thin, it is difficult for the traditional sand casting to meet the design requirements. Therefore, in order to meet the requirements of the drawing, some improvement measures must be taken when producing ferrous castings, such as changing the molding sand and applying the vibration coefficient technique.
Changing the molding sand can increase the compaction of the sand layer. The vibration coefficient technique is based on the casting process. The vibration coefficient is built into the mold. The vibration coefficient technique can improve the fill-forming of the sand cavity, reduce the surface deviation and meet the slenderness requirements of the casting design. It is a commonly used technology for improving the minimum wall thickness of sand casting.
In addition to adopting the above two methods to improve the minimum wall thickness of sand casting, the following points should also be noted:
1. The moisture content of the sand should be controlled properly. If the moisture content of molding sand is too high or too low, it will affect the demoulding of castings and make it difficult to meet the requirements of the drawing.
2. The temperature of the casting and the cooling time should be controlled properly. Improper temperature control and cooling time control can lead to casting shrinkage defects, making it difficult to meet the requirements of minimum wall thickness.
3. Select appropriate model to make up the core. If the core is too thick, it will reduce the excess and pressurizing space of sand core, thus resulting in insufficient wall thickness.
In addition to these, there should also be sufficient filling time in the production process, proper core position and moderate core hardness, which is beneficial to the improvement of wall thickness of sand casting.
The above is some common methods for improving the minimum wall thickness of ferrous castings. Of course, manufacturers also need to continuously improve their production process, equipment technology and improve their understanding of the characteristics of ferrous materials in order to create castings of better quality and higher strength.
