Chromite sand as foundry chilling sand
Chromite sand is a non-metallic mineral product with an iron content of about 25%. The main component is chromium oxide. Chromite sand has the characteristics of high sintering temperature and strong thermal conductivity. Therefore, chromite sand can be used as chilling sand in complex castings that are difficult to shrink, or in the flow channels and hot spots inside castings. Chromite sand working as chilling sand can shorten the cooling time of castings. In the meantime, it can intervene in the cooling sequence between different parts of castings. Especially for large thick wall steel castings and ball-milled cast iron castings, chromite sand improves the density and mechanical properties of castings.
The chilling effect of chromite sand has the following function:
1. Cooperate with the pouring system and riser to control the solidification sequence of the casting, strengthen the sequential solidification conditions of the casting, and increase the longitudinal shrinkage length of the riser.
2. Accelerate the solidification cooling rate of castings, improve and optimize the metallographic structure of castings, refine grain size, and enhance the mechanical properties of castings.
3. Divide the feeding area of the riser, control and expand the feeding range of the riser, and improve the feeding efficiency of the riser.
4. Reduce and prevent segregation of thick wall castings, and avoid chemical sand sticking.
5. Reduce the tendency of casting shrinkage and porosity, reduce the size of the riser, and improve the process yield.
6. Reduce the modulus of hot spots in castings, eliminate local thermal stress, and avoid cracking defects in castings.