Casting alloy casting

The process of pouring molten metal into a mold is called pouring. Improper pouring process will cause defects such as porosity, shrinkage, cold barrier, insufficient pouring, slag inclusion, cracks, fire running, sand sticking and other defects in the casting. Pouring work is not properly organized, and accidents may occur.

1. Preparation before pouring

1) Prepare pouring ladle. The pouring ladle is a container that holds the molten metal flowing out of the smelting furnace, and then pours the molten metal into the mold. Pouring ladle can be divided into end ladle, lifting ladle and hanging ladle according to the capacity. The choice of pouring ladle should be determined by the size of the casting.

2) Clear the channel. When pouring, there should be no debris in the passage, let alone stagnant water.

3) Drying appliances. Drying utensils can avoid splashing and cooling of molten metal due to moisture caused by pouring ladle, slag hook and other utensils.

2. Matters needing attention when pouring

1) Pouring temperature. If the pouring temperature is too low, the fluidity of the molten metal is poor, and castings are prone to defects such as pores, cold barriers, and insufficient pouring; if the pouring temperature is too high, the castings are prone to shrinkage, cracks, fire, sand sticking and other defects. Normally, the pouring temperature of gray cast iron is 1230℃～1380℃, the pouring temperature of cast steel is 1520℃～1 620℃, and the pouring temperature of aluminum alloy is 680℃～780℃; the upper limit is taken for complex thin-walled parts.

2) Pouring speed. If the pouring speed is too slow, the temperature of the molten metal is too much, and the castings are prone to defects such as slag inclusion, cold barrier, and insufficient pouring; if the pouring speed is too fast, the castings are prone to defects such as porosity, sand washing, box lifting, and fire running.

3) Pouring technology. When pouring, attention should be paid to slag removal, slag blocking and ignition.

4) Estimate the weight of the molten metal. The mold should be filled at one time, and the flow should not be interrupted during the pouring process, and the sprue cup should always be kept in a full state.