What problems do ductile iron foundy need to pay attention to when casting ductile iron castings?

Ductile iron is one of our more common materials, because of the good characteristics of ductile iron, so it is generally used in the production of parts with complex stress, strength, toughness and wear resistance, etc., some tractors, internal combustion engines The crankshaft and camshaft of these machines, as well as the medium pressure gate valve in the general machinery are cast with ductile iron, so when the ductile iron is cast, what does its fluidity and pouring process look like? Next, the ductile iron manufacturers will introduce to you the pouring process and fluidity of ductile iron:

When spheroidizing is carried out, ductile iron manufacturers will add nodularizing agent to it, which will reduce the temperature of the metal liquid, and will also make the magnesium and rare earth and other elements in the liquid form slag inclusion in the gating system. After spheroidization, the fluidity of liquid metal will decrease, and if slag inclusions enter the cavity, it will cause defects such as pinholes, inclusions and rough surface of castings.

If you want to solve these problems, you should pay attention to the following points in the casting process:

(1) When pouring, ductile iron manufacturers should also appropriately increase the pouring temperature, which can also improve the filling capacity of the liquid, and the increase in temperature will also help to avoid carbides. According to relevant statistics, when the wall thickness of the casting is 25 mm, the pouring temperature cannot be lower than 1315 °C; When the wall thickness of the casting is 6 mm, the pouring temperature cannot be lower than 1425°C.

(2) Ductile iron manufacturers can also use semi-closed gating system, according to the data recommended by foreign foundry societies, the ratio of cross sprue, straight sprue and inner sprue is 4:8:3.

(3) If you want to prevent slag inclusion, you can also place a filter in the casting system.

(4) The scum on the surface of the molten iron in the pouring bag must be cleaned up, and it is better to use the teapot spout to pour the bag at this time.

(5) It is recommended to control the residual amount of magnesium at 0.06% as much as possible.

(6) If you want the metal liquid to fill the cavity as soon as possible, the gating system should maintain sufficient size and avoid turbulence as much as possible.

(7) The opening of the inner sprue should be opened at the bottom of the mold as much as possible.