The main points of quality control of ductile iron casting

Kunfeng heavy Industry focuses on the production of ductile iron castings, the main representative products are steel ingot mold, slag filling, sintering trolley body, heat insulation pad and so on. Here are some key points of quality control of nodular graphite castings based on our years of experience. 

With the development of casting in the direction of high strength and lightweight, the market of spheroidal graphite castings is getting bigger and bigger. 

Due to the need for inoculation and spheroidization of molten iron, process quality control of ductile iron is very important. 

The following principles should be paid attention to in the production of ductile iron castings: 

1. Casting principle parting surface as far as possible to put the main mold cavity in the bottom box, conducive to process design, sand box rigid less sand consumption, balanced solidification, the thick part of the use of direct cold iron or sand cold iron, accelerated cooling to get qualified structure. 

The design principle of gating system is quick pouring, slag blocking, feeding, economy and easy cleaning. 

The shape of the inner gate with a better distance (rectangular or approximate square) is easy to be filled and the temperature difference of filling mold is small. 

The inner gate of semicircle or triangle should not be provided with poor shrinkage effect, the center of semicircle or triangle gate has strong thermal insulation, and the joint of gate center and casting is easy to form shrinkage cavity. 

2. Solidification after mold filling can quickly improve the smoothness and internal density of castings, the simplified process without risers saves the cost, and the risers are easy to operate with dark pressure risers as far as possible. if large parts cannot be poured at once with open risers, manual fire booking (hot metal replenishment) is necessary. 

3. The production of ductile iron castings should be controlled not to produce white mouth and hard edge. 

Solution: 

1) Control of chemical composition. 

2) enlarge the gate. 

3) the temperature of molten iron is more than 1450 ℃, and the pouring temperature is increased.