Lost foam casting technology for ductile iron castings

The lost foam casting technology for ductile iron castings mainly includes the following types:

1.Lost foam casting technology

Lost foam casting technology is a new type of casting technology that combines lost foam casting technology with pressure solidification and crystallization technology.It is a casting method,in which molten metal is poured into a pressure bag with a sand box to vaporize the foamed plastic,and then the pressure bag is sealed and pressurized gas is injected to make the molten metal solidify and crystallize under pressure.The characteristic of this casting process is that it can significantly reduce casting defects such as shrinkage,porosity,and porosity,increase the density of castings,and improve the mechanical properties of castings.

2.Vacuum low-pressure lost foam casting technology

Vacuum low-pressure lost foam casting technology is a new type of casting technology developed by combining negative pressure lost foam casting method with low-pressure counter gravity casting method.The characteristics of vacuum low-pressure lost foam casting technology are:(1)combining the technical advantages of low-pressure casting and vacuum lost foam casting,the filling process is completed under controllable air pressure,improving the casting filling ability of the alloy;Compared with die casting,it has lower equipment investment,lower casting cost,and castings can be processed through heat treatment.Compared with sand casting,castings have lower surface roughness and better performance;Under the action of anti gravity,the main flow channel becomes a filling and shortening channel,resulting in low pouring temperature loss.The liquid alloy solidifies under controllable pressure,and the pouring system of the alloy casting is simple,with a dense structure;Vacuum low-pressure lost foam casting has a low pouring temperature and is suitable for many non-ferrous alloys.

3.Vibration lost foam casting technology

Vibration lost foam casting technology applies frequency and amplitude vibrations during the lost foam casting process,causing the casting to solidify under the action of the vibration field.Due to the vibration time of the metal solution during the solidification process of lost foam casting,the vibration force causes the liquid phase and solid phase to move relative to each other,causing dendrite fracture,increasing the number of crystal nuclei in the liquid phase,refining the final solidification structure of the casting,supplementing shrinkage,and improving mechanical properties.This technology utilizes the existing compact vibration table in EPC,which generates mechanical vibrations through a vibration motor to nucleate the molten metal under dynamic excitation,thereby achieving the goal of refining the microstructure.This is a simple to operate,low-cost,and environmentally friendly method.

4.Semi solid lost foam casting technology

Semi solid lost foam casting technology is a new type of casting technology that combines lost foam casting technology with semi-solid casting technology.Because the characteristic of this technology is to control the relative ratio of liquid and solid phases,it is also called phase change controlled semi-solid forming.This technology can increase casting density,reduce segregation,improve dimensional accuracy and casting performance.

5.Lost foam casting technology

Lost foam casting technology is a new type of casting method that combines investment casting technology and lost foam casting.In this method,several layers of refractory material are coated on the surface of the foam mold,which has the same shape as the parts made of the foam mold,and after hardening and drying,the foam mold therein is burned,vaporized and disappeared to form a mold shell,which is baked and then poured to obtain a cast iron platform with dimensional accuracy.It has the characteristics of large size of lost foam casting patterns,as well as the advantages of investment casting skin formation and high strength.Compared with ordinary investment casting,it has the characteristics of low cost of foam plastic mold material,convenient pattern bonding and combination,easy evaporation and disappearance,etc.It overcomes the problem of investment deformation caused by easy softening of investment casting mold material,and can produce various large size complex alloy castings

6.Lost foam suspension casting technology.

Lost foam casting technology is a new practical casting technology that combines lost foam casting technology with suspension casting.The technological process of this technology is:after the molten metal is poured into the mold,the foam pattern is gasified,the suspending agent mixed in the riser model(or placed in a specific position of the pattern,or made into a foam pattern with EPS)reacts with the molten metal physically and chemically,and the overall(or local)microstructure and properties of the casting.