Take the commonly used EPS beads as example,EPS beads characteristics:semitransparent, preforming rate: 40~60 times,beads diameter: 0.18 to 0.80 millimeters,6 different sizes,generally, original beads diameter should be less than,1/9~1/10. or equal to 1/9 to 1/10 of the minimum wall thickness of the castings,Raw material prefoaming follows right beads selection,Pre foaming of foam beads.

Prefoaming

Before fed into mould,EPS beads need to be pre expanded to a certain size,The prefoaming process determines the density,dimension accuracy and stability of the models,There are mainly two kinds of equipment for EPS bead prefoaming:electric steam prefoaminq machine,and pure steam prefoaming machine,both of which are equipped with the most advanced PLC technology.

Ripening

Pre-foamed EPS beads are placed,in a dry and ventilated silo for a certain period of time,making inside and outside of beads pressure balanced,optimizihg the elasticity and the expandability,and removing water on the bead surfaceThen sent to curing storage hopper through automatic feeding system.

Foam modeling

After curing ripening,EPS beads are fed into lost foam mould cavity by pressure feedinq system and heated,so that the beads are expanded again and fused together,filling the cavity and forming a smooth surface,Models should be cooled and settled before ready,After modeling, there should be enough time for models drying and stabilization,The white model is wet on the surface,and contains moisture inside,so it must be thoroughly dried.

There are mainly two types of forming equipment: hydraulic forming machines and screw forming machines.The lost foam mould-die is made of aluminum alloy,and designed according to different product structure,Model cutting and bonding,Modeling products may only be part of the model or initial forminq blanks,which need further processing such as cutting and bonding,This process is to combine multiple white foam models with gating,and riser models by lost foam special glue to make model clusters.

Yellow area of LFC

Mainly used to brush special coating on white model clusters and to dry in drying rooms,The main functions of coating in LFC are to insulate metal liquid and model,to discharge model gasification waste gas,to ensure surface quality of castings,to improve the strength and stiffness of models and to prevent damage or deformation of the models to a certain extent.

This requires the coating to be air permeable, fireproof coating suspension adhesive in order to reduce the defects on castings such as blowholes, sand burning so as to ensure the rate of finished produtts generally, there are generally four methods for coating and hanging: brushing, dipping, sprinkling, and spraying.

According to the characteristics of different models,several methods can be applied comprehensively in actual production,After coating, models are moved to drying rooms with 45~55℃,circulating hot air for drying,During drying, models should be placed reasonably and supported to prevent deformation,At the meantime, temperature and humidity should be strictly controlled to get thoroughly dryout,After thoroughly dried, model clusters are eady for pouring.

Black area process is the stage of solid casting,Dry model clusters are placed in sand boxs,Special dry sand is fed to sandbox by movable showerfeeding machine for moulding,Molten liquid is poured under negative pressure state,Models gasified with molten liquid replaced,Models gasified with molten liquid replaced,Thus, qualified castings are produced.

The black area of the lost foam casting process is to replace white foam models with molten iron and form casting,There are three steps:vibration moulding,casting replacement fand sand treatment.

The moulding station adopts a vibration platform combined with a shower sand feeding machine for moulding,sand boxes move to position under sand storaqe hopper.The rain shower sander adds bottom sand to the sand box,After the bottom sand is added, the model cluster is put into the sand box, and the rain shower sander again to add sand to the flat gate position.During the whole sand fillinq process,vibration table keeps vibrating to ensure molding,sand is filled to hollow section around foam model cluster.After vibration completed, adding sand to the surface and cover plastic films, finish moulding.

Lower the vibrating table, reposition the sand box onto the track, and use a hydraulic box pushing machine to push the sand box away from the moulding station under the sand storage hopper for the next box moulding.

After moulding,sandboxes are moved to the pouring section one by one,This section is equipped with negative pressure automatic butt-joint machine,When pouring, EPS model is vaporized under the heat of liquid metal,The gasified gas enters negative pressure system through the coating and molding sand.Liquid metal continuously occupies the position of EPS model and occurs the replacement process of liquid metal and EPS model,Finally, qualified castings are formed.

After pouring, the castings need to be cooled down for a certain time in sandbox,then be turned over out of box.Automatic turnover machine is used to seperate castings from molding sand,molding sand goes to sand treatment system,while castinqs qo to shot blasting machine to remove surface coating.

Sand treatment system is a very important production process of LFC,Molding sand after box turnover is primarily cooled by water cooling sand shakeout machine,Then it is separated from casting residue and sundries by screening conveyor,The screeninq conveyor is equipped with air cooling system,which could reduce sand temperature quickly and efficiently,The residue is taken out by the slag lifting machine while the molding,sand is lifted by elevator to sand temperature regulator for major cooling,After all these process,the sand is transferred to storaqe hopper for production.