Preliminary study on lost mold casting technology

EPC technology, referred to as “the EPC, also known as gasification casting or mold casting, is the traditional wooden and other regular shape to switch to plastic foam shape instead of an entity, a firm of modelling, this kind of casting method, after making good blank, don’t remove appearance, but directly poured into good all kinds of metal melting liquid on appearance,After high temperature of metal liquid, under the action of will to that of foam plastics, high temperature heating gasification combustion and finally disappear, melts the metal liquid, will replace the original foam plastic shape space position in the sand box, metal solution after cooling, solidified at room temperature, can obtain the required mechanical processing and other castings.


1 EPC process flow

The process of EPC is divided into two parts: white area and black area.

1.1 Process flow of white area

The white area is the process of making foam models.Foam model production is divided into manual production and foaming molding.

1.1.1 Foam forming process

According to the material and wall thickness of the casting, choose the foaming bead suitable for it.Then, the original foaming bead is added to the intermittent prefoaming machine for pre-foaming, so that it can reach the required density of the process. After drying in the vulcanization bed of the prefoaming machine, it is sent to the curing chamber for curing.The matured bead is transported to the molding room, and the bead is injected into the prefabricated mold on the molding machine. The steam is used to expand and melt it to form the casting shape, and then the cold water is used for cooling and cooling, so that the foamed white mold has the same strength.

1.1.2 Manual molding process

First of all, according to the blank drawing, the prefabricated blank is divided into several modules, and then the special tool is used to cut each module on the selected foam board, and then according to the blank drawing, each module is glued together with glue or glue stick, and then the United States paper is used to seal each joint well.

In order to ensure the’s strength, stiffness and surface quality, choice of the density of foam board can’t too low, the bubble of the slab good bonding strength between each bead, bead can neither, there is a big gap between at the same time also can’t have too many impurities, in general cases, the need to be made by EPS material, bubble billet surface finish requirement is higher, mechanical machining methods must be adopted if the future production, the production of surface may produce hair fall off or bead and produce corrugated concave and convex surface and the phenomenon such as holes, holes, then in later, must increase the necessary repair, filling process, so as to improve the quality of castings.

The white mold after production is transported to the module room for assembly and bonding of the pouring riser.Then the assembled white mold is transported to the paint room for the first dip brush paint.The raw materials for the production of paint will be mixed in the paint mixer according to a certain proportion, and the paint density will be tested after the required time is reached. The qualified paint will be put into the paint tank to be used.The soaked and brushed white mold will be put on the drying car and transported to the yellow mold drying room for drying. The dried yellow mold will be transported to the secondary coating room for secondary dipping and brushing, and then transported to the yellow mold drying room for drying and repair to reach the required coating thickness.The yellow mold after secondary drying will be transported to the molding department of the black area by drying truck for box filling and molding.

1.2 Process flow of black area

Put the special interlayer sand box on the vibration working table, put the bottom sand about 100MM thick, spend the shaking table, vibrate the bottom sand, and scrape the upper surface.The yellow mould or yellow mould model cluster produced in the previous process is placed on the bottom sand of the sand box. After the position is arranged, the sprue and sprue nozzle are connected. The sand box is filled with dry sand and vibrated in accordance with the specified time of the process.The mouth of the packed box is covered with plastic film, and the sprue cup is placed at the sprue, and the edge of the box body is pressed with quartz sand.The pipeline under the vacuum system hoses connected to the case, to start the vacuum system vacuum vacuum operation, the time schedule of the technique and technological requirements of dry sand tightness after, will have good molten metal casting solution through sprue cup poured onto Huang Mo, waiting for the gasification disappear, high temperature metal liquid instead of position, and out of the gate, after pouring.After the casting is completed, the pressure holding cooling is carried out. After the pressure holding, the vacuum butt machine is reset and removed. After the pressure holding, it enters the cooling section for cooling.After the casting has condensed, turn over the box and remove the casting from the loose dry sand.


2. Disappear the advantages of die casting process

Because of the polystyrene foam, the density is very small, so the labor intensity of the workers in the operation process is low.Using lost mold casting technology, compared with the traditional casting method, because of the cancellation of the core production, so can greatly simplify the molding process, casting sand processing process is relatively simple, in the process of processing white mold and transportation, it is also easy to achieve mechanization and automation of production.Due to the good fluidity of dry sand molding, the sand mixing equipment is exempted, and the molding and compacting equipment is simplified, so the noise and dust can be greatly reduced.The lost mold casting method cancels the core production, and the precision of the blank casting is higher.In the process of pouring, the white mold material is decomposed and gasified under the action of high temperature. The waste gas such as CO and CO2 produced in the production process is not a lot, and these generated waste gas can be connected to the dust collector for optimal treatment in the vacuum machine in the process of vacuuming.The whole production line is equipped with dust removal system, and the air volume regulating valve is added in each equipment room.The dust concentration in the air is obviously lower than the national standard.


Post time: Apr-26-2021