Notes for lost mold casting

Epc has certain specifications and requirements.The following aspects should be paid attention to in the forming process: the requirement of using silica sand in epc is 85% ~ 90%.In terms of air permeability and fire resistance, cast steel and cast iron components are usually selected from silica sand with particle sizes of 0.850 to 0.300mm.

First, a layer of dry sand of about 100mm thickness was placed at the bottom of the sand box. Then the EPS mold and the pouring riser with paint were placed in the center of the sand box and the sand was compacted.Until the dry sand is about 50mm away from the top of the box.When the grinding stops, cover the dry sand with the plastic film, then place the pouring cup on top of the sprue and remove a layer of loose sand from the film to prevent spatter of iron.When dumped, the film blows through the film and causes leakage.

pouring

In epc process, the whole process includes seven links, each of which has a great influence on the quality of epc.Of course, the casting process is also an important part of the whole process.The key to producing high quality lost mold castings is to strictly control every detail of casting process.

The casting process is the process of filling molten steel and evaporating the foam mold.Note :(1) the runner should always be filled with molten steel.If not satisfied, because the coating strength is limited, prone to sand collapse and air intake phenomenon, resulting in casting defects.(2) when pouring molten steel, be sure to hold to ensure stability, accuracy and speed.Fill the sprue cup immediately and finish a large amount of molten steel quickly and continuously in about a minute or so.If the molten steel in the same box casting is sucked into the air, it may lead to sand slip or increase the porosity of the casting, resulting in scrap of the casting.(3) if the lost foam casting is closed under negative pressure, it must be closed under the gate cup.The molten steel enters the forming mold, begins to liquefy and burn, vaporizes and disappears.The front end of the molten steel forms a temporary cavity at a short distance, so the steel fills almost as fast as the foam model disappears.In order to prevent the high-temperature radiation of molten steel from melting other models in the same tank, the runner should be kept away from the casting model appropriately.The position of the sprue shall be selected from the lowest position of the FCL casting.When pouring, pay attention to adjust and control the vacuum suction in a certain range.After pouring, it is kept under a certain negative pressure for a period of time.The negative pressure stops and the molten steel condenses out of the box.

To prevent the gush after

A method to prevent reverse injection in lost mold casting

Lost mold casting is one of the casting processes.There are various casting defects in the casting process, which lead to defects in the casting and the loss of foam casting is no exception.Back spray is a kind of phenomenon that often happens in lost mold casting.When the back spray is serious, it may endanger the personal safety of pouring workers.It has to be taken seriously.To reduce spraying, the following measures can be taken:

First, the density of the foam model should be small.The foam should be as light as possible to reduce the amount of gas produced during pouring while ensuring the surface quality of the foam and the strength of the model.Secondly, the foam model must be dried before coating.Weight changes during drying of each batch of foam models should be checked and a baking weight change curve should be performed.Only when the weight does not change can the coating be applied.Third, the gating system, especially the sprue and runner, should not be coated so that the gas produced during the pouring process can be pumped out quickly and completely without coating, which saves coating consumption.Finally, a baffle is placed at the top of the spout cup to prevent the spray of molten steel from spilling out, endangering field operators.

The above method can effectively prevent the reverse spray phenomenon in the process of epc, better prevent the casting defects, improve the casting quality and further improve the production safety.