1. Process, effect and prospect of EPC
(1) What is lost mold casting process: lost mold casting process is known as solid mold casting, vaporization mold manufacturing, invented by the United States Sroll and obtained a patent in 1958, at the beginning of the process for the production of arts and crafts castings, at the end of the 1950s West Germany first lost mold casting process for the production of industrial castings.It is characterized by dry sand molding without binder, high frequency and low amplitude vibration compaction, no need to take out the shape after molding.During pouring, the foam is gasified and decomposed under the action of the metal.After the foam plastic decomposes the space position is replaced by the metal liquid, and the metal solidifies and becomes the desired casting.
(2) epc process results characteristics: first, foam in the process of production without complete whole, can block production of adhesive again into the required shape, does not need to draw when modelling, can produce where traditional method can’t production of complicated castings, casting dimension accuracy and surface finish and, of course, the manufacturing precision of foam plastic is proportional to the, have reached a stable investment casting castings, a substantial reduction in the blank of the mechanical processing capacity.Secondly, the process is optimized and simplified, the molding has no sand core, no parting, no need for mold and box, sand treatment does not need to mix sand, sand is simple and convenient, but also can effectively eliminate the casting defects caused by water, adhesives and additions.
(3) The research direction of EPC process: First, the research of EPC model material and mold making technology. EPC is a casting production process that makes molten liquid metal replace plastic model. Therefore, the shape material and molding quality directly affect the quality of casting products.Therefore, the material requirements of the casting model are less gas, less density, and its strength can resist the sand pressure and deformation caused by external forces.At present, the EPS material used in EPC is prone to surface wrinkling and surface carburization in the production of cast steel and cast iron castings, and the EPS mold is prone to damage in the production process due to its low density.
The second is to study the new foundry materials: because of the different from the traditional process, epc is paint besmear is in good shape for the dry before embedment of sand casting, so the requirement of coating is the guarantee of high strength and good air permeability, so that rapid gas overflow, the flow of liquid metal coating also rise to control the speed, keep and vaporization membrane between the appropriate pressure of molten metal, so the requirement of coating over the traditional cavity casting coating required.
2. Sand casting process and effect
(1) Sand casting process: it is a casting system composed of molding, core making, drying, blending, pouring, sand falling, cleaning and other processes.The difference between the products cast by the sand casting process is that the sand casting process is worthy of the name. These product models and other process equipment are used to make “sand molds” and then the molten liquid metal is filled into the sand molds and the desired castings are obtained when they are cooled.Sand casting is not limited by the number of casting, suitable for a variety of different castings.
(2) The effectiveness of sand casting process characteristics: its advantage is that the working temperature of the sand mold produced by the sand casting process is not more than 300℃ compared with other molds, the working pressure is not more than 1.5MPa, and the mold material selection range is wide, the service life is long, and the use cost of the mold is low.Its disadvantages have three aspects: the first is the problem of unstable dimensional accuracy, because the casting is made according to the mold, the mold size will be affected by the casting without exception.Especially for some complex castings, due to the use of multiple molds, the accumulated errors have seriously affected the casting size;Secondly, the surface of the casting is rough, and the sand mold inevitably has some rough places, so it is difficult to get a bright and clean casting appearance.Again, the casting defects, most of the casting defects from the poor quality of the casting, such as uneven bending or tilt of the surface of the mold, the damaged model surface will cause defects in the product;In the process of installation installation deviation will lead to squeezing box, sand hole;The non-standard or random installation of the gating system leads to the deviation of the metal liquid flow from the process requirements, resulting in shrinkage and porosity.
(3) The prospect of sand casting process: with the development of social economy and the continuous progress of the casting industry, the high compaction molding method of sand casting process (including high pressure molding, injection molding and air punching molding) will be widely used.It is characterized by less damage and less deformation in the process of transporting, closing and casting, high dimensional precision, greatly improved surface quality and less waste products.
Post time: Jan-27-2021