1. Process, effect 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 obtained a patent in 1958, at the beginning of the process for the production of arts 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 low amplitude vibration compaction, no need to take out the shape after molding.During pouring, the foam is gasified decomposed under the action of the metal.After the foam plastic decomposes the space position is replaced by the metal liquid, the metal solidifies 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 need to draw when modelling, can produce traditional method can’t production of complicated castings, casting dimension accuracy surface finish , 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 simplified, the molding has no sand core, no parting, no need for mold box, sand treatment does need to mix sand, sand is simple convenient, but also can effectively eliminate the casting defects caused by water, adhesives additions.
(3) The research direction of EPC process: First, the research of EPC model material mold making technology. EPC is a casting production process that makes molten liquid metal replace plastic model. Therefore, the shape material molding quality directly affect the quality of casting products.Therefore, the material requirements of the casting model are less gas, less density, its strength can resist the sand pressure deformation caused by external forces.At present, the EPS material used in EPC is prone to surface wrinkling surface carburization in the production of cast steel cast iron castings, 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 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 good air permeability, so that rapid gas overflow, the flow of liquid metal coating also rise to control the speed, keep 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 effect
(1) Sand casting process: it is a casting system composed of molding, core making, drying, blending, pouring, sand falling, cleaning 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 other process equipment are used to make “sand molds” then the molten liquid metal is filled into the sand molds the desired castings are obtained when they are cooled.Sand casting is 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 more than 300℃ compared with other molds, the working pressure is more than 1.5MPa, the mold material selection range is wide, the service life is long, 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, the sand mold inevitably has some rough places, so it is difficult to get a bright clean casting appearance.Again, the casting defects, most of the casting defects the poor quality of the casting, such as uneven bending 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 random installation of the gating system leads to the deviation of the metal liquid flow the process requirements, resulting in shrinkage porosity.
(3) The prospect of sand casting process: with the development of social economy the continuous progress of the casting industry, the high compaction molding method of sand casting process (including high pressure molding, injection molding air punching molding) will be widely used.It is characterized by less damage less deformation in the process of transporting, closing casting, high dimensional precision, greatly improved surface quality less waste products.