Simple instructions for casting

In the mid-1930s, plexiglass was cast with methyl methacrylate prepolymer (see polymethyl methacrylate). During the Second World War, unsaturated polyester casting products were developed, followed by epoxy resin casting products, and nylon monomer casting products appeared in the 1960s.

Casting (see polyamide). With the development of molding technology, the traditional casting concept has changed. Polymer solutions, dispersions (referring to polyvinyl chloride paste) and melts can also be used for casting. The melted flat film is extruded with an extruder, and cast on a cooling drum to form a polypropylene film, which is called the extrusion-casting method.

In the mid-1930s, plexiglass was cast with methyl methacrylate prepolymer (see polymethyl methacrylate). Casting During the Second World War, unsaturated polyester casting products were developed, and then epoxy resin casting products were developed, and nylon monomer casting appeared in the 1960s. Casting (see polyamide). With the development of molding technology, the traditional casting concept has changed. Polymer solutions, dispersions (referring to polyvinyl chloride paste) and melts can also be used for casting. The melted flat film is extruded with an extruder, and cast on a cooling drum to form a polypropylene film, which is called the extrusion-casting method.

Casting molding generally does not apply pressure, does not require high equipment and mold strength, has small restrictions on the size of the product, and the internal stress in the product is also low. Therefore, the production investment is small, and large-scale parts with excellent performance can be produced, but the production cycle is longer, and machining must be performed after molding. On the basis of traditional casting, methods such as perfusion, insert casting, pressure casting, rotary casting and centrifugal casting are derived.

  • ① Perfusion. The difference between this method and casting is that the product after casting is released from the mold; while the mold is an integral part of the product itself during pouring.
  • ②Inlay casting. Put various non-plastic parts in the mold cavity, solidify together with the injected liquid material, and encapsulate them.
  • ③Pressure casting. Putting a certain pressure on the material during casting is beneficial to inject the viscous material into the mold and shorten the filling time. It is mainly used for epoxy resin casting.
  • ④ Spin casting. After the material is injected into the mold, the mold rotates around a single axis or multiple axes at a relatively low speed. The material is distributed on the inner wall of the cavity by gravity, and the shape is shaped by heating and curing. Used to manufacture hollow products such as spherical and tubular.
  • ⑤ Centrifugal casting. A quantitative liquid material is injected into a mold that rotates at a high speed around a single axis and can be heated, and the material is distributed on the inner wall of the mold cavity by centrifugal force, and solidified into a tubular or hollow cylindrical product through physical or chemical action. Monomer cast nylon parts can also be formed by centrifugal casting.

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