Molding
The casting is the act of taking a fingerprint which is then used to mold in which to place a material which will draw or produce multiple copies of a model. The mold is then placed in a material (liquid, paste, powder, sheet, plate, parison , preform, pellet, etc.). in a mold whose shape it takes. The material and / or mold are heated.
Summary |
A successful casting requires a lot of thought and taste. Before any operation, we must study carefully the forms, feel every detail. With a little experience, the careful observation of the model combined with a little practice to determine the choice of technology and products to use.
It is mainly the work of the modeler , who after the play to be performed, determines the models to make the footprints in the molds, cores, and the taking into account the need for stripping, removal of the material. The modeler is one who designs the tools within the design office, but also realizes that models the toolroom.
Different types of molding
Sand Casting
Very common technique in casting , mold by destruction of the mold. The advantage of this technique is that it allows working with a refractory material (sand), and the mold is inexpensive to manufacture.
- Wet sand casting
- the sand is mixed with a resin of any kind, but takes its moisture condition. The molding is carried out either in horizontal, in frames (where the oldest and most common) or in the form of lumps with vertical joint plane and is the root ball or casting process Disamatic.
- Molding sand thermal curing
- hardening takes place either in or outside the footprint impression.
- Chemical hardening molding sand
- hardening occurs by chemical reaction , either between components (resins), or by the action of a gas.
- Physical hardening molding sand
- hardening occurs by direct action and physical on the sand as vacuum molding or V-process method.
- Casting
- techniques are the most diffuse, for the oldest, that of casting lost wax and the more modern, the casting model polystyrene known as the Lost Foam process or PMP.
Metal Casting
The metal mold is reusable several times. The release is made possible by the difference of material between the mold and the cast metal. The mold is still undergoing a Diecasting before introduction of molten metal.
- Gravity casting
- Parts aluminum (piston motor).
- Low-pressure molding
- semi-automatic process for the manufacture of castings of high quality, accurate and uniform in small and large series. The metal, usually aluminum, is introduced into the mold through the bottom at low pressure (0.2 to 2 bar).
- Pressure die casting
- aluminum parts (automotive, aerospace) and zinc alloy , or plastics ( injection molding ).
Special methods of molding
- Moulding with inserts
- an insert, usually metal, is placed in the mold before casting the metal and will be secured to the finished part.
- Molding chillers
- metal parts temporarily put in the mold during casting and which are designed to rapidly cool the metal at the point of contact and cause local quenching.
- Centrifugal casting
- the metal is poured into a mold in fast rotation. Also used to manufacture composite (reinforcement more resin).
- Casting Bimetal
- obtained by flowing successively for two different alloys, in the final, one-piece two components having different characteristics depending on the location in question.
- Continuous casting of metals
- a process where the graphite mold with open ends, is supplied with molten metal that solidifies to produce a bar, a tube or any profile.
- Molding flexible footprint
- the emergence of flexible molds (primarily in gelatin , rubber, latex, rubber and today especially silicone ) allows significant simplification in the design of molds, as well as the direct production of forms which would have required machining after molding with a rigid mold (cons undercut forms in particular).
- Casting by freezing
- method of tying the sand with ice by injecting nitrogen or liquid CO 2.
- Molding liquid forging
- metal mold, commonly known as squeeze-casting, applies to light alloys, with a solidification under very high pressure.
Purpose of molding
The molding technique is most often the objects of mass production more or less important. In-pressure casting, the object can be solidified once released (release) without deterioration of the mold, and molding sand molds are made as much as parts (if the foundry sand).
Notes
Related articles
Other techniques:
- Overmolding
- Plaster cast
- Casting staff ultralight
- Lottinoplastie
- Plastiform
- formwork
External Links
- [Pdf] Different casts
- The site Nonferrous Foundry provides online technical and economic information.
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