Investment casting is a casting procedure.
Around cast pieces with highest dimensional accuracy and best surface quality to received this procedure is used. The model is manufactured thereby out special waxes or similar thermoplastics or their mixtures for example in the injection moulding procedure. The models are squirted first into simple or multi-impression moulds. These tools consist of aluminum, steel or Weichmetall, for which a Urmodell is necessary. Depending upon total number of items, shape of the cast piece and kind of the model material the appropriate tool is selected. Around Hinterschneidungen in the outline with to bring in preformed water-soluble or ceramic cores can be necessary, for whatever an auxiliary tool is needed.
Another possibility for the production of the physical collecting mains forms the use of technologies of the rapidly prototyping (construction). It concerns lost models in each case out of a bloomable, gasable or material solvable in a
In the next step the models with the casting system already appropriate are joined to so-called model grapes/clusters. This model grape/cluster is then dipped into a so-called binder suspension (picture). The binder suspension is a ceramic mass for the production of a mask from fine quartz sand as form raw material and ethyl silicate as bonding agent. Applied on this layer a granular, fireproof material, usually consisting of dry quartz sand, in a fluidized bed or through sprinkle. For fuses of the wax models with approximately 150 "°C special fuse furnaces serve, while burning the finished forms is made with approximately 900 to 1200 "°C. With it is important to fuses that when removing the Urmodells no enlargement of its volume arises. This would lead to a destruction of the ceramic(s) form. The finished burned forms are given now to a box, and behind-filled with dry quartz sand as filler. This is however not compellingly necessary, because one can pour also into this mask problem-free. Pouring happens however usually into the forms still hot of the burner, thereby also close cross sections and purifies outlines cleanly "runs out ", how it designates the caster. After the casting and the complete solidification of the melt in the form the plastic material is knocked off, and the cast parts are separated by means of friction disk, saw or vibration from the casting system, and radiated according to it either polished or metallic blast grain.
With this procedure cast pieces with a mass can be poured from 0,001 to 50 kg and in special cases also up to 150 kg. The tolerances are thereby however with approximately 0.4 to 0.7% of the nominal dimension. Steel and alloys can be poured on iron, aluminum, nickel, cobalt, titanium, copper, magnesium or zirconium basis. Likewise the so-called aviation materials are poured. Depending upon complexity degrees of the cast parts manufacturing from small rows to mass production becomes possible.
This procedure has a large advantage in the fact that the finished poured parts are parts usually ready to be installed. The economy and the surface quality of the cast part depend however strongly on the kind of joining the models to the model grapes/clusters. When rule of thumb applies to economy however always the fact that investment casting (like it is also designated) is the construction unit is arranged particularly favorably, the more complicated and/or the more with difficulty it can be worked on.
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