Vacuum-forms is a casting procedure.
The vacuum-form procedure is characterized favourable by application of a vacuum and very in relation to other casting procedures. Because contrary to other procedures one can do here without the form bevels, which are to aim at the simpler lifting of the cast part out from the form. A further advantage of the procedure is a good reproducible dimensional accuracy with outstanding surface quality. The form burr on the division levels and at the Kernmarken is likewise very small. To be poured all can after today's conditions admitted pourable metals and alloys, whereby the maximum pourable weight is dependent on the casting plant only, not of the procedure. With the suction casting procedure tolerance deviations from 0,3 to 0.6% are possible.
When used model for the collecting main a continuous model, with which one manufactures the mold. This consists of quartz sand. The solidification of the moulding sand takes place via creation of a negative pressure from about 0.3 to 0.6 bar inside the model. To the fact it is necessary that the model is provided with small nozzle bores, so that a foil can be pulled from 0,05 to 0,1mm thickness punched, i.e. over the model half. The foil is heated up before the deep-drawing by means of a core few seconds, so that it is plastic ductile. During the deep-drawing the foil puts contour truly and closely to the model. On these the binder-free quartz sand is then up-poured. After forming out the gate pool and stripping the half-mold of the model the molding box is covered with a further foil, so that the sand can be consolidated. This takes place over the negative pressure between the two foils, which developing friction forces between the causes, so that a solidification between them occurs. Afterwards one can take the model off again. Both sides, upper and Unterkasten, are thus formed in this kind. Up to complete solidifying of the cast part after pouring the negative pressure between both foils will keep upright. The vacuum is only turned off for taking the finished cast part. The quartz sand is then re-usable. With this procedure small to mass production is manufactured.
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|Vacuum pressure pouring|