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» Personal Loan No Credit Check, Online Economics » Prototypes » Topics begins with P » Pressure pouring


Page modified: Wednesday, July 13, 2011 19:57:36

Pressure pouring is an industrial casting procedure for the production of parts and products.

With the pressure pouring the liquid melt of a non-ferrous metal alloy under high pressure is pressed from about 10 to 200 MPa and with a very high speed of up to 120 m/s into a Druckgussform (mold), where it cools off then. The special at the pressure pouring procedure is that with a continuous form, i.e. without model, one works. Thus the expenditure of the form production results only once and it a high output is obtained, in particular with a warm chamber pressure casting machine (WKM) with a series of same construction units, with which the casting container and thus also the thrust cylinder constantly is in the melt (only with very lowmelting metals possible).

The most frequently used materials are

  • Aluminum (aluminum pressure pouring),
  • Zinc (die-cast zinc) and
  • Magnesium (Magnesiumdruckguss).

The tools needed in the pressure pouring procedure in the tool construction respectively in the building of forms are manufactured.

As material for the molds one mostly uses special materials or high-strength hot-work tool steels according to DIN EN ISO 4957, like e.g.

Material short nameMaterial number
32CrMoV 12-281.2365
X37CrMoV 5-11.2343
X40CrMoV 5-11.2344

Characteristics

Smooth, clean surfaces and edges possess pressure pouring hurry. The moreover one this procedure permits smaller wall thicknesses than others procedure with zinc for example can the parts a wall thickness of 1 mm and with aluminum of 1.4 mm, in cases of outer taking even under 1 mm have.

The attainable tolerances are with 0.05 to 0.15 mm, so that also of details or also Fertigguss is spoken. With large cast parts one needs however somewhat larger tolerances.

It is possible parts from other materials, how e.g. sockets to cast in screw mountings or pins with. Internal threads are manufactured directly with swivelling steel cores, which can be removed then later again. Contrary to other procedures one calls here the casting "shot ". It is to be accomplished possible up to 300 shots per hour. Depending upon casting material the output per sharpening of the forms to 500,000 shots amounts to.

With aluminum service lives are reached of approx. 100,000 shot. For a long time aluminum pressure pouring was not considered as weldingsuitably and not warm-treatable. In the meantime succeeded in complex investigations manufacturing aluminum pressure pouring however weldingsuitably and warm-treatable. However it is necessary for these characteristics to consider with the construction the requirements of the procedure.

History

The pressure casting process became at the beginning 20. Century in the USA under the name "injection moulding" admits. Also the terms "die cast" and "Fertigguss" were common. Today the most applicable designation "pressure pouring" is only used.

Admitted European companies, which diecasting machines manufacture are among other things Mueller wine garden AG, Oskar impudently GmbH or AG. Pressure pouring parts for customers become for example of DGS pressure pouring of systems AG or the G.W.P. AG G.W.P. AG manufactured. Chromium plating-able casting is manufactured under others by the company pressure pouring Westphalia.

Pressure casting machine

Pressure casting machines consist of a form closing unit, which serves opening and closing the pressure mold. Further inventory hurry are a firm machine plate for the admission of the being certain casting in half-mold and the casting set, a mobile machine plate to the admission of the ejector die and four guide column, which takes up the form closing unit, the Zuhaltekraft produced and for the guidance of the mobile machine plate provides.

The vacuum-supported pressure casting process makes workpieces possible with small or no occluded gases. With this procedure aluminum or magnesium melt is proportioned with the help of a vacuum, which is produced in the form and filling chamber. The dosage is determined here over a defined time.

Shrinking behavior of aluminum silicon melts

If one in such a way pours liquid aluminum of for instance 700"°C into a form cavity that the form is exactly filled out, then the volume of the metal up to ambient temperature is reduced due to its contraction by altogether about 13%. From this total value 0.5% are allotted to the liquid, 7,5% to the solidification and 5% to the solid concentration.

This volume deficit of 13%, that with aluminum alloys is not many smaller than with Reinst metal, becomes apparent at the solidifying cast part in form of volume errors. These errors appear apart from normal shrinking partly as idea places, partly as macro pipes or as shrinking pores.

Shrinking cannot carry out itself in a pressure mold as unhindered as e.g. in Sandgussform.Der expression "shrinking "meant in the giessereitechnik except a procedure a measure size the proportional deviation of the cast part cooled off of the dimensions of the Formfasson in Betriebstemperatur.Ob now a shrinking freely or handicapped taking place can, depends almost exclusively on the geometrical shape of the cast part. It is thus possible the fact that one can use mass to and the same cast part for many the today generally usual shrinkage dimension of 0,5% while for other ranges 0.4% could be still too much. The form dimensions are to be specified with consideration on the basis a shrinkage dimension design of the pressure casting alloys concerned.

Shrinkage dimensions for pressure pouring

Diecasting alloyShrinkage dimension in %
Aluminum alloys0,5 - 0,7
Magnesium alloys0,5 -0,8
Zinc alloys0,4 - 0,6

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