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Moulage sous pression

Pressure die casting is a metal casting process. It is characterized by applying high pressure to the molten metal using the mold cavity. Molds are usually machined from stronger alloys, a process similar to injection molding. Most die castings are iron-free, such as zinc, copper, aluminum, magnesium, lead, tin, and lead-tin alloys and their alloys. Depending on the type of die casting, a cold chamber dies casting machine or a hot chamber die casting machine is required.

Pressure Die Casting

Le moulage sous pression est une méthode de coulée spéciale qui s'est développée rapidement dans la technologie moderne de traitement des métaux avec peu ou pas de coupe. C'est le processus de remplissage du moule fondu sous haute pression et haute vitesse et de cristallisation et de solidification sous haute pression pour former des pièces moulées. La haute pression et la vitesse élevée sont les principales caractéristiques de la coulée sous pression. La pression couramment utilisée est de dizaines de MPa, la vitesse de remplissage (vitesse dans la porte) est d'environ 16 à 80 m / s et le temps de remplissage de la cavité du moule avec un liquide métallique est extrêmement court d'environ 0,01 à 0,2 seconde.

Avantages du moulage sous pression

Le moulage sous pression est la méthode idéale pour produire un grand nombre de pièces métalliques avec une excellente finition de surface et une excellente stabilité dimensionnelle.

Le cycle de production de HPDC comprend:

1. Metering of metal into the shot sleeve.
2. Plunger movement.
3. Rapid die filling. The steel dies, typically 200-300°C, dissipates the latent heat.
4. During solidification, the casting is pressurized hydraulically by the plunger to feed the solidification shrinkage. Locking forces up to 4000 tons are commercially available to withstand the large pressures
5. The die is opened.
6. The casting is then ejected. The hydraulic energy is provided by a computerized system that permits control of metal position, velocity and plunger acceleration to optimize the flow and the pressure during filling and solidification.

Application of Pressure Die Casting

Le nombre de pièces varie de 50 ou 100 pièces prototypes à des milliers d'exigences de production de masse, qui seront toutes produites d'une manière minutieuse et précise que nous appliquons à tous les projets.

  • Pièces automobiles telles que roues, blocs, culasses, collecteurs, etc.
  • Moulages aérospatiaux.
  • Boîtiers de moteurs électriques.
  • Ustensiles de cuisine tels que l'autocuiseur.
  • Armoires pour l'industrie électronique.
  • Appareils de quincaillerie générale, pièces de pompe, pièces de plomberie.

Essai's die casting equipment has the ability to process internal molds and can produce molds with a weight of 2.5KGS and a size of up to 500x500x250mm. We have 10 die-casting machines with clamping forces ranging from 80T to 630T. The commonly used casting materials are aluminum (usually ADC10 / 12 and A380) and zinc (3 # / 5 #). Castings can also be subjected to a large number of second processes in Essai's own processing facilities, as well as various cosmetic processes including powder coating, spray coating, anodizing, polishing, and electroplating.

1. High pressure dies casting can be divided into "cold-chamber" and "hot-chamber" processes.

2. In the cold-chamber process, molten metal is metered into a cold chamber for each machine cycle (or shot).

3. The molten metal is then forced by a single plunger through a narrow feeder channel (or gate), into the die cavity itself, by the application of pressures from 7 to 207 MPa.

4. The metal solidifies rapidly because the die is water-cooled within a fraction of a second.

5. Upon solidification, the dies are opened and the casting is removed using ejector pins.

6. Most of the castings will have flash where the two die halves come together. This is usually removed in a trimming die.

7. The high cost of dies (up to £250,000) and the capital cost of machines (£175,000–£350,000) limit this process to the high volume production of components.

8. Hot-chamber die casting is limited to the low melting point magnesium and zinc alloys, where contamination by the iron will be less extensive. A gooseneck shot sleeve is submerged in a heated pot of molten melt. A plunger descends and forces the molten metal into the die. As the piston retracts, the cylinder is filled with metal.

1. High pressure dies casting is restricted to the lower melting point alloys.

2. The bulk of die casting is carried out in zinc-, magnesium- and aluminum-based alloys.

3. The most popular zinc-based alloys (known as Mazak) contain 3.8–4.3% aluminum and 0.10–1.25 wt% copper, with tensile strengths of 293–355 MPa, and elongations of 3–4%. Zinc alloys have a higher impact strength than die-cast aluminum alloys.

4. There is six main aluminum die casting alloys used in the UK. All contain 4–13 wt% silicon, which is used to promote good castability. The most common alloy is LM6-M (BS 1490), which contains 10–13% silicon, and has a tensile strength of 280 MPa and an elongation of 2–5%.

5. The strict melting practice is required with magnesium-based alloys, which are mainly used on hot-chamber machines. The most popular alloy contains 9–10% aluminum and 1% zinc, achieves a tensile strength of 215 MPa and an elongation of 2%.

6. The degree of retained porosity in the die casting affects the properties of the product.

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