Pressure Die Casting

Content.

  1. Introduction
  2. Cold chamber Die casting
  3. Advantages & limitations of cold chamber Die casting
  4. Application of cold chamber die casting
  5. Hot chamber – gooseneck type
  6. Hot chamber – plunger type

Introduction

History:

  • Pressure Die casting is believed to have begun sometime during middle of 19th century.
  • According to records, Sturges patented the first manually operated pressure Die casting machine during 1849.
  • Various compositions of tin & lead were first Die casting alloys.
  • Their importance and use declined with the development of zinc alloys & the Mg a Cu followed.

Introduction content

  • Pressure Die casting types:
  • Cold chamber pressures die casting.
  • Hot chamber pressure die casting.

Specialty of Die casting process:

A “metallic mold” is used to prepare sand mold with which larger number of casting are made. The metallic mold is known as “die”.

Cold chamber Die casting

  • In this machine, the metal is melted separately in the furnace and transferred to these by means by small ladle. After closing the die, the molten metal is forced into the die cavity by a hydraulically and pressure is maintained till solidification. These machines can either have vertical plunger or horizontal plunger for forcing molten metal into die These machines can either have a vertical plunger or flat plunger for driving liquid metal into biting the dust.
  • Advantages & limitations

Advantages of cold chamber die casting:

Straightforward development Thus the expense of the gear isn’t extremely high.

Limitations of cold chamber Die casting:

Slower cycle time due to the need to transfer the molten metal from furnace to the cold chamber machine. Hence, the rate of production will be less.

Alloys cast with cold chamber die casting:

  1. Aluminum alloys:

A360 alu die casting, A383, A384, A290, A413, A418, A380 aluminum die casting,

  • Zinc alloys with larger proportion of aluminum:

ZA-12, ZA-27

  • Magnesium alloys:

AZ91D, AM60A, AS41A

  • Copper alloys

Hot chamber pressure die casting

Hot pressures die casting types:

  • Gooseneck air injection type
  • Submerged plunger type

Goose neck air injection type

In this machine, the goose neck container is operated by lifting mechanism. Initially it is submerged in molten metal and filled by gravity, and then it is raised so as to bring the nozzle in contact with die opening and is looked in that position. Compacted air at that point powers the metal into the bite the dust and weight is kept up till hardening. When solidification is complete, the goose neck is lowered down and casting is removed by ejector pins after opening the dies.

Plunger type

I this machine, the goose neck type container always remain immersed in metal pot. The molten metal from metal container is forced inside the die with help of plunger submerged in molten metal comes up and fills the cylinder and when plunger moves down, the metal is forced into die. The moveable die platen is synchronized such that when plunger is moving up, the moveable die platen moves away and casting is removed.