Die casting machine

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The die-casting machine is a technical device ( machine ) that uses the die-casting process to manufacture products or their preliminary stages.

There are essentially two types of die casting machines, namely those with cold and warm filling chambers.

Hot chamber process

A special feature of the die-casting machines with a warm filling chamber is a construction that connects the furnace with the die, called a casting container , directly in the melt , which is kept warm in a crucible . The die casting machine and the holding furnace form a unit. The casting unit (casting container) is also located in the melt. This makes it impossible to cast aluminum or copper-based materials , because at the higher temperatures of at least 700 ° C there is a risk of destruction of the bare metal permanent forms due to uncontrollable diffusion.

This process can be fully automated in industry, resulting in fast cycle times of three to four seconds, depending on the size of the machine. In such machines, the liquid metal (zinc, tin and magnesium alloys) is sucked in by the plunger moving upwards. During the downward movement, the inlet opening is closed and the liquid metal is pressed into the die casting mold. The die-casting machines have a high heat dissipation speed. As a result, the structure of the cast part is very fine-grained and very dense immediately below the edge shell of the parts. As a result of the high inflow speed of the liquid metal, the air cannot escape from the mold cavity quickly enough. In this way, porosities , i.e. air inclusions, are often found in the inner part of the castings .

Accordingly, the hot chamber process has the following disadvantages, in addition to the restriction that it cannot cast any materials containing aluminum or copper:

  • the duct system up to the mouthpiece is always hot (with magnesium alloys temperature up to 700 ° C),
  • Leakage problems (at the transition from the casting container to the nozzle body, nozzle body to nozzle tip, nozzle tip to die casting tool),
  • high wear on the piston and casting container,
  • Air inclusions due to high pressures.

Well-known manufacturers of hot chamber die casting machines are

Common machine sizes for hot chamber die casting machines range between 5 and 800 t of locking force.

Cold chamber process

In cold chamber die casting machines, the die casting machine and the furnace for providing the liquid metal are always arranged separately, and the required amount of melt is dosed into the filling chamber manually or automatically (using a dosing furnace or scoop device). In the case of cold chamber die casting machines, a distinction is also made between those with a horizontal and vertical arrangement. In the following section, the cold chamber die casting machine with a horizontal arrangement is explained.

In cold chamber die casting machines, the liquid metal is first poured into the filling chamber. With the horizontally movable plunger, the mold is filled and solidified under pressure. After opening the die casting mold, the “shot” (casting, sprue, overflows and press cake) is ejected from the movable mold half.

This method is particularly suitable for alloys based on aluminum and copper. But magnesium alloys are also processed using the cold chamber process. Due to the nature of the process, this process does not achieve the same performance as the hot chamber die casting process.

Well-known manufacturers of cold chamber die casting machines are:

as well as formerly Müller Weingarten Druckgusstechnik which was taken over by Oskar Frech.

Common machine sizes for cold chamber die casting machines range between 125 and 4100 t locking force.