Except for the common high pressure die casting and low pressure die casting, there is another type of die casting process – gravity die casting. Unlike pressure casting, the working of gravity casting involves the application of gravity.
Gravity die casting, one of the oldest known metal fabricating processes, is a permanent mold casting in which the molten metal flows by the force of gravity without the use of external pressure, tilt pouring is a modified form of gravity die casting features a mechanized system tilts the mold and directs the molten metal into the casting mold, the metal is transferred manually or automatically into the mold, the casting is allowed to cool and solidified casting will be ejected out of the mold. During the gravity die casting, the rate of the flow of material into die cavity and the rate of heat transfer during solidification should be controlled.
Advantages of Gravity Die Casting
– Good surface finish
– Tight dimensional tolerance
– Take small floor space
– Thin castings can be produced easily
– Ideal for mass production
– Reduces the requirements on skills
Disadvantages of Gravity Die Casting
– High initial cost of the mold
– Not suitable for casting made of metals with a high melting point
– The mold is cleaned using a wire brush or compressed air to remove dust and other particles from it.
– It is preheated to a temperature of 200-280 ℃ by gas or oil flame and then the surface is sprayed with a lubricant.
– When the mold is closed tightly, the liquid metal of the desired composition is poured into the mold under gravity.
– After the metal cools and solidifies, the mold is opened and the casting is removed.
– Gating and risering systems are separated from the cast part.
– The mold is sprayed with lubricant and cleaned for the next casting process. The mold does not need to be preheated again.
The permanent mold for gravity die casting will be made with metallic materials, it will be dividing into two halves, the two halves will be get together and be aligned with the help of locating pins. There will be clamping systems, cavity from both the modes, pouring cup, riser, and more parts. The molten form of the metals will be pouring into the permanent mold. With the help of the bladder, the metal will be pouring into the sprue, so passing through the sprue, that will be entering and with the help of gravitational, it will fill the cavity and towards a riser, so by the gravity that will be used to making components, this is also a permanent mold casting process. After the solidification, the dies are opened and cleaned, then ready for the next cycle of operation. The gravity die castings or permanent mold castings is a casting process in which the molten metal is poured into a metallic mold called as a die under the influences of gravity. The mold is usually made from cast iron materials, tool steels, graphite, copper, or aluminum alloys, and the choice for the particular materials depends upon the type of metal to be cast. The gating and risering systems are machined either in one or both the mold halves.