Author: haroonkhan

This process lies between gravity die casting and high-pressure die casting. In a low-pressure casting process, the molten metal is forced upward by gas or air pressure into a graphite or metal mould. The mould is located just above the furnace. It may take half a minute to fill up the mould, so any entrapped…

Cold-chamber die casting is used for relatively high melting point non-ferrous alloys such as aluminium, magnesium, and brass which require higher pressure and temperature for melting. These metals are not melted in a self-contained pot as in hot-chamber die casting due to short life of pot (Figure 20.21). Therefore, the metal is melted in an…

A hot-chamber die casting machine is shown in Figure 20.20. This machine is used with alloys of low melting points because of the difficulties encountered such as increased corrosion of the machine parts at high temperatures. Since many metals have an affinity for iron, only those casting alloys are used that do not attack the immersed…

There are two types of high pressure die casting.

This process was developed by Carthias in France and mainly used for ornamental products. A definite amount of metal is poured into an open ended mould, and a close-fitting core is forced into the cavity, causing the metal to be forced into the mould cavities with some pressure. The core is removed as soon as…

This is a special type permanent mould casting in which hollow casting is prepared without core since solidification of molten metal starts from mould surface towards centre. The molten metal is kept inside the mould cavity for a pre-determined time for solidification of particular thickness and then the mould is turned down. The rest of…

In this casting method, metallic moulds are used which can withstand the high temperatures of molten metal. The permanent mould is made into two parts; both parts are hinged at one end and clamped at other end. Mould is pre-heated before filling the molten metal. After solidification mould is opened and casting is removed. Again…

Following sand testing are used in foundry. Moisture Content Test: To find the moisture content in sand, moisture teller equipment is used. It consists of cast iron pan and an infrared heater bulb fitted in a shade. Twenty grams of sand is taken in a pan and it is exposed in infrared heater for 2–3 min.…

Core is a sand body specially prepared in a core box and it is used to form a cavity/hole/recess or projection in a casting for different purposes. As core is surrounded by liquid metal from all the sides, it has to have better characteristics than the moulds. Better raw sand and binder are used for…