Metal casting is a method of processing metal without removing material. Casting represents the technology of forming metal objects by casting the molten metal into the molds in order to get the drip molding after cooling it inside the mold. Casting is a very convenient process for making machine parts whose shape is complicated and it contains internal contours and irregular channels. Casting is used for the economical making of machine parts and elements. Modern technology and modern equipment for casting allow obtaining castings of different dimensions, accuracy and surface quality, so the need for subsequent mechanical treatment is less present, which leads to less expensive costs of production.
Almost all metals and their alloys can be formed by casting. However, the most widely used are metals and their alloys whose properties and characteristics correspond well to the process of casting. The most important properties of metals and alloys that come to the fore during the casting are the degree of castability and the level of material volume change at cooling. Especially good materials for casting are gray cast iron, zinc, tin, lead, copper and most non-ferrous metals.
Methods of casting
– Centrifugal casting in molds
This method of casting is the process of casting the rotating elements using the principle of centrifugal force. The centrifugal force is generated by rotating the ingot, and then it comes to the distribution of molten metal on the walls of inlet cavity. This allows the production of hollow rotating elements and objects whose axis of symmetry is an axis of rotation. To create a centrifugal force they use molds that turn on or about its horizontal or around its vertical axis.
– Continuous casting
In the process of continuous casting, molten metal is continuously and uniformly flowed out of the pot into a metal mold which is on the one side water-cooled constantly. The molten metal in the form of a hardened product of the metal extracts on the other side of the mold. This method provides the production of castings of different shapes. In metallurgy and foundry process of continuous casting has been applied more and more each year. Continuous casting can achieve higher productivity and greater cost-effectiveness compared to the other casting methods.
– Casting in metal molds
Casting in metal molds has a very wide application in making aluminum castings. Gravity castings apply to all branches of mechanical engineering – internal combustion engines, gas appliances, shipbuilding, etc. Compared to other casting procedures, this method has certain advantages, and it is very widespread.
– Casting in sand molds
To make molds for this casting method it is necessary to provide models that are produced in molds department and those are usually made of wood and metal. The most common and best wood for modeling is the linden. If the cast has an inner cavity, they used to produce specialized cores for each casting object or element. Spraying is an important part to be done so the wet sand does not stick to the model. After compaction of sand, there must be provided channels for the evacuation of gasses from the mold (called stacks) that can cause porosity of castings and thus making them unusable.