Aluminum alloy castings – everything you need to know
Foundry is one of the most commonly used methods of producing aluminum products. This technology is relatively simple and involves filling previously prepared forms with liquid aluminum.
This type of production generates low costs, and the products created as a result of this method have exceptionally good properties, are durable and long-lasting. The most commonly used techniques include sand casting and pressure casting.
Sand casting and pressure casting – differences
Each of the mentioned techniques is based on different technological processes. Aluminum sand castings are made in disposable molds made by hand. In the first phase, a model of a given item is prepared, e.g. from wood or resin. During the next step, the model is placed in the molding box, covered with mass, which is then thoroughly compacted around it. In this way, a mold is created into which, after removing the model from the box and supplementing it with a core imitating the internal shape of the casting, liquid aluminum is poured. After hardening, the semi-finished product is removed from the molding mass, cleaned and further processed. Sand casting is mainly used to produce parts, including spare parts, for various machines and devices.
Pressure castings, on the other hand, are made in foundry machines called pressure machines. The work is carried out in several stages. In the first phase, mold halves made of appropriate steel are mounted on the machine and clamped together with a force of several hundred tons. Then, liquid metal is poured into the pouring chamber, and under the influence of the pressure created by the piston, it is forced into the mold through the pouring slot and takes the expected shape. In the final phase, the product undergoes further processing and its surface is appropriately protected, e.g. by powder coating or galvanizing. This technique is mainly used in the production of parts for the automotive industry, machines and devices.
Characteristic features of sand and pressure castings
Sand and pressure castings differ not only in the way they are made, but also in their mechanical properties, surface quality and dimensional accuracy. Sand castings usually have a rough surface and their shape and details are not very precise. The dimensions are also not very accurate. However, their advantage is low manufacturing costs and quick implementation into production.
As for products made of aluminum pressure casting, they are distinguished by good mechanical properties, a smooth and aesthetically made surface, as well as high dimensional accuracy. This means that matching individual elements to each other is not a major problem. Thanks to this, the products are used in many demanding industries in serial and large-scale production.