Short description about aluminum alloy sand casting
Sand casting has been used for centuries for most popular and simplest types of castings. Sand casting could be used to small and large parts, main steps include drawing confirmation, mould, core-making, modeling, melting and pouring, heat treatment, cleaning, blasting, machining, surface coating, and so on.
The traditional method is to obtain the casting drawings and send them to the foundry. This process can be completed in the quotation. Nowadays, more and more customers and foundries use computer-aided design instead, and its good for quotation by drawing in stp, x_t, pdf, cad, igs, etc. Also make supplier know the qty, material type, like in A356, alsi7mg, etc. (for sand casting aluminum material is even same like low pressure casting )
Following is common aluminum alloy sand casting material types:
In sand casting, moulds are made of wood and inner metal materials. In this process, we require our engineers to make the die size slightly larger than the finished product, and the difference is called shrinkage margin. The aim is to ensure the solidification and shrinkage of molten metal by the action of molten metal on the die, to prevent voids in the casting process.
Core-making requires placing resin sand grains in the die to form internal surface castings. Therefore, the gap between the core and the die eventually becomes casting.
A set of moulds should be prepared during the melting process. Forming usually involves the support frame of the die, pulling melted aluminum into die, melting the previously placed core in the die and closing the die.
The purpose of cleaning is to remove sand grains, grinding and excess metals in castings. Welding and sand removal can improve the surface appearance of castings
The burned sand core and scale were removed to improve the surface appearance of casting. Excess metal and other risers were removed. The next step is welding and grinding. Finally, check defects and comprehensive quality. Blasting, is a must step and free step for every part to get smooth and beautiful surface.
Reprocessing(Heat treating, machining, coating, etc) before shipment. According to the requirements of different customers, we can do heat treatment, machining, surface treatment, additional inspection and so on.
Sand casting part usually are some big part, like some pump body, frame, base, big wheel, etc.
But now, more and more sand casting parts are choosing low pressure casting, as low pressure casting could share more advantages.