Sand Casting

Sand casting, also referred to as sand molded casting, is a process of creating metal objects using sand as the mold material. It is a widely used method in metal casting, accounting for over 60% of all metal castings. Sand castings are made in specialized factories known as foundries. The sand used in this process is inexpensive and suitable for use in casting even steel. A bonding agent is added to the sand to increase its strength and plasticity. The mixture is moistened, usually with water, to form the mold. The mold is created by compacting the sand around a model or pattern, carving directly into the sand, or using 3D printing. The mold is contained in a frame or mold box known as a flask.

Die Casting

Investment Casting

Investment casting, also known as lost-wax casting, is a metal forming process that is renowned for its precision, versatility, and integrity in producing components from a range of metals and high-performance alloys. The process involves creating a wax pattern of the desired part and then coating it in a refractory material.

This refractory material is then heated until the wax pattern is melted and lost, creating a mold that the metal is poured into. The hard refractory material used in investment casting results in high-quality surface finishes that often require minimal post-casting processing.

There are two main investment casting methods: water glass and silica sol. The water glass method is more economical, but the silica sol method offers a better surface finish. Regardless of the method used, investment casting can produce both small and large parts and can handle complex shapes that may be difficult to achieve with other casting methods.

Although investment casting may have higher per-unit costs compared to die casting or sand casting, the costs decrease with large production volumes. This makes investment casting a cost-effective solution for high-volume, precision casting projects.

Lost Foam Casting

Lost-foam casting (LFC) is a method of casting that resembles investment casting, but instead of using wax for the pattern, foam is used. The process takes advantage of the low boiling point of foam to make investment casting easier by eliminating the need to melt the wax out of the mold. To start, a pattern is created from polystyrene foam through various methods such as hand-cutting, machining, or mass-production through a process similar to injection molding. After the pattern is made, it is coated with a ceramic investment or refractory coating to protect the foam surface and control permeability, allowing the gas created by the vaporized foam pattern to escape. The coated pattern is then placed into a flask filled with unbonded sand and compacted using a vibration table. The mold is ready for pouring and automatic pouring is often used in LFC due to the critical nature of the process. The melt is poured directly into the foam-filled mold, burning out the foam as it pours. The low density of the foam results in relatively small amounts of waste gas, which can escape through the permeability of the mold.     

Permanent Mold Casting

Permanent mold casting, also known as gravity die casting, is a high-precision method for casting complex metal components. This process is typically used to produce high volumes of parts with tight dimensional accuracy and a finer grain structure, such as cylinder heads with internal sand cores.

The mold used in this method is made of steel, cast iron, or graphite and filling occurs simply through the force of gravity without the use of external pressure. This method eliminates the risk of turbulence and low gas porosity by allowing the molten metal to be poured into the mold through gravity.

Centrifugal Casting