A tundish is a piece of equipment which is used in metal casting. The tundish holds molten metal right before it is poured into the mold, making it one of the last steps in the casting process. Tundishes come in an array of sizes and styles ranging from small versions used for casting in home studios by artists to massive containers utilized in the continuous casting process. Tundish technology has been around for a very long time, and numerous companies manufacture these devices along with attachments and accessories.
The tundish is made from extremely durable materials which are capable of coping with the high heat of molten metals. The equipment is usually lined with a material with low conductivity, and may be fitted with a nozzle to control the flow of molten metal. In other designs, the pour is controlled by hand or by machine. Controlling the pour is important to avoid casting a piece with flaws such as cracks and bubbles, and to accommodate the needs of different metals.
While in the tundish, the composition of the molten metal can change as it interacts with the air. This change in composition needs to be tightly controlled to achieve the desired effect in the finished product. At all stages of the casting process, the metal needs to be monitored as it moves through different phases and interacts with the surrounding environment. Small variations in the process can sometimes result in very different final products.
Over time, the inside of the tundish can become coated in layers of metal. These layers need to be removed to free up room in the tundish and to avoid reactions between different kinds of metals. These remains, known as skulls, can be removed with cutting or scraping devices. Some facilities recycle skulls to make various metal products, illustrating that one person's waste materials can be another person's treasure.
In automated casting facilities, people may not interact with the tundishes very often unless a problem develops. For people casting by hand, however, contact with the tundish will be required. The equipment needs to be handled with care, both to protect the integrity of the casting and to protect the health of people working in the area. Being splashed with molten metal can be extremely painful and potentially very dangerous, and metalworkers are careful to wear adequate protections and to follow safety protocols while casting or working with hot metal.