In a foundry various processes have to be done so that metals such as iron and steel are made usable. One of the most important factors used in a foundry is probably the sand. Let’s have a look.
Foundry sand is superior quality silica based sand that has homogeneous physical properties. On the other hand, Recycled Foundry Sand is the remains of the ferrous and non ferrous metal castings. Sand had been used for hundreds of years in the foundry due to its excellent heat conducting capabilities. However, nowadays in modern foundry setups, the sand is not thrown away but recycled and reused several times. Surveys in the foundry industry may assume that around 100 million tons of sand is used every year. Out of this approximately 6 to 10 million tons may be thrown away every year. The rejected sand is consequently recycled and used by other industries.
The sand used in foundries may be supplied by the National Industrial Sand Association. Professional people who work in the foundry must assure that quality wise the sand meets all stipulations. Otherwise, this may lead to imperfections in the metal casting. As a matter of fact, probably in every foundry, there may be a quality control team to assess the superiority of the sand. By doing such tests, foundry owners may be sure to maintain uniformity in their sand and hence supply end products without any defects.
Moreover, there are many other casting techniques. These can be described as: investment casting, die casting and permanent mold casting. But sand casting may be the most preferred one. In a foundry, sand can be used in two separate ways: as a molding substance and as cores. When sand is used as a molding material in a foundry, it forms the outer shape of the cast part. On the other hand, when it is used as cores, it produces the blank spaces such as in engines parts. Additionally, sand grains may not stick to each other. So, prior to introduction of the molten material, binders may have to be added to the sand so that they stick together to hold the shape of the molten metal.
Furthermore, in a foundry, two possible types of binder systems may be used. These can be described as follows: green sand and resin sand. Each of these different types of sand can be recycled but they have different physical properties. Foundry use of Green Sands in the US may reach around 90 percent of the casting quantity. Green sands may be made of natural elements combined together. The materials that are used to make green sands are: silica sand, water and bentonite clay among other substances. The green sand is normally black in colour.
On the other end, resin sands may be used in a foundry for coremaking and mold making. In the coremaking process, considerable power may be essential to resist the heat produced by the molten metal. Such sands can be bonded chemically in a foundry. Basically, organic binders may be used in such circumstances and are triggered by a catalyst. Chemically bonded sands may remain lighter in colour.
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Sanjou is the author for
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