Foundries are found all over the world and have become an essential part of human lives. Many people don’t even know what a foundry does, or what a foundry looks like. In simple terms, a foundry is a type of factory that produces castings made up from melting various types of metals, pouring these liquid metals into a mold, and then allowing the metals to solidify, therefore generating a product.
It is said that most people are never more than 10 feet away from some type of casting, which is not hard to believe when you look at the products that foundries produce (American Foundry Society, N/D). The list of items produced by foundries includes just about anything that is made from a type of metal. Some examples include but are not limited to:
|– Building supports||– Train wheels|
|– Crane sections||– Iron and metal gates|
|– Pots and pans||– Exhaust manifolds|
|– Ground water pumps||– Fire Hydrants|
|– Golf clubs||– Grills|
To fully understand the purpose of a foundry, it is important to know the casting process. Metal casting is the process of pouring high-temperature liquid metal into a mold. These molds can be made of sand, metal, or ceramic. The most common metals that get casted are iron, aluminum, magnesium, zinc, steel or copper-based alloys but any major metal can be cast. The general steps in the casting process are patternmaking, molding, melting, pouring, ejecting, cleaning, fettling, and inspection.
When the casting process begins, a casting pattern is selected for the project. These patterns are intended to replicate the desired object and to direct metal into the mold at the correct spot and at precise speed.
Once the molds are created, the metal is melted at extremely high temperatures (often 2600 degrees Fahrenheit or 1425 degrees Celsius and higher) until it becomes molten (Reliance Foundry, 2020). Robotic arms, vessels, and gravity generated pouring machines are used to transfer the molten metal. Skilled workers will also pour this metal using a ladle and an advanced system of gates and risers helps direct the molten metal to its correct location.
These gates, risers, and the mold all fill with metal and is left to cool. Once it is cooled, solidified metal can be found within the mold, risers, and gates. It is then ejected from the mold as one piece and the excess metal from the gates and risers is removed in the cleaning process. During the cleaning process, the cast is checked for any impurities or faults, and is then fettled (the process of trimming or cleaning up rough edges). The cast then goes through a series of inspections until it is deemed safe for sale or use.
Foundries are one of the largest contributors to the manufacturing recycling movement (American Foundry Society, N/D) Metal casting foundries are one of the top primary markets for the recycling of scrap metal. Many foundries use sand for their molds because they are easily able to recondition and reuse the material for other molds.
There are two distinct types of foundries that cast metal. There are ferrous (meaning iron or steel) and there are non-ferrous (meaning metal that does not contain iron or steel like copper, brass, aluminum, etc.) foundries. The type of equipment used in this process is determined by the type of metal being cast.
Equipment used by modern foundries includes everything they need to produce casts. These machines are specially designed to withstand heat, making them reliable in the melting shop. Some of this equipment includes melting furnaces, ladles, forklifts, cranes, conveyors, and more.
Melting furnaces: There are electric furnaces used for melting ferrous metals (steel and iron) and induction furnaces used for melting non-ferrous metals (not containing steel or iron). These furnaces can come in a variety of sizes, from small to extremely large and melt metal down to a liquid.
Ladles: Ladles can come in a range of sizes. They can be a small hand-carried vessel (like you would find in a kitchen) or they can large machines capable of holding hundreds of tons. In the foundry, there are often three types of ladles
Casting ladle: This is used for pouring molten metal into molds to produce the cast
Transfer ladle: This is used for transporting (usually a large amount of) molten metal from the furnace to the mold.
Treatment ladle: This is a ladle used for a process that takes place within the ladle. The purpose it to change the properties of the metal. For example, a treatment ladle is used to convert cast iron into ductile iron by adding different elements into the ladle. (Wikipedia, 2021)
Forklifts: In foundries, forklifts are often used to transport a variety of different materials including equipment and metal.
Cranes: Cranes are very important to the metal casting process. They are used to lift a variety of objects including large ladles and other pouring equipment. Special considerations are made in the production of these cranes as they must be able to withstand the extreme temperatures produced in the melting shop.
Conveyors: These are used to moved material from one area to another. Adding conveyors to a foundry improves workplace safety and production. It reduces forklift traffic, production is improved and becomes more streamlined, and when it comes to putting metal into a furnace, the operators are kept at a safe distance (Anspaugh, B. 2021)
Workplace Safety in the Foundry
Now that we understand what a foundry is and does, it is no surprise to learn that they can be highly hazardous work environments. Foundries are hot work environments where the potential for burns or fires is greatly increased around furnaces. Molten metals produce fumes that can be toxic and sand molds can pose a health risk as they can create silica dust that is bad for our respiratory system (exposure to silica dust can cause silicosis – a type of lung disease).
During the cleanup process, grinding, sandblasting, and chipping create dust and the use of conveyors and/or stamping machines pose a risk for crushes/catches.
To counter act these dangers, workplaces put certain rules, procedures, and plans in to place. Employers must provide their employees with proper work procedures and techniques, sufficient ventilation, and workers must always have personal protective equipment in the workshop.
Proper work techniques and procedures can be lifesaving when applied in the foundry. If proper procedures are not put into place, detrimental results may come. An example of this would be the use of water in a foundry. Water is a huge danger within a foundry. Because of the extremely high temperatures used in the furnaces to melt materials, if a single drop of water enters the active furnace (or if the metal had moisture in it) it will expand rapidly – to 1600 times its original volume. Trace amounts of water within the furnace can cause a large steam explosion. This means that if there is a fire in the shop, other procedures like using a class D fire extinguisher or dry sand, will be used to extinguish the flames. It is necessary for all workers to understand small techniques and practices like this, as small mistakes or misjudgment could be catastrophic.
Proper ventilation is very important anytime a worker is present in the foundry. There are an abundance of bad dusts and chemicals to breathe in. Melting metals produces fumes, clean metal is less dangerous, but scrap/reused metal poses a higher threat because they can produce fumes from old paint, coatings, chromium additives and more. Sand molds often contain crystalline silica (also known as the common mineral, quartz) which is found in a variety of materials like soil, sand, rock, concrete and more. Crystalline silica has been classified as a human lung carcinogen and it only takes a small amount of dust to pose a health hazard. Foundries are one of the most common workplaces to see the threat of silica exposure (Bass, H. 2017) It is so important for employees to have proper ventilation by means of exhaust hoods and properly fit respirators.
A foundry is one of the places where you should wear as much PPE as possible, as there are so many risks and dangers in the shop. There is the risk of extreme temperature and of fumes and dusts, but there is also the risk of crushes, catches, molten metal explosions, light and hazardous radiation, heat stress, physical hazards, and more (Elliots, 2021). Types of PPE equipment that should be used for this industry include but are not limited to hard hats, aprons, jackets/capes, leather spats, fire retardant material, steel toe footwear, respirators, safety glasses with protective siding, and more. The American Foundry Society published a guide called PPE Guide for Metalcasting Operations, 6th Edition (American Foundry Society, 2020), for those who want to take a deeper look at PPE in the foundry.