Introduction: A foundry is where the elaborate metal casting process takes place. A metal foundry may specialize in making one particular item or a variety of products using different alloys. Based on the production requirement, there are small foundries that employ few people and large industrial foundries that employ thousands of workers.
History: Foundry operations of the present day is an outcome of thousands of years of experimenting with different metals and casting methods. Very little documented evidence of casting and foundry operations are available of the ancient time. The proof of castings are in the form of jeweleries, household items and religious times that were unearthed during excavations or preserved as historic relics.
The foundry process was first documented circa 1500 by Vannoccio Biringuccio who is know as the “father of the foundry industry”. Rapid growth in the casting industyr took place in the industrialisation age. With the invention of machines and equipment in the industiral age, casting could be done on a large scale. The scientific revolution in this century increased the demand of casting products for automobiles, machines, weapons, etc. In the modern era, metal casting finds its application from kitchen wares to aircraft components.
Types of Foudries: Depending upon the type of end users, the wide variety of molding or the casting process can be basically divided into- Commercial foundry and Hobby foundry.
Commercial Foundries: Here the production activity is on a large scale and in abidance to the international standards of manufacturing practice. This type of foundry offers semi-finished or fully finished products like Railroad Equipment, Machine Tools, Farm Machinery, Mining Machine, etc. Major types of casting employed in commercial foudries are sand casting, die casting, investmet casting and lost foam casting. According the type of foundry activity that the foundries are involved in, commercial foundries are known as:
Types of Commercial Foundries:
|»||Captive foundry: These foundries are part of a manufacturing company which uses the casted products to meet the companies own production need.|
|»||Independent foundry: Here casting are produced as per the customers specification.|
|»||Jobbing foundry: These are fully equipped foundry which does not have its own individual casting business, but undertake contractual casting for other companies. Mostly, production are taken up for small quantity only.|
|»||Production foundry: In such foundries casting operations are done in bulk for one types of casting. The advantage in this method is that this fully equipped foundry unit can deliver flawless products at the most economical rates.|
|»||Semi production shop: It is the kind of operations where the company operations follow both the jobbing and the production casting.|
Hobby Foundries: These are small but fully equipped foundry units setup inside a house or in the backyards. Such foundries are set up by amateurs who loves tocreate casting products according to ones desire. The home foundries also serves other purpose like mending the worn our metal items and for casting special part or component that are not available in the market.
Basic aspects to be considered for setting up foundries:
Many factors are taken into account while setting up a foundry operation. The basic settings are done in consultation with experts and by taking suggestions from potential customer who are the ultimate beneficiaries of the foundry operations. Some of the basic conserns are:
|»||Environmental: The environmental study is done to ensure that the foundry operations does not effect the natural surroundings. It is essential for the foundries to follow the standard guidelines for setting up the industry, so that the residential areas near the foundry are not affected in any way. While setting up a foundry care must be taken also to protect the flora and fauna, and the water bodies in the surrounding areas.|
|»||Economical: The economic capacity of the foundry owners and the end-users is an important aspect while selecting the equipment and machines for the foundry operations. Cost effective and premium quality castings can be manufactured by selecting the appropriate metallurgical designs and making optimum use of alloys. Foundry operations can also be made cost-effective and convenient by avoiding patterns which are difficult to draw or molds . In addition, coring can either be eliminated or reduced for economic reasons.|
|»||Technicians: Mutual understanding and coordination between the professional working in different foundry activities is essential. Especially, the patternmakers and the molders should work in close coordination because patternmaking is an art whereas, molding is technical in nature. A pattermmaker can do simple molding and the molder can make simple patterns, but beyond a point they are dependent on each other for sophisitcated and innovative castings.|
|Crucible||It is the vessel used to hold the molten metal before it is poured into the mold. The crucibles are made of the mixtures of graphite, silicon and clay, which have a higher melting point than that the metals that are to be melted in it.|
|Gas gun||Instrument used to introduce gas triggers like CO2 into sand moulds.|
|Ingot||Metals cast into blocks or other shapes so as to enable easy handling and further process of the metals. for eg. gold ingots.|
|Lock-in||When there is an inner and outer mold, the outermold may be designed to penetrate into the inner design, inorder to make the mold very tight. This prevents the mould from disengaing during the casting process.|
|Undercut||A surface feature which is incoporated in the pattern, which forms a sharp overhang or deep pocket.|
|Master pattern||Basic complete pattern that is designed by artist or designer.|
|Molding material||Materials like sand, plaster, etc. used to pack around the pattern. When the pattern is removed it leaves a cavity in the shape of the pattern.|
or parting surface
|These lines are the marks that will indicate where the different segments of the molds meet, when the mold is closed for casting.|
|Ramming up||The act of compressing refractory sand medium around a master pattern or core box.|
|Fins||Projections designed on a casting to extract heat, which are later removed while cleaning.|
|Inoculates||The additional materials made to the molt inorder to control the microstructure of the metal cast|
|Thermal arrest||During the thermal arrest the material is converted from a liquid to a solid.|
|Stripping||The process of removing the master pattern from the flask after the mould has been set.|