Design Resource
Dhokra Metal Casting, Adilabad - Telangana
An Ancient Bell Metal Craft
by
Prof. Bibhudutta Baral and Rakshitha
Making Process
The metal artifact that has to be made is initially prepared in clay. The preparation of this clay is made by mixing anthills mud with cow dung in an appropriate ratio. This mixture is kneaded thoroughly with water and acquired the desired consistency. Further using this mixture of clay, the core model is made. On the next level the pure form of clay is applied to render the fine smooth layer. This clay model is further allowed to dry and upon this, the wax threads are wound all around to form a layer and to acquire the chosen design pattern. Further on the wax coating again a layer of clay mixed with sand is applied. Here the sand is used for the tightness of the mixture. Further two holes (channels) are made and allowed for drying. These channels are made to pour the liquid metal and to release the air out. Once the clay model is completely dried, a mixture of sand with minimal quantity of clay is applied and then the process gets continued by baking the clay - wax model in furnace. When this clay – wax model is baked, the wax in-between the clay layers get melted and oozes out of the opening. Thus the space gets emptied and remains as a hallow space in-between the clay layers. Then the clay mould is taken out of the furnace and the molten metal is poured into the funnel like opening on the upper surface of the mould. This molten metal is acquired by melting the metal crucibles. These metal (brass) crucibles are initially arranged in a graphite container and carefully heated to get the molten metal. A tinge of salt is added to metal crucible while heating it, to obtain the pure form of molten metal and to speed up the process.
Once the liquid metal is poured into the mould, it acquires the shape and pattern of the model eventually, by taking the impression of the wax model in all its detail. It also gets hardened between the core and the inner surface of the mould. Further it is allowed to cool down completely by dipping the mould in water. It is then slightly hammered to remove the burnt mould completely and brushed thoroughly to clean from inner and outside. Then it is neatly polished by rubbing the file tool all over the metal product. And thus the finished product is prepared. The whole process carries four days to complete when the objects are created in bulk. As the making of clay model acquires a day time, winding of wax threads to the clay model takes another day’s time. While the baking and further process requires at least of one or two days to prepare the end product.
Flow Chart:
