What requirements must satisfy a home furnace for melting metals? It needs to possess a wide heat range, be compact and convenient to use. If you have the skills and abilities you can assemble the system in which carbon and graphite powder is filled between two the same composition of electrodes to which is supplied the voltage 25-50 V. will also Need a powerful enough transformer (such as welding).
Due to the resistance in a graphite powder formed by the gradual intense heat. In this electric furnace, the temperature can reach up to 3000оС, this mode allows you to melt small portions of almost all metals, including gold.
The heating time of the oven is in the range from 3 to 5 minutes. This allows you to control the process of melting metal, including turning off the transformer. Since the metal is melted in small portions, it does not spread inside the furnace and sufficiently holds its shape well.
Electric melting furnace is made of available materials: tile or cement tiles, graphite and mica. Stove dimensions may be different and depend on the capacity of the network and the output voltage of the transformer. The higher the voltage, the greater the distance between the electrodes. Thus, the use of the welding transformer issuing up to 60 In requires the distance between the electrodes is about 200 mm. In this volume of the furnace can melt several tens of grams of gold or silver.
As electrodes suitable brush from the powerful motor. If you cannot use these brushes can be cut from a piece of graphite. In the electrode provide two side holes of 5 mm diameter into which is inserted the copper wire. On the inner side of the electrodes with a file make a notch to improve the contact with graphite powder.
Mica plays the role of the lining layer of the furnace wall. It is a good insulator. Exterior walls, reinforce cement tiles with a thickness of 10 mm. Stand for the furnace to serve as common brick, laid on enameled metal tray with sides.
Carbon and graphite powder can be obtained by processing a file with used rods. In the process of melting the powder will gradually fade and require replacement.
Assembled oven is connected to the transformer and thick copper wires with an outer insulation to avoid short-circuit. The oven is ready heat, so that later it worked without soot and fumes.
Melting takes place so: first, with blades in the middle of the oven make a hole in the powder, it put the first portion of the metal and buried. If you use goldth scrap of different sizes, first place the largest piece, and as it is melting add the smaller parts.
To ensure that the metal is melted, a little rock oven. The surface of the powder will be dangling. After melting the metal is turned over and melted again. So to repeat until the workpiece does not take a spherical shape (this indicates the quality of the melt).
After melting the metal blank to be forged. The product should be headed hammer, tap on the anvil with a small hammer.
Remember that welding transformer requires very careful handling. The mains switch of the transformer needs to be around you, in a convenient location. Do not leave the heater unattended. Next keep a container of water, which will cool the hot billet.
In order to maintain the precious metal it can be placed in a glass vial under medication and melting like this. The crust is made of glass then it will easily crumble when cooled in water.