Billets

• Billets are semi finished product
• We manufacture square billets of size 100*100 sq.mm
• We use Induction furnaces and continuous casting machine for billets manufacturing.
• The process of manufacturing Billets is a two stage process. The first stage consists of feeding M.S. Melting scrap, Sponge Iron, Pig Iron and other alloys in the induction furnace and then melting it to a liquid state by applying electrical power. The melted liquid is poured into a ladle.
• The induction furnace / continuous casting machine section is a mostly automated unit with manual operations at some places.

Induction Furnace

• Induction furnace is an electrically run furnace mainly used for melting metals.
• Induction furnaces are cylindrical, open-topped, tilt-able refractory crucibles which is a melting container made of heat resistant
  material with a water-cooled induction solenoid coil installed on the outside, around the side wall.
• Copper solenoid coils are kept cool by water circulating from a special cooling tower.
• Large capacity Induction furnaces have a rammed that is compacted and dried refractory mass as lining. The refractory wall of the crucible is usually thin enough to achieve good penetration of the electromagnetic field into the charge.
• Electromagnetic induction is the process that allows an induction furnace to work.
• During induction, an electric current is passed through a metal coil which creates a magnetic field.
• When metal is introduced into the magnetic field, an electrical current passes through the metal and causes it to heat. The heat produced by the electromagnetic charge melts the metal.
• Scrap is introduced into Induction furnace and carbon compensating alloys are added for necessary availability of carbon in molten metal.
• The electromagnetic field stirs the melt well, and this is beneficial for alloying. This stirring is essential to maintaining the integrity of the metal.
• After reaching desired molten stage & temperature small piles of sponge iron is continuously introduced.
• In this process “Slag” is formed which is lighter than molten metal and it floats on the top in the induction furnace.
• Formed floating slag is constantly removed during melting.
• Sample is taken from molten metal for laboratory chemical analysis.
• The advantage of the induction furnace are that it is a clean process, energy-efficient and melting is controllable process compared to other means of metal melting

Now in second stage, the molten metal in the ladle is taken to the continuous casting billet machine and is poured in it. The metal solidifies in the machine & casted billet of required size is obtained.

Continuous Casting

• Continuous Casting is the process where molten metal is continuously casted into a semi finished product called billet.
• Continuous casting is an excellent technology to manufacture Bars stock. Billet manufactured with the continuous casting process has number of advantages over the Ingots manufacturing process where steel is poured into stationary molds.
• Ingots can have surface imperfections and may contain impurities which can seriously affect the strength, durability and other properties of metal.
• Billets produced through continuous casting process is cost effective and better quality with little or no chance of impurities making their way that may effect the strength and durability of the product.Continuous casting helps to achieve improved yield, quality, productivity and cost efficiency. It allows lower-cost production of metal sections with better quality, due to the inherently lower costs of continuous, standardized production of a product, as well as providing increased control over the process through automation.
• Temperature is taken of the molten metal in the Induction furnace with the help of disposable thermocouple, being satisfied with the temperature of the molten metal it is alloyed example Manganese.
• Hot molten metal is poured into the ladle from Induction furnaces. Molten metal goes through ladle treatments and after arriving at the correct temperature, the ladle is transported to the top of the casting machine. The ladle sits on the casting machine.
• The hot metal is transferred to a tundish from the ladle. The tundish allows a reservoir of metal to feed the casting machine while ladles are switched thus smoothing out flow and regulating metal feed to the molds.
• Metal is drained from the tundish into the mould tube.
• The dimension of mould tube can vary, depending on the desirable casting size.
• The Copper Mould tube is water-cooled, continuously lubricated and has near vertical curved path to prevent the metal sticking to the mold walls while casting.
• Lubricant in form of powder or liquid is used in the mould tube to prevent sticking, and to trap any slag particles that may still be present in the metal.
•  Aluminum wire is continuously introduces in moderate amount during casting as a good oxidizing agent and to remove impurities.
• Depending on the unit design Continuous casting process has the capability to feed several molds from the same tundish.
• In the copper mould tube, a thin shell of metal next to the mold walls solidifies before the metal section. It is called a strand.
• Solidification in continuous casting (CC) technology is initiated in a water-cooled open-ended copper mould.
• The steel shell which forms in the mould contains a core of liquid steel which gradually solidifies as the strand moves through the caster guided by a large number of roll pairs.
• The solidification process in the mould is completed in secondary cooling zones using a combination of water spray into a spray chamber exits the base of the mold into a spray-chamber.
• The bulk of metal within the walls of the strand is still molten.
• To increase the rate of solidification, the strand is sprayed with large amounts of water as it passes through the spray-chamber. Final solidification of the strand may take place after the strand has exited the spray-chamber.
• There are different types of casting machine. We have curved apron casting machine.
• In this type of casting the strand exits the mold on a near vertical curved path and as it travels through the spray-chamber.
• The rollers gradually curve the strand towards the horizontal.
• Molds in a curved apron casting machine can be straight or curved.
• After exiting the spray-chamber, the strand passes through straightening rolls and withdrawal rolls.
• The strand is cut into predetermined lengths by traveling handheld oxyacetylene torches or by mechanical shears.
• Finally Billets are piled in a horizontal vertical continuous order and is marked by numbers commonly known as heat numbers or lot numbers to keep track of production.
• Casted Billets are cooled and then sent to the rolling mill for rolling.