Furnaces for Casting Processes

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Questions and Answers

What type of furnaces are most commonly used in foundries?

Direct fuel-fired furnaces, Crucible furnaces, Electric-arc furnaces, Induction furnaces, Cupolas

Which type of furnace is used primarily for melting steel?

  • Electric-arc furnaces (correct)
  • Direct fuel-fired furnaces
  • Crucible furnaces
  • Induction furnaces

_______ is used in induction furnaces to develop a magnetic field in metal.

Alternating current

Match the following descriptions with the correct furnace type:

<p>Uses heat generated from an electric arc = Electric-arc furnaces Metal melted without direct contact with burning fuel mixture = Crucible furnaces Uses alternating current to develop magnetic field in metal = Induction furnaces</p> Signup and view all the answers

What are the five most commonly used furnaces in foundries?

<p>Direct fuel-fired furnaces, Crucible furnaces, Electric-arc furnaces, Induction furnaces, Cupolas</p> Signup and view all the answers

Which types of metals are generally used in direct fuel-fired furnaces?

<p>Nonferrous metals such as copper-base alloys and aluminum (A)</p> Signup and view all the answers

Electric-arc furnaces are primarily used for melting steel.

<p>True (A)</p> Signup and view all the answers

Match the following types of crucible furnaces with their descriptions:

<p>lift-out crucible = b) type where molten metal must be ladled stationary pot = a) type used for melting bronze, brass, and alloys of zinc and aluminum tilting-pot furnace = c) type that can be tilted for easy pouring of molten metal</p> Signup and view all the answers

What is the primary advantage of cupola furnaces?

<p>High productivity</p> Signup and view all the answers

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Study Notes

Furnaces for Casting Processes

  • Direct fuel-fired furnaces are small open-hearth furnaces that use natural gas fuel burners to heat the charge, and are generally used for nonferrous metals such as copper-base alloys and aluminum.
  • Crucible furnaces, also known as indirect fuel-fired furnaces, melt metal without direct contact with the burning fuel mixture, and are used for nonferrous metals such as bronze, brass, and alloys of zinc and aluminum.
  • Electric-arc furnaces melt the charge by generating heat from an electric arc, and are used primarily for melting steel due to their high power consumption and high melting capacity.

Crucible Furnaces

  • Crucible furnaces come in three types: lift-out, stationary, and tilting.
  • The container (crucible) is made of refractory material or high-temperature steel alloy.

Electric-Arc Furnaces

  • Electric-arc furnaces can be designed for high melting capacity, but require high power consumption.
  • They are primarily used for melting steel.

Induction Furnaces

  • Induction furnaces use an alternating current passing through a coil to develop a magnetic field in the metal, causing rapid heating and melting.
  • The electromagnetic force field also causes mixing action in the liquid metal.
  • Since the metal does not contact the heating elements, the environment can be closely controlled, resulting in high-quality and pure molten metals.

Ladles

  • Ladles are used to transfer molten metal from the melting furnace to the mold.
  • There are two common types of ladles: crane ladles and two-man ladles.

Cupola Furnaces

  • Cupola furnaces are the oldest type of furnace used in foundries, and are used for melting iron and ferro-alloys.
  • Advantages of cupola furnaces include simplicity in operation, high productivity, continuous production, and economical use.

Construction of Cupola Furnaces

  • A cupola furnace has a steel shell lined with refractory blocks, bricks, and fire clay.
  • The furnace has a round cross-section, and features a spark arrester, charging door, air injection by tuyeres, drop bottom, tapping hole, and slag hole.

Operation of Cupola Furnaces

  • The operation of a cupola furnace involves closing the drop bottom, charging the coke bed and wooden parts, firing, and repeating the layering process.
  • The furnace is cooled, and the lining is rebuilt after each operation.

Zones of Cupola Furnaces

  • The zones of a cupola furnace include the well zone, combustion zone, reducing zone, melting zone, preheating zone, and stack zone.
  • Each zone has a specific temperature range and function in the melting process.

Cupola Charge

  • A cupola charge consists of metal charge, coke, limestone, and air.
  • The charge is calculated using the material balance technique, considering factors such as carbon equivalent, manganese loss, silicon loss, phosphorus, and sulfur gain.

Furnaces for Casting Processes

  • Direct fuel-fired furnaces are small open-hearth furnaces that use natural gas fuel burners to heat the charge, and are generally used for nonferrous metals such as copper-base alloys and aluminum.
  • Crucible furnaces, also known as indirect fuel-fired furnaces, melt metal without direct contact with the burning fuel mixture, and are used for nonferrous metals such as bronze, brass, and alloys of zinc and aluminum.
  • Electric-arc furnaces melt the charge by generating heat from an electric arc, and are used primarily for melting steel due to their high power consumption and high melting capacity.

Crucible Furnaces

  • Crucible furnaces come in three types: lift-out, stationary, and tilting.
  • The container (crucible) is made of refractory material or high-temperature steel alloy.

Electric-Arc Furnaces

  • Electric-arc furnaces can be designed for high melting capacity, but require high power consumption.
  • They are primarily used for melting steel.

Induction Furnaces

  • Induction furnaces use an alternating current passing through a coil to develop a magnetic field in the metal, causing rapid heating and melting.
  • The electromagnetic force field also causes mixing action in the liquid metal.
  • Since the metal does not contact the heating elements, the environment can be closely controlled, resulting in high-quality and pure molten metals.

Ladles

  • Ladles are used to transfer molten metal from the melting furnace to the mold.
  • There are two common types of ladles: crane ladles and two-man ladles.

Cupola Furnaces

  • Cupola furnaces are the oldest type of furnace used in foundries, and are used for melting iron and ferro-alloys.
  • Advantages of cupola furnaces include simplicity in operation, high productivity, continuous production, and economical use.

Construction of Cupola Furnaces

  • A cupola furnace has a steel shell lined with refractory blocks, bricks, and fire clay.
  • The furnace has a round cross-section, and features a spark arrester, charging door, air injection by tuyeres, drop bottom, tapping hole, and slag hole.

Operation of Cupola Furnaces

  • The operation of a cupola furnace involves closing the drop bottom, charging the coke bed and wooden parts, firing, and repeating the layering process.
  • The furnace is cooled, and the lining is rebuilt after each operation.

Zones of Cupola Furnaces

  • The zones of a cupola furnace include the well zone, combustion zone, reducing zone, melting zone, preheating zone, and stack zone.
  • Each zone has a specific temperature range and function in the melting process.

Cupola Charge

  • A cupola charge consists of metal charge, coke, limestone, and air.
  • The charge is calculated using the material balance technique, considering factors such as carbon equivalent, manganese loss, silicon loss, phosphorus, and sulfur gain.

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