Working Principle of Muffle Furnace and Parts

What is muffle furnace? a muffle furnace is a particular style of jacketed enclosure used to heat a material to extremely high temperatures while completely isolating it from outside pollutants, chemicals, and substances.

Muffle Furnace Definition

An energy efficient muffle furnace enables quick high-temperature heating, recovery, and cooling in self-contained cabinets. A muffle furnace isolates the heating object from any by-products from combustion from the source of heat. In modern electric furnaces, convection or radiation energy is used to transfer heat into an enclosed space by using a high temperature heating coil in an of a material that is insulated. The material that is insulating serves as a muffle stopping heat from exiting.

Principle of Muffle Furnace

Muffle furnace working principle is based on the working principle and the law of conservation of energy, which converts electric energy into heat energy in order to heat materials.

When the electric furnace operates normal, current and voltage is applied to the heater (resistance). The heating element produces an enormous amount of heat within the work area and creates thermal radiation and convection. The insulation material used in the room absorbs and emits a little amount of heat. It also absorbs the majority of heat, ensuring that the temperature inside the work area gradually increases until it reaches the temperature set of the heating element.

Once a specific temperature has been attained, the temperature of the room is controlled through a thermocouple before being is fed back to the temperature control device (PID controlling). The current and voltage are controlled to regulate the power in the electric furnace in order to achieve the temperature that was set.

Parts of Muffle Furnace

Muffle Furnace Diagram

Figure 1: Muffle furnace diagram

Temperature Range: Its temperature in this furnace can reach 900 degrees. It is equipped with an exclusive ceramic insulation which allows it to be light. It’s an ideal device to melt or anneal precious metal, metal, and glass materials.

Heating Element: The heating component that is part of the Muffle furnace employs a nichrome-wire, and it is a complete process of heating a material inside the chamber (muffle furnace diagram:1). Any liquid or solid which needs to be tested at high temperatures has to be removed from the furnace.

Heating Zone: The chamber is very deep with a capacity at 2kW. The electric heater is used to heat the chamber up to 500˚C (muffle furnace diagram:1). The temperature is measured with thermocouples of type T located in the middle at the top, bottom and the sides.

Controller: The temperature controller in this muffle furnace will show you two main things: the current temperature and the set temperature.

Construction: The body of the furnace is composed of steel and MS powder coated (muffle furnace diagram:1). The controller is equipped with a display that shows the temperature of the set and displays when power is on as well as an operating panel. The chamber also has doors.

Doors: Lab muffle furnaces come with doors that are insulated and have board insulation. There is no heating in the door due to insulation (muffle furnace diagram:1).

Types of Muffle Furnace

1. Electric Muffle Furnace

Electric furnace is a kind of electric furnace used for moulding drying, melting, and heating up materials. Electric muffle furnaces are similar to an induction however they utilize electrically heated refractory components inside a container made of solid metal instead of creating electromagnetic fields that heat the material within the. The electric muffle furnace is able to operate with higher temperature than conventional induction furnaces, and larger power densities.

2. Nabertherm Muffle Furnace

An Nabertherm muffle is a specialized heating system designed for industrial use. These furnaces can be used in a variety of industries, from steel and other metallic production, to glass production, food processing and ceramics as well as car manufacturing and aerospace.

3. Thermolyne Muffle Furnace

An Thermolyne muffle furnace can be described as a distinct kind of industrial bench top muffle furnace which can reach the maximum temperature of 1200˚C. This high temperature offers the possibility of obtaining different temperatures for various applications in which the user can use the furnace in an industrial environment. They can be used to heat, anneal and tempering glassware as well as Crucibles.

4. Carbolite Muffle Furnace

Carbolite muffle furnaces are useful in heating materials to high temperatures. They have an insulated chamber with fuel burners at the bottom and a heat-resistant door at the top. These are available from 30 to 3000˚C.

5. Laboratory Muffle Furnace

Laboratory muffle furnaces can be useful to heat up tasks like binder burnout, melting, and sintering. They utilize radiant heat transfer to warm objects that are placed in their chamber. They are often useful for setting up specific temperatures in order for scientific research or to fabricate products in a controlled way. The heat is evenly distributed through baffles made of metal in between heating components.

Muffle Furnace Process

Starting Process

  1. Put the items in the furnace carefully. Be careful not to scratch or damage the thermocouple that is located behind the furnace. After the oven has been full of whatever will be baking to bake, be sure that the door is shut.
  2. If the oven isn’t currently on, you can use the switch to switch on the oven. Utilizing the arrows on the digital reader located on the left side of the door, alter the temperature target (the yellow numeral) to the temperature you want to.
  3. Be sure that the temperature you want is not over the melting point of the components in the furnace. Click the blue buttons to adjust the temperature. It can take up to one hour for it to get the temperature you want.

Stopping Process

  1. After the furnace is at the right temperature for the required time, press the downward arrow on the digital reader to reduce the temperature to 20˚C and hit the blue switch to adjust the temperature.
  2. Do not unlock the doors until it is at 100˚C or lower (unless you are making heated gas to make Isotopes that are clumped).
  3. Do not attempt to remove anything out from your oven before the temperature on the display is set at around 25˚C. The process of cooling the oven can take longer than heating the oven.

  4. When the material is cool remove the objects from the oven. Be careful not to scratch the thermocouple. Place the items in their proper places. Close the oven’s door.

Uses of Muffle Furnace

Research and Analysis

The instrument is able to be utilized in laboratories to conduct studies on the different properties of various materials. The instrument is utilized to convert the material into absolute as ashes. This ash is used in analysing different characteristics of the materials that are being evaluated. It is the most efficient method to analyze what chemical attributes are present in various materials.

Heat Treatment

The device is employed in various metallurgical processes used for the treatment of heat for various materials. The process of heat treatment is utilized to make any structural change in the material. The muffle furnace can be set at temperatures up to that high that can cause desired changes to the material on a molecular level.

Aerospace Industries

The aerospace industry utilizes a muffle furnaces to test properties of flame retardant materials at extremely high temperatures and are installed in the aircraft.

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