Introduction to muffle furnace

For the classification of muffle furnace, it can be classified according to its heating element, rated temperature and controller. See the following for details:

1) According to the heating elements, there are: electric furnace wire muffle furnace, silicon carbon rod muffle furnace, silicon molybdenum rod muffle furnace;

2) According to the rated temperature, it is generally divided into: muffle furnace below 1000 ℃, muffle furnace at 1000 ℃ and 1200 ℃, muffle furnace at 1300 ℃ and 1400 ℃ and muffle furnace at 1600 ℃ and 1700 ℃. 1800 ℃ muffle furnace.

3) According to the controller, there are the following: pointer table, ordinary digital display table, PID regulation control table, program control table; according to the insulation material, there are two kinds: ordinary refractory brick and ceramic fiber.

1. After opening the package, check whether the muffle furnace is intact and whether the accessories are complete. The general muffle furnace does not need special installation, it only needs to be placed on the flat indoor floor or shelf. The controller should avoid vibration and should not be placed too close to the furnace to prevent the internal components from working normally due to overheating.

2. A thermocouple is inserted into the furnace for 20-50mm, and the gap between the hole and thermocouple is filled with asbestos rope. The best way to connect the thermocouple to the control is to use compensation wire (or insulated steel core wire), pay attention to the positive and negative poles, and do not connect them in reverse.

3. Additional power switch should be installed at the leading in of power line to control the main power supply. In order to ensure safe operation, the furnace and controller must be reliably grounded.

4. Before use, the thermometer indicator should be adjusted to zero point. When using compensation lead and cold junction compensator, the mechanical zero point should be adjusted to the reference temperature point of the cold junction compensator. If the compensation lead wire is not used, the mechanical zero point should be adjusted to the zero scale position, but the temperature indicated is the temperature difference between the measuring point and the cold end of the thermocouple.

5. After checking the wiring, cover the controller shell. Adjust the setting pointer of the temperature indicator to the required working temperature, and then turn on the power supply. Turn on the power switch, at this time, the green light on the temperature indicator is on, the relay starts to work, the furnace is powered on, and the ammeter shows the current. With the increase of the internal temperature of the electric furnace, the pointer of the temperature indicating instrument gradually rises, which indicates that the system works normally. The temperature rise and constant temperature of the electric furnace are indicated by the traffic light of the temperature indicator. The green light indicates the temperature rise, and the red light indicates the constant temperature.

When muffle furnace is used for the first time or used again after long-term shutdown, it must be dried up. The drying time should be at room temperature 200 ℃ for four hours. 200 ℃ to 600 ℃ for four hours. When using, the furnace temperature should not exceed the rated temperature to avoid burning the electric heating elements. It is forbidden to pour all kinds of liquids and soluble metals into the furnace. Muffle furnace should work under 50 ℃ below the maximum temperature. At this time, the furnace wire has a long life. 2. Muffle furnace and controller must work in the place with relative humidity not more than 85% and no conductive dust, explosive gas or corrosive gas. When metal materials such as grease need to be heated, a large amount of volatile gas will affect and corrode the surface of electric heating element, which will destroy and shorten the service life. Therefore, the heating should be timely prevented and sealed containers or appropriate openings to eliminate.

Muffle furnace controller should be limited to the ambient temperature range of 0-40 ℃.

According to the technical requirements, regularly check whether the wiring of electric furnace and controller is in good condition, whether the pointer of indicator is stuck or not when moving, and calibrate the error increase caused by magnetic steel, demagnetization, wire expansion, fatigue of shrapnel and balance damage by potentiometer.

The thermocouple should not be pulled out suddenly at high temperature to prevent the jacket from bursting.

Keep the furnace clean and remove oxide in the furnace in time.