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 furnace dimensions 
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Post furnace dimensions
The temperature near the furnace is not uniform, so it is difficult to meet the process requirements. Therefore, the effective heating zone is smaller than the actual size of the furnace. Generally, 250-500 mm is taken at both sides of the flame furnace and 400-600 mm is taken at the top and bottom of the flame furnace.

brief introduction

Resistance furnace used in industry is generally composed of electric heating elements, masonry, metal shell, furnace door, furnace machinery and electrical control system. Heating power ranges from less than one kilowatt to several thousand kilowatts. The working temperature is below 650 C for low temperature furnace, 650~1000 C for medium temperature furnace, and 1000 C for high temperature furnace. It is heated mainly by radiation in high temperature and medium temperature furnaces. In the low temperature furnace, convective heat transfer is used to heat the furnace. The electric heating elements are installed in the air duct and forced to circulate gas in the furnace through the fan to enhance convective heat transfer. The resistance furnace has chamber type, well type, trolley type, push rod type, stepping type, muffle type and tunnel type and so on. Controlled atmosphere furnace, vacuum furnace, mobile particle furnace and so on are also resistance furnace.
HEAT TREATMENT OF ALUMINUM ALLOY

Electric heating element

It has high heat resistance and high temperature strength, low resistance temperature coefficient and good chemical stability. Commonly used materials are metal and non-metallic two major categories. Metal electric heating element materials are nickel-chromium alloy, chromium-aluminum alloy, tungsten, molybdenum, tantalum, etc., generally made of helix, waveform, waveform belt and waveform plate. Non-metallic electric heating element materials are silicon carbide, molybdenum disilicide, graphite and carbon, generally made into rods, tubes, plates, strips and other shapes. The distribution and line connection of electric heating elements depend on the furnace power and furnace temperature.
METAL HEAT TREATMENT SERVICE

power

The power of resistance furnace is determined according to the principle of heat balance of resistance furnace. The power of resistance furnace can be calculated accurately by heat balance calculation. The required power of electric furnace should include furnace heat storage, workpiece heating needs heat, workpiece heat preservation needs heat, atmosphere cracking needs heat, heat loss and so on. The furnace regeneration is determined by the furnace size, structure, main size, lining thickness, material thermal conductivity. Generally speaking, the larger the furnace, the greater the heat storage of the furnace, and vice versa. The heat required for heating the workpiece and the heat required for heat preservation of the workpiece are determined by the output of the furnace, the nature and size of the workpiece, the working temperature and the time. The greater the output of the furnace, the greater the power, and vice versa. The heat required for pyrolysis is determined by the nature of the atmosphere.
Heat treatment of aluminum alloy
The heat loss includes the heat loss at the inlet, the outlet and other parts. The calculation of furnace power has theoretical calculation method and empirical calculation method based on the principle of heat balance. The main parameters of theoretical calculation are output, temperature and heating up time. There are three commonly used methods of empirical calculation: calculating power according to furnace volume and working temperature, calculating power according to furnace inner surface area and working temperature, or calculating power according to the analogy of the output of the same kind of furnace. The general calculation power is mainly checked by one method and checked and corrected by another or two methods. After determining the power, according to the division of the resistance furnace, power distribution, selection of heating elements, selection of materials, calculation of its parameters, including cold resistance, power supply voltage, wire diameter, length. The material selection should consider the oxidation resistance, high temperature resistance, carburization resistance, processing technology, surface load and so on. The surface load of the strip heating element is larger than that of the filamentary heating element, which can increase by 50.


Sat Sep 29, 2018 8:17 am
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