A casting workshop added a new aluminum alloy solution treatment line. The process requires the furnace chamber to maintain temperature uniformity within ±5℃ in the 400℃–550℃ range and to have 30-segment programmable heating capability. During the selection stage, three options were evaluated: box-type resistance furnace, trolley-type furnace, and heat transfer oil furnace. Ultimately, because the trolley sealing structure of the trolley-type furnace tends to form edge low-temperature zones in this temperature range, and the heat transfer oil furnace is difficult to meet process expansion above 600℃, the solution was locked as the box-type resistance furnace. However, the designers subsequently found that conventional box-type furnaces need to be checked item by item on two indicators—temperature control accuracy and furnace chamber temperature field distribution—otherwise the consistency of batch workpieces is difficult to guarantee.
Resistance furnaces rely on heating elements to generate heat, which is transferred to workpieces through radiation, convection, and conduction. They have a simple structure and good temperature uniformity, covering a process range of 400℃–1700℃. Induction furnaces use an alternating magnetic field to generate eddy currents inside conductive workpieces for self-heating, featuring fast heating rates and high thermal efficiency, but they are significantly affected by workpiece conductivity and geometry, making them more suitable for through-heating and surface quenching of bars, tubes, and rings. Arc furnaces generate heat through electrode discharge at extremely high temperatures and are mainly used for steelmaking and metal melting. Electromagnetic heating furnaces use high-frequency alternating current to make the metal container itself generate heat, with low heat loss and fast response. During design selection, if workpieces are mainly block-shaped, powder, or thin plates, box-type resistance furnaces have advantages in loading flexibility and temperature field controllability.
The overall thermal efficiency of industrial resistance furnaces is usually between 50% and 80%, with temperature control accuracy reaching ±1℃, supporting 30–50 segments of programmable heating and automatic constant temperature. When a resistance furnace is heated to 800℃, its heating efficiency is about 55%–68%, while that of an induction furnace is 72%–85%; however, induction furnaces are more sensitive to workpiece shape, and the induction coil must be readjusted when changing workpiece specifications. For design and selection personnel, if the process curve has multiple holding platforms in the 400℃–600℃ range and the loading quantity fluctuates greatly, priority should be given to a box-type resistance furnace with multi-segment programmable temperature control and a furnace chamber hot air circulation structure, to avoid unqualified workpiece microstructure caused by temperature overshoot. If the temperature range is selected too wide, equipment volume and investment increase; if selected too narrow, it is difficult to cover process margins.
The equipment needs to be equipped with safety mechanisms such as over-temperature alarm, thermocouple break protection, and leakage protection. For daily inspection, it is recommended to record the deviation between the temperature controller display value and the set value every shift; check whether the furnace door sealing strip is intact to avoid heat leakage causing low edge temperatures; observe whether electrical wiring terminals are loose or discolored from heat; and listen to whether the fan and contactor operate with normal sounds. Operators must receive professional training and work with certificates, and user organizations should establish operating procedures covering startup, operation, shutdown, and emergency shutdown.
The RXG-75-10 industrial electric heating furnace is suitable for annealing, quenching, tempering, and normalizing in metal heat treatment, and can also be used for sintering of ceramics, powder metallurgy, and new energy materials, as well as ashing and high-temperature ignition of laboratory samples. The rated temperature of the equipment is 1000℃, and the furnace chamber size and power configuration can be adjusted according to the size of loaded workpieces. Heating elements use resistance wires arranged on both sides and at the bottom of the furnace chamber, combined with an SCR power regulator to achieve continuous power adjustment.
