Due to imperfect sealing at the furnace opening and door, box-type furnaces experience significant heat loss, resulting in temperatures at the opening that are lower than those at the center of the chamber. If strict temperature uniformity is required for the workpiece, the effective heating zone-and consequently the usable furnace area-must be reduced. This prevents the furnace from operating at full capacity, leading to wasted energy and labor hours, as well as increased unit consumption. Therefore, it is essential to maximize the uniform temperature zone within the box-type furnace. Specific methods include:
1. Installing electric heating elements at the furnace door to raise the temperature at the opening and improve overall temperature uniformity. For high-temperature box-type furnaces using resistance wire heating, if testing reveals low temperatures at specific points, adjusting the heating current to those wires can bring temperature uniformity within process specifications.
2. Strategically distributing heating power (resistance wires) along the length of the furnace-such as increasing power at the opening or employing zoned control methods.
3. Installing fans to force gas convection within the furnace, which significantly enhances temperature uniformity.
4. Modifying the furnace casing's paint color; since emissivity varies with color, spraying the casing with silver-gray or black paint-based on experimental results-can reduce heat dissipation into the surrounding space.
5. Upgrading the temperature control system and employing appropriate regulation methods. Switching to PXR-series temperature controllers and utilizing continuous PID control instead of analog instruments can ensure temperature uniformity meets production process requirements.
