Continuous sintering furnaces are widely used in industrial production. There are four common methods for conveying compacts and sintering boats in continuous sintering furnaces: mesh-belt type, roller-bottom type, push-rod type, and walking-beam type.
1. Mesh-Belt Continuous Sintering Furnace
The mesh-belt type is the most widely used. The belt is woven from nickel-based high-temperature alloy wire and driven by large drums at both ends of the furnace. Compacts can be placed directly on the mesh belt or in trays made of wire mesh. The furnace door leaves only a small gap, just enough for the compact to pass through. A large amount of protective gas is required during operation.
A specialized version of the mesh-belt furnace, called the humpback furnace, is used specifically for sintering stainless steel parts. This is a modified mesh-belt furnace and will not be detailed here, though interested readers can search for more information.
2. Roller-Bottom Continuous Sintering Furnace
The roller-bottom furnace has a conveying mechanism consisting of horizontal high-temperature alloy rollers arranged at the bottom of the heating zone. Bearings driving the rollers are located outside the high-temperature zone, and roller lengths range from 15–25 cm.
The cooling end uses a chain and sprocket system to maintain uniform rotation. While the high-temperature zone rollers are made of heat-resistant alloys, the other sections use steel rollers. Furnace doors open only during feeding and discharging. Once the rollers start rotating at high temperatures, they must run continuously to prevent bending.
Advantages of this furnace include a higher loading capacity compared to mesh-belt furnaces, due to the stronger rollers.
3. Push-Rod Continuous Sintering Furnace
The push-rod furnace has a simple structure. Sintering boats loaded with compacts are placed on a baseboard, one after another, and pushed into the furnace using a mechanical or hydraulic push-rod. The push-rod can operate either continuously or intermittently. The sintering temperature can reach up to 1650°C.
4. Walking-Beam Continuous Sintering Furnace
The walking-beam furnace can achieve the same high sintering temperature as a push-rod furnace but does not require heavy sintering boats.
In this furnace, a movable beam runs along the furnace length. Parts are placed on ceramic carrier plates. The beam lifts the carrier plate off the fixed furnace bottom, moves it forward a set distance, and then lowers it onto the fixed furnace bottom. The beam then returns to its original position. In this way, the beam gradually moves the parts through the furnace and cooling section in a stepwise manner.