How does a sawdust briquette making machine work?

Jan 20, 2026

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The core working principle of the sawdust press machine is the same as that of a wood pellet machine, both relying on the lignin properties of biomass raw materials to achieve molding. However, it is specifically optimized in terms of pressure, temperature parameters, and structural design to adapt to the production of block fuel. Lignin is the natural binding component in wood chips. Under high temperature (160-200℃) and high pressure (10-30MPa), it softens and melts to form a binding medium, binding loose wood chips together. After cooling, it forms dense block fuel without the need for any chemical binders, reducing costs and ensuring environmentally friendly combustion.

The complete workflow of the sawdust briquette press can be divided into four main steps: raw material pretreatment, feeding and extrusion, molding and cutting, and finished product cooling. Controlling the parameters at each stage directly affects the quality of the finished product. The first step, raw material pretreatment, has similar requirements to but slightly different from that of a wood pellet mill: the wood chip size needs to be controlled between 2-8mm (2-5mm for a wood pellet mill). Too large a particle size leads to uneven molding, while too small a particle size increases equipment wear. The moisture content should be controlled between 8%-12% (12%-15% for a wood pellet mill). Too high a moisture content will cause the finished product to crack, while too low a moisture content will prevent the lignin from softening. Moisture needs to be adjusted through drying or sun-drying, while simultaneously removing impurities such as stones and metal.

The second step, feeding and extrusion, is the core of the sawdust briquette press machine. The pretreated wood chips are fed uniformly into the molding cavity via a screw feeder to prevent uneven pressure buildup. Inside the molding cavity, the pressure rollers and the die (flat or ring die structure, similar to a wood pellet mill but with larger apertures) rotate at high speed driven by a motor, applying high pressure to the wood chips. Simultaneously, a heating device outside the molding cavity maintains the set temperature, allowing the lignin to soften fully.

Under the combined action of high pressure and high temperature, the wood chips are extruded into the die holes, forming a columnar shape.

The third step is forming, cutting, and cooling. After the cylindrical material is extruded from the mold, it is cut into uniformly sized fuel blocks by a pre-set cutter. The freshly formed product is at a high temperature and needs to be cooled naturally or by a cooling device to room temperature to prevent it from absorbing moisture and deteriorating due to high temperature. The entire process is similar in logic to the production process of a wood pellet grinding machine, but the wood pellet press requires higher precision in temperature and pressure control to ensure the density and strength of the finished block.