What is an agglomerator, how does it work, and why does it densify low-density plastics such as film, fiber and foam before extrusion? An overview of the agglomeration process.
An agglomerator is a machine that softens low-density (lightweight, bulky) plastic waste — such as film, fiber, foam and thin sheet — with the help of friction heat and turns it into small, dense particles (agglomerate). The aim is to reduce the volume of the material and increase its bulk density, thereby producing a more stable, processable raw material for the next stage.
Inside the agglomerator, a rotating bladed rotor cuts and rapidly mixes the material. The friction heat generated by this motion brings the plastic close to its softening point without melting it; a controlled amount of water is often sprayed in to cause sudden cooling, and the material gathers into particles. The result is a free-flowing structure suitable for extrusion.
Agglomerate is a friction-densified intermediate product that has not passed through the melting, filtration and pelletizing steps. A granule (pellet), on the other hand, is a more homogeneous final raw material produced by melting in an extruder and passing the melt through a melt filter. The agglomerator is generally positioned as a preparation stage that increases the efficiency of the granulation line.
When bulky materials such as film are fed directly into an extruder, feeding irregularities and efficiency losses can occur. Agglomeration improves feeding stability by densifying the material and helps the line run more steadily. For this reason, it is frequently preferred on film/fiber-focused recycling lines.
Does an agglomerator produce granules on its own? No; agglomerate is an intermediate product. An extrusion stage is generally required for the final granule.
Can every plastic be agglomerated? Agglomeration is particularly suitable for film, fiber and lightweight materials; for rigid and thick parts, a crusher/shredder is a more appropriate starting point.
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