Why we recommend a shredder in front of a plastic recycling extruder

Machines in the WLK series are ideally equipped for a wide range of plastics tasks. The machine design is characterized in particular by its durability and robustness. Thanks to the conveyor belt cut-out, all machines can be seamlessly integrated into any production line. They also offer a wide range of options in terms of drive and cutting geometry.

With rotor lengths of 1,400 to 2,200 mm, the shredders in the W5 series shred large-volume plastic tanks and plastic garbage cans with ease. The hydraulically upward pivoting screen basket and the inspection flap allow foreign objects to be removed quickly and simplify maintenance. Large quantities of plastic flakes can be removed via the wide conveyor belt cut-out.

The shredders in the S7 series stand for maximum stability, performance and versatility. With their robust design, various sizes and over 80 equipment options, they offer flexible solutions for the most demanding shredding tasks.

With a shredder, the preconditioning unit (PCU) has significantly less work and therefore works more stably. Stable means fewer temperature fluctuations in the PCU, which leads to a consistently high feed/fill ratio of the extruder screw. Less chipping in the PCU = longer service life of the PCU knives = less downtime for knife changes and lower costs.

The hopper of the shredder acts as a buffer so that material has to be fed less frequently. The automatic stop/start system ensures even extruder feeding, which means that no additional full-time force is required for high throughputs.
Feeding bulky material is also easier. Feeding is possible by forklift truck, wheel loader, feed belt or manually. The WEIMA discharge conveyor can be equipped with a magnetic roller to automatically separate small FE-
particles automatically in front of the EREMA metal detector.

Pre-shredding means that the extruder works more efficiently as it no longer has to shred coarse material. This lowers the specific energy consumption, avoids peak loads and reduces electricity costs. At the same time, the mechanical stress on the screw, barrel and drive components is reduced, which minimizes wear, extends maintenance intervals and reduces unplanned downtimes. The optimized division of work between shredder and extruder thus ensures an energy-efficient, cost-saving and more durable production line.

Pre-shredding ensures a uniform material size, allowing the extruder to melt the plastic more efficiently and gently. Lower mechanical and thermal stresses prevent overheating and preserve the polymer structure. This results in high-quality recycled pellets with better mechanical properties, homogeneous coloring and a reduced reject rate – ideal for further processing or sale.

A high-performance shredder makes it possible to process a wide range of plastic types – from bulky hollow bodies and start-up lumps to films and fibers. This means that even difficult-to-handle materials can be recycled efficiently, making the procurement of raw materials more flexible and cost-effective. The system also remains adaptable for future material changes and new business opportunities.

The robust design of WEIMA shredders makes them less sensitive to metal contamination compared to an extrusion line and of course easier/cheaper to repair if foreign bodies get into the cutting chamber. In addition, the discharge conveyor can be equipped with a magnetic roller to automatically remove small FE particles in front of the EREMA
metal detector.