A recycling line is a cascade of size reduction. Attempting to granulate a whole pipe will destroy the machine. Attempting to extrude dirty flake will block the screen. This guide explains the engineering hierarchy of Primär, Secondary, Und Tertiary processing.
Zugehörige Ausrüstung: integrierte Zerkleinerungs- und Granuliermaschine, Einwellen-Häcksler.
1. Primary Reduction: The Shredder (20:1 Ratio)
- Eingang: Everything (Bales, Purging, Pipes, Pallets).
- Mechanismus: Scheren. Low Speed (60-80 RPM) + High Torque.
- Rolle: To create a manageable “flowable” chip (40-60mm).
- Warum: You cannot feed a 1-meter pipe into a granulator. The shredder acts as the “Pre-Conditioner.”
- Vulnerability: Tramp Metal. (Requires Overband Magnet).
2. Secondary Reduction: The Granulator (5:1 Ratio)
- Eingang: Shredded Chips (Clean or Dirty).
- Mechanismus: Scissor Cut. High Speed (400-600 RPM).
- Rolle: To create a uniform “Regrind” (8-12mm).
- Warum: Washing lines require small particles to clean effectively (friction). Extruders need uniform bulk density to melt consistently.
- Vulnerability: Heavy shocks. The high inertia rotor will explode if it hits a solid bolt.
3. Tertiary Processing: The Pelletizer (1:1 Ratio)
- Eingang: Clean, Dry Regrind/Flake.
- Mechanismus: Plastification (Melting + Filtration + Degassing).
- Rolle: To create a virgin-like “Pellet” (3mm).
- Warum:
- Filtration: It is the only step that removes non-melting contaminants (wood, paper, aluminum) via a Laser Filter.
- Entgasung: Vacuum venting removes volatiles (inks, moisture) that cause bubbles.
- Flowability: Injection molders cannot run light fluffy regrind; they need dense pellets.
Vergleichsmatrix
| Besonderheit | Aktenvernichter | Granulator | Pelletierer |
|---|---|---|---|
| Geschwindigkeit | Slow (80 RPM) | Fast (500 RPM) | Variable (Screw) |
| Drehmoment | Massive | Mäßig | Mäßig |
| Noise | 80-85 dB | 95-100 dB | 80 dB |
| Ausgabe | 50mm Chips | 10mm Flake | 3mm Pellet |
| Wartung | Low (Rotate knives) | High (Sharpen daily) | Medium (Screens) |
System Design Rules
Rule of 40mm
Never feed material $>40mm$ into a standard granulator. It wears the blades exponentially faster. Let the shredder do the heavy lifting.
The Bulk Density Curve
- Baled Film: 200 kg/m³.
- Shredded Film: 300 kg/m³.
- Densified/Granulated Film: 400 kg/m³.
- Pelletized Film: 800 kg/m³.
Increasing bulk density reduces storage and transport costs.
Referenzen
[1] “Size Reduction of Plastics,” Society of Plastics Engineers. Size Reduction of Plastics
[2] “Extrusion Processing Guide,” Battenfeld-Cincinnati. Extrusion Processing Guide
