Stretch Film Waste to Pellets: Processing Flow and Machine Selection
Release time:
2025-08-15 17:54
Stretch film (typically referring to LLDPE stretch film) is one of the most widely used consumables in the modern logistics and packaging industries, resulting in a massive volume of waste material. How to efficiently and economically manage this waste has become a critical factor for businesses seeking to reduce costs, improve efficiency, and achieve sustainable development. So, how can stretch film waste be granulated? This requires a professional process and equipment selection analysis. This article will provide a detailed breakdown of this process, helping you turn waste into valuable resources.
Characteristics of stretch film waste: Why does it require special handling?
Before discussing how to pelletise stretch film waste, we must first understand its unique physical characteristics, which are the fundamental factors determining equipment selection.
- Lightweight and bulky: Stretch film waste typically has a large volume and low bulk density.
- High elasticity and toughness: It is difficult to be effectively shredded by ordinary shredders.
- Prone to tangling: During conveying and feeding, it easily tangles around rotating components.
These characteristics mean that equipment designed for processing hard plastics cannot be simply used, as this would lead to feeding blockages, low output, or even equipment damage.
The Complete Process of Granulating Stretch Film Waste
An efficient granulation process primarily includes the following four key steps.
1. Pre-processing: Shredding and Agglomeration
For bundled or rolled waste film, volume reduction is first required.
- Shredding: Use dedicated single-shaft or double-shaft shredders to shred large bundles of waste film into smaller fragments for subsequent processing.
- Washing and drying (optional): If the waste film comes from post-consumer recycling and contains impurities such as sand, oil stains, etc., additional washing and drying steps are required.
2. Core Steps: Compaction, Plasticisation, and Deaeration
This is the core function of a plastic pelletising machine.
- Cutting and Compaction: This is the most critical step. Waste film fragments are fed into a compaction chamber (Compactor/Agglomerator) equipped with rotating blades. Through high-speed cutting and friction by the blades, the waste film rapidly heats up, contracts, and agglomerates into blocks, which are then forced into the extruder screw.
- Melting and Plasticisation: Within the extruder's screw and barrel, the agglomerated material is further heated, sheared, compressed, and mixed to form a uniform melt.
- Degassing: If there is a small amount of moisture or printing ink on the surface of the waste film, it must be removed through the vacuum degassing port on the screw.
3. Filtering: Removing impurities
Before entering the die head, the melt must pass through a screen changer to filter out any small impurities (such as paper scraps or wood chips), ensuring the purity of the final pellets.
4. Pelletising: Moulding
Water ring die face hot cutting: This is currently the most efficient and mainstream pelletising method for processing stretch film waste. After the melt is extruded from the die holes, it is immediately cut by rotating blades closely adhering to the die face. The cut pellets are carried away and cooled by high-speed water flow, then dried by a centrifugal dewatering machine to produce uniformly shaped and aesthetically pleasing recycled pellets.
Equipment Selection Analysis: Choosing the Right ‘Three-in-One’ Pelletiser
Given the characteristics of stretch film waste, the most ideal equipment on the market is a ‘three-in-one’ recycling pelletiser that integrates ‘shredding, compaction, and extrusion’ functions.
| Equipment Module | Function | Selection Criteria |
| Cutting and Compaction Chamber | Aggregates and densifies loose waste film, and forces feeding | Chamber dimensions and motor power must match the extruder's output; blade material must be wear-resistant |
| Extrusion System | Melting, plasticising, homogenising, and degassing | Screw length-to-diameter ratio (L/D) typically ranges from 30 to 36:1; choose single-stage or dual-stage degassing as needed |
| Screen changer | Filter impurities | Recommend using a hydraulic dual-station or larger-area screen changer to reduce screen change frequency |
| Granulation system | Particle formation | Strongly recommend water ring die face hot cutting for high automation and good particle quality |
Conclusion: Professional equipment is the guarantee of efficient recycling
How to pelletize stretch film waste? The answer is to adopt a professional, integrated solution. As demonstrated by equipment provided by professional manufacturers such as Wintech, modern recycling technology has already reached a high level of maturity. For large-scale production facilities, such as factories with multiple cast film extrusion line, the generated scrap material can even be directly returned to the stretch film making machine via an online recycling system, achieving ‘zero-waste’ production. However, for more specialised materials like PVC food wrap, downstream equipment such as cling film rewinding machine may be required to process the scrap material centrally.
As advocated by the industry authority Association of Plastic Recyclers (APR), adopting the right technology is key to enhancing the value of recycled plastics. By investing in a granulation system specifically designed for stretch film waste, you can not only solve the challenge of waste disposal but also open up a new profit growth point, injecting strong momentum into your company's green development.
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