Plastic Shredder for Recycling: From Scrap to Usable Regrind

Updated October 2026

A plastic shredder for recycling cuts bulky scrap into pieces that a recycling line can handle. The pieces still need to have the right composition, cleanliness, and shape for their next use. A drum becoming smaller is easy to see; whether the shredded material can become a useful product requires a closer look.

When planning a size reduction and/or size separation system, think about the end product. Is it a feedstock for an extruder? Regrind for a molding process? Is it washed flakes? Whatever the case may be, work backwards. For PP and PE rigid scrap, film and production lumps, recycling plastics successfully starts with an outlet for the recovered material.

What a Plastic Shredder Does in Recycling

Shredding plastic is a means of size reduction. It can be used to ease conveying and processing bulkier materials. Shredding (or tearing) is accomplished by cutting the feedstock. Extrusion can melt the feed. A shredder performs a different task from each of those operations.

In a typical plastic shredder machine, a driven rotor and cutting tools engage the feed. Some designs use a ram to push the material to the cutters. Where a screen is present, it holds the material in the cutting chamber until it can pass through an opening.

Consider a rigid HDPE barrel. Breaking its shell into manageable pieces can make subsequent wet cutting and washing practical. Labels, caps and residue from the barrel’s previous contents don’t disappear when the shell is cut. The British Plastics Federation’s recycling overview describes washing as a separate operation for removing adhesives, residual contents and other contamination.

For a recycling business, the right question is how much acceptable feed reaches the next machine. A large pile of mixed shreds may reduce waste volume while still leaving costly sorting work. See KITECH’s plastic shredder equipment for machine configurations. The process route below shows where those machines fit.

Shredder, Granulator and Pelletizer: Where Each Fits

A shredder may be used to process bulky and difficult feed, followed by a granulator to regrind the scrap to smaller size, and a pelletizing system to pelletize the polymer. A line may use all of them. Sometimes production scrap, if clean and manageable, can be directly charged to a properly specified granulator and avoid an extra step.

Equipment names tend to overlap. A supplier may name a cutting granulator as either a plastic grinder or a crusher. When in doubt, ask what physically goes in and comes out. Is it a large, irregular lump of feed, a screened flake or a pellet? The term “granule” by itself doesn’t help in writing a purchase specification. Instead, determine the functions of various equipment before comparing their names, and then compare equipment of the same function.

In Plastics Technology’s machine-role comparison, Vincent Carpentieri discusses the direct granulation of suitable sprues and runners, as well as the shredding of bulkier scrap. This helps to distinguish between types of injection molding scrap: an actual feeding problem should be solved by the addition of an extra shredder, as opposed to the standard purchase of a shredder regardless of the material.

Compare the single-shaft and dual-shaft arrangements against the same feed and required discharge. A heavy duty label doesn’t answer those questions. The separate shredder versus granulator guide covers the differences in equipment in more detail.

From Plastic Waste to Shreds: The Process

A workable shredding route starts with an identified and accepted feed, continues with controlled feeding and cutting, and ends with an inspection of discharge. This protects the equipment and the scrap being recovered. The order of washing and cutting depends on the type of contaminant and the equipment being used.

How can you shred plastic?

Purpose-built equipment should be used to process plastic according to its form, thickness and contamination level. Identify and sort the material, remove prohibited objects, feed it through the designed loading system and collect the discharge for the next process. Guards and interlocks should remain functional. Isolate the machine using the authorized procedure to remove a blockage. Don’t reach into the hopper.

1. Identify the incoming lot. Record polymer, source, previous contents and visible contamination before mixing lots.
2. Prepare accepted feed. Remove foreign objects and route unsuitable or regulated material away from ordinary recycling.
3. Feed within the approved envelope. Match piece dimensions and loading method to the installed machine.
4. Cut and discharge. Keep feeding, cutting and evacuation balanced so material does not accumulate between stages.
5. Inspect the output. Check size distribution, composition and suitability for the intended washing or reuse route.

The Association of Plastic Recyclers’ process description places grinding before washing, followed by rinsing, drying and extrusion. Others precede the reduction with washing to get rid of dust and other impurities. These are configured sequences, so copying a diagram without considering dirty feed can lead to grit and other unsuitable materials being fed into the cutting chamber.

Maintain the original lot identity with its output bin. If a batch is producing extreme contamination or odd melt behavior, traceability allows the plant to isolate the batch instead of blending the issue with the good batches. Record the observed shred size with that batch, as opposed to nominal settings on the bins.

How HDPE, PP, Film and Lumps Behave

The forms that a polymer takes affect how cutters interact with it. Flexible film and purge can be from the same polymer family as rigid containers, but behave very differently in a hopper. State both the polymer and the object being scrapped. “Polyethylene scrap” is nondescriptive and leaves out info required to pick an optimal route.

Film shredding shows that a polymer name isn’t sufficient. In a sponsored technical article, Greg Parent of Vecoplan mentions that stretch wrap can compact to material that the rotor can engage, while woven strands can be difficult to cut and may wrap. His form-specific film discussion is more helpful than assuming that every flexible plastic needs identical feeding equipment.

Keep PET bottles and HDPE containers in their intended sorting routes. Polyethylene terephthalate is a different resin from polyethylene; a wide variety of materials entering one hopper doesn’t result in a broadly reusable blend. PET bottles and packaging made from another resin therefore require a separate acceptance decision. For the machine selection questions raised by these feed types, use the existing plastic shredder selection guide.

What Shredding Leaves in the Plastic

In many cases, cuttings contain a lot of contaminants. Metal removal, washing and separation accomplish different goals and require a specific target. A flake can look clean but still contain the wrong resin. In particular, the floating fraction from a water tank can contain regular HDPE and/or PP.

In a published density-separation experiment, the tested PP grade had a density of 0.910 g/cm³ and the HDPE grade was 0.953 g/cm³. Both floated in water. These measurements are for the experiment’s virgin grades; filled or differently formulated waste can behave differently.

APR’s HDPE packaging design guidance recognizes floating PE and PP components and states that sufficiently filled HDPE can sink. For a buyer interested in an HDPE-rich flake, removing sinking dirt is only part of the job. Polymer sorting and a composition specification are still needed.

PVC or polyvinyl chloride requires its own acceptance decision as opposed to being casually combined with PE or PP. Regulated contamination can also determine if material recycling is permitted at all. For example, England’s Environment Agency guidance requires that separated materials containing regulated persistent organic pollutants be destroyed. Route unknown or restricted feedstock through the applicable waste management assessment prior to shredding.

From Shredded Pieces to Usable Regrind

Usable regrind meets the next process’s requirements for geometry and composition and other handling characteristics. Determining if regrind meets specification typically requires an inspection. Inspect a representative discharge sample, measure and assess size fractions and contaminants, and compare to the receiving process specification. Water can increase the apparent mass of the regrind so ensure mass is determined on a consistently dry basis.

3-Output Shredding Check

The 3-Output Shredding Check compares particles’ geometry and composition and downstream fit prior to a shredded batch entering its next process.

This is a check for product quality. For other regulatory and legal requirements (i.e. safety, emissions, and legal waste disposal) their own assessments are required. Use the following to evaluate what needs attention.

A 2023 bottle-cap recycling study measured flake distributions using 2.0 mm, 4.0 mm, 8.0 mm and 11.2 mm sieves. Those were experimental measurement sizes, not universal acceptance limits. The practical lesson is to measure a distribution instead of reporting only a machine’s screen opening. Detailed aperture choices belong in the screen-size selection guide.

In business, distinguishing disposal costs from recovered-material revenue will benefit purchasing. Operations needs a stable feed. Quality needs an acceptable composition. Finance needs the mass actually released to the chosen outlet. An attractive nominal throughput can’t make up for these.

A real-world application of a circular economy requires recovered plastic materials to replace suitable feed. To reduce plastic sent to landfill, determine a suitable outlet and account for rejects as well as retained product. This makes sustainable waste management a material-routing task, rather than a claim based on the amount of scrap cut.

Plastic Shredding Problems and Their Causes

In general, factors resulting in unstable feeding, wrapping, heat and fines can occur due to multiple mechanisms. Therefore, changing a screen or adjusting feed pressure won’t always solve the problem. Compare the condition of the incoming material against the approved duty of the machine. Inspect the cutting condition and discharge through the authorized maintenance procedure. Treat a jam as a controlled situation.

• Hopper bridging: light or awkward pieces may not reach the rotor consistently. Review the feeding arrangement before assuming the motor lacks power.
• Wrapping or stalled discharge: long film strands and an unsuitable evacuation path can interrupt flow. Match the remedy to the actual material form.
• Fines or heating: inspect shredder blades, cutting clearances and recirculation according to the manufacturer’s procedure. Repeated cutting can change output quality.

Fines and Longs are discussed with respect to the geometry of screens and sieves in a 2025 Plastics Technology article by Paige O’Meara of Wittmann. Consistent particle size is a measured outcome, not a reason to continually reduce the screen opening and not check the resulting fractions.

“Push buttons, selector switches and other control circuit type devices are not energy isolating devices.”

For servicing and jam clearing, authorized personnel must follow the appropriate hazardous energy control procedures. An emergency stop isn’t a substitute for isolation. Keep machine guarding intact during normal operation.

Dust also needs its own control plan. Swinnerton and colleagues’ 2024 experiment observed increased airborne particle counts while shredding PET, PP and HDPE. Good retained mass alone therefore can’t establish low airborne emissions; assess capture and worker exposure for the actual installation.

Connecting Shredding to a Washing Line

Connect a shredder to washing by agreeing on the material that each stage receives and delivers. Coarse shreds may require further wet cutting, prior to rinsing and drying. While assessing the transport and buffer storage systems, also evaluate water treatment and reject handling, as well as the overall system’s capacity. A restriction at any point can potentially limit useful output from the entire system.

KITECH’s public AGS single-shaft shredder table offers 40-100 mm screen options, while their HDPE/PP rigid washing-system page offers 8-15 mm final flakes. Keep in mind that these values indicate different stages of a process. The complete line includes further processing. The final-flake listing shouldn’t be interpreted as the specification for the primary product discharge of a shredder.

For barrels, crates, baskets and lumps, the relevant line context for KITECH’s HDPE/PP rigid plastic washing system is available in the aforementioned product description. Send the dimensions, composition and previous contents of the feed, as well as the required output destination, so the proposed stages address the same material.

• Mechanical interface: conveying method, discharge height, buffer capacity and access for maintenance.
• Utilities: available electrical supply, water circuit, drainage, drying demand and dust extraction.
• Quality interface: accepted size fractions, polymer composition, contamination and moisture at each handoff.
• Waste interface: captured solids, wastewater particles, filter residues and their approved destinations.

Washing removes contaminants from the product and the removed material needs to be discharged somewhere. In one of the studies by Brown and others (2023), wash water from a UK facility contained microplastics. Also, filtration performance was size dependent. Don’t assume that clean-looking product means discharge water is clean.

What is the price of a shredder machine?

The price is configuration-specific: A standalone machine and an installed shredding-and-washing system have different supply scopes. Compare quotations for the same feed, accepted output, conveying, controls, and commissioning. Include consumables and rejected material handling in your calculation for operating cost. KITECH’s industrial shredder cost guide summarizes the primary cost items.

Check the feed and output acceptance tests based on samples representative of the feed and output agreed upon in the Contract. The recycling equipment trial and acceptance guide provides information on this procedure. For EU projects, consider the responsibility for integrating machinery within the framework of the general application of Regulation (EU) 2023/1230 from 20 January 2027.

Frequently Asked Questions

The most practical route to recycling depends on the nature of the material and who can beneficially use the material after recycling. Small scale print waste, clean production scrap and mixed post consumer packaging require different technologies and outlets. The questions below address how to shred and recycle material without treating every piece of shredded plastic as ready for a new product.