Stacks of plastic lumps

Shredding and recycling of plastic lumps and purgings

Information on proper recycling

One of the most common material applications of plastics shredding is the processing of so-called plastic lumps, which are usually generated as a waste product during the extrusion of plastics. The economic potential of this "purge" is enormous. It is expensive to dispose of the unused purge lumps. Recycling offers the possibility of seamlessly reintegrating production scrap into the manufacturing process instead of using new resources.


Shredding plastic purge with a WEIMA S5.18 lift-up @ Plastic Recycling Inc. South Carolina

A WEIMA S5.18 lift-up single-shaft shredder shreds plastic purge at Plastic Recycling Inc. in South Carolina.


Call it what you want, we make it small.

Plastics, which accumulate as production waste at the beginning of the extrusion or injection molding process are known as plastic lumps, petrochemical lumps or extrusion lumps. It is also called "purge" in the US.

Contaminated start-up lump

Massive plastic lump

WEIMA WLK 10 shredder for plastic lumps in production line

Compact WLK 10 lumps shredder


How are plastic lumps formed?

During injection molding production, there are often production waste and scrap. These occur primarily when molded parts do not meet the desired specifications, edge trims have to be made or injection molded parts are cast on. Moreover, plastic waste also occurs during production breaks, machine tests or in the start-up phases of the machines. If the waste material is pure, it can be returned to production on site. The recycling of start-up lumps reduces the amount of waste and thus effectively reduces the impact on the environment and on disposal costs.

Various plastics

Mixed petrochemical lumps

Various plastic lumps

Stack start-up lumps before shredding

Stacked extrusion lumps

Production waste from plastic barrel production

Plastic bin production waste


Large, voluminous, heavy and bulky – by no means worthless

Many companies worldwide rely on shredding technology from WEIMA when it comes to the first process step of recycling extrusion lumps, for example Rowad Plastic and Napco National . Plastics manufacturers, plastics processors and chemical companies must reduce the material to a homogeneous particle size for further processing. Usually this is done by using a single-shaft shredder and downstream granulator.

Giant white start-up lumps on a pile

Storage of petrochemical lumps


What are thermoplastics?

Thermoplastics are types of plastics that are easily deformable at a defined temperature. In contrast to thermosets and elastomers, however, forming can be repeated as often as required. The only restriction is the need to avoid overheating, which would otherwise lead to thermal decomposition of the material. Well-known thermoplastics include polypropylene (PP), polycarbonate (PC), polyamide (PA), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC) and acrylonitrile butadiene styrene (ABS).

Source: Ruge, Wohlfahrt (2013) Technologie der Werkstoffe


Did you know?
The forefather of thermoplastics is celluloid. It has been known and produced the longest.

Source: Ruge, Wohlfahrt (2013) Technologie der Werkstoffe


PE lumps shredding with a WEIMA S7.20 shredder @Remondis Staffanstorp, Sweden

A WEIMA S7.20 single-shaft shredder shreds large and heavy PE lumps at a recycling plant of Remondis in Staffanstorp, Sweden.

Inquire about a plastics lump shredder today Request a quote

WLK 4: The entry to plastics recycling

With a working width of 600 mm and a rotor diameter of 260 mm, the WLK 4 shredder is one of the most compact of its kind. It is perfectly suited for small and medium throughput rates and, thanks to its comparatively small footprint, requires very little floor space. Nevertheless it is as robust and versatile as larger model series.

To the WLK 4

WEIMA single-shaft WLK 4 for plastic waste

WEIMA WLK 4 shredder


WLK series: High throughput plastic shredders

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


x-ray image of the WEIMA WLK 1500 single-shaft shredder

WEIMA WLK 1500 interior view


WEIMA WLK 800 shreds PE injection moulding waste


W5 series: Maintenance-friendly all-rounders with swing ram

With the W5 series, you can shred anything: from hard, large-volume injection molding waste to tear-resistant fibers and films. The innovative inspection flap guarantees maintenance-friendly access. The swing ram optimizes material feed and thus the shredding result.

To W5.18

x-ray view of the WEIMA W5.18 single-shaft shredder

WEIMA W5 shredder interior view


WEIMA W5.18 single-shaft shredder with Hägglunds hydraulic drive shreds petrochemical lumps


S7 series: For extreme throughput requirements

With their extremely sturdy design and large rotor diameters of up to 700 mm, shredders of the S5 and S7 series offer almost unlimited possibilities for the shredding of plastic waste. They are up to any challenge and can be equipped with a powerful hydraulic drive.

To the S5 and S7 series

WEIMA WLK 25 Super Jumbo single-shaft shredder

WLK 25 Super Jumbo


Two-stage processing of plastic production waste

In order to optimally prepare plastic waste for extrusion lines, it must be shredded to the smallest possible particle size. Usually this is done in a two-stage process, consisting of a pre-shredder and a post-shredder, which are connected to each other with conveyor technology (conveyor belt or screw conveyor).

While the pre-shredder shreds the plastic to a size of approx. 20-60 mm, the granulator grinds the material to approx. 3-12 mm.


PE lumps shredding with a WEIMA S7.20 shredder @Remondis Staffanstorp, Sweden

A WEIMA S7.20 single-shaft shredder shreds large and heavy PE lumps at a recycling plant of Remondis in Staffanstorp, Sweden.

Two-stage plastic shredding with shredder and granulator

Two-stage plastic shredding with shredder and granulator


Precise cut at high throughput with profiled V-rotor

The V-rotor developed by WEIMA is universally applicable and made of solid material. Its aggressive material feed with up to two rows of knives guarantees a high throughput with low power requirements. It can be equipped with hardened steel cutting knives in the edge lengths 30 mm and 40 mm. These can be turned several times in case of wear, which drastically reduces maintenance costs.

Profiled V-Rotor from WEIMA

Profiled V-Rotor with counter knives


Heavy duty machine design

WEIMA shredders for processing highly abrasive materials can be protected with various options to reduce wear and thus downtime and maintenance costs. The heavy wall thickness of the machine frame makes WEIMA shredders particularly robust. The rotor can be reinforced with Vautid, the screen with Creusabro. To protect the cutting knives against the impact of foreign objects, large knives with edge lengths of up to 130 mm x 130 mm can be selected. If the number of knives is small. Vautid can also protect knife holders.

To avoid increased wear of the rotor face plates, we recommend the installation of replaceable Creusabro wear plates on both sides. The cutting chamber can also be reinforced and optionally lined with exchangeable Creusabro plates. Wear protection does not stop at the screen, which defines the material size. For particularly high wear, we offer a screen reinforced with Creusabro with a wall thickness of approx. 20 mm.

Proteção contra a vácuo do rotor do triturador PreCut

Proteção do rotor Vautid

Proteção contra o desgaste de veículos

Vautid weld-on for shredder rotor

Concha Vautid no rotor PowerLine

Proteção contra o desgaste do rotor Vautid

Casco do rotor Vautid

Revestimento de rotor Vautid

ANteção antidesgaste com revestimento de tinta

WEIMA WKS rotor concha vácuo

Proteção contra o desgaste do revestimento do rotor

Revestimento Vautid para pré-triturador


What is Creusabro?
Creusabro is a high performance wear resistant steel. Compared to low alloy wear resistant steels, Creusabro has a higher heat resistance. WEIMA uses Creusabro with a hardness of 58 HRC.


What is Vautid?
Vautid is a buildup welding material that can be applied to components as a welding alloy. In WEIMA shredders, Vautid with 62 HRC is applied.


What is Hardox?
Hardox it an abrasion resistant steel and is mainly used as wear plate with a hardness of up to 600 HBW. Depending on the requirements, different degrees of hardness can be applied.


Select your preferred drive type


Electromechanical drive

In most cases, single-shaft shredders are equipped with an electromechanical drive. The power is transmitted by means of a norm motor, the specially developed WEIMA WAP gear and a power belt. The speed is adjustable.

Transmissão por correia com caixa de velocidades WEIMA

Acionamento eletromecânico com engrenagem WEIMA WAP

Transmissão por correia com caixa de velocidades WEIMA

Acionamento eletromecânico com engrenagem WEIMA WAP

Power belt drive with WEIMA gearbox

Electromechanical drive with WEIMA WAP gear

Shredder with power belt drive

WLK Jumbo with electromechanical drive


High-torque drive

The high-torque, multi-pole synchronous motor from Baumüller is produced in Germany and is characterized by its insensitivity to foreign objects. Without gears, the drive resists shocks and vibrations and thus has a particularly long service life – even when shredding challenging material streams.

High-torque drive from Baumüller

Acionamento de alto binário da Baumüller

Hägglunds hydraulic drive on a WEIMA single-shaft shredder

Hägglunds hydraulic drive in action

Hägglunds hydraulic drive on WEIMA FineCut

Hägglunds hydraulic drive on WEIMA FineCut

Hägglunds Hydraulic Drive System on WEIMA PreCut shredder

Powerful hydraulic drive from Hägglunds on a WEIMA PreCut Shredder

Opened inspection flap on the back of the WEIMA PowerLine shredder next to the Hägglunds Bosch Rexroth hydraulic drive

Aba de inspeção de uma destruidora WEIMA PowerLine

Hägglunds hydraulic drive on WEIMA PowerLine 3000

Hägglunds hydraulic drive on WEIMA PowerLine 3000


Hydraulic drive

Hydraulic drives from Hägglunds / Bosch Rexroth have no gearbox and are therefore particularly insensitive to many impurities. Speed and torque can be adjusted without current peaks. The robust drive provides high torque at low kW power. The speed can be variably adjusted by means of a regulating pump.


Only at WEIMA

Heavy-duty machine design
for solid plastic lumps and rigid plastics

Adjustable counter knives
for continuously sharp cuts

Large feed hopper
for voluminous parts, without material build-up

Easy maintenance
for minimized downtimes

Many drive options
for maximum throughput

Fast service
for highest customer satisfaction

All from one source:
Machine, conveyor system, metal detection, support, spare and wear parts


See for yourself

The WEIMA show room is equipped with shredding and briquetting machines of all sizes and technologies. This enables us to simulate your application as realistically as possible. You have the possibility to send us your material or visit us directly in Ilsfeld. From our gallery you have the best view directly into the cutting chamber. So you can observe the shredding process live.

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Alternatively you can send us material for testing.
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Granulate of laminate from the cutting mill

Material test plastic granulate