Hard Plastic Purge Lump Recycling Application: Two-Stage Shredding and Crushing for Size Reduction

Plastic purge lumps are generated as part of normal plastic processing operations.
Typical sources include:
• Extrusion purge material 
• Injection molding purge lumps 
• Machine startup waste 
• Production changeover waste 
• Extrusion head waste 
Unlike loose film or small production scrap, purge lumps are usually:
• Large 
• Dense 
• Irregular in shape 
• Relatively hard 
These characteristics make direct feeding into conventional crushers or pelletizing equipment difficult.
The first requirement is therefore to reduce the size of the material before further processing.

The biggest challenge in this application is the physical form of the incoming material.
Large purge lumps can be difficult to:
• Feed continuously 
• Cut with conventional high-speed equipment 
• Process directly through a granulator 
• Maintain stable downstream material flow 
This is why the application uses two different size-reduction stages.
Primary Stage
Low-Speed, High-Torque Shredding
Handles the large and dense purge lumps.
Secondary Stage
High-Speed Crushing
Further reduces the shredded material into smaller and more uniform flakes.
The two machines therefore perform different functions rather than duplicating each other.

The actual process presented in this application is:
Plastic Purge Lumps → SR1400 Single-Shaft Shredder → Coarse Shredded Material → Plastic Crusher → Approx. 14 mm Plastic Flakes → Subsequent Recycling Process
The current application uses approximately 40 mm screen size in the shredder for rigid plastics, followed by a crusher with a 14 mm screen.

The first stage uses the SR1400 Single-Shaft Plastic Lump Shredder.
The SR1400 is designed for large and rigid plastic materials, including:
• HDPE lumps 
• PP lumps 
• ABS lumps 
• Injection molding purge lumps 
• Extrusion head waste 
The main function of this stage is coarse size reduction.
The shredder uses a low-speed, high-torque cutting system to process the large purge lumps.
This makes the material substantially smaller and easier to handle in the downstream crusher.

The SR1400 uses a hydraulic ram feeding system to push the purge lumps toward the cutting rotor.
This is particularly useful for large, irregularly shaped material.
The hydraulic feeding system helps:
• Push dense material into the cutting chamber 
• Maintain continuous feeding 
• Reduce the possibility of material blockage 
• Adapt feeding according to the material load 
For hard purge lumps, controlled forced feeding is an important part of stable primary shredding.

The application page specifies the following SR1400 configuration:

After primary shredding, the material enters the downstream plastic crusher.
The crusher performs the second stage of size reduction.
Its purpose is to further reduce the coarse shredded plastic into smaller and more uniform flakes.
For the application presented on the page, the crusher is configured with:
• 500 mm rotor diameter 
• 800 mm rotor width 
• 485 × 800 mm crushing chamber 
• 14 mm screen 
• 37 kW motor 
The two-stage configuration therefore follows a clear division of responsibilities:
Shredder = handle large purge lumps
Crusher = produce smaller, more uniform flakes

After secondary crushing, the material passes through the 14 mm screen.
The result is a more uniform plastic flake material suitable for subsequent recycling processes.
Compared with the original purge lumps, the final material is:
• Smaller 
• More uniform 
• Easier to convey 
• Easier to store 
• More suitable for downstream processing 
The final output in this application should therefore be understood as recyclable plastic flakes, not finished recycled pellets.

This is one of the most important points of the application.
A large purge lump and a small plastic flake require completely different cutting conditions.
The SR1400 is responsible for the first heavy-duty size reduction.
The crusher then performs the finer size reduction.
The process can therefore be understood as:
Large + Dense Material → High-Torque Shredding → Smaller Material → High-Speed Crushing → Uniform Flakes
This staged approach allows each machine to perform the task it is designed for.

The main value of this solution is its ability to process large, dense purge lumps that are difficult to handle with a single conventional crusher.
1. Heavy-Duty Primary Size Reduction
The SR1400 handles large and rigid purge lumps using low-speed, high-torque shredding.
2. Controlled Feeding
The hydraulic ram helps push irregular and dense material into the cutting chamber.
3. Secondary Fine Crushing
The downstream crusher further reduces the shredded material.
4. More Uniform Output
The 14 mm screen produces smaller and more consistent plastic flakes.
5. Preparation for Subsequent Recycling
The processed flakes can be transferred to downstream processes such as extrusion and pelletizing, depending on the customer's complete recycling configuration.

The application can be summarized as:
Large Plastic Purge Lumps → SR1400 Single-Shaft Shredder → Primary Size Reduction → Plastic Crusher → Secondary Size Reduction → Approx. 14 mm Plastic Flakes → Subsequent Recycling
The process converts difficult-to-handle purge lumps into a more manageable feedstock for further recycling.

This application demonstrates a two-stage size reduction solution for hard plastic purge lumps.
The main challenge is the large size, high density, and irregular shape of the incoming material.
The solution combines:
SR1400 Single-Shaft Shredding
Secondary Crushing
to progressively reduce the material size.
The current configuration uses a 40 mm shredder screen for rigid plastics followed by a 14 mm crusher screen, producing smaller and more uniform plastic flakes. 
The resulting material can then enter subsequent recycling processes according to the customer's requirements.
This application therefore focuses on front-end size reduction and material preparation, rather than presenting the system as a complete pelletizing line.

If your production generates large and dense purge lumps that are difficult to process directly, a two-stage size-reduction system can provide a practical preparation step for further recycling.
The application presented here combines:
SR1400 Shredding → Secondary Crushing → Approx. 14 mm Plastic Flakes
The processed material can then be transferred to subsequent recycling processes according to the customer's requirements.
Contact ACERETECH to discuss your purge lump size-reduction application.