Purge lump solution
Purge Lump Recycling and Shredding Solution
Plastic purge lumps form when resin discharged from injection-molding or extrusion equipment cools into solid, irregular blocks. This page explains why these lumps can be difficult to process and the two recycling setups used by Hetian Machinery customers.
Thick, irregular purge lumps
Use the waste photograph to recognise the application before comparing the machines.
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See the HSS-600 PC customer case
HSS-600 Small Shredder processing a thick, irregular purge-lump application example; this is not a maximum input-size or throughput specification.
HSS-400 Small Shredder processing plate-like purge material; this example does not define a maximum input size.
Front and side views of a real purge-lump application example.
What Are Plastic Purge Lumps?
Plastic purge lumps form when molten resin is discharged from injection-molding or extrusion equipment during a color or material change, start-up, shutdown or machine cleaning. The discharged plastic cools into a solid block, so it is often thick, solid and irregular rather than shaped like a normal production part.
You may also hear this waste called plastic purgings, purge cakes or purge waste. Start-up scrap is a broader term that can include purge material as well as other rejected material made while production is stabilizing. If your factory uses a different name, send a photo so we can assess the waste by its form.
- Color or material change
- Start-up or shutdown
- Machine cleaning or purging
Purge-lump processing
Why Are Purge Lumps Difficult to Process?
Purge lumps in the applications covered here can reach approximately 50–60 mm at the thickest point. A cutting machine must take its first bite into a solid, uneven block rather than a thin-walled rejected part.
Thick, solid cross-section
The cutting system must work through a thick, solid section of plastic.
Irregular size and shape
Uneven surfaces can make each lump sit and feed differently.
Difficult first bite
A conventional crusher may struggle to catch and cut the whole lump directly.
Higher cutting load
Direct crushing can increase power demand, blade wear and damage risk when the machine is not matched to the application.
The 50–60 mm thickness is a real application example, not a maximum HSS feed-size specification.
Customer-site evidence
Customer Case: HSS-600 Shredder Processing PC Purge Blocks
The customer tested an HSS-600 with their PC purge lumps and filmed this video at their own site.
- Customer-confirmed input
- PC purge lumps, approximately 10–20 mm thick. No pre-cutting — the purge lumps were fed in their original form.
- Machine used
- HSS-600 Small Shredder, tested by the customer with their own PC purge lumps.
- Customer-reported result
- After installation, the customer told Hetian they were satisfied with the material feeding and shredding speed and sent this operating video as feedback.
Inside the machine
How the HSS Cutting System Handles Purge Lumps
HSS uses low-speed, high-torque cutting to reduce thick, solid purge lumps into smaller pieces.
Lower speed, more turning force
A conventional crusher may run at around 360 rpm, using higher speed and lower torque. HSS runs at 60 rpm with higher torque, giving the rotor more turning force to cut through thick, solid plastic. Moving blades work against fixed blades to make repeated cuts.
Prepare for further processing
HSS reduces the lump first. For applications needing further size reduction, an HPC High Speed Crusher can cut the pieces smaller.
If a block cannot be cut, HSS reverses and tries again. It stops if it still cannot cut the block.
See the HSS cutting system →Two routes for purge-lump processing
Hetian Machinery's customers usually process purge lumps with a single HSS shredder or in two stages, with HSS followed by an HPC High Speed Crusher.
Single machine
HSS on its own
A screened HSS can shred purge lumps without a separate crusher. Most standalone HSS applications need a screen.
The screen holds larger pieces in the cutting chamber for repeated cutting until they can pass through its holes. This lets one machine carry out the size reduction, usually at lower throughput than a two-stage setup.
Two-stage route
HSS + HPC High Speed Crusher
The more common route starts with HSS to cut the purge lumps into smaller pieces. An HPC High Speed Crusher then cuts them smaller.
Already have a crusher? Share its details so we can check whether it can work with HSS.
Factory test
HSS shredder + HPC High Speed Crusher: factory test
This video shows a customer’s HSS shredder and HPC High Speed Crusher working together at Hetian’s factory. One conveyor feeds purge lumps into HSS. A second conveyor carries the shredded pieces to HPC for further cutting.
- Purge lumps
- Infeed conveyor
- HSS shredder
- Transfer conveyor
- HPC High Speed Crusher
Watch the factory testClose video
Compare HSS-400 and HSS-600
HSS-600 covers a wider range of purge-lump applications, including thick or difficult-to-process lumps. HSS-400 is an alternative for smaller purge lumps.
| Model | Purge-lump starting point | Reference shredding capacity* |
|---|---|---|
| HSS-600 | Thick or difficult-to-process purge lumps. | 250-400 kg/h |
| HSS-400 | Suitable for smaller purge lumps. Larger pieces may need pre-cutting before feeding HSS-400. | 200-300 kg/h |
Purge-lump starting point
- HSS-600
- Thick or difficult-to-process purge lumps.
- HSS-400
- Suitable for smaller purge lumps. Larger pieces may need pre-cutting before feeding HSS-400.
Reference shredding capacity*
- HSS-600
- 250-400 kg/h
- HSS-400
- 200-300 kg/h
Application thickness examples: approximately 50–60 mm for HSS-600 and 20–30 mm for HSS-400. These examples are not minimum or maximum feed-size limits.
* Reference capacities are for HSS shredding ordinary-strength, non-reinforced injection-molding plastic. Reinforced or abrasive materials are outside this reference.