What is the difference between a shredder and a crusher?

A shredder performs coarse size reduction (50-200mm) using slow-speed rotating knives, ideal for whole items like bottles, pipes, and bales. A crusher performs fine size reduction (3-15mm) using high-speed rotating knives/hammers, ideal for producing uniform flakes or granules. In most recycling lines, material goes through a shredder first, then a crusher for final sizing.

Which roller type is best for PET bottle recycling?

V-type rollers are best for PET bottles. The V-shaped cutting profile grips and cuts round bottles efficiently with minimal slip. The hollow design also allows water injection during crushing for initial rinsing. For PET bottle washing lines, we recommend the PS-500 or PS-800 with V-type rollers and a 12mm screen.

Can a plastic crusher process metal?

Standard PS Series plastic crushers are NOT designed for metal. For metal scrap processing, use the LP Series vertical crusher which has hardened alloy cutting tools and a heavy-duty gearbox designed specifically for metal. Attempting to crush metal in a plastic crusher will damage the knives, rotor, and bearings.

What screen size should I use in my crusher?

Screen size determines output particle size. For PET washing lines: 10-15mm screen. For cable separation lines: 5-8mm screen. For pelletizing feed: 8-12mm screen. For coarse pre-crushing before a second stage: 20-30mm screen. Smaller screens reduce throughput by 20-40% but produce more uniform output.

Equipment Guide

Crusher Selection Guide: PS Series, Vertical & Hammer Crushers

June 21, 2026 9 min read LVKESORT Engineering Team

The crusher is the heart of any fine-size-reduction stage in a recycling line. Unlike a shredder that does coarse cutting, the crusher produces uniform flakes or granules at 3-15mm — the size needed for washing, separation, and pelletizing. Choosing the wrong crusher means poor flake quality, high fines, low throughput, and excessive energy waste.

1. Shredder vs Crusher: What's the Difference?

This is the most common question we get. Here's the clear distinction:

Feature	Shredder	Crusher
Function	Coarse size reduction	Fine size reduction
Output Size	50-200mm	3-15mm
Speed	Slow (30-100 RPM)	High (500-800 RPM)
Cutting Action	Tearing / shearing	Scissoring / impacting
Motor Power	22-110 kW	11-75 kW
Screen	Optional (double shaft)	Always present
Feed Size	Whole items (bottles, pipes)	Pre-shredded pieces
Position in Line	First stage	Second stage (after shredder)

Rule of thumb: If your material is larger than 30mm or includes whole items, you need a shredder first. The crusher then refines the output to the exact size needed for your process. Only small, thin materials (films, thin sheets) can go directly into a crusher without pre-shredding.

2. PS Series Plastic Crusher: The Workhorse

The PS Series is the most versatile and widely used crusher in plastic recycling. Its high-speed rotating knives cut plastic into uniform flakes that pass through a screen at the bottom of the cutting chamber. The key to selecting the right PS crusher is choosing the correct roller (knife) design:

V-Type Roller

V-shaped cutting profile with angled knives that grip round and hollow items. The hollow center allows water injection for simultaneous crushing and rinsing.

Best for: PET bottles, HDPE containers, shampoo bottles, any round or hollow plastic items

Advantage: Minimal material slip, self-feeding grip, water injection capable

Step-Type Roller (Flat-type)

Stepped cutting edges that create a scissor-like shearing action. Excellent for thick, solid materials that need precise, clean cuts.

Best for: Thick plastic pipes, solid lumps, thick-walled containers, hard plastic blocks

Advantage: Clean cuts with low fines, handles thick materials without jamming

Flower-Type Roller (Claw-type)

Multi-claw design with aggressive gripping teeth. Best all-around performer for mixed plastic waste of varying shapes and thicknesses.

Best for: Mixed plastic waste, thin films, woven bags, heterogeneous materials

Advantage: Most versatile, handles widest range of shapes, good for general-purpose

PS Series Model Specifications

Model	Rotor Diameter	Capacity	Motor	Screen	Best Application
PS-300	Ø250mm	100-300 kg/h	11 kW	8-20mm	Small workshop, lab testing
PS-500	Ø300mm	300-500 kg/h	22 kW	10-25mm	Small-medium washing line
PS-600	Ø350mm	400-700 kg/h	30 kW	10-25mm	Medium recycling facility
PS-800	Ø400mm	600-1000 kg/h	45 kW	12-30mm	Large-scale washing line

3. LP Series Vertical Crusher: For Metal & Heavy Duty

The LP Series vertical crusher is a completely different machine from the PS Series. It uses a vertical shaft with heavy-duty hammers or impact plates to crush materials by impact force from above. It's designed specifically for:

Scrap metal — car door frames, aluminum profiles, copper busbars
WEEE waste — circuit boards, electronic housings, hard drives
Aluminum cans — beverage cans, food cans, aerosol cans
Motor rotors — small electric motor disassembly and recycling

Important Warning

Never put metal into a PS Series plastic crusher. The high-speed knives will shatter on metal contact, causing dangerous projectile hazards and severe equipment damage. Metal processing requires the LP Series with its hardened alloy impact tools and reinforced crushing chamber.

4. Hammer Crusher: Coarse Primary Crushing

The hammer crusher sits between a shredder and a fine crusher. It uses swinging hammers mounted on a rotating shaft to shatter materials by impact. It's not designed for fine, uniform output — instead, it excels at:

Car Shell Recycling

After shredding car shells, the hammer crusher breaks flattened metal into spherical particles for smelting.

Bulky Waste Processing

Furniture, mattresses, and bulky household waste that needs coarse size reduction before sorting.

RDF/SRF Production

Coarse crushing of textiles, plastics, and wood waste into 50-100mm pieces for alternative fuel production.

Construction Waste

Breaking down mixed construction debris for sorting into recyclable fractions.

5. Complete Application Matrix

Material	Recommended Crusher	Roller Type	Screen Size	Line Position
PET bottles	PS Series	V-type	10-15mm	After shredder / label remover
PP/PE films	PS Series	Flower-type	15-25mm	After pre-shredder
PVC/HDPE pipes	PS Series	Step-type	12-20mm	After pipe shredder
Plastic lumps	PS Series	Step-type	15-25mm	Direct feed
Woven bags	PS Series	Flower-type	20-30mm	After pre-shredder
Cable waste	PS Series	V-type	5-8mm	After cable shredder
Aluminum scrap	LP Vertical	Impact hammers	20-40mm	After shredder
Circuit boards	LP Vertical	Impact hammers	10-20mm	After shredder, before separation
Car shells	Hammer	Swing hammers	50-80mm	After shredder, before sorting
Bulky waste	Hammer	Swing hammers	50-100mm	After shredder, before sorting

6. Screen Selection & Maintenance Tips

The screen at the bottom of the crusher determines output size. Getting it right is critical:

Screen Size	Output Size	Throughput Impact	Best Application
5-8mm	3-6mm	-30 to -40%	Cable separation, fine granulation
10-12mm	8-10mm	-15 to -25%	PET washing, pelletizing feed
15-20mm	12-16mm	Baseline (100%)	General washing line
20-30mm	15-25mm	+10 to +20%	Coarse crushing, pre-processing

Crusher Maintenance Checklist

Daily: Check knife sharpness, clear screen blockages, inspect belt tension
Weekly: Rotate knives (front ↔ rear), clean bearing housing, check oil levels
Monthly: Sharpen or replace knives, inspect screen for wear, check motor alignment
Quarterly: Full bearing inspection, replace worn screens, check electrical connections
Key rule: Dull knives increase motor load by 30-50% and produce excessive fines. Sharpen early!