Home/Machines/Pelletizing systems/Water-Cooled Strand Pelletizing

Pelletizing · Water-Cooled Strand Pelletizing

Water-Cooled Strand Pelletizing: How Kerke Builds It

Strands of melt pulled into a water bath, dried and cut into uniform cylindrical pellets — the workhorse for filler and colour masterbatch up to 70% filler and for PA, PBT and PC engineering compounds.

Updated 11 November 2026

Scope Masterbatch · engineering plastics

Output 100–2,000 kg/h

Pellet Uniform cylinder

Water-Cooled Strand Pelletizing — workshop photo 1, Kerke workshop, Nanjing

Water-Cooled Strand Pelletizing — workshop photo 2, Kerke workshop, Nanjing

Water-Cooled Strand Pelletizing — workshop photo 3, Kerke workshop, Nanjing

Water-Cooled Strand Pelletizing — workshop photo 4, Kerke workshop, Nanjing

Water-Cooled Strand Pelletizing — workshop photo 5, Kerke workshop, Nanjing

Water-Cooled Strand Pelletizing — workshop photo 6, Kerke workshop, Nanjing

Quick answer

Water-cooled strand pelletizing pulls extruded strands through a flowing water bath, wipes them dry and cuts them at a speed-controlled pelletizer. It is the default choice for filler and colour masterbatch, PA/PBT/PC compounds and recycled PET — simple, cheap to maintain and easy to change over between colours.

100–2,000 kg/hcapacity range

3–4 mmstrand diameter

70%max filler on strand

20–40 mincolour change

Workshop photos — shot on our own lines in Nanjing, not stock images.

How the water-cooled strand pelletizing line works

Melt leaves the die head as 3–4 mm strands through a heated die plate.
Strands drop into a stainless water trough with controlled flow and temperature (typically 25–35 °C).
An air knife or suction wiper removes surface water before the pelletizer.
A two-knife pelletizer with spring-loaded strands guide cuts dry strands to 3–4 mm pellets.
Pellets are conveyed to a vibrating screener and hopper; fines return to the line.

Where this method wins

Water-cooled strand wins where pellet shape must be uniform and the material tolerates full water contact. It stays our recommendation for filler masterbatch up to about 70% CaCO₃ or talc, colour masterbatch, PA6/PA66, PBT, PC and recycled PET/PP strands. Above 70–85% filler the strands begin to break; at that point move to a hot die-face method.

Reference data

**Table 1.** Water-Cooled Strand Pelletizing — reference selection data.
Item	Value
Best for	Filler/colour masterbatch, PA, PBT, PC, recycled PET
Output range	100–2,000 kg/h (die-hole count decides)
Pellet shape	Uniform cylinder, low dust
Watch out	Floor space, strand breakage at high filler, colour-change purging

Reference output measured on the stated material family; subject to a material trial. Die hole count sets the capacity ceiling — check the die, not the label.

Selection notes from our floor

Keep the water bath short but temperature-controlled: cold water stiffens high-filler strands and they snap at the guide; warm water leaves strands soft and they flatten under the knife. For colour work, choose an open trough with quick-release strand guides — changeover time drops from hours to minutes.

FAQ

What filler level can water-cooled strand handle?

We commission strand lines routinely up to 70% CaCO₃ or talc. Between 70% and 85% it depends on the polymer and strand diameter — test it. Above 85%, use water ring or air-cooled hot die-face cutting.

How do I avoid wet pellets?

The air knife is the critical part, not the pelletizer. Set the squeegee gap and air velocity so strands enter the cutter visibly dry; residual moisture below 0.1% is normal on a tuned line.

How long does a colour change take?

With open troughs and quick-release guides, 20–40 minutes including purging. Closed troughs take longer — we recommend open ones for colour houses.

Where these numbers come from

Output ranges, pellet shapes and watch-outs come from Kerke commissioning records and the pelletizing systems parameter table. Where a catalogue value and a trial value disagree, the trial value is the one we quote.

Reviewed by the Kerke process team, Nanjing. Page updated 11 November 2026.

Not sure which pelletizing method fits your material?

Send 25–50 kg — we return pellets, a video and a report with the parameters we used, in 3–7 days.

Get a quote Send material for trial

Water-Cooled Strand Pelletizing — the short version

What separates pelletizing methods is where the cut happens and how much water the pellets see. Water-cooled strand wins on simplicity and changeover speed — shortlist it first for masterbatch and engineering compounds, then confirm the choice on a trial with your own powder.