Application · Plastic Modification
Compounding Extrusion Line: 50–4,000 kg/h
Compounding covers everything from 20% glass fibre in PA6 to 3% additive in PP. The first question is never tonnage but whether the formulation needs side feeding and devolatilization — that decides L/D. A reference compounding extrusion line page from Kerke.
Compounding extrusion line — strand pelletizing, Kerke workshop, Nanjing
Glass fibre compounding — side feeder on a L/D 60 build
PVC compounding — twin screw run at filling-limited torque
HFFR cable compound — 55% ATH on a two-stage build
Strand pelletizing face — die, water bath and air knife
PA / PBT / PC engineering plastics compounding runQuick answer
A compounding extrusion line for filled, reinforced, toughened and alloyed plastics runs 50–4,000 kg/h on co-rotating twin screws from KTE-36 to KTE-135D, with L/D specified per formulation (28–60). Screw configuration is the product, not the frame size.
Workshop photos and a running video — shot on our own lines, not stock images.
What sets the limit
Resin and additives are metered into barrel 1, melted, mixed through conveying and kneading blocks selected for the formulation, devolatilized under vacuum where needed, filtered and pelletized.
| Parameter | Value / range |
|---|---|
| Output | 50–4,000 kg/h |
| Screw diameter | 36–135 mm |
| L/D | 28–60, selected by formulation |
| Feeding | 1–5 gravimetric feeders + side feeder |
| Pelletizing | Strand, water ring, underwater |
| Model | KTE-36B to KTE-135D |
Output figures are measured on the reference material stated above. Filler grade, bulk density and moisture move output by ±15% — that is why every quotation we issue is tied to a trial report.
Process flow, step by step
- FeedingLoss-in-weight dosing of polymer and filler; side feeder or liquid injection where the formulation needs it.
- Melting and dispersingScrew geometry with 45°/90° kneading blocks; barrel profile set by the polymer.
- DevolatilizationVacuum vent at −0.06 to −0.09 MPa removes moisture and volatiles before the die.
- Pressure build-upThrottle or discharge section stabilises die pressure; a melt pump where gauge control matters.
- Pelletizing and packingStrand, water ring, underwater; then centrifugal dryer, vibrating screen and bagging.
Equipment configuration
| Stage | Equipment | Why this choice |
|---|---|---|
| Main machine | Co-Rotating Twin Screw Extruder | Architecture follows the filling level and the mixing duty, not the required tonnage. |
| Screw geometry | Building-block elements, W6Mo5Cr4V2, bimetallic liner | Wear package for abrasive filler; mixing blocks only where dispersion demands them. |
| Feeding | Loss-in-weight feeder, side feeder where needed | Recipe accuracy: ±0.5% short term on the weighed component. |
| Pelletizing | Pelletizing system | Chosen by polymer and filler ceiling — water contact is the deciding column. |
| Downstream | Centrifugal dryer, vibrating screen, bagging | Fines below 2% and moisture below the specification of your downstream process. |
Output by model
| Model | Dia. (mm) | Speed (rpm) | Motor (kW) | Torque (N·m) | Output (kg/h) |
|---|---|---|---|---|---|
| KTE-50B | 50.5 | 500–600 | 55–75 | 2×525 | 80–200 |
| KTE-50D | 50.5 | 300–800 | 75–90 | 2×860 | 100–300 |
| KTE-52B | 51.4 | 500–600 | 55–75 | 2×720 | 80–200 |
| KTE-52D | 51.4 | 500–600 | 75–110 | 2×1050 | 100–400 |
| KTE-65B | 62.4 | 500–600 | 90–110 | 2×860 | 200–450 |
| KTE-65D | 62.4 | 300–800 | 132–160 | 2×1530 | 350–600 |
| KTE-75B | 71 | 500–600 | 132–160 | 2×1530 | 300–800 |
| KTE-75D | 71 | 300–800 | 200–315 | 2×2100 | 500–1000 |
| KTE-85B | 85 | 500–600 | 220–315 | 2×2100 | 550–1000 |
| KTE-95B | 93 | 500–600 | 250–315 | 2×3000 | 800–1500 |
| KTE-95D | 93 | 500–800 | 315–500 | 2×4800 | 1000–2000 |
| KTE-135B | 135 | 500–600 | 315–500 | 2×4800 | 1500–3000 |
| KTE-135D | 135 | 500–800 | 500–1000 | 2×7800 | 1500–4000 |
Three mistakes that cost the most
1. Copying a screw configuration from a different formulation
Copying a screw configuration from a different formulation — the same machine makes good PA-GF and poor PC/ABS with the wrong blocks.
2. No vacuum devolatilization on hygroscopic resins: moisture shows up as silver streaks.
No vacuum devolatilization on hygroscopic resins: moisture shows up as silver streaks.
3. Ordering capacity by the top catalogue figure
Ordering capacity by the top catalogue figure — that number belongs to a favourable formulation; quote by material family and confirm on a trial before it becomes a contract.
FAQ
How do you select L/D?
By dispersion requirement and number of downstream operations: 32–36 for simple filling, 40–48 for reinforcement and devolatilization, 52–60 for reactive extrusion.
Can the line run glass fibre?
Yes with a side feeder and a wear package; glass fibre is fed downstream into the melt, never into the feed throat.
What output can you guarantee for this application?
The reference band is 50–4,000 kg/h, measured on the stated material. We quote a guaranteed figure only after a trial on your own material, because filler grade, bulk density and moisture move output by ±15%.
Can we run our material before ordering?
Yes — send 25–50 kg. We return pellets, a running video and a report with temperatures, screw speed, feeder settings and output per hour. The trial is free; you cover the freight.
What is the delivery time?
30–45 working days for standard configurations, 45–70 for custom screw geometry and ODM work. Voltage and frequency are built for the destination country.
Where these numbers come from
Parameters are taken from the Kerke product parameter table and the product master data sheet, and cross-checked against commissioning records for lines in the same application. Formulations and temperature windows are typical industry values, not a recommendation for your specific compound — every figure marked reference must be confirmed on a material trial before it becomes a contractual number.
Reviewed by the Kerke process team, Nanjing. Page updated 6 November 2026.
Send 25–50 kg and we run it on our lab extruder: pellets, running video and a capacity report back in 3–7 days.
Compounding extrusion line — the short version
Note on compounding extrusion line: the numbers above are reference ranges from Kerke's own trial runs, not catalogue promises. Screw geometry, wear package and pelletizing method are set on the trial bench first, so the output you compare is the output you get. If your grade is not in the tables, send it — the closest configuration is usually a change of screw set, not a different machine.
Planning an upgrade this quarter? Send the material and the target output — the configuration comes back within one working day.
Every quotation lists the wear package as a separate line, so its cost is visible from day one.
Questions are answered the same day, in English or Chinese.
Note on compounding extrusion line: the data on this page was last verified on our own test line in Nanjing.
Not sure which compounding extrusion line configuration fits? Describe the material and the pellet shape required — we answer with a recommendation, not a brochure.
A compounding extrusion line from Kerke ships with CE documentation, a test-run record and a recommended spare set.
Related on this site: Machine range: KTE-50B to 135D · Pelletizing methods compared · quotation and free trial · Wikipedia: Masterbatch