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Application · Specialty & Low-Temperature

EPP Foaming Base Material: Bead Pelletizing

We make the EPP base resin, not the foam. That distinction matters: the extruder produces HMS-PP with nucleating agent, and the expansion itself happens in the customer's autoclave. A reference epp foaming base material page from Kerke.

EPP Foaming Base Material — workshop photo 1, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 1, Kerke workshop, Nanjing
EPP Foaming Base Material — workshop photo 2, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 2, Kerke workshop, Nanjing
EPP Foaming Base Material — workshop photo 3, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 3, Kerke workshop, Nanjing
EPP Foaming Base Material — workshop photo 4, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 4, Kerke workshop, Nanjing
EPP Foaming Base Material — workshop photo 5, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 5, Kerke workshop, Nanjing
EPP Foaming Base Material — workshop photo 6, Kerke workshop, NanjingEPP Foaming Base Material — workshop photo 6, Kerke workshop, Nanjing
Running video — EPP Foaming Base Material, Kerke workshop
Running video — EPP Foaming Base Material, Kerke workshop

Quick answer

EPP bead base material (high-melt-strength PP) is compounded on a twin screw with L/D 44–52 and pelletized into uniform micropellets for autoclave foaming. Output 100–600 kg/h. Melt strength, not output, is the specification that decides whether the beads expand evenly.

0.5–2%nucleating agent
HMS-PPbase resin
underwaterdie-face cutting

Workshop photos and a running video — shot on our own lines, not stock images.

What sets the limit

HMS-PP with nucleating agent and modifiers is compounded, devolatilized and underwater-cut into micropellets, then dried and packed for the foaming line.

Table 1. Key parameters for epp foaming bead base material line. Reference values — confirm on a material trial.
ParameterValue / range
Base resinHMS-PP (high melt strength)
L/D44–52
Pellet size0.8–1.5 mm micropellets
Output (reference)100–600 kg/h
ModelKTE-50B, KTE-65B

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

  1. FeedingLoss-in-weight dosing of polymer and filler; side feeder or liquid injection where the formulation needs it.
  2. Melting and dispersingScrew geometry with 45°/90° kneading blocks; barrel profile set by the polymer.
  3. DevolatilizationVacuum vent at −0.06 to −0.09 MPa removes moisture and volatiles before the die.
  4. Pressure build-upThrottle or discharge section stabilises die pressure; a melt pump where gauge control matters.
  5. Pelletizing and packingdie-face or strand pelletizing, see the pelletizing page; then centrifugal dryer, vibrating screen and bagging.

Equipment configuration

Table 2. What the line is made of, and why each part is specified that way.
StageEquipmentWhy this choice
Main machineCo-Rotating Twin Screw ExtruderArchitecture follows the filling level and the mixing duty, not the required tonnage.
Screw geometryBuilding-block elements, W6Mo5Cr4V2, bimetallic linerWear package for abrasive filler; mixing blocks only where dispersion demands them.
FeedingLoss-in-weight feeder, side feeder where neededRecipe accuracy: ±0.5% short term on the weighed component.
PelletizingPelletizing systemChosen by polymer and filler ceiling — water contact is the deciding column.
DownstreamCentrifugal dryer, vibrating screen, baggingFines below 2% and moisture below the specification of your downstream process.

Output by model

Table 3. Co-rotating twin screw KTE — reference output. Full range on the machine page.
ModelDia. (mm)Speed (rpm)Motor (kW)Torque (N·m)Output (kg/h)
KTE-50B50.5500–60055–752×52580–200
KTE-50D50.5300–80075–902×860100–300
KTE-52B51.4500–60055–752×72080–200
KTE-52D51.4500–60075–1102×1050100–400
KTE-65B62.4500–60090–1102×860200–450
KTE-65D62.4300–800132–1602×1530350–600
KTE-75B71500–600132–1602×1530300–800
KTE-75D71300–800200–3152×2100500–1000
KTE-85B85500–600220–3152×2100550–1000
KTE-95B93500–600250–3152×3000800–1500
KTE-95D93500–800315–5002×48001000–2000
KTE-135B135500–600315–5002×48001500–3000
KTE-135D135500–800500–10002×78001500–4000

Three mistakes that cost the most

1. Inconsistent melt strength between batches shows up as uneven bead density.

Inconsistent melt strength between batches shows up as uneven bead density.

2. Dull cutter blades produce doubles and tails that block the pre-expander.

Dull cutter blades produce doubles and tails that block the pre-expander.

3. Underwater circuit without temperature control

Underwater circuit without temperature control — bead density follows the water temperature, so hold it to ±2 °C or batches drift apart.

FAQ

Do you supply the foaming line too?

We supply the base-material compounding and pelletizing line; autoclave foaming is a separate process we can advise on but not build.

What pellet size for EPP?

0.8–1.5 mm depending on the target bead density; the cutter and die are matched to the size.

What output can you guarantee for this application?

The reference band is 100–600 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.

Tell us your material — we will tell you the line

Send 25–50 kg and we run it on our lab extruder: pellets, running video and a capacity report back in 3–7 days.

EPP foaming base material — the short version

Note on epp foaming base material: 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.

Related on this site: Machine range: KTE-50B to 135D · Pelletizing methods compared · quotation and free trial · Wikipedia: Masterbatch