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Product Description
Every formulation trial in polymer development faces the same dilemma: the production-scale extruder is too big, too slow to change over, and too expensive to feed. A compounder testing a new PVC recipe, a processor qualifying a new PE grade, or a teaching laboratory demonstrating extrusion principles does not want to heat up a 100 kg/h line to make 3 kg of sample. The cost of the trial becomes the cost of the machine, the cost of the material, and the cost of the waiting.
That is exactly the gap the Chenxing SJ-25/25 Laboratory Mini Plastic Single Screw Extruder Machine is designed to fill. It is a laboratory-grade single screw extruder built for the extrusion experiments of PVC, PP, PE, PS, and ABS — supporting product development, sample production, and small batch output at 12 kg/hour. It gives the R&D bench a real extruder: a genuine screw, a genuine melt, genuine extrusion dynamics — but with a compact footprint, quick changeover, and material consumption measured in kilograms, not tonnes.
This page explains the machine's verified specifications, its three core structures, the advantages it brings to laboratory and pilot work, and how it fits into a production-scale Chenxing plant when your trials move into production.
The SJ-25/25 is the entry point of the Chenxing laboratory extruder series. Its verified parameters:
| Parameter | Specification |
|---|---|
| Model | SJ-25/25 |
| Screw diameter | 35 mm (compact lab screw specification) |
| L/D ratio | 25:1 / 28:1 |
| Driving power | 3 kW |
| Center height | 1000 mm |
| Output | 12 kg/hour |
| Screw material | High-quality nitrided steel 38CrMoALA, nitriding + fine grinding finish |
| Drive type | Variable frequency motor, direct gearbox drive through coupling, stepless speed regulation |
| Speed readout | Tachometer on the control panel (also readable on the governor) |
| Design materials | PVC, PP, PE, PS, ABS — plus PET, PC, PEX, HDPE in application |
Parameters not listed above — heating power, temperature control accuracy, screw speed range, inverter brand, machine dimensions, and weight — are customized to the installation and are available on request from the Chenxing engineering team.
The SJ-25/25 is not an isolated machine; it is the smallest member of a full single screw extruder family. When laboratory results move into pilot production, the same process principles scale through the series:
| Model | Screw Diameter | Driving Power | Output |
|---|---|---|---|
| SJ-25/25 | 35 mm | 3 kW | 12 kg/h |
| SJ-45/25/28 | 45 mm | 11 kW | 30 kg/h |
| SJ-50/25/28 | 50 mm | 15 kW | 40 kg/h |
| SJ-65/25/28 | 65 mm | 22 kW | 60 kg/h |
| SJ-75/25/28 | 75 mm | 45 kW | 120 kg/h |
| SJ-90/25/28 | 90 mm | 55 kW | 120 kg/h |
| SJ-110/25/28 | 110 mm | 75 kW | 140 kg/h |
| SJ-120/25/28 | 120 mm | 90 kW | 240 kg/h |
| SJ-150/25/28 | 150 mm | 132 kW | 350 kg/h |
Series models share the same single screw extrusion principle, with screw diameter, drive power, and output scaled for production duty. L/D configuration for the larger models is arranged on request, matched to the material and product type.
The SJ-25/25 is a complete single screw extrusion system in three core structures, each engineered for laboratory reliability.
The screw is the key component for the transportation and plasticization of plastics. As it rotates, the plastic is pushed forward to achieve compaction, melting, and mixing. The thread is composed of different functional sections, each contributing to conveying, compaction, mixing, and plasticization — the combination delivers a better melt and higher output.
For laboratory use, screw quality matters even more than in production: the trials run on the SJ-25/25 are the basis for production decisions, so the melt must be representative of the production line. The screw is manufactured from high-quality nitrided steel (38CrMoALA), finished by nitriding and fine grinding. The result is high corrosion resistance, high wear resistance, and a long service life — critical when the same screw switches between PVC, PP, PE, PS, and ABS compounds.
The head flange joint connects the die head to the barrel. It is heated by a heating ring, which prevents the molten plastic from cooling while it transitions from the barrel into the die. A stable melt temperature at this transition is what keeps laboratory samples representative — a cold joint produces a frozen skin, irregular flow, and unrepresentative test results.
The transmission system rotates the screw evenly with the necessary torque under the selected process conditions, completing the plasticization and transportation of the plastic to the screw. Because different plastic products require different screw speeds, the machine uses a variable frequency motor that directly drives the gearbox through a coupling, with a governor providing speed regulation. The screw speed is smoothly, steplessly regulated within the speed range, and the speed is read directly on the tachometer of the control panel — and can also be read directly on the governor.
This stepless speed control is the heart of the laboratory machine: the operator can run the melt slowly to observe flow behavior, speed up to test output, and hold any intermediate speed to verify process stability.
In operation, the laboratory line follows the standard single screw sequence: the hopper feeds the granules into the screw channel; the rotating screw conveys the material forward through the feed zone, compression zone, and metering zone while barrel heating melts the polymer; the homogeneous melt is pressurized through the head flange joint and out through the die; and the extruded product — pipe, sheet, profile, or strand — is cooled and collected for evaluation. The 35 mm screw and 25:1/28:1 L/D give a realistic melt history in a laboratory footprint, so the samples produced match what a production extruder of the same material would deliver.
Feature: A 12 kg/hour output classifies the machine as a true laboratory and pilot extruder, not a scaled-down production line.
Advantage: Formulation trials, color matching, and sample production consume kilograms of material instead of tonnes, and changeover between compounds is fast.
Benefit: R&D cost drops sharply — more formulations can be tested per budget, and development cycles shorten without sacrificing extrusion realism.
Feature: The screw is made of high-quality nitrided steel 38CrMoALA, finished by nitriding and fine grinding, with functional thread sections for conveying, compaction, mixing, and plasticization.
Advantage: High corrosion resistance and high wear resistance keep the screw geometry — and therefore the melt quality — stable even as it switches between PVC, PP, PE, PS, and ABS compounds.
Benefit: Trial results are repeatable and trustworthy, and the screw's long service life protects the laboratory investment.
Feature: A variable frequency motor directly drives the gearbox through a coupling, with a governor providing stepless speed regulation; screw speed is read on the control panel tachometer or the governor.
Advantage: The operator can set any screw speed within the range smoothly and hold it precisely, without gear-change steps.
Benefit: The full process window — from slow melt observation to maximum throughput — is available in one machine, which is exactly what material development and teaching require.
Feature: The head flange joint between head and barrel is heated by a heating ring.
Advantage: The molten plastic is prevented from cooling at the critical barrel-to-die transition.
Benefit: Consistent melt temperature at the die means representative samples and stable extrusion behavior across the whole trial.
Feature: A 1000 mm center height and compact screw specification make the machine easy to integrate with laboratory take-off equipment, cooling troughs, and pelletizers.
Advantage: The line is quick to set up, quick to reconfigure, and fits a laboratory or teaching space.
Benefit: Less floor space, faster experiments, and a machine that adapts as the research program changes.
Feature: The SJ-25/25 belongs to a single screw extruder series extending to the SJ-150/25/28 at 132 kW and 350 kg/h.
Advantage: Process data developed on the laboratory machine transfers to the same screw principle at production scale.
Benefit: The compounder validates the recipe once and scales it with confidence — the laboratory and the production line speak the same extrusion language.
The SJ-25/25 is specially designed for the extrusion experiments of PVC, PP, PE, PS, and ABS — the workhorse polymers of profile, pipe, sheet, and compounding industries. The application scope also covers PET, PC, PEX, and HDPE, extending the machine to optical, cross-linked, and engineering polymer trials. For materials that require pre-drying — PET, PC, and other hygroscopic polymers — the machine works with the Chenxing drying range (see the supporting equipment section below).
1. Pipe Extrusion Experiments
The laboratory machine supports pipe development across the full range of modern pipe materials: PP-R pipes, PE gas pipes, PEX cross-linked pipes, aluminum-plastic composite pipes, ABS pipes, PVC pipes, HDPE silicon core pipes, and various co-extruded composite pipes. A compounder qualifying a new pipe grade, or a pipe manufacturer testing a new additive package, can extrude short pipe samples and verify melt strength, surface quality, and dimensional behavior before committing to a production run.
2. Sheet and Board Extrusion
For PVC, PET, PS, PP, PC, and other materials, the machine extrudes profiles, sheets, boards, wire, and rod samples. Material developers use these samples to evaluate color development, filler dispersion, and surface finish — properties that only become visible in the extruded form.
3. Profile Extrusion
By adjusting the extrusion speed and changing the screw structure, the machine applies to the production of various plastic profiles in PVC and polyolefins. For a profile manufacturer, the laboratory machine is the platform where a new profile geometry meets a new material formulation before the production die is cut.
4. Modified Compounding and Granulation
The machine serves the blending, modification, and reinforced granulation of various plastics. Research centers use it to develop masterbatches and filled compounds, then granulate the trial output for injection molding or further extrusion evaluation.
| Equipment | Typical Output | Best For |
|---|---|---|
| SJ-25/25 laboratory mini single screw extruder (this page) | 12 kg/h | Formulation trials, product development, sample and small batch production, teaching |
| Parallel co-rotating twin screw extruder | Production scale | High-intensity compounding, masterbatch, filled and reactive modification |
| PETG pipe production line | Production scale | Transparent copolyester pipe for food and medical applications |
| PC LED light cover extrusion line | Production scale | Optical PC/PMMA tubes and LED lamp covers with online precision cutting |
The laboratory extruder is the development partner of the production equipment: every production line in the Chenxing range — the PVC shelf label strip extrusion line, the PVC UV marble sheet making line, the PETG pipe production line, or the PC LED light cover extrusion line — starts its materials in a laboratory, and the SJ-25/25 is the machine that validates them there.
The SJ-25/25 integrates with Chenxing's material preparation and handling range. For hygroscopic materials, the 750A dehumidifying dryer supplies production-scale low-dew-point air, while the 201A/J conveying integrated crystal dehumidification dryer and the 530A crystal dryer cover compact and crystalline-polymer duties; the STG-U hopper drier plastic resin dryer is the lightweight option for general resin drying. Material transfer into the hopper uses the VLF powder suction machine, the VLF-L continuous powder suction machine, or the FSP crushing material suction machine, with the screw feeder automatic feeding machine for controlled dosing. Blends and dry colors are prepared in a high-speed mixer industrial mixer; magnetic protection at the feed point comes from a CJ magnetic frame hopper magnet. Trial output can be granulated with a plastic pelletizer or a PVC hot-cutting pelletizing line, and scrap regrind is handled by the plastic crusher and the agglomerator / film densifier. For a complete turnkey development-to-production facility, the 990A Advanced Material Processing EPC Project designs the entire material path around your process.
The SJ-25/25 is specially designed for the extrusion experiments of PVC, PP, PE, PS, and ABS — covering product development, sample production, and small batch output for plastic enterprises. Its four application categories are pipe extrusion experiments (PP-R, PE gas, PEX, aluminum-plastic composite, ABS, PVC, HDPE silicon core, and co-extruded composite pipes), sheet and board extrusion (PVC, PET, PS, PP, PC and other profiles, sheets, wire, and rod), profile extrusion for PVC and polyolefins, and modified compounding and granulation.
The design materials are PVC, PP, PE, PS, and ABS. The application scope also covers PET, PC, PEX, and HDPE. For hygroscopic materials such as PET and PC, pre-drying is required before extrusion — the machine works with Chenxing's dehumidifying dryers, such as the 750A dehumidifying dryer or the STG-U hopper drier / plastic resin dryer.
The SJ-25/25 delivers 12 kg/hour, with a 35 mm screw diameter, 25:1/28:1 L/D ratio, and 3 kW driving power at a 1000 mm center height. This output class is intentional: it is large enough to produce representative samples and small batches, yet small enough to keep trial material consumption economical. The same screw principle scales through the SJ-45 to SJ-150 series up to 350 kg/h for production.
The SJ-25/25 screw is made of high-quality nitrided steel (38CrMoALA), finished by nitriding and fine grinding. Nitriding creates a hard, corrosion-resistant surface layer on the screw, while fine grinding maintains the precise geometry of the functional thread sections. In laboratory work, the same screw repeatedly switches between PVC, PP, PE, PS, and ABS compounds — some of which release corrosive agents during processing. High corrosion and wear resistance keep the screw geometry, and therefore the melt quality, stable, so trial results remain repeatable over a long service life.
The transmission system uses a variable frequency motor that directly drives the gearbox through a coupling, with a governor providing speed regulation. The screw speed is smoothly, steplessly regulated within the speed range, and the current speed is read directly on the tachometer of the control panel — it can also be read directly on the governor. This stepless control lets the operator sweep the full process window, hold any intermediate speed, and reproduce conditions from previous trials.
Yes. The SJ-25/25 is the smallest member of the Chenxing single screw extruder series, which extends from the SJ-45/25/28 (11 kW, 30 kg/h) to the SJ-150/25/28 (132 kW, 350 kg/h). Process data developed on the laboratory machine — screw speed, melt temperature, output rate — transfers to the same single screw principle at production scale. For larger compounding duties, Chenxing also supplies the parallel co-rotating twin screw extruder, and for turnkey plants the 990A Advanced Material Processing EPC Project engineers the full production system.
Step 1 — Define Your Laboratory Task: Tell us what the machine will do — formulation trials for PVC/PP/PE/PS/ABS, product development for a specific pipe, sheet, or profile, or small batch production. Share the materials you will run and whether pre-drying (PET, PC) or compounding (masterbatch, filled compounds) is in scope.
Step 2 — Choose the Machine Configuration: Chenxing configures the SJ-25/25 laboratory line around your task: the extruder with the 38CrMoALA nitrided screw, the die and calibration tooling for your product form (pipe, sheet, profile, strand), and the take-off, cooling, and granulation equipment matched to a 12 kg/h output. Heating power, temperature control, screw speed range, and inverter selection are specified for your material mix — with full parameters provided on request.
Step 3 — Request a Quote from Nicole: Contact Nicole at +8615951187228 or ceo@cxsljx.com with your laboratory task description. We respond within 24 hours with a formal quotation, configuration list, and delivery schedule. Chenxing provides installation guidance, commissioning support, and operator training on screw setup, temperature profiles, and speed regulation for representative laboratory trials.
Step 4 — Validate, Scale, and Produce: Run your formulations on the SJ-25/25, build your process window, and carry the data into production — on the Chenxing single screw series up to 350 kg/h, on the parallel co-rotating twin screw extruder for compounding, or on a complete PETG pipe production line, PC LED light cover extrusion line, PVC shelf label strip extrusion line, or PVC UV marble sheet making line. From laboratory bench to production floor, the process stays under one roof.
Chenxing's full supporting range — plastic pelletizers, PVC hot-cutting pelletizing lines, agglomerators / film densifiers, high-speed mixers, dryers, and EPC engineering — completes the picture. As a single-source partner, Chenxing Machinery supports your development from first pellet to full production.
Contact Chenxing Machinery Today:
Contact Person: Nicole
Phone / WhatsApp: +8615951187228
Email: ceo@cxsljx.com
Company: Zhangjiagang Chenxing Machinery Co., Ltd.
Website: www.chenxingmachinery.com
