A screw loader is a closed auger conveyor that moves PVC powder, granules and additives from storage to a mixer or extruder with a steady, metered flow. Material enters the inlet hopper, a rotating screw flight pushes it along the tube or trough, and it drops out through the discharge into the downstream machine. Typical conveying capacity runs from about 100 to 3,000 kg/h depending on screw diameter and speed, confirmed at enquiry, and the closed tube keeps dust inside the conveying path.
Chenxing Machinery builds the screw loader for the short-distance feeding step in a PVC compounding plant. It sits between a storage silo or day bin and the machine that needs material, usually a hot and cold PVC mixing unit, a single screw extruder or a PVC pelletizing production line. The screw does the work: the flight spacing and screw speed set how much material moves per minute, so the loader behaves like a metering device, not just a transporter.
The loader is built around the jobs an operator sees every shift:
A closed tube or covered U-trough keeps powder and granules inside the conveying path.
Flange connections and gland seals stop dust leaking at the joints and the drive end.
A variable frequency drive lets the plant change screw speed to match the mixer cycle.
A level probe or rotary valve at the discharge gives the PLC a signal for the next batch.
An anti-bridging agitator or vibration assist clears cohesive powder at the hopper throat.
A compact footprint lets the unit fit between existing silo legs or above a mixer inlet.
The screw pitch is chosen against the material angle of repose. Free-flowing granules sit at a shallow angle and move fast; fine PVC powder can be cohesive, so the flight is pitched steeper and the speed is kept lower to avoid packing the material into a plug.
The screw loader works in a fixed sequence. Material enters the inlet hopper, the screw flight picks it up and carries it along the tube, the discharge opens into the downstream machine, and a level signal tells the control system when the hopper needs more. Because the screw fills the tube cross section, the flow is continuous and the feed rate is set by screw speed.
For PVC powder, the inlet hopper is often fitted with an agitator that breaks bridging at the throat before the material reaches the flight. For granules, the screw turns faster and the tube can run at a steeper angle. The gland seal at the drive end is checked during commissioning because a worn seal is the first place dust appears on a screw loader. Where a line already runs vacuum conveying, the loader can be paired with continuous powder suction conveying or a vacuum powder loading system so long runs stay on the suction side and the screw handles only the last meters.
The table below lists typical industry reference values. None of them are fixed Chenxing model data, and every figure is confirmed at enquiry before an order.
| Item | Typical industry reference |
|---|---|
| Conveying capacity | about 100 to 3,000 kg/h depending on screw diameter and speed |
| Screw / tube diameter | about 89 to 219 mm |
| Conveying distance | about 1 to 10 m |
| Screw speed | about 20 to 120 rpm, adjustable with variable frequency drive |
| Material handled | PVC powder, granules and additives, dry free-flowing or slightly cohesive |
| Structure | closed tube or U-trough with cover, flange connected, dust sealed |
| Discharge | gravity drop or side outlet, optional rotary valve or level probe |
| Drive | geared motor with VFD and PLC interlock |
| Wetted material | painted carbon steel, SS304 or SS316 |
| Power supply | 380V 50Hz 3 phase, other voltages on request |
| Anti-bridging | hopper throat agitator or vibration assist for cohesive powders |
All values above are typical industry reference figures, confirmed at enquiry. The actual screw diameter, pitch and speed are selected around the bulk density and particle size of the material, and the loader is sized so it can keep up with the downstream machine without starving it.
Sizing starts with the material and the required feed rate. A loader feeding 500 kg/h of PVC powder to a hot mixer needs a smaller screw than one feeding 2,000 kg/h of granules to a pelletizing line, because the powder is lighter and packs differently. The screw diameter, pitch and speed are then fixed together: a bigger diameter carries more, a steeper pitch pushes faster, and a variable frequency drive covers the range in between.
The second decision is the conveying distance and angle. Screw loaders are short-distance machines, typically about 1 to 10 m, and the tube angle affects how much the material slides back over the flight. Steep angles need a closed tube and a faster screw for the same net flow.
The third input is the downstream cycle. If a mixer empties its hopper every 8 minutes, the loader must refill it inside that window with a margin. The level probe position sets the refill point, and the discharge rotary valve, when fitted, is interlocked with the mixer cycle so material never feeds into a closed batch.
The screw loader shows up wherever powder or granules must move a short distance with a controlled feed rate. The table below lists the main applications and what the loader does in each one.
| Application | What the screw loader does |
|---|---|
| PVC pipe extrusion solution | Meters resin and filler to the compounding mixer ahead of the pipe line |
| HDPE pipe production line | Feeds granules to the extruder hopper without dust or spillage |
| Double wall corrugated pipe line | Carries compound from mixer to the corrugated pipe extruder feed |
| PVC marble sheet line | Moves dry blend to the sheet line mixer at a steady rate |
| Film washing recycling line | Returns regrind and fines to the compounding step |
| Plastic recycling line | Feeds recycled granules to the pelletizing extruder |
In a PVC compounding plant, the loader usually runs between the storage silo and the automatic PVC compounding line. In a pipe plant it tops up the mixer hopper on a timed cycle. On a recycling line the material is rougher, so the screw and tube are checked more often for wear, and the inlet grate keeps oversized scrap out of the flight. Sheet work uses the same loader on a PVC sheet production line, and profile shops run it with profile extrusion machinery.
Customization is available where it changes the loader's fit to a line. The fixed part is the engineering principle: a screw moves material in a closed path.
| Customizable | Fixed |
|---|---|
| Screw diameter, pitch and speed range | Closed screw conveying is the core position of the loader |
| Tube length, angle and discharge position | Dust sealed conveying is always part of the design |
| Inlet hopper volume and anti-bridging agitator | The loader is a conveyor, not a mixer or a silo |
| Material grade: painted carbon steel, SS304 or SS316 | |
| Drive: geared motor, VFD, PLC interlock | |
| Discharge: gravity drop, side outlet, rotary valve, level probe |
A loader feeding two machines alternately gets a diverting discharge and a PLC sequence. A loader handling cohesive PVC powder gets a larger hopper throat and an agitator that keeps material moving into the screw. What does not change is the closed path: the tube and the seals stay in the design because that is what keeps the powder off the plant floor. The same feeding principle is applied across the compounding line design options that Chenxing offers.
Chenxing Machinery has run ISO9001 quality management since 2002 and CE certification applies to the machine series. The factory has been building plastic machinery for more than 20 years, and the screw loader is welded and inspected under the same routine as the rest of the plastic processing auxiliary machinery range.
Each loader goes through a documented run-out check before shipment. The inspection list covers the screw flight alignment and tube straightness, the gland seal and flange joints, the drive coupling and VFD settings, the level probe function, and the painted coating. The unit is test run with the actual material sample where possible, so the operator sees the flow direction and the dust tightness before the machine leaves the shop.
The package includes the inspection report and the certificate of conformity, plus a 1 year warranty on the machine. Installation and commissioning support can be arranged through the EPC plastic turnkey projects program or as a separate service.
The minimum order is 1 set, and the lead time is confirmed on the order because it depends on the screw size, tube length and material grade. Export packing uses wooden cases or steel frames, with the tube sections and the geared motor separated and braced so the screw flight does not get bent in transit. Recycling plant orders follow the same packing rule, whether the loader ships alone or with a two stage recycling machine or a washing recycling production line.
Trade terms cover FOB, EXW, CFR, CIF and CIP, and payment is by T/T or L/C. The destination port is needed at quotation stage so the freight and packing plan can be sized correctly.
A screw loader is a closed auger conveyor that moves PVC powder, granules and additives over a short distance with a steady, metered flow. A rotating screw flight pushes material along a tube or trough from the inlet hopper to the discharge point.
Dry free-flowing and slightly cohesive materials: PVC powder, granules, fillers, stabilizers and recycled fines. The screw pitch and speed are matched to the material angle of repose so the flow stays even.
Typical industry reference is about 100 to 3,000 kg/h depending on screw diameter and speed, confirmed at enquiry. The exact capacity depends on the bulk density and the tube angle of the installation.
Screw loaders are short-distance conveyors, typically about 1 to 10 m, confirmed at enquiry. Longer runs are better handled by vacuum conveying arrangements on the continuous powder suction machine side of the range.
Yes. The tube or covered trough is flange connected and dust sealed, and a gland seal protects the drive end. That closed path is the main reason plants choose a screw loader over an open conveyor.
Yes. A variable frequency drive changes the screw speed, so the loader can meter more or less material to match the mixer or extruder cycle. The PLC interlock keeps the feed in step with the downstream machine.
Cohesive PVC powder can bridge at the hopper throat. An anti-bridging agitator or vibration assist keeps material moving into the screw flight, and the hopper throat is sized wide enough to avoid a dead zone.
Yes. The loader sends level and speed signals to the compounding PLC and refills the mixer hopper on demand. It works inside an automatic PVC compounding line as the short-distance feeding module between storage and mixer.
The MOQ is 1 set. Lead time is confirmed on the order because screw size, tube length and material grade change the build. Export packing and FOB, EXW, CFR, CIF or CIP terms can be arranged.
Send the following information so the loader can be quoted and sized correctly:
Material type, bulk density and particle size
Required conveying capacity in kg/h
Conveying distance and angle, horizontal or inclined
Inlet and discharge arrangement
Downstream equipment: mixer, extruder or pelletizing line
Material grade: carbon steel, SS304 or SS316
Voltage, frequency and phase
Destination port and preferred trade terms
For the wider range of conveying and feeding units, browse the complete plastics machinery catalog, the PVC compounding solutions and the product FAQ list. To arrange a material test, send material test request with the list above, or check the Chenxing news page for line updates. view more machine details
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