Application
Mechanical Conveying in Plastics Processing
Answer in brief
In plastics the mechanical conveyor is chosen to avoid what pneumatic transfer does to pellets.
No high velocity means no angel hair and no fines, but a screw brings its own shear, so the choice depends on the product rather than on preference.
- Avoid shear zones for soft or coated pellets.
- Ground everything; dry polymer charges strongly.
- Keep contamination out, because it shows in the part.
Reviewed October 21, 2026 · Updated October 21, 2026
The problem
Pellets are damaged by shear at screw flights and by impact at drops, and the fragments become defects downstream.
Static causes clinging in chutes and a credible ignition source where dust is present.
Desired outcome
A conveying line that delivers the rate, keeps the product and the room separated and can be maintained without dismantling the plant around it.
Process approach
Vibratory conveyors and wide slow belts move pellets with almost no shear, which suits soft, coated or filled grades.
Screw conveyors are used where enclosure and compactness matter, with generous clearances to avoid trapping pellets at the flight edge.
Contamination control runs through the whole design: contact materials that do not shed, magnets before sensitive equipment and covers that stay closed.
- Transfer geometry that avoids trapping pellets between moving parts.
- Grounding and bonding throughout the line.
- Metal detection before the extruder.
Selection factors
- Pellet grade, hardness and coating.
- Acceptable fines and streamer content.
- Contamination limit, which is strict for medical and food-contact grades.
- Static control measures and the area classification.
- Whether regrind with its irregular shape is handled on the same line.
Common failure modes
- Pellets sheared at a screw flight edge
- Static causing clinging and uneven discharge
- Metal contamination reaching the extruder
- Regrind bridging in equipment designed for virgin pellets
Partner with powderbulkvideos.com
Put a relevant technical solution in this decision path.
Connect your company and video evidence with clearly labelled visibility where engineers evaluate this material, application, industry or product.
Related content
Continue exploring
Move from this page to the companies, videos and technical topics that add useful context.
Companies
Videos
ScrapeTec International GmbH
AirScrape: New conveyor skirting for your transfer points
The footage presents the AirScrape contact-free conveyor skirting concept at a belt transfer zone. It shows the position above the belt edge, the angled lamella arrangement and the intended inward direction of air and material.
Total reach: 10,400
PUCEST protect GmbH
PUCEST: Lower Belt Scraper Roller
The footage shows a motor-driven PUCEST lower belt scraper roller acting on the return side of a conveyor. Flexible lamella rings rotate against belt travel to remove material that remains after discharge.
Total reach: 4,054
WAMGROUP
Tubular Screw Conveyors and Feeders
WAMGROUP presents enclosed tubular screw conveyors and feeders used to transfer or meter powders and bulk solids.