A star screen solves the problem a classic screen cannot: wet, sticky material that blinds the openings. Instead of a fixed perforated surface, here several rotating shafts carry elastic star-shaped discs. The shafts turn, the discs pass close to one another and clean each other, so the screening surface never clogs.
The effect on the material is different too. The star claws throw the waste upward and push it forward, in a hopping and tumbling motion. Anything smaller than the gap between the discs falls through. Anything larger, particularly flat material such as paper and cardboard, stays on top and advances to the next stage. See the full range of waste sorting equipment and how the machines combine.
Key Advantages of a Star Disc Screen
• It does not clog, the star discs rotate against one another and clean each other, so a star screen keeps running on wet and sticky waste where a fixed screen would blind within hours.
• Cleaner paper and cardboard, flat material stays on the screening surface and advances while the fine fraction drops between the discs, so cardboard comes out with fewer stuck-on contaminants.
• Cut point adjustable on the fly, the separation size is changed from the shaft speed, with nothing to dismantle and no screen panels to swap.
• Modular construction, sections can be added, removed or reconfigured, so the machine adapts if the line is extended.
• Simple maintenance, the discs are inexpensive wear parts replaced individually, with no work on the machine structure.
• Smaller footprint, for the same screening duty, a star screen needs less length than a rotary drum.
Technical Specifications, Star Screen
| Parameter | 1.2 m width | 1.6 m width | 2.0 m width |
|---|---|---|---|
| Working width (mm) | 1200 | 1600 | 2000 |
| Screening element | Shafts with elastic star discs | Shafts with elastic star discs | Shafts with elastic star discs |
| Cut point adjustment | Disc spacing and shaft speed | Disc spacing and shaft speed | Disc spacing and shaft speed |
| Shaft speed | Adjustable via VFD | Adjustable via VFD | Adjustable via VFD |
| Construction | Modular | Modular | Modular |
| Self-cleaning | Yes, by disc friction | Yes, by disc friction | Yes, by disc friction |
The throughput of a star screen depends strongly on the number of sections, the chosen cut point and the material composition, so it is set at configuration rather than given in a table. Tell us your flow and we calculate the number of modules needed.
Applications for the Disc Screen
• Household waste sorting plants, separating the fine and organic fraction, wet by nature, where a perforated drum would blind.
• Paper and cardboard recovery, producing a clean flat fraction from the recyclables stream, for a better sale price.
• Composting, screening compost and removing contaminants, on material with high moisture content.
• Biomass and green waste, grading wood chip and plant residue, which clump easily.
• Construction and demolition waste, separating wood, metal and aggregates into size fractions.
How It Works
Several parallel shafts cross the width of the machine, and each shaft carries elastic star-shaped discs. The shafts rotate in the same direction, and the star claws strike the material from below, throwing it upward and pushing it forward. The material therefore travels in hops rather than sliding. Pieces smaller than the free gap between the discs fall through, under their own weight and the overturning force from the shafts. Larger pieces, particularly flat ones, stay on top and continue to the end of the machine. Because neighbouring discs rotate very close to one another, anything stuck to one disc is rubbed off by the next. That is where the self-cleaning property comes from.
Selection Guide
A star screen is chosen in two situations. First, when the material is wet, sticky or rich in organics, which is exactly the household waste from kerbside collection. Second, when you specifically want a clean flat fraction, typically paper and cardboard for sale. If your flow is dry and relatively clean, a trommel screen is usually the simpler and cheaper solution. Width is chosen from throughput, and the number of sections from how precise the separation must be. Many plants use both screen types, at different points in the line.
Frequently Asked Questions
When do I choose a star screen and when a trommel?
A star screen when the material is wet, sticky or high in organics, and when you want a clean flat fraction of paper and cardboard. A trommel screen when the flow is drier, more mixed and you need a clear size cut at high throughput. They are not competitors, many plants use both at different stages.
How is the separation size changed?
Mainly from the shaft speed, adjusted with a variable frequency drive, and from the disc spacing set at configuration. The big advantage is that the speed adjustment is made while running, with nothing to dismantle and no screen panels to swap as you would on a perforated drum.
How often are the discs replaced?
The discs are wear parts and their life depends on how abrasive the material is. They are replaced individually, which makes the intervention cheap and quick. For flows with a lot of abrasive material, such as construction waste, a stock of spare discs is recommended.
What happens with long items such as textiles or film?
Long flexible material can wrap around the shafts, and this is the weak point of any star screen. It is countered by disc geometry, by rotation speed and, where the flow contains a lot of textile or film, by placing the star screen after a stage that already removes those materials.
Is the equipment supplied new?
Yes. We supply new units only, made to order for your application, with complete technical documentation.
What maintenance does it need?
Periodic inspection of the discs for wear and for material wrapped around the shafts, checking the bearings and the drive, plus cleaning the area beneath the machine. The modular construction gives quick access to each section, so maintenance requires no major dismantling.
Why URSTAG?
URSTAG is a premium brand of recycling equipment, with over 15 years of experience. You don't just get a machine, you get a solution engineered by specialists, built from top-tier components and backed by a team that supports you from design through commissioning.
• European engineering, every machine and every complete line is designed by our engineering teams in Europe, with a focus on reliability, safety and energy efficiency.
• Premium components, we build on motors and automation from industry leaders: Siemens, Schneider Electric, ABB, WEG, SEW-Eurodrive, NORD Drivesystems and Bonfiglioli.
• Over 15 years of experience, we know how materials and machines behave in real-world operation, and we configure each solution for your flow and volume.
• New equipment, configured for you, we supply new units, made to order for your application, with complete technical documentation.
• Delivery, installation and training included, we handle transport, commissioning and operator training, with support throughout the equipment's life.
As a premium brand, URSTAG relies on European engineering, top-tier components and experience. You choose a partner that supports your production long term, with equipment built to run reliably in demanding industrial environments.
