Choosing a Screener: Trommel vs. Scalper vs. Star Screen vs. Vibrating
Trommel, scalper, star screen, or vibrating incline? Match the screening type to your material — compost, aggregate, C&D, or organics.
A screener sorts material by size, but not all screens sort the same way — and the four common types (trommel, scalper, star screen, and vibrating incline) each excel on different material. Pick the wrong one and you'll blind screens, carry over fines, and never hit the production the spec sheet promised. Here's how to match the screening technology to what you're actually running.
Trommel screens — the forgiving all-rounder
A trommel is a rotating cylindrical drum with screen panels. Material tumbles through as the drum turns, and undersize falls out along the length.
Best for: compost, topsoil, mulch, wood waste, and light C&D — sticky, wet, or organic material that would blind a vibrating deck. The tumbling action and easy panel changes make trommels the go-to for organics and recycling.
The trade-off: lower throughput per footprint than a vibrating screen on clean, dry aggregate, and typically a single separation (though double-drum units exist).
Scalpers — heavy-duty primary separation
A scalper is a rugged, heavy-deck screen built to take abusive primary duty — big, dirty, variable feed straight from a dig face or a primary crusher.
Best for: removing dirt and fines before crushing, sizing large quarry feed, recycled concrete and asphalt, and any high-abrasion primary screening job. Scalpers are built to survive impact and heavy loading.
The trade-off: they're primary machines — coarse separations, not fine finished-product sizing.
Star screens — precision on tough organics
A star screen uses rows of rotating shafts fitted with interlocking stars. Spacing between the stars sets the separation, and the agitating action resists blinding.
Best for: compost, mulch, biomass, and wet/sticky organic material where you want sharp, accurate sizing and high throughput without blinding. Star screens shine exactly where vibrating decks struggle, and the separation size can often be changed on the fly.
The trade-off: more moving parts and wear points than a trommel, and less suited to hard, abrasive rock.
Vibrating incline screens — high-volume aggregate
The classic multi-deck vibrating screen sizes material across two or three decks by vibration and gravity, producing several finished products at once.
Best for: clean, dry aggregate at high tonnage — sand and gravel, quarried and crushed stone, spec products. Nothing beats a good vibrating screen for volume and multiple simultaneous sizes on the right material.
The trade-off: wet, sticky, or organic material blinds the decks and tanks production. It's an aggregate machine, not an organics machine.
The quick decision
- Compost, topsoil, mulch, wet/sticky organics → trommel or star screen
- Sharp sizing on tough organics, resists blinding → star screen
- Dirty primary feed, scalping fines before a crusher → scalper
- Clean, dry aggregate, multiple sizes, high volume → vibrating incline
Match the screen to the material first, then size it to your tonnage — and remember the screen has to be balanced with the feeder and stackers around it or it starves or backs up.
At RPG Equipment we broker every screening type across the major brands and help operators match the machine to their material and target product. Tell us what you're screening and we'll point you to the right unit. Call (413) 478-2525 or browse rpgequipment.com/equipment/screeners.
RPG Equipment is a heavy equipment brokerage based in Worcester, MA specializing in grinders, crushers, screeners, and material processing equipment. Contact us to buy or sell equipment, or browse more articles.