SS Single-Shaft Shredder (horizontal pusher)

SS single-shaft shredder (horizontal pusher)

A single-shaft shredder has one rotor, and that single fact drives every other design decision on the machine. With only one shaft there is nothing for the material to be pulled into — no counter-rotating partner to grip a lump and drag it down. Something has to push the charge onto the blades and hold it there. On the SS series that something is a hydraulic pusher, and it is not an accessory. It is the machine.

The four SS models cover 200–1,500 kg/h on lumps. What follows is why this machine is built the way it is, and where the line falls between choosing it and choosing a twin-shaft.

The pusher does half the work

The photograph above is the machine during fabrication, before the panels go on, and it shows the arrangement more clearly than a finished unit ever does: the bladed rotor along the bottom, and the flat pusher plate that travels horizontally across the chamber towards it.

The pusher is hydraulically driven, with its own power unit rated from 2.2 kW on the SS600 to 5.5 kW on the SS1200. It advances, presses the charge against the rotor, retracts as the load is consumed, and advances again. That cycle is what turns an intermittent, gravity-fed pile into a steady cutting load.

Two consequences are worth understanding before comparing spec sheets:

Throughput is a function of feeding, not just cutting. A rotor that could theoretically process more will not, if the material is bridging above it. On light and springy feedstock — film, foam, empty containers — the pusher is the component that determines whether you reach the rated band or sit well below it.

Some machines use a swing arm instead of a horizontal plate. A pivoting arm sweeps down in an arc; a horizontal pusher travels straight. The arc suits tall, light charges such as baled film, which it presses down from above. The horizontal plate suits dense lumps and offcuts sitting on the chamber floor, which it drives sideways into the rotor. This page is the horizontal-pusher configuration.

72 rpm, and why that is not the same as fast

The SS rotor turns at 72 rpm. Single-shaft shredders as a class run anywhere from 20 to 72 rpm, and this series sits at the top of that band — roughly five times the speed of the twin-shaft machines in the DS series, which turn at 8–15 rpm.

That difference is not a claim about which machine is better. It follows from how each one cuts. A twin-shaft tears material between two opposing rotors and needs enormous torque to do it, so it is geared down hard. A single-shaft slices material between the rotating blades and a fixed counter-knife, then keeps it circulating in the chamber until it is small enough to pass the screen. That is a repeated, lighter cut rather than one massive shear, so it can afford speed — and it needs speed, because most pieces get cut many times before they leave.

Compared with a granulator running at several hundred rpm, 72 rpm is still firmly in low-speed territory: enough torque for thick-walled and reinforced material, low enough that friction heat does not soften film into lumps.

The screen is what sets output size

Under the rotor sits a perforated screen. Material stays in the chamber, cut again on every pass, until a fragment is small enough to fall through a hole. Smaller holes produce finer shreds; the screen is changeable, so the same machine produces different output sizes on different jobs.

This is a structural difference from a twin-shaft, not a detail. A twin-shaft can run without a screen at all, simply passing material through the mesh of its two rotors and out. A single-shaft cannot — without the screen there is nothing to define when a piece is finished, and material would leave the chamber at whatever size it happened to reach.

The practical trade-off: a finer screen gives you a smaller, more uniform product and lower throughput, because each piece is recut more times before it can escape. Specify the screen against what the next machine actually needs, not against the finest fraction available.

Blades: 30 to 80 of them, in D2 or SKD11

Blade count rises steeply across the range — 30 on the SS600, 56 on the SS800, 68 on the SS1000, 80 on the SS1200. Compare that with 12 to 32 cutting discs on a twin-shaft of similar rotor length. A single-shaft carries many small blades bolted in a helical pattern around a solid drum; a twin-shaft carries fewer, much larger discs.

The helical arrangement matters. If every blade struck the counter-knife at the same instant, the machine would hammer itself and the drive with a shock load once per revolution. Setting the blades on a helix means they engage in sequence, spreading the cut across the whole rotation. The result is a steadier current draw and less vibration through the frame.

Blades are hardened alloy steel, typically D2 or SKD11 — equivalent grades in different standards, both chosen for edge retention under abrasive conditions. Individual blades are bolted on and replaced individually, and most are square or rectangular, which means an edge that has worn can often be indexed to a fresh side before the blade is scrapped.

Single shaft or twin shaft: where the line falls

This is the question most buyers actually arrive with, and the honest answer is that the two machines are good at different things rather than one being an upgrade of the other.

Choose a single shaft when output size matters. The screen gives you a defined, repeatable fraction. If the shred feeds a granulator, an extruder or a washing line that expects consistent input, that repeatability is the whole point.

Choose a twin shaft when the input is the problem. Whole drums, pallets, bulky composites, material with metal in it — a twin-shaft grips and tears where a single-shaft would stall or damage blades. It will not give you a tightly controlled output size, but it will swallow things the single-shaft cannot.

A common answer is both. A twin-shaft opens up the difficult material, a single-shaft brings it to a defined size. On the SS series there is also a middle path: adding a parallel shaft converts it into a DSS twin-shaft machine, roughly doubling output capacity. That configuration is aimed specifically at compressed PE film bales and synthetic fibres — materials that a single rotor struggles to grip but that do not need the brute torque of a full heavy-duty twin-shaft.

The four SS models

Three things in this table repay a second look.

Every model offers two motor ratings. The SS1000 can be built with 55 kW or 75 kW on the same rotor. The higher rating is not there to raise throughput on easy material — it is there for thick-walled, reinforced or stubborn feedstock where the rotor needs more torque to keep turning through the cut. If your material is light film, the lower rating is the cheaper machine to buy and to run.

SS1000 and SS1200 share a rotor length. Both are 1,000 mm. What changes is diameter (⌀400 to ⌀450), blade count (68 to 80) and power. The larger diameter gives a bigger bite and more room in the cutting circle, which is where the extra capacity comes from — the machine is not longer, it is stronger.

Capacities are quoted for lumps. Solid purge lumps and offcuts are dense and feed predictably. Film, big bags and foam have a fraction of that bulk density and will run lower on the same machine, which is exactly the situation the DSS parallel-shaft option addresses.

What it is used for

Size reduction. Large plastic items — lumps, cut-offs, pipes, film — brought down to flakes for further processing.

Pre-shredding. Mixed or bulky plastics prepared ahead of granulation or extrusion. The photograph above is that idea taken one step further: shredder and crusher built as one unit, with a blower, cyclone and collection bag handling the output in a single pass.

Volume reduction. Cutting the space that waste occupies, and with it the cost of storing and moving it.

Post-consumer and industrial waste. Rigid HDPE, PP, PVC, ABS, PS and PET — bottles, crates, automotive parts. Flexible LDPE and LLDPE film, PP big bags and woven sacks. Engineering plastics including nylon, PC and POM when fitted with appropriate blades. Plastic-metal composites such as electronics housings, where the machine is specified for it.

See the machine running

Frequently asked questions