Plastic Granulator and Crusher for Screen-Controlled Regrind

Rotor speed and what it lets the machine do. A granulator runs fast and cuts against a screen, giving controlled regrind of roughly 8 to 16 mm, but it cannot accept whole items. A shredder runs slow with high torque and shears whole drums and bales, but its output is rough and uneven. Most lines need both, in that order.

Yes, if your material already fits the inlet: loose bottles, offcuts, purge and thin-wall parts are fine. Whole drums, pallets, full-length pipe and baled material are not, and forcing them in damages knives and wastes power. If your feedstock is mixed, a shredder in front is cheaper than a crusher rebuild.

Ask whoever buys your flake, or check what your pelletizer needs. Then specify the screen for that. Most rigid plastic recycling settles between 8 and 16 mm, and PET bottle lines commonly run 12 to 20 mm. Do not specify finer than you need; throughput falls and power per ton rises.

By how abrasive your stream is, not by budget. Clean plastic does not justify the harder grades. Sand, soil and glass fines do, because sharpening frequency rather than purchase price will dominate your cost. If metal may arrive occasionally, the hardest grade plus automatic overload reversal is the safest combination.

Several times, until the geometry no longer allows the correct clearance against the fixed blade. The number depends on the grade and how badly they were worn before regrinding. What matters more in practice is keeping a spare set on site, so a sharpening cycle never stops the line.

Rigid PVC is harder on edges than PE or PP, and it is also unforgiving of overheating. It can be crushed, but the knife grade, clearance and feed rate all need to be set for it. Tell us if PVC is in the stream, because it changes both the specification and what we would advise about the rest of the line.

On dry crushing of rigid plastic, usually yes. Dust is both a housekeeping problem and a quality problem, since fines depress the value of your flake. On wet crushing it is much less of an issue, because the water carries the fines away. Which route suits you depends on whether you have water treatment on site.

A plastic granulator is a screened cutting machine. A rotor carrying knives turns against fixed bed knives, and the material stays in the cutting chamber until it is small enough to fall through the screen underneath. The screen aperture, not the motor, is what sets the output size. BKL builds this category from 37 to 132 kW, producing regrind typically in the 8 to 20 mm range.

In recycling, “granules” usually means one of two products. Regrind, or flake, is cut mechanically by a granulator and keeps the irregular shape of the original part. Pellet is made afterwards by melting clean flake, filtering the melt and cutting it into uniform cylinders. Flake is cheaper to produce and sells for less; pellet is easier for a converter to dose and commands a higher price.

Recycled granules go back into injection moulding, extrusion, blow moulding and fibre production, usually blended with virgin resin at a ratio the end product can tolerate. HDPE and PP regrind commonly return to pipe, crates, pallets and non-food packaging. PET flake goes to fibre, strapping and sheet. The application is what fixes the contamination limit you have to hit upstream.

Three routes exist: direct to converters, through a resin trader, or back to the company whose scrap you are processing under a toll arrangement. Converters pay the most and inspect the hardest, usually on melt index, colour consistency, moisture and visible contamination. Agree the specification before buying equipment, because it decides whether you need a washing line and a pelletizer or only a granulator.

Dry granulation is the default for clean and rigid scrap. Wet granulation, where water is fed into the cutting chamber, is used on PET bottles and dirty streams: it cools the knives, keeps dust down and starts removing dirt during cutting. It costs more because it brings water handling with it, so it is worth it only when the material is genuinely contaminated or the flake goes straight into a washing line.

A plastic granulator will cut softwood, but it is the wrong machine for it. Wood dulls knives far faster than plastic, generates dust that a plastic granulator is not extracted for, and grit in bark will chip the blades. If wood is an occasional contaminant in your plastic stream, specify harder knife steel and accept a shorter resharpening cycle. If wood is a regular input, it needs its own machine.

Material is fed into a cutting chamber where a rotor carrying knives turns against fixed bed knives. Pieces stay in the chamber, being cut repeatedly, until they are small enough to pass through the screen underneath. The screen aperture sets the output size. Below the screen, flake is drawn away by a blower or screw conveyor, usually through a cyclone that separates dust before the material reaches storage or the next station.

It can be granulated, but it cannot be melted and re-formed. Thermosets such as bakelite, cured epoxy and vulcanised rubber are chemically cross-linked, so heat will degrade them rather than soften them. Granulated thermoset is normally used as a filler powder in new compounds, not as a feedstock for pelletizing. If your material is thermoset, a granulator is the end of the mechanical route, not the middle of it.