JG Plastic Squeezer (Densifier Squeezing & Plasticizing Machine)

JG plastic squeezer (densifier)

Film comes off a washing line clean and wet. Washed film typically retains up to 15% moisture, and it is also extremely bulky — a tonne of washed film occupies far more space than a tonne of anything else in the plant. A squeezer deals with both problems in one pass, and that is the reason it exists as a separate machine rather than as a drying stage.

It is worth being precise about what this machine is, because the name undersells it. A squeezer is not a dryer that happens to compress. It is a short, heavily built extruder that removes water mechanically, softens the plastic with its own friction, and pushes the result through a die as semi-molten slices. Water out, density up, in one screw.

Why 15% moisture is a problem downstream

Wet film entering a pelletiser causes trouble in three separate places. Water flashes to steam in the barrel and has to be vented, which limits throughput. It hydrolyses moisture-sensitive polymers and shows up as voids and bubbles in the strand. And it makes feeding erratic, because damp film clumps and bridges in the hopper instead of flowing.

The JG squeezer removes 95–97% of the moisture. What remains is a residue rather than a process problem. The pelletiser that follows can then be sized for output rather than for coping with water.

How the water actually leaves

Wet film drops into the feed hopper — on difficult, low-density material an optional forced feeder pushes it down instead of relying on gravity — and lands on a large-diameter screw turning inside a barrel.

The screw does two jobs at once. It conveys material forward, and because the flights compress along the barrel, it squeezes that material progressively harder as it travels. The bottom of the barrel is perforated. Water pressed out of the film escapes through those holes while the plastic itself, now compacted into a plug, is too large to follow it and carries on down the barrel.

That is the whole dewatering principle: no spinning basket, no hot air, no consumables. Pressure against a screen, generated by a screw driven through a heavy gearbox — which is why installed power on these machines looks high for a piece of auxiliary equipment. On the JG380 it is 250 kW, and nearly all of it is going into mechanical pressure.

Friction does the heating; the heater only assists

By the time material reaches the second half of the barrel it is compacted and moving under load, and the friction between plastic, screw and barrel wall generates substantial heat on its own. The machine uses that self-friction as the primary heat source and adds an electric heater to bring the material the rest of the way to a semi-plasticised state.

Semi-plasticised is the important word. The target is not a melt. Film that is fully melted would need a melt filter and a proper extrusion die; film that is softened just enough will bond to itself under pressure and hold its shape when cut. That is all the machine needs to convert loose film into a dense solid.

From die plate to cooled slice

At the end of the barrel the screw forces the semi-molten plastic through a perforated die plate. As each strand emerges, rotating blades cut it into uniformly sized slices against the face of the plate. A blower cools the slices immediately — they would otherwise stick back together into a single lump — and conveys them into a cyclone and storage silo.

Cutting at the die face rather than downstream is what makes the product uniform. The blade sweeps past every hole at the same interval, so slice length is set by blade speed against extrusion rate rather than by where a strand happens to break.

What comes out, and why it is easier to sell and to feed

The output is a chunky, irregular slice with fused, slightly fibrous edges — not a pellet, and not trying to be one. It has three commercial advantages over the washed film that went in.

It feeds. Loose washed film bridges in a pelletiser hopper and has to be force-fed. Dense slices flow under gravity, which is often the single biggest reason a plant buys this machine.

It stores and ships economically. The bulk density increase is large enough that transport cost per tonne drops sharply. For recyclers who sell material rather than pelletise it themselves, this alone can change the economics of a route.

It is a saleable intermediate. Squeezed slices are a recognised trading form. A plant with no pelletising line can stop here and sell.

Squeezer, or centrifugal dryer plus hot air?

These are the two routes for getting water out of washed soft plastic, and they are not interchangeable.

Centrifugal dewatering followed by hot air removes water and nothing else. Material comes out clean, dry and exactly as bulky as it went in. That is correct for rigid flake, where bulk density is already reasonable and where melting the material at this stage would be wrong.

A squeezer removes water and densifies in the same pass, at the cost of thermally working the material once. For film that is usually a good trade, because the bulkiness is as much of a problem as the water. For rigid flake it is usually the wrong trade.

Note that the two are not mutually exclusive: a film line often runs mechanical squeezing ahead of thermal drying, using the squeezer to take out the bulk of the water and the dryer to finish. The decision that matters is whether your material benefits from being densified, not simply which machine dries harder.

The five JG models

The model number is the screw diameter, and diameter is the variable that everything else follows from.

Power scales faster than capacity at the small end, and slower at the large end. From JG250 to JG300, power rises 47% for a capacity increase of roughly 60%; from JG350 to JG380, power rises 25% for a capacity increase of around 40%. The larger screws move more material per revolution against the same die resistance, so cost per tonne of installed power improves as you go up the range.

There is a gap between JG300 and JG320. Capacity jumps from 300–500 to 600–800 kg/h — the largest single step in the range. If your line runs at 500–600 kg/h you are choosing between running a JG300 at its ceiling and a JG320 below its floor; the second is usually the better machine to live with, because a squeezer held permanently at maximum load wears its screw and barrel much faster.

Quoted capacities assume film at typical washed moisture. Very wet or very light material will run at the lower end.

What it takes

HDPE, LLDPE and LDPE films. PP raffia. Nylon yarn and polyester fibre. EVA and EPE foam. Plastic powder with high moisture content.

The common thread is a high surface-area-to-mass ratio: everything on that list holds a lot of water relative to how much it weighs, and everything on it is bulky relative to its weight. Those are exactly the two conditions that make a squeezer the right machine. Rigid flake meets neither, which is why washing lines for bottles and rigid plastic use a centrifugal dryer instead.

See the machine running

Frequently asked questions