Plastics compounding
Federal Equipment Company buys and sells used plastics compounding equipment from Cleveland, OH, where we keep more than 1 million sq ft of storage. Our stock covers the machines that turn polymer, fillers, and additives into finished pellets. That means gravimetric feeders, high-intensity mixers and coolers, twin-screw extruders, screen changers, melt pumps, and strand and underwater pelletizers. A compounder retiring a line can sell it to us directly, consign it, or put it up at auction.
What this covers
Plastics compounding melts a base polymer, mixes fillers, reinforcements, colorants, and additives into it, and cuts the result into pellets with set properties. The product may be a color masterbatch, a mineral-filled polypropylene, or a glass-reinforced nylon.
Rubber compounding runs on internal mixers and two-roll mills, so it sits on our rubber processing equipment page. Reclaim and repro lines that pelletize scrap are on our plastic recycling equipment page. Film, sheet, and molding lines are on our main plastic processing equipment page, and making the base resin in reactors belongs with our chemical process equipment.
Compounding equipment usually reaches us when a compounder or material producer closes a division, consolidates lines, or retires a site, so complete lines turn up alongside single extruders and mixers.
Process train
A compounding line works when its machines have compatible capacities for the formulation and the output you need. Feeders meter each ingredient at its own rate into a continuous extruder, while preparation such as PVC dry blending often runs in batches ahead of it.
Some ingredients need work before they reach the extruder. Nylon, PET, and other resins that absorb moisture are dried in a desiccant hopper dryer so they do not foam or degrade in the barrel. Rigid PVC is dry blended in a high-intensity mixer, where friction heat drives stabilizers and lubricants into the resin. The hot batch then drops into a cooler before storage.
A compound is only as consistent as its feed. Loss-in-weight feeders weigh their own hopper as they discharge and adjust screw speed to hold each ingredient at its set rate. A line usually runs one feeder for each resin, filler, or additive stream. Volumetric feeders meter by screw speed alone and suit steady, forgiving streams, while crammer feeders force fluffy, low-bulk-density material into the throat.
The twin-screw extruder melts the polymer and disperses everything else through it. Co-rotating twins carry kneading blocks wherever a formula needs shear. Side feeders downstream add glass fiber into the melt, which limits fiber damage, and they make room for high filler loadings and fillers with low bulk density. Counter-rotating twins, parallel or conical, build pressure with less shear, which suits heat-sensitive rigid PVC.
Moisture, residual monomer, and trapped air leave the melt through vent ports along the barrel. An atmospheric vent just past the melting zone lets trapped air and steam escape. A vacuum vent closer to the die pulls out volatiles that would otherwise show up as voids or odor in the pellet. Ask whether a used line includes its vacuum pump and condensate trap.
A screen changer holds a screen pack in the melt stream to catch gels, unmelted particles, and contamination. Manual and slide plate designs stop flow briefly while the screen is swapped, and continuous and dual-piston designs keep the line running. A twin-screw extruder builds its own discharge pressure, but a gear pump can take over the pressure the screens and die need and ease that load on the screws. Some lines pump ahead of the screen changer, others filter first, and many run without a pump; it depends on the compound and the rate. A polymer diverter valve lets the operator dump off-spec melt during startup.
The pelletizer sets the shape and finish of the product. Strand lines run strands through a water bath and an air knife to a rotor that chops them, an arrangement that is easy to start up and adjust. Underwater pelletizers cut at a die plate submerged in tempered water, and they make round pellets at high rates. Water ring pelletizers cut at the die face into a spinning ring of water.
Pellets from an underwater or water ring cutter leave wet, so a centrifugal spin dryer strips off the water first. A vibrating classifier then screens out fines, longs, and doubles, and the finished compound is conveyed to a silo, gaylord, or bagging station. Bagging and palletizing are on our packaging equipment page.
Terminology
Many compounding machines go by two or three names. Here is how they line up.
All three name one machine: a jacketed bowl with a fast impeller near the floor that heats a PVC or powder blend by friction. Henschel's name is often used for the whole type, so a Henschel-type mixer may come from MTI, Papenmeier, or Littleford. A mixer cooler, or heating-cooling mixer, pairs it with a slower, larger cooler mounted below it.
Gravimetric means the feeder controls by weight. A loss-in-weight feeder weighs its hopper and screw together and is the usual choice at an extruder throat or side feeder. A weigh belt feeder weighs material moving across a belt and suits higher rates of free-flowing material.
A compounding extruder is usually a co-rotating twin-screw, and makers sell them under series names such as ZSK, ZSE, and MP. A side feeder, sometimes called a side stuffer, is a short twin-screw that pushes filler or fiber into a port in the barrel wall. Some older lines pair a continuous mixer with a short single-screw extruder that builds pressure for the die.
A masterbatch, or color concentrate, carries a high load of pigment or additive that a processor lets down into virgin resin at the machine. Filled and reinforced compounds carry minerals, glass fiber, or other fillers for stiffness or cost. They run on the same kind of line, though high filler loadings often call for side feeding.
Scale
The same steps run on bench units and on production machines. The past examples below show what we have handled, not a limit on what we can source.
| Twin-screw extruders | 3 mm to 133 mm nominal barrel size; the largest ran an 800 HP drive |
|---|---|
| Co-rotating barrel length | 20:1 to 56:1 L/D |
| High-intensity mixers | 8 liters to 2,000 liters |
| Coolers | Up to 4,600 liters |
| Screen changers | 2-inch to 10-inch breaker plate diameter |
| Melt pumps | Gear pumps with 5 HP to 40 HP drives |
| Strand pelletizers | 0.25-inch to 32-inch cutting width |
| Tempered water systems | 60 to 250 gpm |
Micro compounders such as the Xplore MC5 and MC15 mix batches of 2 to 15 ml in a vertical conical twin-screw barrel. Bench twin-screw extruders from 16 mm to 27 mm include Leistritz Nano and Micro machines and APV MP19 units. They often come as complete lines with gravimetric feeders and small strand pelletizers.
Formulation labs pair them with torque rheometers such as the Brabender Plasti-Corder and Haake PolyLab, and with Tinius Olsen melt flow indexers. Our lab equipment category lists the wider lab, and plastometers and rheometers have categories of their own.
Scale-up goes more smoothly when the lab and production twins come from the same screw design family.
Services
Three things decide whether a used compounding line starts up well, and we help with each of them.
Condition
We run equipment under power where we can, so a twin-screw drive, a mixer, or a pelletizer can be seen turning before it ships. Many compounding buyers send an OEM representative to look over the gearbox and screws, and a live video tour covers the machine when a trip is not practical. Whether a line suits your compound depends on a review of your application.
Sourcing
Tell us the polymer, the filler loading, the rate, and the pellet you need. We will look for a complete line or for the pieces that fit the extruder you have. Request sourcing help to start.
Shipping
Refurbishment, inspection, and testing can be arranged before shipment, including motor testing and seal replacement. We also handle skidding, crating, and freight, which matters when a line ships as many separate pieces.
Manufacturers
These are the makers and model series we have handled at each step of a compounding line.
| Equipment | Manufacturers and model series |
|---|---|
| Twin-screw extruders | Werner & Pfleiderer ZSK co-rotating twins Coperion ZSK and ZSK Mc co-rotating twins Leistritz ZSE, Micro, and Nano twin-screws Berstorff ZE co-rotating twins Baker Perkins MP twin-screws APV MP twin-screws Davis-Standard Gemini counter-rotating twins Cincinnati Milacron CM conical twins |
| High-intensity mixers and coolers | Prodex-Henschel JSS and FM mixers and KM coolers Thyssen Henschel FM mixers Henschel Mixers America mixers and coolers Littleford W and CY mixers and K and KM coolers Papenmeier TGAHK and TSAHK mixers MTI M and W mixers |
| Feeders | K-Tron feeders Acrison feeders Schenck feeders Brabender Technologie feeders Metalfab feeders AccuRate feeders |
| Melt filtration and pumping | Maag Extrex and Thermoex melt pumps Dynisco melt pumps and screen changers Beringer slide plate screen changers Berlyn slide plate screen changers Kryenborg K-SWE continuous screen changers |
| Pelletizing | Gala SLC, MUP, and LPU underwater systems, spin dryers, and tempered water systems Conair strand pelletizers Cumberland strand pelletizers Cumberland stair-step dicers Beringer WRP water ring pelletizers Randcastle lab pelletizers |
| Drying and lab | Novatec resin dryers Una-Dyn resin dryers Conair resin dryers Brabender Plasti-Corder torque rheometers Tinius Olsen plastometers Xplore micro compounders |
Brand pages
All manufacturers
Buying used
A used compounder is judged on more than whether it turns. Four things decide whether it will run your formula at your rate.
On a segmented twin-screw, ask for the current screw configuration and any spare elements, because they decide what the machine can compound without new parts. Check flight and kneading block wear and the barrel bores, especially after filled or glass-reinforced compounds. Count the barrel sections that are open, vented, or set up for side feeding, since that layout is harder to change than the screws.
Compounding rates are often limited by torque rather than screw speed, so the gearbox rating matters as much as the screw diameter. Compare maximum screw speed and drive power against your formula and rate.
Gravimetric feeders depend on their load cells and controllers, so confirm both come with the feeder and that the controls can work with your line. A feeder sold without its screws or agitator needs those parts before it runs. Match each feeder's rate range to the stream it will meter, because a feeder sized for the main resin will not meter a minor additive accurately.
The pelletizer, water system, spin dryer, and classifier all have to keep up with the extruder at your rate. A line that ran together at one plant arrives matched for the rate it last ran. A new compounding line has to be built to order. A used one can ship in days or weeks once inspection and any refurbishment are complete.
Selling surplus
We can buy a compounding line outright on a set date, or sell it on consignment so you share in the final price. For a whole site, an auction is often the better route.
We have sold a compounding division at auction, with its twin-screw lines, underwater pelletizing systems, and lab instruments, and our liquidations have included compounding and pelletizing equipment. Our auction archive shows what has sold.
Send an asset list with nameplate photos, call 800-652-2466, or email sales@fedequip.com. Include the screw configuration, spare elements, and feeders for each extruder, because they change what a line is worth.
Sell your equipmentBuying instead? Tell us what you are looking for, or meet our team at AMI Plastics World Expos North America in Cleveland, OH. Dates are on our trade show schedule.
FAQ
Still have a question? Call 800-652-2466 or email sales@fedequip.com.
Most lines start with loss-in-weight feeders, one for each resin, filler, or additive stream, feeding a co-rotating twin-screw extruder. The extruder melts and mixes the formula and vents off moisture and volatiles. A screen changer cleans the melt, a melt pump may steady its pressure, and a strand or underwater pelletizer cuts it. Spin dryers and classifiers finish the pellets, and PVC lines add a high-intensity mixer and cooler at the front.
The mixer's impeller heats the blend by friction, often past 100°C, so stabilizers, lubricants, and plasticizers absorb into the PVC particles. Hot dry blend clumps and can degrade if it sits, so it drops into a slower cooler that brings it down to a safe storage temperature. The cooler usually holds more than the mixer it serves, because the blend needs longer to cool than it took to heat.
Co-rotating twins handle most compounding. Their modular screws can be built with as much or as little mixing as a formula needs, and they run fast for high output. Counter-rotating machines, in parallel or conical designs, convey more positively at lower speed and shear. They are common on rigid PVC compound and on PVC pipe and profile. On a used machine, the rotation and screw design decide which formulas it can take, so tell us the resin and additives first.
The screen changer filters the melt, and the melt pump builds steady pressure, either ahead of the screens or ahead of the die. On a used line, ask which screen sizes and breaker plates come with the screen changer, and whether its hydraulic power pack is included, since many are sold without one. A melt pump earns its place on high-rate lines and heat-sensitive compounds. Lower-rate lines, where the extruder can build die pressure on its own, often run without one.
Strand pelletizing suits filled and engineering compounds and smaller lines, and a strand line has the fewest parts to move and reconnect. Underwater systems suit high rates and soft or sticky polymers, but they need a tempered water system and spin dryer sized to the rate. Water ring pelletizers are often used for polyolefins. Choose by the polymer, the rate, and the pellet shape your customers expect.
Ask to see it run under power, because a gearbox that is noisy or leaking is expensive to repair. Then measure the clearance between the screw flights and the barrel at a few points, since worn bores cost both output and mixing. Confirm that the heaters, cooling circuits, and controls come with the machine, and ask how long it has sat idle. An OEM representative can inspect it before you buy.
Yes. We handle micro compounders such as the Xplore MC5 and MC15, which mix batches of 2 to 15 ml. We also see bench twin-screw lines from 16 mm to 27 mm with gravimetric feeders and small strand pelletizers. Torque rheometers and melt flow indexers come through too. Stock changes all the time, so tell us what you need even when nothing is listed.
Start with nameplate photos of the extruder, gearbox, feeders, and pelletizing system, plus the date the floor must be clear. Add the screw configuration and any spare elements, the number and type of feeders, and what the line last ran. With that, we can say whether to buy the line, consign it, or offer it at auction. We front the removal cost and recover it from the sale proceeds, so selling has no upfront cost.
Call 800-652-2466 or email sales@fedequip.com. You can inspect equipment in Cleveland, OH by appointment.
Processing Assets: Blenders, Mixers, Dryers, Mills & Material Handling
November 6 - 12, 2026
A complete, never-commissioned anhydrous ammonia handling system — (4) 120,000-gallon storage bullets, compressor skid, dual-pump skid, and full railcar & truck unloading stations.
Steam Turbine & Heat Recovery System
Well maintained power generation solution available now for redeployment.
Comprehensive Selection of Processing, Inspection, and End-of-Line Equipment
A curated mix of freeze drying, palletizing, weighing, and accumulation systems suitable for biotech, pharma, and general manufacturing.
Processing Assets: Blenders, Mixers, Dryers, Mills & Material Handling
November 6 - 12, 2026
A complete, never-commissioned anhydrous ammonia handling system — (4) 120,000-gallon storage bullets, compressor skid, dual-pump skid, and full railcar & truck unloading stations.
Steam Turbine & Heat Recovery System
Well maintained power generation solution available now for redeployment.
Comprehensive Selection of Processing, Inspection, and End-of-Line Equipment
A curated mix of freeze drying, palletizing, weighing, and accumulation systems suitable for biotech, pharma, and general manufacturing.
Federal Equipment Company sends out emails with equipment and information curated for our Pharmaceutical, Chemical, Plastics, Packaging, and Food & Beverage customers each week. If you want to sign up to receive any or all of these emails, click the button here.
